Test strip questions

[Cybertrash]

When you make test strips, what is it exactly you're looking for when judging the exposure time? I've heard that you should look at the highlights, and then use contrast filters to place the shadows where you want them (I've also heard the inverse), but sometimes I find that that doesn't really work for me (for example on a shot I was unable to achieve the highlights I wanted without the blacks turning gray).

Also, when you make test strips, do you use entire sheets of paper or just small scraps? Roughly how large would a "test strip sheet" for say a 9.5x12" print?

 

[fretlessdavis]

You can also do split grade printing-- do a test strip at the lowest contrast to determine highlight exposure, and then the highest contrast to determine your shadow exposures.

Test strips can be whatever size you want, though. Personally, I cut a sheet of 8x10 paper down into 2 4x5's and 8 1.25" x 4" pieces (approximately). I do small strips on certain areas where contrast or tone is important until I feel comfortable, then I expose a 4x5 with my settings in an important area of the print. If I'm happy, I then do a full print, otherwise start over with small strips.

EDIT:

I also usually start with small prints, usually 5x7, printed full frame. From there I can start devising a dodging and burning plan, if necessary, without using up another sheet of 8x10 or 11x14 paper.

 

[fretlessdavis]

oops, sorry about the double post.

 

[cliveh]

When you make test strips, what is it exactly you're looking for when judging the exposure time? I've heard that you should look at the highlights, and then use contrast filters to place the shadows where you want them (I've also heard the inverse), but sometimes I find that that doesn't really work for me (for example on a shot I was unable to achieve the highlights I wanted without the blacks turning gray).

Also, when you make test strips, do you use entire sheets of paper or just small scraps? Roughly how large would a "test strip sheet" for say a 9.5x12" print?

Different people will approach this in different ways, but if I am making a print on a 10" X 8" paper, I may cut a sheet into several strips to put across the image, straight or at an angle to pick up the darkest shadow, brightest highlight and mid-tones. I would also do this initially with zero contrast control, as you can then decide if contrast control is necessary. If so and/or if not make further tests to fine tune your exposure/contrast.

 

[snapguy]

varies

Let's say you have a seascape photo with a very thin bank of fog in the middle of the pic. You might want to make a test strip just an inch wide and place it where the fog bank would be, to test for the right contrast or exposure. Or you might run the test strip at right angles to the fog bank, to get an idea what the beach, fog, water and sky look like so you can judge what needs more work (burning in or holding back.) You might do several test strips until you get it how you like it. You could make a 4x5 or 8x10 test "strip" -- whatever you want.

 

[gone]

It's best not to over think this and keep it simple. I use one third sheet of paper to economize, and place it diagonally. That usually works fine. My first print is basically a proof print based on that test strip, and any adjustments will be made after that first proof is printed. Sometimes the proof print is fine as it is, other times you'll see right away where it needs adjustment.

 

[Doremus Scudder]

When you make test strips, what is it exactly you're looking for when judging the exposure time? I've heard that you should look at the highlights, and then use contrast filters to place the shadows where you want them (I've also heard the inverse), but sometimes I find that that doesn't really work for me (for example on a shot I was unable to achieve the highlights I wanted without the blacks turning gray).

Also, when you make test strips, do you use entire sheets of paper or just small scraps? Roughly how large would a "test strip sheet" for say a 9.5x12" print?

Let's review a couple of different approaches here. Then you can choose or mix-and-match to suit your tastes. Most importantly, a test strip should help you roughly determine both contrast grade and basic print exposure. Refining of these and manipulations are usually done with a full sheet.

Approach 1:
Those of us that come from printing on graded paper usually have a good idea of what contrast grade we want to start with for a couple of reasons; either we are using an exposure/development system (like the Zone System) that targets a particular contrast grade, or we have proper proofed, or both (in my case). So, for me, and to optimize the usefulness of test strips I say,

Step 1: Proper proof your negatives on a middle contrast grade paper, e.g., grade 2 or 3. When the negatives are proofed at an exposure that is just long enough for the clear film rebate to reach maximum black in display lighting, you have a lot of information. Not only about exposure and development, but also about which contrast grade the image will likely print well on. If it looks great on your grade 2 proof sheet, then start with grade 2. If it needs more or less contrast, then start with a harder or softer grade.

Step 2: The "expose for the shadows and develop for the highlights" rule adapted to printing yields, "expose for the highlights and adjust contrast for the shadows." This is my usual approach. I cut my paper into thirds lengthwise and position the strip in the image so that as many important highlight areas are contained in it as possible.

