How do you do test strips?

Kevin Kehler · Oct 31, 2008

I have recently seen several home-made test strip makers in photos of darkrooms and was wondering if anyone is willing to part with a good design for making one? I was thinking of buying 1" piano hinges, attaching a 1" wide slat of wood molding (painted black) to each hinge and then attaching 6-8 hinges along an old wooden frame which I could place over the paper for exposure. The advantage is I can easily construct such a device (about $15-20 by my estimate) and it is easy to use. The disadvantage is I cannot measure the same portion of negative for each exposure, but instead move along the negative where contrast/tonality can change. What I would truly like is a design where the paper rolls along and the portion of negative being tested remains the same for each exposure.

I realize that companies such as RH Designs make electronic meters that are supposed to replace the need for test strips but (1) they are beyond my immediate price range and (2) several photographers I have read/talked with say the meters will only take you 90% of the way, a physical test strip is needed to truly be accurate; perhaps someone would like to give their opinion in this?

Kevin Caulfield · Oct 31, 2008

Well, there is definitely some skill required in determining exactly which portion of negative is used for the strip, and how truly representative it is of the tonal range of the whole negative.

Nick Zentena · Oct 31, 2008

I just slide a piece of paper over the strip. This way if I'm doing 30 to 50 seconds then I don't need a bunch of long exposures.

I'm not sure why you need anything fancier.

If you really want something how about taking two pieces of mattboard. Tape hinge them. Cut a hole in the middle. Put your paper in between and pull. You get the same part of the neg. It's cheap and easy to make.

IMHO meters are great when you're doing lots of prints in a short period of time. Not really needed if you're working on one neg during a session trying to get a perfect art print.

PanaDP · Oct 31, 2008

I agree with Nick. Just do the cumulative exposure with a piece of paper thing.

If you really want to see the same area exposed a bunch of times: Just cut a rectangle out of a piece of paper. Tape the paper down on the easel. Slip your printing paper underneath. Expose a strip, pull the paper an inch or so, expose next strip, repeat. Easy as pie. I don't know why everyone has to make a complicated gadget for everything.

Denis P. · Oct 31, 2008

I've posted my solution (there was a url link here which no longer exists).

It can also be made out of two pieces of cardboard, taped along the "hinge". I used a cardboard one for couple of years

Otherwise, the thing you're looking for is called "Nova Step and Repeat" - HERE's a review.

Denis

nze · Oct 31, 2008

I use to print with split grade method do I prefer to use a carboard

Andy K · Oct 31, 2008

I just hold a piece of black card/paper over the test strip and move it an inch every few seconds.

Nicholas Lindan · Oct 31, 2008

Kevin Kehler said:
The disadvantage is I cannot measure the same portion of negative for each exposure

Along with the DIY solution, above, Durst made a printer that allows this. A little sliding shutter door advances the paper and covers it between exposures. You can either make x tests of the same spot or move the printer between spots and do several mini-tests over the surface of the print. No longer available, it may give some ideas if you are making one for yourself.

Michael Kadillak · Oct 31, 2008

Stopped making test strips years ago when I learned that you actually use more paper with the test strips than when you use the outflanking procedure and use a full sheet for each exposre. In other words the value of visually seeing a full print under and over exposed provides you with valuable information that allows the printer to dial in all parts of the print and minimize the iterative process to the final result. Test strips are worthless because the variable density requirements of the print are never consistent laterally or vertically and varying the degree of exposure in a series of increments provides the printer with nothing more than another independent variable with small snippets of virtually no meaningfull information about the remaining image area. When you make the first print after the test strip you are literally starting the outflanking process - so why do it?

A better approach is to make a full print purposefully underexposed and then another overexposed and then take it from there because with this method you get to see exactly how each section of the print (lights and darks) are responding to a significant range of exposure giving you the printer much more usable information with which to use going forward.

I proved it to myself a long time ago and have not looked back. I was on average using a minimum of two additional sheets of paper for each print using test strips than employing the outflanking procedure. The more complicated the printing procedure, the more additional paper I used.

Just because someone a long time ago aspoused this technique in a photo instruction book does not make it the optimal procedure.

Cheers!

El Gringo · Oct 31, 2008

Michael Kadillak said:
Stopped making test strips years ago when I learned that you actually use more paper with the test strips than when you use the outflanking procedure and use a full sheet for each exposre. In other words the value of visually seeing a full print under and over exposed provides you with valuable information that allows the printer to dial in all parts of the print and minimize the iterative process to the final result. Test strips are worthless because the variable density requirements of the print are never consistent laterally or vertically and varying the degree of exposure in a series of increments provides the printer with nothing more than another independent variable with small snippets of virtually no meaningfull information about the remaining image area. When you make the first print after the test strip you are literally starting the outflanking process - so why do it?

