I need to start printing Holga work for a show coming up in July. Up until recently I've been lazily scanning both regular 120 Holga and 35mm sprocket hole ("Sprolga") negatives for web use by just putting them directly onto the glass of my flatbed scanner. I needed a better solution for high resolution scans. I have limited access to a drum scanner at work, but drum scanning seems like overkill for Holga images. I also have access to an Epson V750, but wet mount scanning is too tedious.
I decided to try one of Doug Fisher's custom film holders for my Epson 4990, and sat down this evening to experiment. I got a single channel, variable height medium format film holder with a piece of high quality anti-Newton Ring glass. I followed the excellent instructions to get the height of the holder calibrated, which optimized the focusing for my scanner. There was a small but noticeable improvement in sharpness over the standard Epson holder.
High resolution scans of 35mm Holga negatives are now really easy -- I just carefully tape the negative to the anti-Newton Ring glass, place the glass into the holder, and scan away.
Scanning regular 120 Holga or Diana negatives also works well -- the custom holder shows a bit more of the film edge than the stock Epson holder, but part of the edge is still obscured. Towards the bottom of the info page for the anti-Newton Ring glass, I found a good solution: part of the thin inner film channel of the 120 negative holder can be removed with a sharp blade in order to scan Holga negatives all the way to the edge of the frame. By only cutting a space large enough for one negative in the center, the holder can still be used to scan regular strips of 120 film without having to tape the neg to the glass. Sweet. Plunk the negative into the holder, put the glass on top, and scan. So far this film holder setup looks like $75 well spent. There's a lot more information and detailed instructions over on betterscanning.com