> Thanks for the reminder. There were some good photos of the lens and > I've never seen one before but had I known I would not have inserted the > link. > > It is on Boz's site but no mention of it on Stan's. Somewhere I read > some discussion regarding the central area of a fisheye but my short > term memory is really short. > > > > What is known about the Pentax SMC-A 16/2.8? Any opinions? It is a > > > fisheye. On an istD would the fisheye be as extreme as on film?
My girlfriend has a 16/2.8 A fisheye and a *istD. I think they've been used together once, just to see what happens. I've used my 17/4 takumar fisheye a little more on my Nikon digitals, which have the same AOV as the *istD, although the 17 is only about 170 degrees AOV (and that's on the diagonals, remember). Distortion of the image with the fisheyes on a DSLR is a lot less than it is on a film SLR, but a lot more than your average ultrawide. It can be corrected with fairly simple hacking in photoshop (with the spherize filter) to look just a little odd. Of course, with careful use the distortion of a fisheye can be pretty subtle anyway. The field of view is pretty much what you'd expect from multiplying the focal length by 1.5--i.e. my 17 fish is just a hair less wide than a 24 on a film camera, and the 16 fish is just about even with the 24. Remember that most DSLRs (and most Pentax film cameras) do not have 100% viewfinder coverage which messes up your estimation of FOV a bit. I found the "24mm" field of view that one gets with a fisheye on a DSLR a real disappointment compared to the 170-180 degree view you get on film. I'd recommend a 14 or 15mm lens if you really want that ultrawide FOV. ANYTHING that wide, fish or rectilinear, has some real problems with the sun hitting the glass. The fisheyes seem to handle it better, and are in general smaller, lighter, and cheaper than the super-ultrawide rectilinears. On a film camera, I like the A16 fisheye a lot. I find it to be a better performer than my non-smc Takumar 17 fisheye in terms of sharpness (and of course contrast). It's a bit big and heavy and takes some babying to protect the front element. Given my needs and resources, I'd personally go for the K17/4 fisheye rather than the A16 (smaller, cheaper, easier to find) but I think the A lens is the better one. On a DSLR, I'd almost advise patience. I bought a sigma 14mm to give me back what my 20mm lens used to do on film. In common with all 14/15mm ultrawides it is big, front-heavy, expensive, has mediocre edge sharpness, and has severe problems with flare and ghosting. Compared with Pentax or Nikon 20/2.8 or 20/4 lenses it's a dog, with the convenience of a yak. Eventually they'll have to come out with 35mm-sized digital sensors (that work well and don't cost as much as some cars), or MUCH better mega-ultrawide lenses. I find it intriguing that Nikon is the only company I know of that currently offers a fisheye designed to give 180 degree coverage on a DSLR. DJE
