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#21 craig

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Posted 27 May 2003 - 05:50 PM

Tom, if you haven't seen the 15mm fisheye with a cropped frame SLR you should try to play with one. You'd really be amazed how unobtrusive it is. The fisheye also has a size/weight advantage and is far less susceptable to flare.

Eric, have you actually corrected for your fisheye distortion? I'd like to see one if you have. I've done it but it's hardly ever important.

On the D100, the fisheyes are much wider than the 14mm. Well over 100 degrees corrected.
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#22 wetpixel

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Posted 27 May 2003 - 06:26 PM

Eric, have you actually corrected for your fisheye distortion?  I'd like to see one if you have.  I've done it but it's hardly ever important.

I've done it for fun, but it hasn't been necessary yet. :lol:
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#23 tshepherd

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Posted 28 May 2003 - 06:45 AM

The fisheye also has a size/weight advantage and is far less susceptable to flare.



Than which lens Craig? The 15-30 or the 14mm?

My current plan is to get the 15-30 first, then look into something like the 15mm fisheye.

Tom

#24 craig

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Posted 28 May 2003 - 07:05 AM

I was thinking of the 14mm, although the 15-30 is fairly large. The fisheyes are are quite small and have much less front curvature than either the 14mm or the 15-30 so they are more resistent to flare than either of those.

It's easy to compare the fisheye to the 14mm. You may like having the zoom on the 15-30.
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#25 tshepherd

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Posted 28 May 2003 - 08:06 AM

Ok, so the conclusion of the issue with Sea & Sea is that the currently available version of the Sigma 14mm, which is the F/2.8 HSM is NOT the same as the "supported" version, which is the F/3.5 ZEN, so the focus gear and ports that are recommended will NOT work with the newer version. What this means is that I can either get rid of the new version of the Sigma and get the officially blessed version, or hack something together on my own, which includes getting a focus gear made and figuring out what extension ring to use (probably the Extension Ring 22). Basically, I'm SOL.

As mentioned above, I'm going to get rid of the 14mm, and try out the 15-30, to avoid the flare issues and because I personally like the idea of a zoom. I originally went with the 14mm instead of the 15-30mm because it was supported, but since that's not really the case and I'm on my own anyway, I might as well get the 15-30 (or for that matter, the Canon 17-40).

This sort of confirms something I've been thinking for a while now, which is that S&S's support for Canon has been an afterthought for the most part. Check out the list of supported lenses and you'll see what I mean. They don't officially support any of the L lenses, unless you look at the Japan website where it says they're in the process of supporting them (the US seems to know nothing of this), and some of the lenses they do support are no longer even available.

If I didn't love my Canon so much, or if the S&S ports were compatible with the Subal.....

Oh well...

Tom

#26 james

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Posted 28 May 2003 - 10:50 AM

Tom,

Whoa nelly! Hang in there.

First question: why do you need a focus gear with your wideangle lens? I always used my 14mm in autofocus and didn't have a problem. If you don't like autofocus, then set the manual focus on the virtual image on the first dive and leave it there. Seriously, try it in the pool at home. This will probably mean setting it near the close focusing distance.

Second question - extension rings. Can you just get a couple and try out the setup in the pool w/ various ring lengths? Send back the rings you don't need.

I've used the 15-30 Sigma above water and the 14mm 2.8 Sigma below water. They both have a very prounounced front element and are both subject to the same flare problems. The 15-30 probably isn't any better than the 14mm in the flare department.

What this means is that you need to make your own hood for the lens to protect the front element. This will cut your flare problems in half:

Posted Image

That's my home-made hood on the 14mm f2.8

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#27 tshepherd

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Posted 28 May 2003 - 11:05 AM

Actually, the problem is as much that I need to add extension rings to the dome port as it is the focus gear. I would have preferred a zoom lens in the first place, but had gone with the 14mm because it was supposed to work with a specific set of port parts and I had a tight deadline on the trip. Since I've got to add extension rings anyway, and because I no longer have a deadline, I'm looking to get the zoom I originally wanted.

I can probably get a couple of rings and try it out, then send them back, which is what I would have done in the first place if I'd had the time. The only downside to the zoom is that then i do need a zoom gear, which is fine.

As for the flare problems, well, I'll either make my own hood, or look into one of the flexhoods someone posted something about a while back.

Thanks for the input though...

#28 Andi Voeltz

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Posted 04 June 2003 - 10:12 AM

Eric, have you actually corrected for your fisheye distortion?  I'd like to see one if you have.  I've done it but it's hardly ever important.

I've done it for fun, but it hasn't been necessary yet. :(

Hi eric,

inspired by this interesting lense discussion and looking for our first uw-lense I went to the store yesterday to try the SIGMA 15mm FISHEYE. It was absolutely disappointing. There is definitely a very strong distortion. I have posted the two examples below, which I took at the shop. Ssecond pic is my girlfriend, but believe me she looks much nicer without the fisheye :blink: . My question is now: Is the CANON 15mm FISHEYE really such a big difference? Maybe someone could post an example, which also has straight lines in the picture. If it's convincing I am OK with spending the additional 329 EUR. Damn expensive CANON lenses,... damn but so good looking... :)

Posted Image

Posted Image
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#29 craig

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Posted 04 June 2003 - 10:44 AM

I'm no Canon expert but I doubt there is much difference between the Canon and Sigma at least in the distortion department. These are fisheyes after all. I thought the sample images were OK. The fisheye distortion is corrected easily but the point is that it is usually unimportant underwater. Notice that the aspect ratio changes after correction. I could have corrected the tilt, too, but chose not to.

Posted Image

Posted Image
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#30 james

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Posted 04 June 2003 - 12:58 PM

I took this picture w/ a 16mm fisheye. Can you tell?

Posted Image

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#31 Andi Voeltz

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Posted 04 June 2003 - 01:04 PM

I took this picture w/ a 16mm fisheye.  Can you tell?  See the diagonal mooring line - looks pretty straight to me.

VERY NICE! Indeed... With Eric's Shark pictures you don't notice much of the distortion either, but I'd like to find out if the Canon performs better than the SIGMA FISHEYE before buying. I assume you were using a Nikkor lense, James?
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