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FAQ or Answers to Frequently Asked Questions Section 46
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Please check "root" file for acknowledgements.
This is a file containing answers, tips, hints and guidelines associated
with recurring questions asked by photographers. If you would like to
add a tidbit of knowledge to this list just send it to ANDPPH@rit.edu
who will gladly add it to this collection.
These files are available in SECTIONS.
This is Section 46 and its contents are listed below.
46.01 -< Supplier of Photographic Flashbulbs >-
46.02 -< Fractional F-stop Chart and how to determine them >-
46.03 -< Photographing large groups and making a profit >-
46.04 -< Valuable Information for Volunteer photo teachers >-
46.05 -< Fundamentals on basics photography by Ultraviolet >-
46.06 -< Exposure suggestions for Lunar Eclipse photography >-
46.07 -< Shedding some light on DOF and Hyperfocal Distance >-
46.08 -< Real vs. Virtual Images - a basic definition >-
46.09 -< Making pictures of water splashes >-
46.10 -< Unsticking photographs stuck to glass >-
46.11 -< What are tintypes and can I make them myself? >-
46.12 -< What to store negatives in? Paper or plastic sleeves? >-
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46.01 --
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>Where can I find flashbulbs these days? Are they still being manufactured?
http://www.flashbulbs.com provides specifications and basic information for
users starting out. Compact and more powerful than most electronic strobes,
flashbulbs offer ease of use without a lot of equipment or access to a wall
outlet. They are being used for general photography, photographing trains,
underground caves, by divers underwater, scientific research, by testing
companies, for stage and motion picture effects, model rocketry, high speed
filming, laser research, etc.
Cress Photo, a division of Lite Station USA Inc.
PO Box 4262, Wayne New Jersey 07474-4262
Tel: 973-694-1280 Fax: 973-694-6965
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46.02 -< Fractional F-stop Chart and how to determine them >-
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> Many years ago, I had a copy of the 'official' f/stops, as promulgated by
> the (then) ASA. This chart listed the f/stops from f/1.0 through f/64 in
> 1/4 and 1/3 increments, and was quite useful in calculating things like
> guide numbers, exposure increases/decreases and DoF ranges. Can you point
> me toward a source for such information?
I have not been able to locate a reference to this but here is my version of
it. I rounded off where it seemed appropriate to me. The difference between 1/3
and 1/4 stop is very small indeed - as well as between 2/3 and 3/4. Often when
one rounds off these end up giving the same number so I did not round off all
the time ... although I probably should have in spite of the fact some numbers
then for 1/4 and 1/3 or 2/3 and 3/4 are the same. Note that when the f-stop
number increases by 1/4 stop the exposure decreases by 1/4 stop assuming a
constant exposure time.
(use courier font to see the table arranged properly)
1 1.4 2 2.8 4 5.6 8 11 16 22 32 45
+1/4 1.09 1.5 2.18 3 4.4 6 8.9 12 17.8 24 35 48
+1/3 1.1 1.6 2.2 3.1 4.5 6.3 9 12.5 18 25 36 50
+1/2 1.2 1.7 2.4 3.4 4.7 6.7 9.5 13.3 19 26 38 53
+2/3 1.25 1.8 2.5 3.6 5 7 10 14 20 28 40 56
+3/4 1.3 1.8 2.6 3.6 5.2 7.3 10.4 15 21 30 42 58
+ 1 1.4 2 2.8 4 5.6 8 11 16 22 32 45 64
... and here is a slightly adjusted set up with just 1/4 stop increments:
1 1.4 2 2.8 4 5.6 8 11 16 22 32 45
+1/4 1.1 1.5 2.2 3 4.4 6 9 12 17.8 24 35 48
+1/2 1.2 1.7 2.4 3.4 4.7 6.7 9.5 13 19 26 38 53
+3/4 1.3 1.8 2.6 3.6 5.2 7.3 10 15 21 30 42 58
+ 1 1.4 2 2.8 4 5.6 8 11 16 22 32 45 64
Finally, just a practical observation: f numbers on lens barrels are somewhat
inaccurate anyway as far as setting them is concerned.
OK ... now here is the _method_ whereby ANY increment could be determined:
To find any desired increment above a particular f number you square the
reference f stop and find the log of that number. Add to that log the value
.075 for a 1/4 stop increment, .10 for a 1/3 stop increment and .15 for a 1/2
stop increment. Now find the antilog of that log and then the square root of
the number will be the new f-stop. (BTW, .075 is 1/4 of .30 - which is 1 stop
in terms of LogH or Log Exposure)
For example: let's add 1/3 stop to f/16 ... (or 1/3 stop less exposure).
16 squared is 256 ... the log of 256 is 2.40 ... to this add .10 and that
becomes 2.5 ---- the antilog of 2.50 is = 316 and the square root of this is
17.78 or 18 (17.78 is exactly it ... most tables would list 17.8 or more
likely 18)
OK ... now how about 1/4 stop bigger than f/16 ... (or 1/4 stop less exposure)
16 squared is 256 ... the log of 256 is 2.40 ... to this add .075 and that
becomes 2.475 --- the antilog of this is = 298 and the sqrt of that is = 17.27
or more than likely 17 in a table.
NOTE that like "regular" f stops the numbers associated with fractional f/stops
also double in size as you increase in two stop increments!.
Andy
Andrew Davidhazy, Professor
School of Photo Arts and Sciences/RIT
andpph@rit.edu www.rit.edu/~andpph
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46.03 -< Photographing large groups and making a profit >-
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>I am a portrait photographer and shoot mainly individuals or families.
>Recently a company approached me about photographing all 100 employees for
>their website and will only be used for that and possibly some brochures.
>I am clueless to what to charge for such a thing.
You need to charge what you need to charge. How much do you want to make from
it? What is your time worth? Are you going to line them up and shoot one frame
then go to the next person? You have to put a value on your time.
