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Monday, July 14

DIY: Localised test strip maker


As most of you know, a test strip (below) is the normal way of working out a print exposure in the darkroom. A piece of paper is given an increasing exposure at set time intervals so that it's possible to decide the proper exposure for the negative.


This works so well that it's a practice that hasn't changed in many decades. The only slight drawback, however, is that when comparing the different densities on the test strip, you're comparing different parts of the negative. Some printers get round that by cutting up several small pieces of paper and exposing them at various times after they have carefully placed them one at a time over the same part of the negative.

For me, that's too much like hard work although I have done it on the odd occasion. Recently on the great Film and Darkroom Users website (sign up now if you haven't already done so!) a FADU "friend" revealed a way of making a localised test strip printer that is simple, cheap and effective. It was such a good idea that I asked for permission from its Canadian creator, Todd Barlow, to write about it here.

The parts required are (sizes converted from inches):

2 x cheap vinyl clipboards (1 x top, 1 x bottom)
1 x 12mm MDF base 267mm x 473mm
1 x 12mm MDF bottom rail 19mm x 473mm
8 x Pan head screws
4 x Rubber feet

A picture paints a thousand words so here are some pictures explaining how to make the test strip printer along with just a few words. The whole thing costs just a few pounds to put together but it looks very capable of doing a job in the darkroom.

Sadly, I have to inform you that my darkroom is still a mess so I'll not be doing any printing for a wee while but once I've got it sorted I'll knock one of these up and will probably wonder how I ever got along without it.

If anyone has a question about the test strip maker, either how it operates or how you make it, please leave a comment and I'll try to help you out.

The test strip printer begins life as two plastic clip boards. The second and third pics
show the finished item.

A saw-toothed design is drawn along the edge of one of the clipboards and the
"teeth" cut out. The whole thing is screwed down onto the MDF to keep
everything together.

In use, you just lift up the top clipboard, locate the first tooth with a thumbnail
and slide the paper along until it hits your nail. Lower the clipboard and make
the first exposure.

Then just repeat the procedure for each other tooth until you have the number
of test strip exposures you want.

The end result is a test strip showing different exposures for the same part of the
negative which can be a better way of assessing the required exposure.

5 comments :

Rick Scheibner said...

Here's the same thing on Flickr, with instructions: https://www.flickr.com/photos/c330shadowcatcher/sets/72157645239299596/

Joe Iannandrea said...

Also looks to be a nice way around of the age old problem of, for example, 5 x 3sec. exposure not quite being the same as 1 x 15sec. exposure.

Alex B. said...

In the book "Way Beyond Monochrome" there is a small chapter dedicated to the use and build of a similar strip maker. But I think I might like this design better. It's a bit simpler.

Paul Glover said...

This is something I plan to put together. Could have used it a couple of nights ago for a print I was making.

Barika said...

Many thanks for sharing ! Very nice idea. We will make one for sure.

Thanks