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Black-and-white process control test strips? Homemade?

BetterSense

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Aug 16, 2008
Messages
3,151
Location
North Caroli
Format
35mm
I use a replenished developer and have had no problems adding 22mL of replenisher per roll and replenishing until 1/2 of the original solution volume in replenisher has been added. Still, I think it would be good to have standard test strips that I could develop to verify that developer activity was as it should be. Then I could possibly change my replenishment routine to maintain process stability.

Has anyone ever shot a 35mm roll full of step wedges or something so that you can see if your developer is changing?

I think it would be good to be able to, before developing some important batch of film, to be able to develop a test strip and know your developer was good.
 
Doesn't sound like a bad idea. Do you have a densitometer to read the strips? There might be some calibration involved to be sure the strips were consistent from test to test. A low speed film, stored in the freezer after shooting the test exposures, might have better latent image keeping qualities and be less prone to base fog, if you wanted to do something like shoot a roll of test shots and pull clips periodically from it to test the developer. Tests from different film batches would have to be calibrated.
 
I don't think a densitometer would be necessary...eyeballing a developed test strip compared to a strip made when the developer was fresh would be enough to see if the process was drifting. I guess a simple picture of a step wedge on a light box would do that trick...or since I don't have a test wedge, a picture of a printed series of strips.
 
Expose three steps II / V / VIII.

Actually, just a Zone V target is sufficient. Make contact prints.
 
BetterSense said:
I guess a simple picture of a step wedge on a light box would do that trick...or since I don't have a test wedge, a picture of a printed series of strips.
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Or a nice neutral gray paint sample 'chip' that has different tones from black to white.

Lee
 
Or a nice neutral gray paint sample 'chip' that has different tones from black to white.
Click to expand...

Good idea; I bet I could get one of those for free.
 
what I did

went to home depot to pick out paint sample cards
Behr Disney series [4c-20 mickey's shadow and cinema star], and pure white
product line

 
Ilford used to produce control strips made of FP4, a total disappointment they stopped selling these. I dont know if Kodaks TMY controls are still available.

dw



 
BetterSense said:
Has anyone ever shot a 35mm roll full of step wedges or something so that you can see if your developer is changing?
Click to expand...

I've been using a second hand X-Rite 334 Sensitometer (not to be confused with a densitometer). This small electronic device was made to expose a film with a 21-step wedge. It's a hand held device in the shape of a clam shell and to expose a film you slip the film into the clam shell and close it. It has a DIP switch to set the base exposure time and I worked out settings to use for film testing in the 100-400 ASA range. It has a blue/green switch, but I have only used mine in the green position. The 21 step strips end up being 5.5" long (13.5 cm), complete with labels to number each step in the wedge. All of the exposure timing is done by the device. When you close the little lid you hear a beep telling you it's done. Exposure takes only a fraction of a second.

I got mine of ebay for almost nothing. I think a lot of x-ray and lithe facilities used them for quality control. The thing I really like about it is that it is so easy to make a control strip in the darkroom. It runs on a 9-volt battery and is as easy to use as a 3-ring hole punch. The only thing that disappoints me is that the control strip is just a smidgen to long to fit on a single edge of a sheet of 4x5 film. To use 4x5 film I have to expose the low wedges on one long edge of the film and the high wedges on the other long edge. It works fine, it's just not as attractive. For 5x7 and up, this wouldn't be a problem.

With 35mm film I usually do one of two things. If I'm testing film, which is my typical use for the device, I expose 6 or 7 wedges on a single roll of film. This evens out development effects that could otherwise be a problem when only a small part of a roll is exposed. If you just want a casual test strip you could go into the darkroom, pull out just enough film to make a single test strip and then roll the exposed film back into the cartridge. Then when you put the roll in your camera, you would skip the first few exposures that would otherwise fall on top of the test strip.

Keep a watch on ebay. If you can get one for chump change, they make a great tool for the darkroom.

Denis K
 
When I do my first developer testing, I do the 35mm test you mentioned. I do it for each camera, and only do it to the level of precision that the camera allows. 1/2 stops is the greatest precision I can get on any of my 35mm cameras. I get two bracketed sets on each roll, and cut the roll in half to test. IME, there is significant variation lens to lens. (Wouldn't it be nice if all of our lenses read t stops instead of f stops?) I do all my testing with a 50mm f/1.4 lens. I have never used this to test the activity of a developer, however. A step wedge exposed onto a piece of sheet film is probably how I would do it.
 
I got a paint test strip but it doesn't have a very good dynamic range to it and not many steps. I think I can make a better one with a sheet of 5x7 paper from all-black to all-white. I'll just shoot a roll of plus-x full of pictures of it. Then I can develop one frame in the fresh developer and put it aside. Later I can develop frames at the same time and compare to the fresh-developer one.
 
BetterSense said:
Has anyone ever shot a 35mm roll full of step wedges or something so that you can see if your developer is changing?
Click to expand...

With 35mm, I expose a step wedge on the beginning of about every 20th roll I spool up. I make a note on the film leader to advance 6 frames before shooting. The step wedge gets processed along with the rest of the roll.

Because of the expense of large format film, I don't do any 'routine' testing. I only test if there is a specific problem to track down.

As Dennis K pointed out, for this type of control testing (and probably most film testing), an inexpensive green/blue sensitometer should be Ok. Just remember to keep it set the same for all your tests. If you can get a white light one that is even better.
 
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I got this pair about 10 years ago and they have served me well (in fact Tobias still makes and services similar products).

I'm posting the picture so that when you see one of those seemingly 'useless little black boxes' at a junk sale or in with a bunch of darkroom or x-ray equipment, you now know what it is, unlike these folks

36850--Toss--Small Black Box – Wejex, Tobias--Uncertain what this is.
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That is a quote from the following site (looks like they just tossed one in the trash...http://www.comm.media.state.mn.us/docucommsale.htm
 
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