The growing standard from something like this would be to charge them a
Creative Fee + Expenses + Usage. Usage is a bit tricky here because they are
unsure of their usage and web pricing is still fairly new so there are not a
lot of guidelines.
Some photographers will charge $100-200 for a Corporate Headshot, but this is
a fee for one person. Coprorate Headshots are usually shot in the environment
the person works in, so you have to be location oriented. Example: You are
Shooting a Dentist, Dr. X. You would probably shoot Dr. X around a chair and
shoot different creative shots. Then you pack up and go to his office for some
creative shots and then to the lobby and so on. You would probably shoot a few
rolls of film working for just one great shot. Its a lot of work and
commanding a couple of hundred dollars a head is justified. Hmmm, $100 head
shot rate * 100 people that $10,000. I doubt the company is willing to fork
over $10K for these mug shots.
Are you going to take that much time and effort for a hundred? Probably not.
You most likely will setup a mini-studio on location and then have each person
come through your studio. You probably are not going to work on dozens of
different lighting setups or poses, a couple, or even just one will do.
So in a way, this is kinda like shooting youth sports teams and selling
packages to the parents. You shoot one frame of each kid in a standard pose
and herd them through as quickly as possible. Most people sell these photo
packages in the $20-$30 range with the expected profits to be $10-20 from each
person. If you are going to hand them 8x10's and they cost you $5 you might be
happy with charging $25 per person ($2,000 in the bank). You may be happy at
$10 per person ($1000) and delivering 4x6's
The other way of doing it is saying: Ok the Job is $1500 + Expenses (Film,
Processing, etc.)
You need to check with other people doing this kind of work and see what they
are charging. If you herd them through, you can do about a photo a minute.
Figure in setup and film changes, and you are looking at 2-3 hours to shoot
them all or longer if you shoot multiple shots of each person. So the shoot
will take a half day, but what about the time working with the lab, buying
film, doing your accounting, delivery? All that has to factor in to your
prices, its really not just showing up and doing your biz. So if you think
about this being a 3 hour job and charging $1500, then that $500 an hour which
is rediculous. However, by the time you factor in all the other stuff,
business overhead, and such and you factor in you don't shoot 40 hours or work
a week, the fee's are not that outragous.
>Will I be needing a contract? If so, what kind (s)? Do I give them a written
>or verbal proposal? If it is a written one what should be included in it?
Yes. Never enter into a business deal with anyone without having the terms in
writing. You don't need a formal contract. More likely you will send them a
proposal outlining the costs and you need to make sure you don't go over those
costs. Include a good estimate of expenses (if you do the Creative Fee +
Expenses approach). Have it be a letter that they have to sign and return. Now
you've entered into a formal business deal and there is no arguing terms once
the papers are signed.
Your proposal/contract should state the dates and times of the shoots, how
much you are going to charge and what and when the results will be delivered.
You also need to put in the terms of payment (Net 30 days 1.5% per month
interest after 30 days or half up front, half at delivery, etc.) You should
probably work out a reshoot/makeup day to get vacationers and such.
>Do they need to know what the film, processing and printing costs?
Yes and no. They don't need to know the film type. However if you do the
Creative fee + Expenses, the expenses have to be outlined, which means film
and processing costs.
>How do I go about this?
Get the book: ASMP Professional Business Practices in Photography and Pricing
Photography. These are two indispensable guides in helping you grow a
business. The other part is all your gut instinct!
Good Luck!
Rob - From: Rob Miracle
and here is some more advice:
> I will be using a 35mm camera and a strobe.
Use the standard Jan Faul/Victor Skrebneski lighting (4x6 foot softbox on the
left and 4x8 foot white card on the right) and don't shoot with 'strobe', but
with 'flash'. Get at least 100 5x7 index cards and have the folks write their
name on it to be placed in the shot, but out of range of the crop. Shoot at f11
for some depth, but not including the wall behind them. Have them sit at least
8 feet out from the background, which can be lit from below two feet out from
the wall behind the sitter to give a very pleasing light to dark transition. If
they have the budget, get a big Rainbow background which does the same, only
artificially.
If you want to make good pictures for them and keep them as a client, don't
schedule more than three (absolute max 4) people per hour. This is going to
take some time and cannot be done in a day or two no matter how crappy the
client gets about schedules and money. Charge them $30 a head (or $125/hr) plus
film & proc and plus any digital manipulations you might need to do on their
clowns.
Shoot color negs and have them scanned onto a CD (or buy a scanner and do them
yourself at $20/ea which is dirt cheap but which will pay for an entire Nikon
LS2000) so you can do the retouch needed (I guarantee it will be needed, as no
matter how hard you try, there will be dummies who cannot manage to keep their
eyes open at all) to open up eyes and remove nose and other shine.
If you have wanted to upgrade your computer, this might be a good time. If you
don't own a good one, buy a Mac to make your learning curve considerably
shorter and your life a lot easier (the PC owners will be furious with this
statement). If you don't know where to get a cheapish one, write me off list.
If you have wanted to buy a CD-burner, this would be a very good time as you
can deliver the whole job on a couple of CD's and probably figure out a way to
make them pay for that too. In case you amateurs on this list don't know it,
this is how many photographers manage to get heaps of equipment essentially for
free -- they indirectly bill the clients for it when these special jobs arise.
Don't let them push you around on either money or scheduling., as it is only
they who will be furious later when the pictures suck. If they have a bit of a
budget for it, get a makeup/hair person to 'do' everybody walking in front of
the camera. The stylist is a must if you are shooting any women. It will show
later and make the client like you even more.
And yes, get it on paper and if possible, get a deposit (25, 33, or 50% will
do) and perhaps a purchase order. Give them onetime use rights for the web and
explain that since they haven't worked out what they're going to do for
brochure use, that will be a separate later bill. If they balk, give them the
option of buying all rights for triple the invoiced hours. After all, a hundred
portraits of employees are never going to appear as stock.
