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One test film

zumbido

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Porting this from another thread to avoid a hijack:


Ralph, I'm curious about this. Can you elaborate? I can't imagine that 36 frames could tell you everything you need to know about various permutations of exposure and development time and other variables. But I may be misunderstanding what you said, or missing something else. I make controlled tests a habit (one learned the hard way working on critical software products), it's the "ONE" part that I'm unclear on.
 

One test, involving six sheets or rolls of film are enough to determine the development and exposure indices (EI) to cover all contrast situation. A step tablet is photographed once onto each sheet or roll of film at constant exposure. The sheets or rolls are then developed at five different development times and results evaluated and plotted.

Six exposures, six developments and never in doubt again!
 

Looks like there's been a hole in my reading so far. Thanks for the tip... any pointers to a good resource for more details?
 
Ralph, there's one thing that's not clear to me. You say, you use one constant exposure, how do you determine that exposure ?
 
...how do you determine that exposure ?

To noumin: my guess at this answer -
the exposure would first be determined with one roll of film, exposed at 5 speeds (box speed, 1 and 2 under, 1 and 2 over), developed at recommended development time. Evaluation of the shadow areas (for the most part not affected by development) will show the best exposure. In addition to the step scale, I would do some of normal scenes, for a practical evaluation.
 

No. You take a picture of a transmission step tablet, such as the one from Stouffer (attached). This way you have ten exposures on one frame! The other benefits:

1. fine increments of 1/3 stop
2. no deviation due to shutter or aperture inaccuracies
3. no deviation due to illumination fluctuations
4. heavily reduced testing time and effort
 

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zumbido said:
Looks like there's been a hole in my reading so far. Thanks for the tip... any pointers to a good resource for more details?
Click to expand...


Get a copy of Phil Davis' Beyond the Zone System. Film testing is based on making five or six exposures on different sheets of film (or rolls), developing them for a range of times, and then plotting the results. One you plot the results you have all the exposure and development information for that film and developer in almost all subject lighting conditions. And the testing is very efficient in terms of time as it only takes about an hour to expose, devleop and dry the negatives, and about 30 minutes to plot the curves.

I don't know what type of system Ralph uses but I would suspect it is not all that different from standard BTZS testing.

Sandy King
 
I'll take a look at that book. I'm assuming that the key takeaway after running this test, then, is how the contrast differs between the six different developments. Correct?

Also: it'd be advisable to run this one's self because everyone's dev technique tends to differ slightly, but are there published examples of this with various common films anywhere?
 
sanking said:
...I don't know what type of system Ralph uses but I would suspect it is not all that different from standard BTZS testing...
Click to expand...

Sandy

I second your book recommendation for this and other reasons. I was fortunate enough to have Phil explain this test to me in person. He used 5 exposures, I have added one to get the film speeds in more reliable ISO units.

To whom it may concern, the required templates are available on my website at the bottom of the Library section, but I'm not sure how useful they are without the book.
 

Thanks for the pointer (in the image caption). I'd casually looked for exposure targets and only found things over $200.

One question, though. How do you take a picture of the transmission tablet? Project it on a white surface and take a picture of that?
 

You need one of these 5x4 Step Tablets - Dead Link Removed

Martin
 
Martin Aislabie said:
You need one of these 5x4 Step Tablets - Dead Link Removed

Martin
Click to expand...

Perhaps my question was poorly phrased.

I have a film I want to test, and I have this calibrated transparency. What do I do then?

Taking a reflected light picture of a transparency seems of little use. So do I put it on a light table? Project it onto a surface? Contact print it onto the film?
 

Get a 4x5 transmission step tablet (31 steps), tape it to a window or small piece of milky glass, get close and photograph it. Alternatively, get a step tablet in the size of your film format, mount it into a slide copier, and photograph it that way. Make sure your light source matches your type of photography. I suggest to use daylight or flash for the test. CFLs, fluorescent and incandescent bulbs have a different color temperature and return a slower film speed. The test results would not be applicable for daylight and flash photography. Set the exposure for the middle gray steps. Roll film users bracket to have a few extra frames and some data beyond the ten stops of the step tablet.
 
Last edited by a moderator:

Thanks. Six months or more ago, I never would have even thought of testing film (beyond "look at results and tweak the meter setting"), so I've got a lot of learning (or unlearning) on proper application of fundamentals.
 
ralph if you have a 4 x 5 31 step tablet is there any reason not to put it on top of the film you are testing and expose it on zone ten using a white back ground.
 
wager123 said:
ralph if you have a 4 x 5 31 step tablet is there any reason not to put it on top of the film you are testing and expose it on zone ten using a white back ground.
Click to expand...

Mitch,

I know you asked Ralph, but that's how I do it and it has served me well. I use a white target close enough to the lens without any focus on the target while in the shade on a cloudless day or very even overcast day. I expose one sheet to determine the curve and the effective EI, then I expose additional sheets as necessary at the effective EI to determine "N" dev and other dev times. I believe it took me a total of 5 or 6 sheets to determine a family of curves for d-76 1:1 at the effective EI and in relatively short time to boot.
 
wager123 said:
ralph if you have a 4 x 5 31 step tablet is there any reason not to put it on top of the film you are testing and expose it on zone ten using a white back ground.
Click to expand...

Mitch

As cporter already said, that works fine for the first 5 exposures to do the development test, because we after relative exposures, and Phis Davis did it that way, but it has one draw back: camera and lens flare are ignored. If you do it in-camera, you get a more realistic test.

The 6th test needs to be done in-camera, because you need to be able to relate the results back to ISO to get a usable EI.
 

Ralph,

Just wanted to make sure I was clear----what I was describing to Mitch were tests inside the camera for effective EI and subsequent exposures for development times. I simply put a 4x5 density scale tablet on the emulsion side of the film for all exposures, then slide both into the film holder, then photograph the target. I'm a firm believer of using the in-camera method with the tablet.
 

Thanks for the clarification. What an ingenious concept!
How do you make sure not to focus onto anything?
 
RalphLambrecht said:
Thanks for the clarification. What an ingenious concept!
How do you make sure not to focus onto anything?
Click to expand...

I set the camera at infinity (to avoid any bellows factor coming into play) but place it close to the target so that it completely fills the GG. I can't take credit for the concept, I learned it from John P. Schaefer's book: The AA Guide, Basic Techniques of Photography, Book 2.

Chuck
 
thank you ralph and chuck. i poorly explaind what i was trying to say . i was refering to doing it like chuck said by putting it and the film in a holder then exposing it in camera.
thanks
 
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