I suppose I should have prefaced my opinion by emphasizing that whatever
impairment may result from filter use is relative to the end product.
I've never considered 35mm to be particularly suitable for images intended
to be enlarged beyond around 8x. If larger images are desired, a larger
format is the better tool. I have tremendous admiration for photographers
who discipline themselves to work with large format cameras in order to
obtain the best possible resolution with the least distortion.
Trying to obtain large format-like images with 35mm is rather like a sniper
chosing a .45 pistol over a rifle. Cool if he can do it successfully, but
pointless.
Me, I'm too lazy and my interest in photography simply doesn't lie in that
direction. I have to fight my instincts to treat every subject as tho' I am
still a photojournalist, grabbing shots on the fly, trying to make a moment
more important than ultimate resolution. One reason, among many, I've
embarked on this petrified wood project is to discipline my shooting habits
a little more.
But if I truly gave a rat's patootie about the project I'd be using a 4x5
view camera.
Lex
===
From: Gary Reese <pcacala@xxxxxxxxxxxxx>
Subject: Re: [OM] Hoya lens?
Date: Thu, 03 Aug 2000 20:32:29 -0700
Lex writes:
<< I doubt the use of any decently made filter (UV/skylight/haze,
polarizer, color correction and similar "clear" filters) impairs
resolution in any way. >>
My test results (and those of my repairman who owns the equipment)
consistently shows elsewise. I have resolution test charts in the
center and corners of many recent SQF test slides. I lack the microscope
to report the resolution values, but the impairment with filters is
detectable upon 24x projection. Other tell-tale signs include a shift in
color rendition (esp. from Cokinlight filters), reduced contrast, and
curvature of field changes that require a focusing shift.
Some of this was covered before you joined the list. I did vertical
autocollimeter testing on a random sample of about 48 used filters. 45
of them had obvious faults in the projection of a star image, indicating
a wide variety of optical faults, especially lack of plane parallelism,
non-liner glass surfaces, glass tilting in the mounts, and no apparent
surface coatings (strong ghost imaging). Bill has found the same to be
true in sampling from his new stock of filters. Neither of us sell lens
with filters attached and we basically say: "Buyer beware" if the
customer insists on a UV or Skylight filter for "protection."
I immediately threw the stack of 45 filters in the garbage. I retrieved
it only in case someone came along who didn't believe that filters can
degrade images. They remain on my desk for doubters.
Gary Reese
Las Vegas, NV
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