🚀 go-pugleaf

In article <1992Aug11.165800.8441@swift.cs.tcd.ie>, mahonj@swift.cs.tcd.ie writes:
> Could anyone recommend a lens of about 50 mm focal length
> optimised for 1:1 reproduction ratio ?
> 
> This would be used with a c-mount video camera with an image
> sensor size of 8.8 x 6.6 mm so a wide angle coverage is not
> important.  What is important is the ability to resolve at
> least 10 microns (preferably much better than that).
> 
> I have already considered enlarger lenses, but I really want
> something for 1:1 which is outside their optimal range.
> 
> It should have an iris, and ideally a focus mount, but this
> is not critical.  Any fitting could be used.
> 

If you really need an optimised 1:1 flat field lens check out the Rodenstock
line. They make the type of lens you are looking for, but I don't have model
numbers. However, you probably don't need a very highly corrected lens, since
you are imaging onto such a small area. Any 35mm macro lens should give a
very good image over a 9mmx7mm square in the center of the field - even a
regular lens would do quite well. 10 micron resolution is only 100 lp/mm 
which is well within the resolution of almost any decent lens as long as you
don't stop it down too far (f11 maybe) and get into diffraction issues. The
optimised 1:1 process lenses will give very wide flat fields - and you will
pay for them! I'd try something like the Nikon 55/2.8 macro to start with.
I actually use a reversed Pentax 55/2.0 lens for in an aplication similar
to yours and find it works very well (certainly 10 micron resolution when
working around f8).

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Bob Atkins  AT&T Bell Labs  email (direct)  att!clockwise!rma
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