As to making the pictures look terrific, well, that's another post. But the
sitters should be relaxed. And if you schedule more than 3 an hour both of you
will be panicked after a few minutes.
Jan - From: Jan Faul
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46.04 -< Valuable Information for Volunteer photo teachers >-
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> I am about to embark on a journey into an area that is causing the
> butterflies to take flight in my stomach. I am volunteering to be a mentor
> to some high school students by exposing them (excuse the pun) to
> photography. I will be supplying the students with cameras, film, etc., on
> my own at first (I hope to build this program enough so I can ask for
> assistance from the community/schools/businesses as far as supplies go in
> the future).
> I'm thinking of going to thrift stores and buying some of the various
> "cheapie-type" plastic cameras (not much beyond a box-like camera) just to
> get the students something to work with. I also believe the more basic the
> equipment, the more grounding in photography they will receive. I don't want
> to go the pin hole camera route--that's a complete project by itself.
> Black and white film will allow me to do the processing and proof sheets,
> saving the expense of a lab, and I can load film cassettes at home, saving
> more.
>
> I've tutored adults before, but not young people. If any of you have taught
> young people, would you please give me an idea of where (camera? film?
> exposure? lighting? shape,form,composition?) and how (classroom? field
> trip? lecture? reading assignments?) you started. I won't have much time
> with the students--maybe one hour a week unless they would be willing to
> meet with me on their free time.
> My hope is for them to have finished prints for a "show" by the end of their
> time with me. Thank you in advance.
Something to consider is using disposable cameras - yeah, color, but kids today
think in color. Perhaps you could get a dealer to donate the cameras and
processing.
Then, you might think about turning them loose to photograph each other. Give
them an assignment to pick one friend and tell a true story about that friend in
pictures. Have them assemble the pictures, and when show-and-tell times comes,
have them talk through why they took the pictures they did. What are those
pictures saying about their friend.
As to reading assignments, I would suggest telling them to go through fashion
magazines and pick pictures they like. Why do they like those pictures - what
is there about them that makes them appealing?
The one thing I would avoid at first is heavy theory. There will be time for
that later after the kids understand the magic of creating an image. One
approach to treating those things is to compare their efforts with pictures that
they really like.
After you do individual assignments, then you might do a group shoot using one
kid as a "model". Normally, teens are reluctant to be photographed, but as
they get turned on to photography, that reluctance will disappear. Once that
happens, they really do loose a lot of inhibitions - the challenge for you will
be to be as open minded as they will be!
You might also consider making the final objective of the program to create a
web page of the images - a day in the life, etc. That is something that the
kids really will relate to (more so than magazines) and they will be more likely
to get excited about doing it.
I would like to see the results - I've been thinking about doing something like
that myself and would like to see how your effort turns out.
=-=-=-=-=-=-=-=-=-=-=
Louie J. Powell, APSA - Glenville, NY USA
http://www.geocities.com/Paris/Maison/7881/
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Don't be surprised if they reject your subject completely! You can get close
to teenagers through photography as they are given an opportunity to express
themselves. Give them some freedom of expression within limits of a
project - "show wealth and poverty (contrast)" "Illustrate a street market
from dawn to dusk"
From: Chris Strevens
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What a fine thing you are doing! But are you going to overload? Cost to
benefit of loading all those cassets? Your time might be better spent
seaking a deal or gift from local photoshops or labs. Even manufacturers
might help if you write and ask, all they can do is say no, or maybe YES!
Also check with the film dealers in Shutterbug who have slightly out of date
film. Heck, even some of the list members might send a roll or two! As to
cameras, don't rule out the possibility that teenagers might have their own
P&S or be able to borrow a basic 35 from parents or other friends and
relatives. If you can teach them to load, compose, focus, expose, load a
nikon reel, devolope, dry, proof, enlarge,and find their own way to and from
a good photo dealer, you will have done MORE than enough! What a fine thing
you are doing. Donald
From: Donald MacMillan
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Hmmm, the problem with these (cheap plastic cameras) is that they're all fixed
f ocus and often have a single shutter speed/aperture. This is fine for nasty
colour prints, because the machine can salvage an image off almost anything.
You, however, might not appreciate it if you're printing them :-)
> I also believe the more basic the equipment, the more grounding in
> photography they will receive. I don't want to go the pin hole camera
> route--that's a complete project by itself.
Personally I'd try to beg, borrow or steal some manual SLR cameras with
some kind of needle or stick and ball meter. The down side is that
you're likely to get a mixed bag and the instructions for use will
differ for each one :-(
See what the kids can come up with.
> Black and white film will allow me to do the processing and proof sheets,
> saving the expense of a lab, and I can load film cassettes at home, saving
> more.
Good idea. It's also easier to pass around proof sheets so everyone can
see them.
> I've tutored adults before, but not young people. If any of you have taught
> young people
Do my kids count? They were only 7 and 10 when they figures out the
manual focus auto exposure camera, and about a month older when they
figures out the manual focus, manual exposure camera.
Their best shots are from the all manual camera.
>, would you please give me an idea of where (camera? film?
> exposure? lighting? shape,form,composition?) and how (classroom? field
> trip? lecture? reading assignments?) you started.
-1) get them to bring in any photos they have already taken with any
type of camera.
0) show them some photos that YOU have made from the same type of
equipment that they're going to use.
1) basic instructions - how to focus what the image looks like when it's
focussed)
2) how the exposure thing works (start with fixed shutter or aperture
that you select and get them to alter the other until the exposure is
"correct"
3) warning on too slow shutter speeds
3.5) how to take picture (stand still, gently squeeze...)
3.7) (lie) tell them film is valuable, try to make each shot count
They need to shoot off at least one frame after being told 1 to 3.5,
even if it's just a quick picture of a tree outside.
4) take them out on a walk around some familiar area (even the school,
but I would recommend walking along the streets. Take pictures of
things you see. YOU take pictures too.
