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Re: [OM] Best FILM for lens testing?

Subject: Re: [OM] Best FILM for lens testing?
From: Ken Norton <ken@xxxxxxxxxxx>
Date: Thu, 2 Jul 2009 16:01:09 -0500
>
> Due to cost I'd like to make it in B&W -- CA would cause blurring, anyway.
> I
> can process B&W by myself.
>

Lens testing I've done on B&W has been done with Ilford PanF and Delta 100
processed in Ilfotec DD-X.  I prefer Delta 100 as the contrast is held
better at the edges giving me better clarity of the USAF test chart
line-pairs.  The PanF has slightly more resolution, but also more grain
scattering which makes the edge-detail a little mushy.

However, some high-acutance developers will allow the grain to "migrate".
This has the effect of sharpening the edges--not unlike USM in the digital
world. This will make it easier to count line-pairs.

You can also use Ilford FP4 film in DD-X. This thick-emulsion film has
tremendous "migration" characteristics which give the lens tests a
definitive yes/no interpretation of the line-pairs.  It mgiht not be the
finest-grain film (about 2-3x that of PanF and Delta 100), but it is
generally less expensive and still quite good.  It's fun, because when you
see image details that are down to a single grain-clump you are assured that
the lens resolved as good as is practical.

Don't use Velvia or Provia because lateral-halation will kill the line-pair
resolution.

AG
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