Re: Advice on Microscope

From: Sandy King <sanking@clemson.edu>
Subject: Re: Advice on Microscope
Date: Sun, 29 Feb 2004 10:41:14 -0500

> I imagine that something on the order of 40-80X would satisfy my
> needs. They key for me is not a lot of magnification but the ability
> to use the instrument for photography.

I suspect you might want to use at least 40x objective and 10x
eyepiece if you want to visualize grains. With 10x obj and eyep, I see
millions of grains in the view and it's hard to get real feeling of
their shape or distribution unless there are distinct patterns from
the target image. If you use scanner, I suppose DOF of scanners are
too deep and they can't selectively focus on just grains, and the
grain shapes may be blurred by film's surface pattern, etc. even if
the nominal DPI resolution is high enough. With microscope, I can look
at very thin layer because of shallow DOF.

When I looked at HP5 Plus and Neopan 400 exposed and processed in the
same metol-ascorbic acid developer to same CI under light microscope,
I could see one film had more clumped grains than the other. However,
I looked at one sample each, and I don't know if what I saw applies to
other emulsion batches so I won't say which is which. (For this, I
think I had to use 40x and 100x immersion objective. 100x obj could
convince me that two grains were in contact or not, though not as
convincingly as EM could. Lower mags didn't give me much more than what
I can see in prints.)

Anyway, if you want to use different tools to evaluate image making
material, it introduces another problem of how to interpret and relate
the results with real world situation unless you carefully break down
the initial problem to pieces which you answer with specific tools
(like microscope), in a way the big answer can be put together from
little pieces.

If you are concerned about comparing graininess of developers X and Y,
why do you worry if you can't see the difference in prints?

--
Ryuji Suzuki
"Reality has always had too many heads." (Bob Dylan, Cold Irons Bound, 1997)