Re: filmscanners: Canon 4000 scanner VS Nikon LS4000

[Arthur Entlich <artistic@ampsc.com>]

I don't believe this is correct.  I own quite a few Kodak and Navitar
lenses for projectors, going back many years. Kodak originally produced 
flat field lenses which were designed for flat slides, but it caused 
Kodak's own mounted slides, (paper mounts) for Kodachrome and Ektachrome 
to look bad.  So they introduced the curve field lenses to deal with 
this.  As you mention, the curve field have the disadvantage of making a 
slide placed backwards into the tray twice as blurry on the edges as a 
flat field lens would.

They might be offering flat field lenses again now as standard since the 
advent of pretty much everyone switching to plastic mounts which float 
the slides to prevent popping.

Art

Jim Snyder wrote:

 > on 11/20/01 2:26 PM, Bill Fernandez at bill_sub@billfernandez.com wrote:
 >
 >
 >>At 9:44 AM -0500 20-11-01, Bruce Kinch wrote:
 >>
 >>>Perhaps it's worth noting that Kodak now provides "curved field"
 >>>projection lenses as standard for normal (cardboard, presumably)
 >>>mounted slides in their Carousel projectors, but their older "flat
 >>>field" design is recommended for glass mounted transparencies.
 >>>
 >>BF: If memory serves correctly this has been the case at least since
 >>the 1970's.  Curved field lenses were standard, and flat field lenses
 >>were special orders.
 >>
 >
 > Actually, I think the problem is that Kodak's original lenses curved the
 > opposite way the film did, exaggerating the out of focus edge 
effects. The
 > flat field lenses corrected this to a much improved image. Accidentally
 > showing a slide reversed often meant sharp corners, but writing that was
 > backwards, etc.
 >
 > Jim (old-timer) Snyder
 >
 > .
 >
 >