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RE: [OM] lens testing - was Difference Between the 50mm Zuiko Lenses

Subject: RE: [OM] lens testing - was Difference Between the 50mm Zuiko Lenses
From: "John and Helen Wheeler" <wheelej@xxxxxxxxxx>
Date: Fri, 16 Nov 2001 17:53:32 +1100
Jim,

It just shows that great minds think alike!

This weekend I was going to do just that. Pin a newspaper on a wall and,
using a tripod, a B&W film etc take the same shot with a series of lenses,
develop the film and make some big enlargements of a mid section and a
corner for each shot/lens. I'd make all exposures the same, keep distances
identical and even use the same film in each camera. Perhaps even use flash
to minimize effect of changing sunlight etc.

I recently came by an OM-20 with a 35-70 f4 and wished to compare it for
sharpness with my 50/1.8 together with an Elmar 50mm and a Mamiya-Sekor
50mm.

Maybe it's not all that scientific but surely it will give some idea of the
sharpness performance of each lens.

Regards,
JohnW.

-----Original Message-----
From: owner-olympus@xxxxxxxxxxxxxxx [mailto:owner-olympus@xxxxxxxxxxxxxxx]On
Behalf Of Jim Brokaw
Sent: Friday, November 16, 2001 3:23 PM
To: olympus@xxxxxxxxxxxxxxx
Subject: Re: [OM] lens testing - was Difference Between the 50mm Zuiko
Lenses

on 11/15/01 2:10 PM, ll.clark@xxxxxxxxxxx at ll.clark@xxxxxxxxxxx wrote:

> Almost any professional photographer will tell you that the only
> reliable way to test lenses for your own use is to test them yourself.
> This is an annoying, time-consuming and demanding task. Virtually all
> consumers lack the patience to do it. Since there is no consumer demand
> for such data, they are not
> produced.
>
> QED.

I was thinking about this recently, and - without getting too involved -
what is a good way to test a lens? I'd welcome comments on my proposed
procedure:

I thought maybe I'd tack an opened flat newspaper page up on the wall (in
sunlight) and set up the camera on a tripod. Vary the distance i.e. close
(minimum focus) medium (6-8 feet?) and distant (15-20 ft?) and maybe a
couple shots further out. Or should I use some multiple of the lens' focal
length? Then shoot (slide film) a range of exposures varying aperture and
shutter speed, being careful to minimize camera vibration on each shot.

Project the slides big, focus the projector carefully, and then go up and
look close at the projected image. Being black and white (approximately) it
should show some contrast information as well as sharpness.

I know there are test charts you can buy, but I'm not getting that obsessive
or scientific about it. I'm just curious enough to invest a roll of film and
developing to see what I can see.

I recently got a Vivitar 90/2.5 macro lens, and I want to see if the lens'
reputation is justified...
--

Jim Brokaw
OM-1's, -2's, -4's, (no -3's yet) and no OM-oney...



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