Larry, yes you are right.
Time ago I was using DigiCamControl ( http://digicamcontrol.com/ ) connectig DSLR to a Laptop with a USB cable. It would be perfect to focus on the easel. The DSLR flip screen is small, good enough if focusing wide open and then stopping two stops, but it would be challenging to focus to see how the enlarging lens behaves wide open.
I've to say that I lended my dslr gear to a friend for 3 months so when another friend came with his D5100 I saw the opportunity . I was happy to see my dslr departing for a long trip but now I longing for it a bit.
The projection method would also be useful to check taking lenses, this is (horizontal) projecting the slide to some x30 the focal length distance on a DSLR without the lens, we would move the dslr to take the right groups and then we would focus conveniently thanks to tethering... This way does not evaluate field flatness but at least it removes the alignment problems in the measurements when evaluating corners.
Yes... stopping two clicks, that it would be around the sweet point, I find that focusing it's quite easy.
Also I guess that it would be easier to displace the negative than the camera and the lens. In this way we may use a tinny illuminator covering only the region that ends in the sensor, we may move the negative carrier and then illuminator and the camera would stay in a fixture. At the end an X5 works a bit in that way, lens and illuminatin stays and film displaces.
To move the glass holding the negative we may use a plain CNC XY kit, around $150:
An arduino cnc controller its really cheap, we only have to write the G code for the movements , the camera triggers and waiting time in beetween. Those controllers have switches for the engraving laser activation that can be used to trigger the camera. This is simply writting the movement instructions in a text file.
Also cheap 3D printer kits can be used, with a RAMPS board, IMHO this is the easiest way to automate the glass movement and camera operation.
I'm proficient patching 3D printer firmware, last summer I spent two weeks understanding internal Marlin firmware structure, I was tracing all the code, it was a fantastic learning because it's a very well made code. Feel free to PM if you need something about that.
Yes... IMHO it's really interesting to evaluate enlarger lenses. Printing the projection of the target slide and inspecting it with a magnifier it's quite easy, and with a DSLR it's even straighter...
Just spending an evening to test our gear at different apertures and magnifications would deliver nice information. There are plenty of gossip around about enlarger lenses, some testing (say 2 hours) would improve a lot our own criterion.
What I'm realizing is that a refined darkroom technique it's the critical factor, as many said before.
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