I have seen a few people using dSLRs to take photographs of their film, instead of scanning them. This makes a lot of sense for a few reasons. First it is MUCH faster. Second, it is MUCH better quality than desktop scanners can produce. Unless its a 5 figure Flextight or Howtek drum scanner that is.
The idea is great except for a small but fatal flaw. That is the fact that the camera is never perfectly parallel to the film in any of the tutorials or articles I have seen.
What happens is that someone will wish to "scan" their negs or slides with their cameras and figures out to back light the film and to shoot it with a macro lens. The film is affixed to a light box and the camera is set on a tripod and the film is copied by the camera. Simple right?
The mistake I see them make however is that the film and the film plane of the camera are never square to each other. They are off by a small amount which results in one half of the frame being in focus and the other half being out of focus. This is macro photography and the smallest error in lining things up results in a big shift in focus.
I have solved this problem with a favorite childhood toy: Legos. Yes, Legos. What I have done is to create a copy stand out of legos. The idea was to devise a way to keep the camera and the film square to each other. I set up the camera and figured out the correct distance the lens needed to be from the film to fill the frame of the viewfinder. What i needed now was a way to keep the camera at that height while being supported from the front of the lens. It occured to me that if I put the film on a light box and shot down on to it rather that from the side, I could keep it from curling with a piece of anti newton glass that I had from my scanner, and then suspend the camera over that at the proper height. I thought about having a metal tube machined for me (remember... this has to be precise, I can't make a perfectly straight cut in a brass tube.) There were things made just like I needed, a copy tube attachment that screwed into the filter ring of the lens, but these were surprisingly expensive. I wanted to do this on the cheap.
Thats when the idea hit me like a ton of (Lego) bricks in the head.
Once I knew what height i needed I then asked the web how tall a lego block is. Since it is the web, it knew. There is a site that someone made that lists all the dimensions of all the lego blocks. Very handy in this situation. Plus legos have all kinds of blocks I would need as well as the flat tiles I knew I would need to put on top of the last pieces of the tower to get a nice flat surface for the camera to rest on.
I spent some time with pencil and pad and came up with a solid interlocking design based on 2x8 bricks. I found my way to Legos website where I could order blocks individually. I got them in all black, to minimize reflections and stray light.
They arrived a few days later and I put them together I lay one brick down on the light table and the another at its base but twisted 90 degrees. this gave a long side of 10 rows, the 8 rows of the first brick finished off by the 2 rows of the second. Then I placed another brick at the base of the second brick, again turning it 90 degrees. The fourth brick was placed at the base of the third brick. At this point none of the bricks were connected. But the fifth brick was stacked on top of the seam between the 1st and 4th bricks. This locked the 1st and 4th bricks together. I repeated this pattern until i reached the top and placed my flat smooth tiles on top for the lens to rest on.
I also got some thin 2x10 tiles to use as spacers so I could place the tower over the anti newton glass as well as some extra bricks should I need them. I did, after I realized I would like a little more working space from the film. Total cost with shipping was $35.
I worked by taping a length of anti newton glass to the lightbox across its left and right sides. This allowed it to be lifted up and down with out shifting around too much. Then the film went down, and the glass over it. Using blue painters tape allows you to lift the tape easily and you do not need to cut new tape for each scan. Shooting the film this way while tethered to Lightroom made very quick work of scanning. I got 102 images captured in about 4 hours. Lightroom also let me check my exposure and sharpness very quickly. I shot all in RAW. I noticed something though... Lightroom has no Invert command like photoshop. So I had to flip the tone curve to get a positive, which worked, but all the tone controls in Lightroom worked backwards. Not a big deal, but if anyone knows a better way to do that please let me know.
I hope this encourages you to dig out your old legos and film.