Hi Joel (and others),
I performed my own little test of distortion with the 35-80/2.8 at 35mm.
First off: thanks for sharing the test results with us!
Interestingly enough, about a week ago I did more or less the same. This
time I decided to do it a little bit more scientifically and borrowed an
extremely heavy Manfrotto tank, ehh.. tripod ;)
Indeed, the tripod is rock solid and it is one of the high end ones (it
belongs to the photographer of the company I work for), so that was good for
doing the set-up. This time I'm certain the set-up was at least completely
leveled, and I hope I managed to get it enough in parallel with the wall.
Then, the shots I took were (all @f5.6, shutter speed approx. 1/15 - 1/30,
distance to brick wall approx. 5 metres):
1-35/2.8 Shift (unshifted)
2-35-70/3.6 @ 35mm
3-35-70/3.6 @ +/- 40mm
4-35-70/3.6 @ 70mm
5-35-80/2.8 @ 35mm
6-35-80/2.8 @ +/- 40mm
7-35-80/2.8 @ 80mm
Now, we'll have to wait until I finish the rest of the roll before I'll have
the results though, and as I'm almost through my rolls of Provia F it may
take a while before we actually get to see the results (as I don't really
feel like quickly blowing the rest of this roll of Provia F).
I hope other list members can perform a similar test, if so, please test
your zooms (there shouldn't be a further need anymore to test the f2.8 and
the f3.6 zooms, as I think your results should be similar to mine for those
lenses) at the following settings:
-35mm
-40mm
-70mm (or 105mm for the 35-105/3.5-4.5)
Please test all of them at f5.6 and at roughly a 5m distance to a brick wall
(or something else which has clearly straight horizontal lines).
Then to return to Joel's message:
I tried but didn't successfully get the film plane precisely parallel to
the wall, so I don't think these tests are definitive by any means, but I
think it is still possible to get an idea of the problem.
Yup, it seems 'em walls over there can be pretty drunk too ;)))
though focus is not as good and the lines of this wall are not ideally
straight for tests of this nature. (Live and learn.) I probably should have
focused directly on the wall, but I didn't (the main subject is the red
pump). The difference in DOF between 35mm and 40mm at f4 may be a factor of
some sort.
Well, I noticed two things in your shots:
1-You were really close to the wall, perhaps the effect is better
demonstrated when shooting from a bit further away, with more lines (like a
brick wall). In your shots I found it very difficult to really judge the
distortion well.
2-You said it: it seems the camera was not in parallel with the wall, so
perhaps that gives a false sense of distortion...
Anyone else who wants to cooperate in these distortion test comparisons? I
myself have tested all the lenses I have that include the 35mm focal length,
but there are still several other zooms that could be tested (i.e.
35-70/3.5-4.5, 35-70/4, 35-105/3.5-4.5, 3rd party lenses)...
Cheers!
Olafo
_________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|