Quote Originally Posted by rdenney View Post
What about using an eyepiece magnifier?
In general, DSLR focusing screens are not designed for manual focus acuity, so magnifying the screen may not help much. In a 5DII you could swap the stock screen for an Eg-S, but if you intend to use a macro lens with a smallish maximum aperture, the extra snap may be lost. Critical focus through the finder also depends on precise alignment of the mirror and focusing screen with the sensor, and that can't be assumed. Despite all that, it might still help you get better results in your particular situation - your camera, your eyes, the particular originals you're trying to copy. The only way find out is to try it.