on 9/9/02 11:19 AM, Daniel J. Mitchell at DanielMitchell@xxxxxxxxxxxxx
wrote:
> Not owning a shift lens, I can't really comment, but I'd guess that if
> you're trying to take pictures of buildings, a 24 shift will be
> "effectively" wider than a normal 24mm, because you could take a shot of the
> top half of a building, shift it, then shoot the bottom half without all the
> awkward perspective issues that normally get in the way with that type of
> thing. Sure, it's not quite the same as a genuinely wider lens, but it's
> worth thinking about.
>
> As for the 17mm, that's a 93 degree field-of-view (horizontally), the 24mm
> is 73 degrees, so it's a fairly substantial gain. From what I remember of
> Paris, though, you can get a fair distance away from most of the things
> you'd want to photo, so it's not going to be as critical as it would be in
> London where the most impressive buildings can be in really narrow streets.
> That said, not taking one is a good way to guarantee you'll need it..
With the 24-Shift you can shift left, take a pic, shift right, take a pic,
and there is about a 700verlap in the middle. The net effect when you
stitch the images is about a 100-degree horizontal view, which is roughly
equivalent to the 18mm wide-angle's HFOV. Of course, if you do this the
vertical angle of view is still only that of a 24mm lens.
The vertical shift allows capturing a building from bottom to top without
tilting the camera causing converging verticals, but then the horizontal
angle is that of a 24mm. You can simulate this by shooting without tilting
the camera with the 18mm and then cropping the bottom portion of the
negative, but you're losing detail/quality along with the cropped portion.
Note that you -can- shift both horizontally and vertically at the same time;
shift to all 'four corners' and you're essentially getting a wide-angle 6x6
image on four 35mm negatives. Of course you really need to do all this
shifting with the camera on a tripod for the best results... which is where
the 18mm lens comes in, as they are hand-holdable.
--
Jim Brokaw
OM-1's, -2's, -4's, (no -3's yet) and no OM-oney...
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