Don't tell them anything about composition. Get the mechanics right
first. Kids are awfully creative, and you don't want to beat any more
creativity out of them.
Talk about that after they see the results. Why are some shots better
than others? Make composition something that sounds positive rather
than a lecture about rules and regulations.
Steve
From: Steve Hodges
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I have worked with young people teaching photography...I worked with my
daughter's scout troop as well as with a group of yearbook photographers for
her grade school...mostly 7th and 8th graders.
I began, as you will, very simply...the basics of how to hold a camera for
good, non-blurry shots, how to load film, how to use the flash, how to advance
and rewind the film.
I spent time looking thru magazines for photos that illustrated concepts I was
teaching... good composition, good lighting, portraits, landscapes,
architecture, sports. I allowed the kids to ask me questions in addition to
the questions I asked them. I brought in some of my own work to share.
I always did my teaching of the "concept" in a classroom because I could use
the chalk board and they could sit comfortably ...taking notes if they liked.
I would pick an area...motion, light, sports, portraits, pets, friends, a
storyline and assign them to shoot it...you will be amazed at the variety of
the results..I always was!
My kids all shot color and were responsible for their own processing...but
since you will be doing this end for them, you may ask if there aren't one or
two who might be interested in helping out...that's how I started my photo
training and I will never forget it! You will do great...have fun! Lea
From: LMurphys@aol.com
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>I always did my teaching of the "concept" in a classroom because I could use
>the chalk board and they could sit comfortably ...taking notes if they liked.
I've just discovered a very nice teaching aid for beginning photography.
It's called the Canon Photograpic Workshop, and it's a CD-ROM that covers
all the basics -- light, film, exposure, depth of field, lenses, shutters -
the whole works. I ordered it from Calumet for $19.95, and plan to use it
in my beginning photo class of college students. I think it would work well
with younger kids, as well. The graphics and examples are first-rate.
----
Phil Vinson - Fort Worth, Texas USA
Photographer/Lecturer in Photojournalism, University of Texas at Arlington
Photo Galleries: http://www.flash.net/~pvinson
e-mail: pvinson@flash.net, pvinson@uta.edu
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I'm getting ready to do a similar project and the folks who put it together
use Holga cameras. They cost very little from Freestyle and are an old
standard for teaching. There is a lot to be said for the large negs. You
could order a bunch of white box 120 film also rather cheaply from them.
There is a cheap 35mm camera available also from Freestyle. There is a big
cost advantage to home loading 35mm. My favorite trick is re-using the
cassettes I get from the photo labs. (I'll explain how that is done needed)
I have often opted for home-loads in a teaching setting just to save the
kids a few bucks. I can load a roll in 20 seconds or less and it costs
about $1.50 a roll. I would never lend a camera to a student that I
didn't want ruined. I have had bad experiences with ham-handed oafs.
As far as explaining the basics, I would keep the lesson to two or three,
one-page handouts: judging light/exposure, stopping action, and composition.
Anything more for an enrichment class is too much. The students will mostly
want to photograph each other. I wouldn't show them ANY photographs until
they have spent some time using the camera, then bring in some books and let
them decide which pictures mean something to them.
Check out this terrific web site:
http://dir.yahoo.com/Arts/Visual_Arts/Photography/Toy_Camera_Photography
also: Freestyle: www.freestylesalesco.com
If you have fun they will, AZ
From: Alan Zinn
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May I suggest that for a field trip you take them to a place where there
are statues? Great for how light affects details. Maybe you could divide
up the course into Subject/Interest, Composition, Technique
From: Palma Allen
--------------------------------------------------------------------
I had same task some years ago. Problem: 40 kids, 2 week maximum project time.
$200 budget.
1. Bought 6 manual 35mm cameras ( w light meters)
from pawn shop. 100' roll of Plus-X. 2 boxes of 100 shts
enlarging paper, D-76, Dektol.
Brought trays, thermometer, stop bath, filters, etc. from home.
2. Explained light meter, camera operation, and composition.
Gave written quiz. Top 6 got cameras overnight:
Assignment: Photograph yourself, and your friends.
3. Processed film and made contact sheets with first 6.
4. Made comments on focus, composition, lighting etc. daily,
till all 40 had taken a turn. Made 8 x 10 prints daily.
5. Third and fourth days of second week was for reshoots
and slow learners.
6. Fifth day of second week, project posted. Returned $30
and four cameras to school. (1 trashed, 1 "borrowed").
I think I had more fun than the kids :) Al Doyle
From: Al Doyle
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46.05 -< Fundamentals on basics photography by Ultraviolet >-
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> My son is working fast and furious on his science project involving
> ultraviolet light and birds. He is getting results that show at least
> some uv markings. Consulting with biologists always causes some disquiet
> though, because the few we are dealing with insist he shouldn't t be
> getting results because the glass in the lens fluoresces in the ultraviolet
> negating all exposures. I thought this happened below 320nm and since we are
> mainly dealing with light in the 300nm-400nm range where the bird sees this
> isn't a problem, but we keep hearing it is not just a problem, but a killer
> problem.
The bottom line or logic behind a determination of whether to worry about
fluorescence of lens glass or coatings is that if this were the case the light
they would produce would not be image forming light but rather a veiling light
that would simply cast an overall fog over the focused UV energy (light).
Since your son is getting recognizable images while shooting through an 18A
filter the conclusion is that regardless of whether the lens or coating
fluoresces the images are _valid_ long-range reflected UV records of the
subjects.
Respectfully suggest your biologist friends to carefully reconsider their
advise.
> Is there any sort of reference, preferably citable, that shows what range
> the lens glass, lens coating and lens cement does fluoresce? and hopefully,
> how much light from a standard source, say from the sun, is in the range
> that causes fluoresence as opposed to uv light that doesn't cause the
> fluoresence?
