Sorry to step on your suggestions Paul with almost the same of my own.
There's about a half hour delay in posting to the list and mine went out
before yours came in...
On 3/2/2015 6:07 PM, Paul Stamler wrote:
> On 3/2/2015 4:30 PM, William Vanden Dries wrote:
>> One drawback I have experienced with this method includes the ability of
>> the SLR to focus on the entire object. If I focus on the center of a
>> cover, the edges tend to be a little out of focus. I experienced this
>> imaging manuscript items on a large-format Digibook as well, which also
>> uses a mounted SLR. I expect this wouldn't be an issue if the objects
>> scanned on a large-format flatbed scanner. However, I find it takes much
>> less time per image using a copy stand instead of a flatbed scanner, and
>> the focus issues are relatively minimal.
> What you're describing is presumably "curvature of field", which is
> often found in zoom lenses operated at wide apertures, as would
> probably be the case in most "available light" situations. One
> possible solution would be to use a fixed-focal-length lens,
> preferably one designed for macro (close-up_ applications. Another
> would be working at smaller apertures, which would be made easier by
> brighter light on the objects being photographed. Obviously, you don't
> want to shine bright floodlights on 78s, for fear of damage; however,
> equipping the copystand with electronic flash units would be an
> alternative strategy.
> Or, of course, you could close down the aperture and use longer
> exposures, if vibration isn't a problem.
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