Digitizing medium format and 4x5; will my intended setup work?

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Originally Posted by Ray Marrero

Hi Alan,

Out of curiosity... were the scans performed with the supplied carrier(s) or aftermarket? Silly question?... but had to ask. Scans with my V700 and V750 were challenging with the included carriers.

Best,

Ray

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Ray, I used the V850 film holders that came with the unit. They have a glass that keeps the film very flat. I believe the V700 does not have the glass. The downside is there are two more surfaces to keep clean of dust. The scanner comes with two holders per format., So you can be setting up the second holder for the next scan while the scanner is currently scanning using the first holder. Each holder holds one 4x5. The holders have adjustments to set the height for the best focus. I checked this when I first received the unit and marked each holder with the best setting. Almost all were actually in the default setting for the best focus. The v850 has an instant start, no warm-up for the light as on the V700 or V800. The medium format 120 holder only holds two 6x7s against 3 for my V600 scanner. So you have to cut them in strips of two rather than three, which is a pain when I store them in a plastic archive sheet. I forget now, but some films need to be slightly cut on the edge to fit exactly. Frankly, I don't know what Epson was thinking when they designed this unit.

I compared the results of the V850 on one of my negatives with a friend who owns a Howtek 8000 drum scanner and scanned the same negative. The comparative results were very good. I was very happy with what I got with the V850. Here's the link to the discussion about it.
https://www.largeformatphotography.i...ghlight=howtek

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Originally Posted by Oren Grad

Telephoto lens designs complicate the discussion of total extension. But in general, starting with a lens focused at infinity, you need additional extension equal to the focal length to get to 1:1 magnification. Anyway, looking across his different lens tests I cannot make heads nor tails of his reported extension values. They must be additional extensions compared to some base value but they are inconsistent across the tests, relative to the focal lengths of the lenses he is testing. This may have to do with his using different mountings for different lenses - different combinations of tubes and bellows - but I can't find any description of his setup nor of how the base value is determined.

For those who are following this discussion, the tests we are talking about are posted here:

https://www.coinimaging.com/Lens_tests.html

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I suppose that in the absence of documentation I'll get the shortest front adapter possible and test for myself.

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Originally Posted by Peter De Smidt

For anyone who's doing scanning, I highly recommend getting one or more of Vlad's targets. https://www.film4ever.info/vtt The targets really help with maximizing the quality of your system, comparing lenses......

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Thanks for this, I'd heard of these targets before but not known where to find them.

Regarding figuring out extension, I do it empirically. I have a bunch of adjustable extension tubes. I figure out the size of the area I want to photograph in mm. I then make a guess on extension tube length, and I focus on a mm ruler parallel to the long edge of the sensor. I then move back and forth to focus. Take a picture. Now check if the distance on the ruler when sharp equals the distance I need. If the distance isn't long enough, I shorten the extension ring setup and try again. If it's too long, I add extension. A bellows can also work, but often it can't compress enough....