You don't need it. Since fluorescence is visible (when it is excited by UV and
"glowing" in the visible!) you can proceed several ways to demonstrate the lens
does not fluoresce (but as I mentioned above even if it does the fact you are
making recognizable pictures makes concern about it pointless). One would be to
take it to a science museum where they have mineral exhibits and place the lens
under one of their UV illuminators. If it fluoresces it will glow like one of
the rocks! Another is to use the 18A filter and make yourself a makeshift UV
sample "box" and use the sun as a source.
SUNLIGHT FALLS ON TO EYE (prevent light from
18A FILTER // // entering box around
_____________________ // // eye - use a tube)
|_____________________| // //
====== =====// //======
| |
| LONG WAVE UV PASSES |
| THRU 18A FILTER |
| | LIGHT TIGHT BOX
| |
| |
| |
| |------------| |
| | lens or | |
| | rock | (fluorescing rock)|
| |------------| |
|===========================================|
If the rock or the lens fluoresces then it will appear to "glow" in the dark
chamber from which "regular" light has been excluded but into which UV enegry
(light) can enter by way of the 18A filter.
Another interesting thing to do is to coat a piece of glass with fluorescent
paint and place it in the focal plane of the camera. Then, in a darkened room
lock the shutter of the camera a open and set the lens to a large opening and
covered with the 18A filter aim it at a source of light and UV ... (well, only
uv is needed but it is hard to get by itself!). Obviously if you have light and
UV the room can't be totally dark but the idea is to try to keep light from
reaching the fluorescent groundglass as much as possible. Or, just fire an
electronic flash aimed towards the lens in a darkened room. Note that some
flashes have a yellowish UV absorbing coating and these won't work as well for
this demo but there is probably enough uv leaking through that most will work
regardless.
Anyway, the point of all this is that you should see an image appear on the
glass coated with fluorescent paint! You have made an "image converter"!! Makes
an invisible UV image visible by causing it to excite fluorescence in the
visible which you can see! truly amazing!
Andy
Andrew Davidhazy, Imaging and Photo Tech - High Speed Photo
andpph@rit.edu, http://www.rit.edu/~andpph, 716-475-2592
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As far as I know it is indeed just the deep-UV that causes problems. My German
bible on IR- and UV-Photography from Guenter Spitzing says this: The shorter
the wavelength, the more materials it will be absorbed by:
- below 330nm it will be absorbed by normal glass lenses
- below 230nm it will be absorbed by gelatine (no film registration possible)
- below 180nm it will be absorbed by ozone (atmosphere) and even Quartz glass
- Between 360 and 313nm the transmission of ordinary glass decreases
from 90 to 0%.
- The more lens elements, and the more coating, the less UV-transmission.
In this regard, old, few-element enlarger lenses are recommended.
- Since most glass elements and the cement in them cause slight
fluorescence effects, contrast decrease can not be ruled out.
- Despite all this, I [Guenter Spitzing] don't want to look at
UV-reflex photography as a too difficult field of photography for
ordinary equipment. I agree with P.W. Dankwortt in his book
'Lumineszenzaufnamen in filtriertem ultraviolettem Licht', where he
says "Our results seem to prove that one can explore UV-reflex with
our basic setup, without special UV-lenses". Much more difficult is
UV-reflex between 360nm and 235nm; unless using a pinhole camera,
special lenses are neccessary.
> 2. the metallic coating on the lens fluoresces, etc.
Non-coated lenses are indeed said to be better....
Yet fluorescence should be *visible*....at least I believe it should by
definition....can't imagine fluorescence caused by UV *and* reacting in
UV.
> 3. the cement used to hold the lens together fluoresces.
> We keep hearing that it is pointless to even try for pictures without a
> $4,500 fused quartz Nikor lens, but the people who tell us this don't
> seem to have tried taking pictures themselves and just know it won't
> work.
> So... are we just missing the boat (big time)? or is this problem being
> exagerated? I haven't been able to come up with a printed reference that
> says it won't work.i Is there any sort of reference, preferably citable,
> that shows what range the lens glass, lens coating and lens cement does
> fluoresce? and hopefully, how much light from a standard source, say from
> the sun, is in the range that causes fluoresence as opposed to uv light
> that doesn't cause the fluoresence?
> thanks,
Why not take a few reference pictures with this film/lens/light(?) combo, ie a
non-exposed frame, an evenly lit frame-filling object (known to be
UV-reflective) and a smaller object from the same material but with a dark
backround (ie a sort of UV-contrast calibration).
Then there is always the pinhole solution....8-))
From: Willem-Jan Markerink
=============================================================================
46.06 -< Exposure suggestions for Lunar Eclipse photography >-
-----------------------------------------------------------------------------
Lunar Eclipse Exposure Suggestions (seconds)
ISO Partial eclipse Total eclipse
f/5.6 f/8 f/11 f/2.8 f/8 f/11
400 1/250 1/125 1/60 1/2 4 8
To determine what the size of the moon will be on your frame take the focal
length of the lens you plan on using and divide it by 100. So a 100mm lens will
make a moon image be about 1mm in size on the film. A 1000mm focal length lens
will produce and iamge of the moon that is approximately equal to 1/2 the
height of a 35mm frame.
Andrew Davidhazy, Imaging and Photo Tech - http://www.rit.edu/~andpph
=============================================================================
46.07 -< Shedding some light on DOF and Hyperfocal Distance >-
-----------------------------------------------------------------------------
> Can you please show me step by step how to work out the following:
> For a camera with a lens 100 mm @ f/16 focused on HD. Please how do I get
> the Depth of field for that equation.???
The formula for HD (Hyperfocal Distance) with any focal length lens at
any aperture is given by:
HD = f squared / (N x C) where f is focal length
N is the f-number
C is the diameter of the
permissible Circle of Confusion
To determine the DOF you need to determine the Near Distance and the
Far Distance that is reproduced acceptably sharp and this can be
determined once the HD has been determined. As follows:
DN = HD x U / (HD + U)
DF = HD x U / (HD - U)
where DN is distance to Near Point in subject reproduced sharply
DF is distance to Far Point in subject reproduced sharply
U is the distance to the Object that the lens is sharply
focused on
DOF = DF - DN
where DOF is the total Depth of Field in the scene.
