The whys and wherefores of test strips

Contributor David M. continues his look at the essentials of the darkroom with a comprehensive guide to one of the simplest but most important "tools" in the printer's armoury.

A good test strip should give you most of the information you need to produce a
satisfying print.

The Stripper

Here is one of the most encouraging things that I ever learned. There are some things that the great darkroom printers do, and we can do all of them ourselves. This is the greatest lesson I learned from watching a printer I admired. He (it was a he) didn’t do anything that I couldn’t do, and do easily. It was not like making Benedictine or becoming an MP. There were no secrets at all.

Here is what all the great printers do. Put the negative in the negative holder, at the top. Switch on the enlarger. Move the enlarger head up or down to the right place. Focus. Switch off the enlarger. Put the paper in the masking frame. Stop down the lens. Switch on the enlarger again. Switch it off again. Develop the paper and fix, wash and dry it. I could do all of that. In fact, it’s what I did already. That, believe it or not, was the lesson.

That is what everybody must do. There are other things that people do, like dodging and burning, changing paper or filter grade, using different developers, toning, bleaching, spotting and host of other refinements, but an actual, real print can be produced without them. It might not be the best possible print, but it will be a print, nonetheless.

Some items are idiot-proof. (Well, nothing is altogether proof against a really dedicated idiot.) Our first doubt will arise when we come to the second switching on and off. Easy, yes, but for how long?

It’s possible to buy all sorts of devices to decide this time for us, but we can rely on our own eyes and our own judgement.

First, we shall make some tests

Let’s assume that we are going to make a 10x8 print for no better reason than that it’s a very common size. We’ll assume that we’ve chosen the negative (clean it first) and got as far as focusing it and stopping down the lens. Most people find that stopping down two or three stops works well. Take a sheet of 10x8 paper and tear it into four 5x4 pieces. A reasonably sized test strip will avoid wasting much more paper later. Put them back into the box, emulsion side up (so we know which is the right way up when you take them out again) and close the box. Use the same paper that you will use for the final print.

Don’t forget that this is all done under the safelight.

Open up the lens fully and examine the projected image. Choose a part that seems to go from darkest to lightest, or one that is pictorially important. Switch off the enlarger and stop down again, then place one of the quarters on your chosen part of the image. It doesn’t have to line up with the sides. Set your timer (some people don’t use a timer but for me, it’s essential) to something like four seconds and expose the whole sheet. (This is my own starting point, but yours may be different.) Cover up a strip at one end with an opaque card and give your timer another click. Do this again and again, covering up an additional strip each time, until you reach the end of the paper, taking care not to move it. About half-a-dozen strips should do. (A sheet of glass or some small weights or magnets will help to keep it still.)

Develop it in your usual way, then when it’s fixed and rinsed, have a look at it in decent light.

Ideally, you will see a series of stripes progressing from much too light to much too dark with a couple that look more-or-less right, somewhere in the middle. It’s very important that both ends are wrong. If you think that one of the ends looks right, you must do it all again, because if the strips are getting better and better, just when you run out of paper, how can you be perfectly certain that the next one won’t be better still? You might believe that you can judge something that isn’t there, but it’s not true. You will simply waste more paper, time and enthusiasm. If all of them are too light, either open up the lens by one stop or increase the time to twice the time you set and do it again. If they’re all too dark, close the lens by one stop, or reset the timer to half the time.

And repeat...

I’m afraid there’s no alternative to doing it again, but the next test should give you a much better idea of the sort of exposure you are going to use for the actual print. If this is your first time, you might possibly need to do a third one, which is unlikely, but not improbable. You still have two more pieces of torn paper to play with. The next time you’re printing, you’ll be much closer from the beginning. After you’ve printed a few more of your own negatives, you’ll have a better idea of what your system prefers and have established your own convenient starting point.

We shall imagine that your second test strip has produced a strip that you think looks right. It’s possible that there are two equally attractive strips. In that case, you can, if you wish, make another test strip to decide. You must give all the paper the same number of clicks as the lighter of the two, then re-set the timer to half the time and continue to make another test strip as before to give you a more detailed choice. You’ll be very close. I usually guess. Develop and examine. Make up your mind which one you think is best. Now you’re getting so close, you might want to give a little thought to the contrast of the print, because any major contrast problem will be evident.

