From: "Olaf Greve" <olaf_greve@xxxxxxxxxxx> -- writ in part:
Then Gary added:
The lens test page at:
http://members.aol.com/olympusom/lenstests/default.htm
already reports distortion and vignetting (fall-off) for all the Zuikos,
including zooms at three different focal lengths (at least). I'm not sure
what another testing round would prove. If there was any distortion
differences to be had, it might be among the floating element designs at a
closer focusing distance.
The idea (at least as far as I'm concerned) is not to see if you've got
your
distortion numbers right, but it's rather a case of "one picture says more
than a 1000 words
I agree. I don't expect to find something different from Gary's results. I'm
just interested in how those results may affect my photography and what I
may wish to do about it. For example, the barrel distortion at 35mm would
be likely to wreck a photo for me in some instances, but the slight waveform
distortion at 40mm much less so.
Olaf, I shot at f8, rather than f5.6, sorry. I shot at approximately 4-5 m.
I painstakingly tried to get the camera square to the wall. This may seem a
little comical. I put a stake in the center of the field of view and then
two stakes along the wall equadistant from the center stake. I pulled
strings of equal length from the outermost stakes, and where these strings
crossed, I put another stake. This gave me an isosceles triangle. I just
ran another string from the center stake along the wall to the top of the
triangle and positioned my camera squarely over this and aligned the
viewfinder circle to a pattern marked on the wall which was squared up with
the center stake.
Was there an easier way to do this?
Using an adapter, I mounted my spirit level on a Bogen QR plate and leveled
the tripod. I noticed that I got a different reading when I put the spirit
level in the shoe of my OM-4. So I have to assume that the shoe is not
perfectly parallel to the base of the camera. I checked my other bodies and
only a OM-2S that John H. CLA'ed in the last couple of years is really
level. So if you use a spirit level in the shoe, you might want to
ascertain where level really is with your camera.
Cheers,
Joel W.
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