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[OM] Zuiko zooms barrel distortion tests

Subject: [OM] Zuiko zooms barrel distortion tests
From: "Olaf Greve" <o.greve@xxxxxxx>
Date: Mon, 18 Jun 2001 14:23:37 +0200
Cc: <evoogt@xxxxxx>, <hans@xxxxxx>
Hi,

Good, I just received the results of my comparison shots to test for the
various types of distortion in the Zuiko zooms, so it's time to add some
more fuel to the fire:

The tests performed (all at f5.6, and roughly at some 5M distance from the
wall, shutter speed varied between 1/15th and 1/30th seconds):
-35/2.8 Shift (neutral position): slight barrel distortion.
-35-70/3.6 @ 35mm: slight to moderate barrel distortion.
-35-70/3.6 @ +/- 40mm: slight barrel distortion.
-35-70/3.6 @ 70mm: slight pin cushion distortion.
-35-80/2.8 @ 35mm: slight to moderate barrel distortion (hardly more than
the 35-70/3.6!).
-35-80/2.8 @ +/- 40mm: very slight barrel or wave-form distortion.
-35-80/2.8 @ 80mm: slight pin cushion distortion.

Then, what happened to "Mr. a-picture-says-more-than-a-1000-words"? Yes,
you're right: as soon as I'll have access to a scanner, I'll scan the
pictures and update the page, after which I'll inform the list of course. ;)
For the meantime, I will have to make use of words though (although I do not
intend to spend a 1000 of them on this): My findings are that I will need to
mark the frames, as the 35-70/3.6 shots are very hard to distinguish from
the 35-80/2.8 shots. After seeing these results, I think anyone's comments
saying the 35-70/3.6 performs better where distortion is concerned are void,
I see no (or at the most very little) difference between the distortion of
the two tested zooms (yes, I do realise that the long ends of the lenses
differ in focal length). Furthermore, the improvement in distortion
reduction by using the 35/2.8 Shift is not shocking either; indeed, there is
less distortion but for the typical run-of-the-mill shot this hardly
justifies switching between these two lenses for these purposes alone.

I know what I wanted to know:
-Hardly any difference between the 35-70/3.6 and the 35-80/2.8 in terms of
distortion;
-The 35/2.8 Shift performs slightly better than the zooms where distortion
is concerned, but the zooms (IMO) do not perform shockingly worse;
-Only for really critical work will I revert to using the 35/2.8 Shift over
any of these zooms when I need to shoot at the 35mm range, for all the other
shots the zooms perform satisfactorily.

So, in my opinion, the 35-80/2.8 owners can sleep again; no need to think
that a HUGE gain in distortion elimination will be had by using the Shift
lens. ;)

To be continued...

Enjoy!
Olafo


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