Re: filmscanners: ICE & GEM Resolution Test on Nikon IV

[Mike Duncan <mgduncan@esper.com>]

Ed,

I just ran a Kodachrome Resolution target on the Nikon IV.  First,  VS7.17
shows no horizontal loss of sharpness (50% at about 500 cpi with sinewaves)
or resolution. But there is some vertical loss.  I can see lines up to 1200
cpi in vertical and horizontal directions with VS and no filter, but with
IR filter there is a null at 800 cpi in the vertical direction with 900 and
1000 cpi visible (50% at about 350 cpi with sinewaves).  Horizontal
resolution is not degraded.

With NS3.1 ICE, the vertical resolution is only visible up to 700 cpi (50%
at about 350 cpi with sinewaves), and lines look much blurrier than with
VS.  1200 cpi is visible in the horizontal direction with ICE (50% at about
450 cpi with sinewaves), but there are halos around the lines with ICE.
There are no halos with VS IR.

Is it normal for ICE & IR clean filters to perform worse in the vertical
direction (landscape) with Kodachrome 64?  The slide mounts are bowed in
the vertical direction (convex facing the emulsion side).  I rotated the
slide 90 degrees and now the resolution is worse in the horizontal
direction (landscape), so apparently the bow is not causing the problem.

The test target has black lines and gray sinewaves (20% to 80%) on a white
background.

>In a message dated 9/2/2001 5:52:43 PM EST, mgduncan@esper.com writes:
>
>> To answer the
>>  burning question, ICE degrades sharpness while VS IR filter does not, at
>>  least on Kodak Max400.
>
>Yes, this is how I designed VueScan's Infrared clean filter.  It only
>smooths the image in the neighborhood of dust spots.
>
>However, I suspect you'll find that NikonScan 3.1 filters the image
>a lot less than older versions of NikonScan on the LS-30 and LS-2000.
>
>> Both ICE and VS IR filter blur Kodachrome, but VS
>>  blurs less.
>
>VueScan occasionally sees image detail as small bits of dust
>with Kodachrome.  It's usually in the darkest parts of the image,
>where there's already little image detail.
>
>Regards,
>Ed Hamrick

Mike Duncan