If the indicated time is very short, it might be sensible to stop down one more stop. A longer time will be useful when dodging and burning, when you make the final “fine” print.

Some people like to make their test strip in reverse, covering up all but the first strip and successively exposing parts of it. The effect is the same – a series of exposures at known intervals, each strip with one click more.

Now you have established a basic exposure we shall make our first print.

Take a whole sheet of paper and put it in the masking frame without altering anything else. Expose it for the same number of clicks as the best test strip. Develop, fix, wash and, if you have time, dry.

This print is the first time you will see your whole image and will act as a guide to what to do next. Examine it carefully. Facial expressions will be clearer. You will often want to change the cropping or framing a tiny bit (Leica owners may ignore this.) You might even revise your opinion on how light or dark the print should be, or how contrasty. It’s probable that one part of the picture looks just right and another part looks a bit wrong. Seeing all these things is why you made this first straight print. You are ready to go on to darkroom glory.

Not all clicks are equal

There are two advantages to using the same number of clicks for the print as you used for the test strip. Firstly, it seems to be agreed that several clicks that add up numerically to the same overall time don’t produce quite the same effect on the paper. The usual explanation is that the lamp takes a little time to warm up each time you click and may get a little hotter and brighter during a single long exposure. It’s not a big effect, but you should know about it. Not re-setting your timer saves time and removes a small source of error.

Secondly, when you come to dodging and burning, the test strip will give you a good idea of what one click more or less will do to the print. You can then dodge or burn by using the right number of clicks – much easier to remember and even record. “+2 clicks” will apply to any print you make, whereas “+2 seconds” will only apply to one specific size. You might use the back of your straight print to keep notes and diagrams for when The Tate buys a copy.

Please note: I like simplicity and this seems the simplest way to make test strips, but it may not be the best. There are other methods, which involve using progressively different lengths of exposure for each successive click, which gives a scale that’s co-ordinated with f-stop numbers. The people who prefer this method speak very highly of it. They write extensively on the web.

Some people like to move the paper along, so that each test exposure is made from the same part of the negative. This has much to commend it, particularly if it’s vital to get one small part of the image (perhaps a face) exposed correctly. It is a bit more trouble and you may need to construct a simple but ingenious device to do it.

We have tacitly assumed a normal grade of paper or filter with a normal negative and we have not mentioned dodging and burning. Your first print will give you a good idea of these things, and experience will tell you when you should change the paper grade or dodge and burn. You will often need both, but it seems sensible to settle on the right grade of paper for the whole image before deciding to dodge and burn bits of it.

Beware the trap of increasing contrast to make the print look better in the relatively dim light of a darkroom. Impact isn’t everything we want from a print, so make this decision under normal bright light. It’s even better to dry the print first, as there’s something called “drydown” that slightly changes the look of a print and may influence your judgement, particularly if the highlights are important.

If the paper grade is right, your dodging and burning will be done for creative reasons and not as a print rescue mission. Dodging and burning is another subject…

In praise of small things

Test strips are all well and good, but making test strips seems to take time, involves mental arithmetic and uses valuable paper. For a beginner, it can seem like a hopelessly time consuming ritual. We long for the moment when that enchanted shadow gazes back from the developing dish. Perhaps, psychologically, we need to suffer from a problem before we embrace the solution.

Kodak used to make a small device called the Projection Print Scale to help in getting reasonably close to proper exposure in the darkroom. It was a small sheet of transparent plastic with a pie chart of progressively increasing densities that you placed on top of a piece of paper under the enlarger.

Then you gave a single exposure to the whole sandwich and developed the resulting print. Somewhere on the pie chart would be an exposure that was quite close to the one you wanted. Not perfect, but for a beginner, or indeed, anyone faced with an unfamiliar tricky negative (all negatives are tricky to the novice) a very handy guide. I seem to recall that it was considered rather infra dig to use one.

Kodak seem to have abandoned this handy and helpful device but if you go to this Firstcall Photographic page you’ll find the very thing.