So, let's assume you are using the lens you mentioned above and assume
you allow a diameter for the Circle of Confusion to be 1/30mm in the
35mm negative (that will be enlarged about 8 times to make an 8x12
print in which the diameter of the CofC will be about 1/100 inch or
.254 mm) - NOTE: you must be able to predict or select an appropriate
diameter for the Circle of Confusion on the negative.
HD = focal length squared / f# x dia. of CofC here about 1/30 mm)
HD = 100mm squared / (16 x .031mm) = 10000 / (16 x .03)
10000 / .48
20833 mm or about 68 feet
Now, let's assume you focus that lens _on_ the HD and see what happens:
DN = 68 ft x 68 ft / (68 ft + 68 ft ) = 68 ft x 1/2 = 34
DF = 68 ft x 68 ft / (68 ft - infinity) = 68 ft x infinity = infinity
DOF extends from 34 feet to Infinity
This shows you an important fact re: HD and that is that when you focus
the lens on the Hyperfocal Distance the Depth of Field extends from
half the Hyperfocal Distance to Infinity!
Now let's change the point on which you focus the lens to 20 feet. What
would the DOF be then?
DN = 68 ft x 20 ft / (68 ft + 20 ft) = 68 ft x .227 = 15.4 ft
DF = 68 ft x 20 ft / (68 ft - 20 ft) = 68 ft x .416 = 28.3 ft
DOF extends from 15.4 to 28.3 feet and thus it is 12.8 feet
You can see how once the Hyperfocal Distance has been determined you
can use it to easily determine the DOF by finding the Near and Far
distances sharp given a particular Subject Distance (U).
Andrew Davidhazy, School of Photo Arts and Sciences/RIT - www.rit.edu/~andpph
=============================================================================
46.08 -< Real vs. Virtual Images - a basic definition >-
-----------------------------------------------------------------------------
> Can you please tell me what a real image is in photography terms.
I don't have a very good definition for this but will give it a shot:
A real image is one that consists of focused light rays and that can be
made visible by placement of a groundglass at the place where its light
rays are brought to a focus by a lens. This is unlike virtual images
that can be seen and even photographed but which are not made up of
focused light rays. Real images are formed by positive lenses and virtual ones
by negative lenses.
Andrew Davidhazy, School of Photo Arts and Sciences/RIT - www.rit.edu/~andpph
=============================================================================
46.09 -< Making pictures of water splashes >-
-----------------------------------------------------------------------------
> I would like to find out how you took the picture of the water splash seen
> at: http://www.rit.edu/~andpph/splash-1m.html? Could you give the detail of
> the way you did it (e.g. back ground, lens(macro?),etc)
The photograph was made some time ago when I had a flash of inspiration to make
some of these photos ... I have not made many lately ... not that I am bored
with it but it is a significant effort ... not so much in terms of "how to do
it" but in terms of the amount of time one needs to dedicate to a project even
if it seems problem free!
I used a synchronizer I made myself and described in an article I have on the
web. It is at: http://www.rit.edu/~andpph/text-cross-beam.html
It is based on a 556 IC chip. It is "analog" in nature and not so precise in
terms of delay setting as a digital might be but for this type of photogrpahy
that is not a problem since you adjust the delay until you see the effect you
want ... after that you let 'er rip!
My students and I make these light/dark/sound synchronizer that include
variable delay and can also be used as intervalometers ... we make them from
scratch including the PC board on which they assemble them. Cost is about $25 -
$50 ... some students do have trouble with the project and then it is usually
up to me to fix things :-( ;-)
As for flash I used various ones and I don't recall which one with this
particular photo. The flashes included a Vivitar 283 at 1/16th power and a
Metz 611 (maybe the 511 ... "potato masher" type ... am not in school so can't
check number) also used at low power. I also used a Mecablitz with a white
light deflector in front of light sensor to drop the power to achieve shorter
durations.
I used a 100 mm lens with extension tubes to get close. The camera was a Canon
A-1 with attached winder 2.
The light was directed at a sheet of opal/groundglass and it was located
at such an angle that its surface where the light primarily shone reflected
off the water surface in such a manner that the drop appeared centered within
it. Essentially the lighting set up what is called "dark line" effect since the
surrounding area was very dark in comparison with the bright spot on the
screen.
The film was tungsten Ektachrome and so it turned quite blue when used
unfiltered with electronic flash. OTOH, I may have had a daylight to tungsten
conversion filter on top of the lens which would have added additional blue to
the photo ... I am not sure anymore. It was also out of date if I recall which
may have added to the color of the final image.
Andy o o 0 0 o . o Andrew Davidhazy, Imaging and Photo Tech
\/\/\/\/\/\/ http://www.rit.edu/~andpph 716-475-2592
________| |____________________________________________
=============================================================================
46.10 -< Unsticking photographs stuck to glass >-
-----------------------------------------------------------------------------
> I found an old photograph stuck to a piece of glass that was used as the
> cover of a desk. Seems that some water got under the glass and the picture
> stuck to it. I'd like to remove it. What is the best way to take care of a
> situation like this?
A couple of guidelines:
1. Before doing anything drastic make a photograph of the photograph ...
using a close-up accessory of some kind.
2. Check to see if you can scan it with a flatbed scanner or photograph
it with a digital camera.
3. Cut the glass around the picture and frame it! (from Glenn Miller!)
- and I also did get this from the father of a Tech student who also runs a
camera store:
Date: Fri, 07 Sep 2001 20:03:50 -0400
From: Jerry Harmen
Hi,
Just humidity can make the pictures stick. Here are a few suggestions.
At least one will work. I am assuming the pictures are no more than 20
years old. It should be obvious that you must remove the glass from the
desk, and turn it upside down, so the back of the print is facing up.