Note: there are many methods of exposing the test strip; regular intervals, f-stop timing, progressively longer, etc. as well as additive and subtractive methods. I prefer a progressively increasing additive exposure scheme based on percentages. I usually start at 10 seconds base exposure and then give additional exposures at 20% of the previous strip. Example: Base exposure 10 seconds on the entire strip; then cover a bit and count 2 seconds (20% of 10 sec.); cover the next bit and count off 20% of 12 sec. (the exposure the previous strip has received; I round this value, so 2 more seconds get counted); strip four gets 20% of the 14 sec. the strip before got, so an additional 3 sec. ... and so forth up to 35 sec. My counting sequence looks like this: 10-2-2-3-4-4-5-6. I end up with a test strip with roughly 20% exposure increase between each stripe and from 10 to 35 seconds.

Anyway, expose your test strip, develop-stop-fix, rinse for at least a minute and then evaluate.

Step 3: Evaluate the highlights and the contrast. The stripe with the desired highlight value usually contains some low values as well with which you can judge contrast. If there is a stripe with both correct highlight rendition and contrast, whip out a full sheet and get to work. If there is no stripe that has an acceptable highlight value, you need to make another test strip on the same contrast with different exposure. If the contrast of the chosen highlight stripe looks wrong, you need to make another test strip at a different contrast grade. Don't bother with a full sheet till you have both acceptable highlights and contrast.

Step 4: Work with full sheets after this point, however, if you find that contrast is still way off (which happens occasionally), then you need to go back to step one and start with a new test strip. Of course, small changes in contrast and exposure still usually need to be made. This you do by trial and error and experience with full sheets; print manipulations as well.

Approach 2:
Those that split-grade print on variable contrast paper often like to make two sets of test strips: one each at the highest and lowest contrast filtration.

Step 1: A low-contrast test strip is made to determine highlight exposure. Ignore contrast here, just get the value you want in the whites of your print. Note the correct exposure.

Step 2: Make another test strip at high-contrast filtration to determine your shadow exposure. Note this exposure as well.

Step 3: Make a full print exposed with both the low and high contrast exposures through the appropriate filters. Evaluate this print and adjust the appropriate exposure times as needed (e.g., the high contrast exposure might bring down the highlights a bit, so the highlight exposure might need to be less, etc.).


I use split-grade printing techniques only rarely, so have just given you a bare bones idea above. The best explanation and method for split-grade printing that I have found is in Ralph Lambrecht's "Beyond Monochrome." He refines the system by choosing base exposures based on target contrast grade. If you feel attracted to this method, I suggest you get a copy of the book. It is one of the best references out there for everything analog.

Hope this helps a bit,

Doremus

 

[Mark_S]

For me, it depends on the image.

If a landscape, I tend to determine the exposure by looking for the shortest exposure that will bring detail up in the highlights, and to get this, I place the test strip where as much of it as possible is in the highlight area. I do logarithmic exposures on the test strip (2s, 4s, 8s, 16s, 32s) so that there is one stop difference between test exposures. I do contact prints for all of my negatives at grade 2, and by looking at the contact print, I am usually able to guess what contrast grade I am going to want for my final print - I use this contrast when doing the test strip exposure.

I then print on a sheet of paper - usually 8x10, and work out what dodging/burning I am going to want to do, and tweak the contrast if necessary. Once I have something I like, I take a light meter reading on the easel, raise the enlarger head to the height required for the final print, and adjust the exposure with the lens aperture to get the same brightness on the easel that I had for my 8x10 test prints.

If it is a portrait, then I tend to do a test strip on the face, and work on placing the exposure for that such that I have the tones that I want on the face, then work with contrast, dodging and burning to make the rest of the frame work. I usually don't print portraits big, so all of the focus is on getting the 8x10 to look good.

 

[ROL]

Making A Proof & Making A Fine Art Print

 

[Oscar Carlsson]

I use small pieces of paper (only a few centimeters) on strategic locations to get a hunch on exposure. A location might be an important highlight area or a face. I expose each piece using f-stop timing, and go for full stops initially. Once I have a good estimation what might be a good exposure (if it falls between two strips I can usually give a good guess anyways), I make a work print, with minimal dodging/burning, using a full sheet of paper. All this on normal contrast (no filters).

From the work print I can usually estimate if the image needs more exposure, more contrast, what needs to be dodged etc. It took me some time to learn that all shadows can't be solved using more contrast, but that burning in is a really, really useful tool. A year ago I printed almost exclusively on grade 5, nowadays I always begin on grade 2. I raise contrast to get proper midtone contrast or if my shadows are really weak.

Good luck!

 

[Mark Fisher]

I do exactly what Clive describes except I take a guess at the contrast I need (nearly always grade 3 plus or minus one) and adjust from there. I use the midtones to judge exposure (since they stay the same-ish across contrast grades) and adjust the contrast to get the blacks and highlights I want. Test strips really aren't going to tell you the correct exposure and contrast, though. It only gets you close. When you see the image as a whole, you'll likely want to adjust.