A group of photographers and I, all members of the Large Format Photography Forum, are trying to design a film scanner. Ideally, we’d like to come up with an open source “how to” article that would allow someone to build the scanner themselves. We’re interested in this approach for speed and quality reasons.
Right now, there’s a huge gap between scanners like the Epson v700/v750 and professional scanners, and even those of us with professional scanner know that their time is limited. Mine, a Screen Cezanne, is about 10 years old, and service, if it’s available at all, is extremely expensive.
With an Epson desktop scanner, most of us think that they only allow about a 4x enlargement with very good quality, while pro flatbeds and drum scanners allow significantly greater enlargements, and the drum scanners do a much better job with high density materials, such as Fuji Velvia. We think that a modified copy stand style system with a dslr might be a viable option.
The idea is to build a structure that holds a dslr pointing straight down, similar to a copy stand. Below the lens there would be a thick, and hopefully very flat, piece of water white glass. A light source would be placed under the glass, and a film holder of the glass sandwich type would sit on top of the glass, which could be slid on top of the glass by a computerized x-y positioning system. The camera would be tethered to a computer with live view, and that’s how precise focus would be confirmed.
For quick scanning, the whole negative could “scanned” at once, using multiple exposures if needed for high density negatives. For higher resolution, multiple pictures could be taken, with the x-y system moving the holder on the glass plate, and these exposures could hopefully be stitched together to produce a high-res file.
We’re hoping to make this affordable, say less than $2000 not counting the dslr, easy to build, easy to modify, e.g. different light sources, lenses…; and scalable, such that people with 8×10 or larger film could scan them.
I’ve done some fast tests with a light box, my PB-4 bellows, and an 80mm Rodagon with a fixed circular aperture of about f8.5. Here’s the overall photograph, shot with a Toyo AX 4×5″ on Fuji Acros with a 120mm Super Angulon. (I know it’s not a very good photo.)
I scanned the film with a Screen Cezanne at 2400 spi.
The scanned file could produce a 30×40″ print at 300 dpi. (Actually the final shot is cropped in a bit, and so it’d be more like 26″ x 40″)
Using my very hodge-podge “scanning” setup, I got the following:
This would produce a picture 8.5×11″ at 300 dpi. On the negative the bible is about 5/8ths of an inch long.
Next is a crop of the adjusted Cezanne scan:
Here is a close up of hodge-podge scan:
And here is a closeup of the Cezanne scan:
Next is a dynamic range test. I hope that’s the right term. I was a liberal arts major:) I photographed a Stouffer 31 step step wedge on a Portatrace light box with a d200 and a 105mm Nikkor AF-D Micro lens. F-stop was f5. This is only meant to test how my equipment will see density with one exposure. The raw file was processed in Lightroom. All of the density/contrast settings were zero. I added what the eyedropper in Photoshop told me the LAB L channel values were and also visual density numbers from my x-rite densitometer.
Next is 3 exposures, 1 stop apart. I used Photomatix’s tone compressor to tone map the HDR file. Obviously, there’s a lot of room for adjustment, and you can always take more exposures.
The results seem encouraging.
One big question, and one I’m hoping you macro mavins can help with, is a choice of lens, hopefully not incredibly rare or more than, say, $1000.
Currently, I have a Micro Nikkor Auto P 55mm f3.5, various enlarging lenses, and a Nikkor 105mm Micro Nikkor 2.8D. So far, I’ve only tried the Rodagon, as I’m going to build a better support structure before doing any more tests.
Apparently, we need about 17 microns of depth of field, assuming a perfectly flat emulsion, but obviously even with a class carrier and plates we’ll need a bit more. For high quality scan, we’d probably use the system at 1:1 or so. Going much higher would lead to an even crazier number of exposures that would need to be stitched, although I suppose some 35mm Tech Pan devotees might go up to 2:1.
In doing the tests, I learned that my PB-4 bellows doesn’t like to be vertical. It works, but focusing is difficult. A lead-screw positioning system would probably be a better idea. I’m hoping that the 55mm Nikkor works out, as they are plentiful, inexpensive, and they go to 1:1 with their helical. Microscope objectives have been suggested, as well as apo macro nikkor, ultra-micro-nikkors, Luminars….be these either seem to be very hard to find, super expensive, or best at much greater magnifications than we need.
Please let me know if you have any advice or suggestions.