How to use a print scale.

A print scale, sometimes also called a step wedge, is a darkroom tool that can make your workflow more consistent and efficient. A step wedge is functionally similar to a print scale but has a slightly different purpose.

Normally to determine the proper exposure of a print you make a test print. This is done after you frame, focus, stop down the enlarger lens, and turn off the not-safe lights. You’d then get a piece of light sensitive paper and a board. You’d set the timer for 1 minute and cover all the photo paper with the board except for a small strip. Turn the enlarger on with the timer and uncover more of the paper every 5 seconds. Process the paper normally and you should be able to determine a good starting exposure from the strip you like the best.

I made my very first prints this way, it does work, but I don’t think it’s the best way. This method has some drawbacks. The first is that it uses a whole sheet of paper which is usually more than the method I’ll tell you about in just a minute. Secondly it’s prone to human error, the strips may be uneven, the timing may not be precise, you might run out of room towards the end or you may have too much room with very thin strips. Finally if you’re print has an important focal point like a face in a portrait the best strip on may not fall on the most crucial part of the image.

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There are other methods of making a test print in strips and by hand but they all have the same principle behind them. Reduce, or increase exposure in 5 second intervals.

Making test prints by hand does take a little getting used to and it’s a necessary part of printing. There is a way to remove this hurdle in printing while addressing many of the pitfalls of hand made test prints.

Let me introduce you to my print scale!
Kodak Step Wedge

There are variations of this: some are more precise, others are for determining densities of processes, etc. This is the one I’ve easily made over 100 prints with.

Here’s How it works:

Each piece of pie increases in density a half stop from almost clear to almost opaque. The numbers in the circles are seconds. This print scale is about 4×5 so you can cut a 8×10 sheet into quarters and use 75% less paper in your test prints. I make a mental note of where the important part of the image is on my easel. Then, under safe lights, put the scale over your photo paper and place the pair over the most important part of your image. Expose this test print for a full minute, then process it normally.

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When the test print has been in the fix for half it’s fix time, you can turn the lights on (assuming you’ve put your paper away) and read the correct exposure off the wedge you like. If the best wedge is a smidge too dark and the adjacent one a tad too light, you can split the difference with an exposure in the middle.

Here’s what a test print using this method looks like:
Step Wedge Test Print

For this print I couldn’t decide between 16 and 12 seconds so for the final print I exposed it for 14 seconds.

 

  • Using this method uses less paper if your printing 8×10 or bigger.
  • It removes much of the human error prone part of making test prints.
  • You can precisely place the print scale to see how exposure effects the most important element of the image.

 

 

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As awesome as this method is, you may need to do some troubleshooting from time to time. After focusing and framing, I usually stop my enlarging lens down two stops. If the lens is a 80mm/5.6 I’ll stop it down to F11 for the print scale. If it’s a 2.8 stop it down to 5.6, and so on.

If you have very over exposed or developed negatives on a thick base film like Foma there may not be a wedge you’d want to print or the exposure times may seem on the long side.

Here’s a test print that I’d open the lens one stop and redo:
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Likewise if you have an under exposed or developed negative on a thin base two stops may not be enough and you may need to close the enlarging lens another stop or two. Generally you don’t want to be choosing between two or three seconds. I try to keep my exposures in the 4-15 sec on range.

Here’s what a test print that is too dark looks like and the solution is to use a smaller (higher number) aperture:
Test print too darkTweet this guide!There is one drawback to using a projection print scale like this.

Remember how I said it’s about 4×5? Well that’s it. That’s its fixed size. This is great for 4×5 through 8×10. It gets a little tricky at 11×14. At 16×20 it’s 1/16th of the image size. There’s a lot of space not being test printed on large prints. It is possible, and maybe someone makes 8×10 print scales, but printing big is tricky with just a little scale. So far, it hasn’t been reason enough for me to switch back to manual test printing.

If you want to try this technique out, head over to FreeStyle Photographic Supply and pick up a print scale for just $10 +shipping. Oddly enough, used print scales are usually just as much or more.

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