Hi, I'm new to this forum but not to large format photography, which I've done since the 1970s. Recently, I started using 5x7, mostly Ilford Delta 100 BW film in that size, but now scanned rather than wet-printed as previously

Initially, I had some difficulties getting a really in-focus scan of 5x7 film with an Epson V850 using both the included Epson Scan program and VueScan. Mostly, the difficulty arose from the lack of 5x7 film holders that would properly register with the scanner's film holder mode Aside from some wet/dry mounts that involve taping the negative to the ANR glass, I found no easy, commercially available 5x7 solutions for home processing and scanning.

I did find a highly satisfactory work-around and want to pass along the information in the hope that it will save others from similar initial hassles. Basically, I constructed my own 5x7 film holder for the Epson scanner by deconstructing and then revising a dual 4x5 Epson 4990 film holder.

Here's what I did: On Ebay, I bought a new Epson 4990 film holder that was set up to scan two 4x5 negatives at a time. I then carefully cut out the center cross-piece between the two 4x5 sections. I also cut the inner edges of the top-clamps for each 4x5 aperture. Use a very thin hacksaw blade carefully to ensure that only the minimum necessary material is removed in the saw kerf. You'll need that tight fit when you relocate the cut segment to the 7" point and epoxy it into place so that the aperture and edge supports exactly fit a 5x7 negative on the 7" side as well as the 5" sides.

Using a Dremel tool, smooth down any raised areas that interfere with negative seating and with top-clamp locking. The remaining portions of both partially-cut top-clamp pieces should close and lock normally. Epoxy part of one of the removed top-clamp segments to bridge the cut, otherwise unsupported, ends of the two 4x5 clamps, basically so that they form a single longer top-clamp and move simultaneously, supporting each other.

The cut-out section of the second top-clamp is used loose and separately as a friction fit top clamp on the second 5" edge that was part of the center section moved and epoxied at 7 inches. As a means to hold down the remaining 5" edge on the relocated center piece, that removable friction fit piece works well if your initial cuts are smooth and fit snugly.

I now had a 5x7 film holder that registered properly as a film holder of the right height in the Epson V850's central 5" high resolution scanning area and that supported the Ilford Delta 100 5x7 negatives quite flatly without requiring ANR glass on top.

Scanning with both VueScan and Epson scan produced very good to excellent edge to edge sharpness when using the makeshift 5x7 film holder at 2400, 3200, and 6400 resolutions and at most VueScan manual focus ranges from -.36 to +.74.

Using this makeshift 5x7 film holder, I judged that VueScan's manual focus seemed best at +.56. Scans at 2400 dpi and at 3200 dpi resolutions seemed to work best. I judged that the 2400 dpi scan had marginally better tonal separation on Delta 100. 6400 dpi scans had excellent sharpness but low acutance, even after strong post-processing in Lightroom. The test images, made with a Fujinon 210/5.6 NWS lens were sharp at 1:1 even when scanned at 6400 dpi inherent resolution but I did not particularly like the tonal quality at 6400 dpi.

Hence, my judgment was that the best 5x7 BW negative scans on the V850 scanner with VueScan seemed to be at manual focus +.56 and 2400 or 3200 dpi. With Epson Scan, setting the film holder setting, with or without setting 6400 dpi (which activates the high-resolution lens system), resulted in good focus.

On a 5x7 negative, 2400 dpi works out to making 40"x 56" digital prints at full native 300 dpi print resolution without any interpolation needed. Luckily, Delta 100 and the Fujinon NWS 210mm lens had ample native resolution.