A better approach is to make a full print purposefully underexposed and then another overexposed and then take it from there because with this method you get to see exactly how each section of the print (lights and darks) are responding to a significant range of exposure giving you the printer much more usable information with which to use going forward.

I proved it to myself a long time ago and have not looked back. I was on average using a minimum of two additional sheets of paper for each print using test strips than employing the outflanking procedure. The more complicated the printing procedure, the more additional paper I used.

Just because someone a long time ago aspoused this technique in a photo instruction book does not make it the optimal procedure.

Cheers!

Surely you need a test strip to know how long and under/over exposed print will take thorugh? I'm not sure I fully understand the procedure you've described here.

Joe VanCleave · Oct 31, 2008

For exposure tests demanding more critical exactness, such as determining proper preflash times for paper negatives, I use the "travelling slit" method, and reset the timer for each slit's exposure; this has the effect of giving each portion of the test strip an exposure time that compensates for the light source's warmup time. If 8 seconds looks correct on the test strip, then 8 seconds on the paper negative will look the same.

However, for most of my pictorial enlargement work, and contact printing under the enlarger, I use the simpler -- and a bit less precise -- method of uncovering each section of the test strip in turn, as the clock runs.

One thing I've learned about the need for test exposures: if your in-camera exposure method is precisely fine tuned, you will have less need for doing test strips in the first place. An example would be printing from a 36 exposure roll of 35mm film; you really don't have time to do test strips of each negative, prior to printing; it would take next to forever to get any work done. So you work to get very consistent frame-to-frame consistency in your exposures; then do a test strip for the first image on that roll, and that should be very close to what the rest of the roll will require.

And with a bit of experience you can judge what portion of each image requires the most precise printing value (especially in street/documentary photography, where there's often an isolated subject of predominant importance, in contrast to a landscape image where there often is no central dominating subject) without resorting to a test strip for each image.

Dodging and burning is a similarly acquired skill: often you can spot areas of the projected negative image that require a dodge or burn, and perform said operation on the initial print without resorting to lots of preliminary testing.

~J

Rich Ullsmith · Oct 31, 2008

I sort of understand that, but it seems like the vital elements of an image can be covered with a 1/3 full-size test. . . jeez, Michael, you do this with 20X24? Obviously, it works for you, so there it is.

Here's a silly little short cut y'all can make fun of: with VC papers, lay your G2 filter and G3 filter on the test strip instead of filtering below the light source. There is not enough difference in exposure between 2 and 3, and you get to see two grades back to back, and immediately. So there's a few scratches on the filters, so what.

Anscojohn · Oct 31, 2008

I get my base exposure by setting up my enlarger for the print. Then shifting the neg so the clear strip between frames is in the center of the easel image. I make three second exposures at the printing f/stop until the strip is completely uncovered. I then soup and fix normally. I count the grey blocks until I get to the one just slightly lighter than the maximum black. Multiply by three and that is my base exposure. I then shift the neg back and make my first test exposure at that fstop and time. I have already decided what the print is going to look like--sometimes at the time I press the shutter release (Weston"s "seeing photographically"). Then contemplate what I want to do next and do this, usually, by adding or substracting contrast. I use the baseline exposure for a foundation black tone as my criterion, and adjust according. Other do it differently.

kenh · Oct 31, 2008

When I do “test strips” I expose the same portion of the frame with 6 different exposures. I have made a custom test easel that holds a 5x7 piece of paper but only allows a 2x2 inch square to be exposed at a time. By sliding the paper around in the gig I can expose different portions of the 5x7 sheet. Thus I have to restart my timer for each exposure (which is an advantage because generally I do split grade printing).

My test easel is made of cardboard. The unit is two sheets of mat board 14x5 inches that are glued together with a spacer mat board strip to make a sandwich where I can insert the printing paper. There is one 2x2 hole in the top mat board to allow the exposure of just one 2x2 inch square at a time. By grabbing the paper and sliding it around and such I can expose 6 different portions of the 5x7 sheet one at a time. When I do the series of exposures I don’t move the custom easel, just the paper. Thus I end up with six exposures of the same part of the picture, but with different exposures. I often adjust contrast in the exposures as well.

The advantage is that I can judge the exposure by looking at the same part of the frame. To me this is a bit closer to the method of exposing an entire sheet to compare exposures side by side.

Sometimes I expose ½ a sheet simply by masking it with a large sheet of cardboard. I then expose ½ the entire picture with one exposure, then rotate the paper 180 degrees and expose again at the second exposure. That way I get two rather large test exposures of the most critical regions of the picture, but with only exposing one sheet.

Michael Kadillak · Oct 31, 2008

El Gringo said:
Surely you need a test strip to know how long and under/over exposed print will take thorugh? I'm not sure I fully understand the procedure you've described here.