1> Go to your local camera store (not a Wal-Mart or other mass
merchant) and buy the smallest possible bottle of Kodak PhotoFlo. When
you get back to the desk, dilute a few drops into a cup of water. SOAK
a clean rag that has not been in chlorine bleach and place the drenched
rag over the entire picture. Leave it there for a few hours, checking
that it does not dry out. At the end of that time, the print should
show signs of loosening. Repeat this process until the print separates
from the glass.
2> Buy a 1 oz. bottle of UnDu. I know that Bed Bath & Beyond carries
the product (as do we). This chemical will not damage you photo,
clothing, desktop, etc. Squeeze a few drops on a corner of the print.
Wait 2-3 seconds. Try to slide the edge of the lid under the photo.
If it comes up easily, continue until the entire print comes off. Do
not exert much pressure - this will work with very little pressure or it
won't work at all. This stuff is amazing!
3> As a last resort, you might try steaming the picture off. It will
probably be blotchy if you succeed, and it will take awhile. You'll
have to suspend the desktop over boiling water, and it will make a mess.
Good luck! Let me know how things work out.
Jerry Harmen
Madison PhotoPlus
40 Main Street
Madison, NJ 07940
jerry@madisonphoto.com
--------------------
andy - andpph@rit.du
=============================================================================
46.11 -< What are tintypes and can I make them myself? >-
-----------------------------------------------------------------------------
> What are tintypes and can I make them myslef?
Try: http://www.rit.edu/~andpph/pf-faq-28.html
or http://www.rockaloid.com/oldtime.html for ferrotype supplies, it might
be worth buying a kit with instructions to get you started.
Another source of chemical is Artcraft: http://www.artcraftchemicals.com/
Alternatively, as tintypes are the same things as ferrotypes, so you might
want to broaden your search a bit. I really have no first hand experience
with the process and my oldest book on photography ('The Ilford Manual of
Photography' first edition, pub 1900) is already talking exclusively about
negatives :-) Here's one description I came across:
"A tintype (ferrotype) is made by coating a wet, light sensitive emulsion on
a japanned metal plate in the darkroom. ...., while the plate is still wet,
it is developed in an iron developer, fixed and washed with water and placed
to air dry. After drying, the plate placed under a brass mat with a clear
glass cover. The whole package is then wrapped with a brass preserver and
placed in a case or frame. The tintype process was introduced in 1852 and
was still popular in the earlier part of the 1900's." I suspect the iron
developer is an oxalate salt.
It's also worth noting that as the process produces a direct positive, the
image is reversed which is perfect for portraits I suppose, as that's the
way people are used to seeing themselves in a mirror :-)
Karl
From: Karl and Anita Shah-Jenner
here are some more sources:
http://www.rockaloid.com/prices.html
http://www.rockaloid.com/oldtime.html
=============================================================================
46.12 -< What to store negatives in? Paper or plastic sleeves? >-
-----------------------------------------------------------------------------
> Yesterday I've been told by one fotofinisher man that it's better to use
> paper based negative folders instead of plastic ones. The man says that
> when stored in plastic (polyethylene) folders, the film is getting wet.
> Any opinion on this? So far, I was using PrintFile plastic folders and
> was happy with it, but now I'm getting a little bit concerned...
The first thought that you should have is, "where does this alleged moisture
come from?" If it's really getting wet, your photofinisher isn't drying your
negatives properly. Seriously though.... The choice of enclosure material
really depends on your needs. It's not a great answer, but it's true.
Paper or plastic? Either one is acceptable in accordance with national and
international standards. Paper has the advantage of being (usually) less
expensive and easier to write on. You can also purchase it as "buffered" or
"unbuffered." This simply means that calcium carbonate (usually) or other
relatively non-soluble metal oxide, carbonate, or bicarbonate has been added
to counter increases in acidity which is deterimental to the enclosure
itself and potentially also to the enclosed photograph (including
negatives.) The standards recommend an equivalent of 3% calcium carbonate in
enclosures for contemporary wet-processed, black-and-white silver-gelatin
photographs. Paper tends to increase in acidity due to the absorption of a
variety of industrial pollutant gases in the air including sulfur dioxide
and nitrogen oxides. The disadvantage of paper is that it's opaque and
photographs of any sort must be slid in and out to view them. This also
increases the risk of handling damage. Any paper enclosure selected for
photographic storage should meet the requirements of ANSI/PIMA IT9.2-1998,
or
the international standard counterpart ISO 10214:1991 (which should be
updated and given a new number within a year.) In particular the paper
enclosure should pass the Photographic Activity Test (PAT). This is a
general screening test used to determine if there are components of the
enclosure that will attack image silver or will stain the gelatin emulsion.
These are the same standards used by museums and archives. It may sound
crazy, but if you want your photographs to last.... Generally you'll be more
successful meeting these requirements if you buy from the archival suppliers
such as Gaylord Brothers, Light Impressions, or University Products. If the
catalog doesn't specify that the enclosure meets the ANSI or ISO standard
(or at least the PAT), then you should be able to ask. If the sales people
can't tell you or have no idea what you're talking about you might want to
avoid the product. By the way, the common practice of storing prints in the
boxes that the paper came in is one of the worst things that you can do. The
stability requirements of silver halide and processed image silver are very
different. Be aware also that "permanent paper" does not necessarily mean
that it's suitable as an enclosure material. Also note that adhesive seams
should run along one edge rather than down the center (as they do with many
of the common kraft envelopes for mailing). Photographs should be inserted
with the base side facing the seam rather than the emulsion side.
