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Re: [OM] Stylus Epic, OM-1 vs 24/21

Subject: Re: [OM] Stylus Epic, OM-1 vs 24/21
From: "Shawn Wright" <swright@xxxxxxxxxxxxxxx>
Date: Sun, 8 Nov 1998 17:54:37 -0800
On 8 Nov 98, at 12:58, Jan Steinman wrote:

> >Sure, I'd love to see a few examples...
> 
> Well, now that I've written that, I can't find any examples that don't have
> a different reason for light fall-off -- a polarizer. The 21mm is so wide,
> that when you use a polarizer with it, the polarizer has different effects
> in different parts of the frame. I've now gone to "polarizerless" shooting
> for panoramas because of this.
> 
> An example is <http://www.bytesmiths.com/photos/CoopersSpurPanorama.jpg>.
> This was shot with the 21/3.5 in portrait, with 13 separate shots, scanned
> in, then stitched together using PhotoVista. I adjusted the polarizer for
> each shot. The 21 was set for hyperfocus. This was at about 8,000 feet
> elevation, about 3,200 feet short of the summit of Mount Hood, about 2,000
> feet above the timberline, about 4,000 feet above the surrounding forest.
> There are other Cascade volcanoes in the distance, really, illustrating my
> earlier point that the distance "goes away" in a lens this wide. Another
> thing you don't realize: the peak subtends at least 70 degrees in real life
> at that location, dominating the scene, but looks rather far away with the
> 21! You can clearly see the banding in the corners when the shots are
> stitched together.

I'm a little confused by this shot - each shot should be about 60 deg. 
coverage, but it appears you've only used a narrow vertical slice of each shot, 
for a total panorama of ~ 150 - 180 degrees (? Just a guess) Was there a 
reason for using so many samples? Or was this necessary to trim off the 
"falloff" from each shot?
Also, the centre two stripes containing the sun seem to lack contrast and 
definition in the rocks. Is this flare related, or is there some other reason? 
I 
imagine with the lighting conditions, matching frames would be pretty tough. 
Did you use the same aperture for all shots?

> I'll continue looking for some non-polarizer shots with the 21 that show
> light fall-off, but the polarizer might be responsible for my entire bias
> at this point!

I have been thinking about polarizers since deciding to get the 21, since I 
have noticed some polarizer "falloff" even on my 35/2.8 under certain 
conditions. But a certain amount of this sky intensity variance is certainly 
natural - today for instance, with the beautiful weather we're having, I 
noticed 
a dramatic shift from very pale "cool" blue to a fairly intense blue when 
looking across the sky with the naked eye.

Thanks for the interesting panorama - I'm looking forward to getting the 21 
tomorrow!


Shawn & Janis Wright
swright@xxxxxxxxx
http://Zuiko.sls.bc.ca/~swright
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