When you work with a particular paper proactively, each time you make a print you should be gaining experience with it that you should be using with the next print. As a result it is possible to be able to look at the illuminated negative on your easel and have a pretty good idea as to where to start.

My point is that it really does not matter because the initial objective is to purposefully make a print that is overexposed and a second print that is underexposed and with these recorded times you can see what your base exposure should be and at the same time where your burn or dodge times should come in at. This procedure is simply more efficient in getting to the end result as quickly as possible by providing the photographer with the information he/she needs from the ENTIRE PRINT.

I make a full print usign the outflanking method each time wheither it be 8x10, 11x14 or 8x20 or ?. Factually speaking it is not wastfull - it is actually far more efficient than the perception of test strips as the way to proceed. Try it and look at your refuse basket at the end of a printing session. Sometimes more is actually less.

I believe that it is stimulating to shaking things up a bit in the interest of the process as opposed to saying nothing. All I care about are results.

kenh · Oct 31, 2008

Michael,
Very interesting. I had never thought about going about it this way. I also have read a lot books and have never heard about this method of deliberately exposing two sheets with one over and the other under.

There is a lot to be said about seeing the entire print. Take a look at this posted on Bob Atkins web site:

http://www.bobatkins.com/photography/technical/optical_illusion.html

The "illusion" is very pronounced in that it shows that your eyes can't really tell absolute brilliance very well, but work on relative brilliance / tones. In this example of the checkerboard if one were to do a test strip in the wrong area of the image one could easily be fooled and end up with the wrong exposure for another section of the checkerboard.

From this illusion I can believe that doing a test strip and getting one portion if the image correct, may result in disappointment when the entire image is printed. Thus I can believe that having the entire image as a "learning" tool may not be nearly as wasteful as one might think at first.

What about printing a full image at a smaller size, then moving the head up when you have discovered how to expose it and simply scaling all the exposures - would this work to save some 11x14 paper - and eat up my 5x7 stock?

rwyoung · Oct 31, 2008

I'm in favor of the full-sheet method for test prints. I try to decide which area is most important for exposure or would tell me the most, perhaps sky w/ clouds. The "strips" will then run perpendicular to that axis. I use two sheets of cardboard and just keep moving them along. Lets me infinitely size the "strip" width.

Furthermore, for the last year or so I've been doing f-stop printing using my regular, old timer and some charts I made in Excel. Working in f-stops (time wise) for printing has been great! I feel like I have a much better sense of how much to increase or decrease exposure to get the tone I'm looking for.

As far as picking a rough starting time and then bracketing around it for the test sheet, I've gone to the trouble of calibrating (at least roughly) all my shutters and lenses (large format) and my main 35mm body for developing times. This has let me establish roughly the "maximum" black time I need for producing full black from the rebate area of the film. That sets my starting point for the f-stop strips. Only have to run those tests once even if there are slight changes or variations in the film, paper or chemistry since that max-black time is just a starting point for centering the times on my test strips. To figure starting times for more or less enlargement than full-frame to 8x10 I have the little wheel in the Kodak Darkroom guide and that spins around to tell me about how to change exposure relative to print magnification. For contact printing, it is of course a non-issue so long as you always set up your light source the same way.

Also keeping better notes on things like drydown and time vs. concentration vs. paper in the toners.

Now, having written all of that, I'm seriously considering building something like the test strip printers described above. Mostly because I've been doing some printing for friends who want to do B&W but don't have darkroom access. Since they aren't "calibrated" to my system, it might be nice to make them some strips of images first. Then they pick which is best, tell me and then I shoot the print.

ic-racer · Oct 31, 2008

Test strips

This is certainly a topic which will have many varied responses. I'll pitch in my contribution, not to suggest any one do it my way, but to emphasize that techniques vary widely.

If you make a single strip with multiple exposures, you DO need to GUESS at the starting times and the step interval.

I just use a little strip of paper at a single exposure for my first GUESS. The information on that piece is enough to guess even closer with the next, without the need for the multi strip exposure (I have not done a multi exposure strip for 20 years or so).

Each little strip can go under the same portion of the image. I have tried exposing multiple strips, at once (at differing times) but, as I pointed out, this is always better after having seen a first single exposure to know the range etc. And every time, after making that single first exposure, I can guess closer for the next strip. Each strip guess is therefore based on the results of the last processed and dried strip, and this cannot be done if they are all exposed at the same time.

After a few test strips like that I am ready for a full sheet.

I adhere to some principles that make the work flow different than others. For example when printing I set the overall intensity of the image (light/dark) by finding a good exposure time (based on heat-dried prints). THEN, I work on contrast control.

I DON'T use different full frame print exposures to 'feel out' the image. I look at the negative. All the information is in the negative! I have never done 'contact sheets' since high school, and prefer to look right at the negative. Once you learn that the overall contrast of the negative is about one-half that of a print, you can pick out the subtle changes in overall density on the negative and you know that these will be twice as prominent in the print.