[Before I continue, ANSI is the American National Standards Institute and
ISO is the International Organization for Standardization. ANSI was formerly
known as the American Standards Association (ASA) ... right. ASA as in the
old film speed numbers. ISO adopted the ASA system and this is why we now
have ISO film speed numbers. ANSI Committee IT9 and ISO Technical Committee
42/Working Group 5 (ISO TC42/WG5) are responsible for the permanence and
physical properties of imaging materials. These are the groups that create
a) manufacturing and processing specifications for black-and-white film (and
hopefully soon, black-and-white photographic paper); b) test methods such as
the standard methods for determining residual thiosulfate in films, plates,
and prints; c) storage standards for color and black-and-white films,
plates, prints, magnetic tape, and optical disks.]
Plastic has the major advantage of being transparent (generally.) This means
that if you're trying to find a particular negative you don't have to handle
every negative (until you find the right one.) The disadvantages are that
plastics tend to have a higher static potential (although paper can also
develop a static charge), they tend to be more expensive than paper, and in
a humid environment they may cause "blocking" or "ferrotyping." Remember how
photographers got an ultra-glossy surface on fiber base papers? (Gad. Don't
I sound like a teacher.) The wet gelatin is very soft and pliable and when
the emulsion surface was pressed against a very smooth surface (glass or
polished metal plates), the gelatin would conform to that smooth surface and
also become very smooth. Under relatively high humidity we can run into a
similar phenomenon where the photograph does the same thing in contact with
glass or smooth plastic. I might add that areas of a photograph that have
blocked or ferrotyped look somewhat wet through the plastic or glass. It may
simply cause a change in surface gloss in an area or in worse cases, may
cause the enclosure to stick to the photograph. This, by the way, is why
photographs should never be framed directly against glass. The standards do
not consider chlorinated or nitrated plastics to be acceptable. Plastics
that are considered to be safe include polyethylene,
polypropylene, polyester, and polystyrene. Cellulose acetate (effectively
filmbase) was once accepted since it was the same as acetate filmbase.
However, we know that cellulose acetate base is not very stable (and if you
aren't using polyester based film, then you have cellulose acetate.)
However, the fact that many of you will have unprintable negatives in the
next handful of decades due to "vinegar syndrome" is another topic.
Polyethylene sleeves come in two varieties, low-density and high-density.
LDPE is the transparent plastic that was often used for produce bags in the
grocery stores. HDPE is translucent, but not transparent. It's the stuff
that the grocery bags are made from (as in "paper or plastic?"). I notice
that produce bags are now more commonly being made from HDPE. The do
deteriorate since nothing lasts forever, but as a plain hydrocarbon polymer
(only made form carbon and hydrogen), the deterioration by-products are
considered to be benign. One problem with LDPE is that you may find slip
agent coming out. Remember how hard it was to get the produce bags open? The
reason for the problem is that the plastic is relatively smooth and tends to
stick to itself. You can imagine if you had a machine for making plastic
sleeves that runs at 10 or 20 or 30 feet per minute that if the plastic
sticks to the transport rollers and jams, you're in big trouble. Your choice
is to either add "anti-blocking" agents or "slip agents." Anti-blocking
agents are inorganic (earth minerals) materials such as clay, talc, or
silica -- none of which you would want in a photographic enclosure (so they
aren't used in this application.) Slip-agents are organic materials such as
waxes that are "dissolved" into the plastic during manufacturing. These are
usually added at a concentration of less than 1% and are intended to slowly
come out of the plastic to form (hopefully) a one molecule thick layer on
the plastic. If higher concentrations are present, they tend to come out and
cause the plastic to become hazy. HDPE will become hazy for other reasons
but if you can rub the haziness off with your finger, then it's slip agent.
We were hoping to have a test for this problem in the standard, but it's
possible that no such test can be created. The waxes are inert and will not
cause chemical deterioration of your photographs (although you may object to
the waxy spot on you negatives and prints.) HDPE is slippery enough that it
doesn't need slip agents, but the enclosures are not transparent. This seems
to be one of the most common plastics that I've seen photofinishers use for
negatives.
Polypropylene also comes in two varieties, cast and biaxially-oriented. The
cast plastic is transparent and resembles LDPE although it has a slightly
stiffer feel to it. While this plastic is also inherently safe, it may also
have the slip agent problem. Of all of the plastics, PE and cast PP are the
least expensive. Biaxially-oriented polypropylene (BOPP), like HDPE, doesn't
require slip agents. (The very stiff PP slide pages that are translucent are
BOPP.) The problem with using BOPP for regular sleeves is that special
techniques (ultrasonic welding) are required in order to fabricate the
sleeves making them approximately as expensive as polyester. I'm not aware
of anyone making regular BOPP sleeves for that reason.
Polystyrene is most commonly used in slide mounts. The only time I've seen
PS film used for photographic storage has been in some photo albums. It's
"crystal clear" but has a tendency to scratch (and get hazy.) It's also less
inert than PE or PP towards many organic solvents.
Polyester is often considered to be the "king" of plastics. It's certainly
the most expensive. It's disadvantages are that it has a particularly high
static potential. (I've seen gelatin dry plate negatives in which the
gelatin emulsion stuck better to a polyester sleeve by static than to the
glass support....and the negatives are no longer.) Polyester also tends to
have a fairly sharp edge so sliding photographs in and out of polyester
sleeves can abrade the emulsion. Many companies make folded sleeves (often
called "fold lock") which allow the enclosure to be opened completely and
thus reduce abrasion damage. As mentioned above, PET must be ultrasonic
welded in order to make a bond. In addition, the plastic dulls blades very
easily and for these reasons (and the cost of polyester resin), PET sleeves
tend to be quite expensive. Beware of "frosted" PET sleeves. There was an
attempt to use a few silica containing PET films for enclosures in order to
prevent the potential for blocking and ferrotyping. The sleeve behaves like
a 1400 grit sandpaper and you can literally sand an image off with it. Look
for sleeves made from uncoated Mylar D (DuPont) or Melinex 516 (ICI).
So many choices to make.....
Good luck.
-Doug
Douglas Nishimura
Research Scientist
Image Permanence Institute
Rochester Institute of Technology
From: Douglas Nishimura
=========================== end of section 46 ==============================
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