
Signature
________________________________
It is useless for sheep to pass resolutions in favor of
vegetarianism while wolves remain of a different opinion.
WILLIAM RALPH INGE, D. D. 1860-1954
> If I were planning on shooting big stuff, the last thing I'd do is
> ditch my wide and ultra wide angle lenses.
Right. But Vandit said he has a 10-20 that would cover that. The 17-70
would be of some use for reef shots and CFWA (I like a 20 and 24 for
that, behind the dome the effective focal length is a bit shorter). But
above about 28mm, its not so useful.
I don't know about the 10-17 fisheye. I've never used a fisheye. So let
me use this as a learning opportunity. In practical terms, what's the
difference between a lens of a given focal length that isn't designated
fisheye, and one that is? Don't they have the same angle of coverage?

Signature
Art Greenberg
artg at eclipse dot net
ben bradlee - 06 Apr 2007 17:38 GMT
> I don't know about the 10-17 fisheye. I've never used a fisheye. So let
> me use this as a learning opportunity. In practical terms, what's the
> difference between a lens of a given focal length that isn't designated
> fisheye, and one that is? Don't they have the same angle of coverage?
Of or being a wide-angle photographic lens that covers an angle of about
180°, producing a circular image with exaggerated foreshortening in the
center and increasing distortion toward the periphery. The key here is the
180 degree, circular, image. You'll know when you see a picture taken with
a fisheye lens. Most pictures taken with a fisheye lens wind up on the edit
room floor. You'll have distortion using a wide angle lens but it's nothing
compared to a fisheye lens. The wide angle lens generally is specified in
polar terms. You'll experience the field of view along one axis.
VK - 06 Apr 2007 19:32 GMT
> Right. But Vandit said he has a 10-20 that would cover that. The 17-70
> would be of some use for reef shots and CFWA (I like a 20 and 24 for
> that, behind the dome the effective focal length is a bit shorter). But
> above about 28mm, its not so useful.
Yeah, I was thinking of ditching the 17-70 myself. I can get CFWA
with the 10-20 as well, and probably to better effect, as well. I've
yet to take too many decent shots with th 17-70. It falls "in
between", as far as lenses go. Also, its image quality isnt on par
with my other topside lenses, so I cannot even use it for topsides
duty.
> I don't know about the 10-17 fisheye. I've never used a fisheye. So let
> me use this as a learning opportunity. In practical terms, what's the
> difference between a lens of a given focal length that isn't designated
> fisheye, and one that is? Don't they have the same angle of coverage?
No, the fisheye has a much larger angle of coverage - at 10mm, the
10-17FE has 180 degree diagonal coverage.
I have to admit, this is a new lens and I havent quite mastered it
yet. Also, unless the big stuff comes really close, I am not sure if
the FE will be that useful either. The curvy distortion is less of
an issue underwater, but the 10-17 is just too specialized. As I only
have 4-5 days in each destination, I want to maximize the photo ops,
and I think with a fisheye, I might be setting myself up to miss some
photo ops that come in my way.
Vandit
Vandit