I still use plenty of paper to make final determinations (full sheets and individual strips as needed), but the process is initiated by what the negative shows to me.

I recently bought a 100 sheet box of 5x7 just to work on improving my printing by working with full frame 'test' exposures. I can say that my results with difficult negatives improved but I don't think I am any better of a printer. What has happened is that I took more time to get each print right! Again emphasizing there is no magic bullet or no shortcut around hard work and attention to detail.

pentaxuser · Oct 31, 2008

Go to sponsors on this site then to Darkroom Magic. Once there click on Publications and the Way Beyond Monochrome book. Once there the contents of that book is listed including articles on a number of aspects which are free of charge. There Chris Woodhouse one of the co-authors( the other is our very own Ralph Lambrecht) gives you details and measurements for an excellent looking test strip printer which allows both section by section strips of a whole neg and also moving the paper to repeat one section. It uses 5x7 paper and does a one inch section so 7 strips.

I am impressed by the generosity of both Chris and Ralph in their "for free" articles. Darkroom Magic is a great site

pentaxuser

Michael Kadillak · Oct 31, 2008

kenh said:
Michael,
Very interesting. I had never thought about going about it this way. I also have read a lot books and have never heard about this method of deliberately exposing two sheets with one over and the other under.

There is a lot to be said about seeing the entire print. Take a look at this posted on Bob Atkins web site:

http://www.bobatkins.com/photography/technical/optical_illusion.html

From this illusion I can believe that doing a test strip and getting one portion if the image correct, may result in disappointment when the entire image is printed. Thus I can believe that having the entire image as a "learning" tool may not be nearly as wasteful as one might think at first.

What about printing a full image at a smaller size, then moving the head up when you have discovered how to expose it and simply scaling all the exposures - would this work to save some 11x14 paper - and eat up my 5x7 stock?

No reason why this would not work as it would seem to me that the net increase in enlargement time necessary to go from a smaller to larger proportions would be consistent. Give it a try.

I do most of my work as contact prints so I do not have that option.

Kevin Kehler · Nov 1, 2008

This is great! Thanks everyone for the discussion.

dpurdy · Nov 1, 2008

This thread has been somewhere between interesting and bizarre to me.
I think the amount of information you need from a test strip changes as you go through hundreds then thousands of prints. I get an awful lot of information just looking at the negative. One little test strip in a well chosen spot can get you in the ballpark for density and contrast. I would certainly never buy a gadget to help me make a test strip.
Dennis

removed account4 · Nov 1, 2008

i never realized there was a special way to make
test strips, or a specialized device one could use.
i just stick a piece of paper under an area that has
a bit more information than a blank sky ...
i put the enlarger on 5 seconds, and close it down to about 4 stops from
wide open ... my device is a piece of cardboard.
actually the cardboard is kind of fancy, it has notes and stuff
written on it from 25 years of use .. and a hole in the middle of it
since i used to use it for burning and it might have some
chew marks in it from a family of mice that i had living in my walls 10 years ago
... ... now the hole is just something for me to stick my finger in as i hold the board.
if i was over or under in my guess of 5 seconds, i change the time
accordingly ... and pull another sheet of paper out of the box.

Poohblah · Nov 1, 2008

I use my school's darkroom, and the all timers are various degrees of broken. So... test strips have become a moot point, to say the least. There are now two ways to guesstimate exposure as far as I am concerned -
1. Keep the enlarger at the same height and aperture as I used for the contact sheet and start from there and make prints until I get lucky, or
2. Stop down all the way, count off using a clock instead of the timer, and hope there is as little human error as possible.
Either way, I use the cheapest paper I can find. Broken timers are pretty much the bane of my existence; they've ruined more prints than I can count (which probably says more about my counting skills than my time spent in the darkroom). I haven't yet reached the point where the total cost of ruined prints has reached the cost of a working timer (why are timers so expensive anyway??), so I don't see the need to get a new timer for the use of the entire student body.

rwyoung · Nov 1, 2008

Poohblah said:
I haven't yet reached the point where the total cost of ruined prints has reached the cost of a working timer (why are timers so expensive anyway??), so I don't see the need to get a new timer for the use of the entire student body.

Too bad about the equipment situation. If you are ok with eBay, I would suggest you get yourself one of the smaller timers. Then if you have a locker at the school darkroom you can keep it there and pull it out for your own use. I've picked up timers for much less than $50. But it is buyer-beware out there.

You might be able to find a metronome to use. At least that way you don't need to keep an eye on the clock. Just count the ticks. Change the rate from say 60/sec down to 10/sec for the longer exposures.

Then work on your best Ansel Adams darkroom curmudgeon impression.

How do you do test strips?

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