Nikon D70 - Nikkor 12 - 24 Zoom Blur Question

With my C-5050, the INON wide angle lens with a dome produces in-focus pictures from corner to corner when I don't zoom the camera. But as I zoom the camera, the corners become progressively more blurred.

Will the Nikkor 12 - 24 lens behind an Ikelite 5503.50 dome blur in the corners as I zoom the lens? None? A little? A lot?

I don't "think" it does. I don't actually have this lens, but from what I've read, it's top of the line.

What you describe with your 5050 is vignetting. If you have the proper dome port (and extension ring if necessary) and diopter (if necessary) you should not have vignetting.

You are getting it with your 5050 as you are zooming the lens to a distance and focal length that is not the correct distance. The wide angle adaptor is design to work with a specific focal length (and length of the camera lens).

I don't think he's talking about vignetting (but I could be wrong) instead I think he's talking about blurry corners. You know, you've seen the shots...it looks like you're flying toward the subject.

I used this lens (12-24DX) on a D100 housing in the pool. The lens doesn't blur when you zoom. I'll post some sample photos when I get off my a$$ and do the review.

Cheers

James

Not vignetting. Yes I think your right about that. He doesn't describe shadows in the corners. I do think the principal is right though. With the 5050 he is moving the lens away from the "sweet spot" that the wide angle converter is designed to work at. This degrades the image and shows up as blur in the corners. Where wide angle lenses usually show their defects.

With the proper set up of the 12-24 lens this should not be an issue. I find mine very sharp. Comparable with my 17-35 and a 35 mm camera. A lens which I found as sharp as my 18 mm primary. A lens noted for it's sharpness.

Of course no wide angle lens in a housing will be a sharp as a high quality dedicated UW wide angle lens. Such as the Nikonos 15 mm lens or some of the Subeye or Nikonos RS lenses. This is due to the limitations of housing/dome systems.

I agree with James that the issue here is blurry corners, not vignetting. For u/w shooting, the problem is often caused by an incorrectly shaped dome or, probably more often, if the nodal point of the lens is not correctly positioned with respect to the dome.

When I used to shoot with a film housing, I shot wide angle with a prime 20 mm lens and the Subal small dome. All my images had significant corner (and edge!) blur. It wasn't a problem shooting a subject in open water, but iI had to crop if there was any significant detail in the corners or the edges.

Shooting the 12-24 DX with the larger Subal dome (and a 50 mm extension ring), I haven't had this problem at all at any zoom power. The lens per se probably isn't the issue - both the Nikon 20 mm prime lens and the 12-24 DX have excellent edge-to-edge sharpness. There is also the 1.5x built in crop factor on the 12-24 (relative to another lens used with full-frame SLR with the same dome).

P.S. [quick edit after seeing Dave's post above]: The 12-24 DX is not only an IF (internal focusing) lens, but the movement of the lens when zooming is minimal. Interestingly, when zooming in from 24 to 12, the forwardmost lens element initially moves back slightly, then moves forward again as the zoom power approaches the shortest focal length. In any case, the change in position is very small. It this lens is properly matched to a dome port with the right extension ring, he shouldn't have any trouble with corner or edge softness with the 12-24 DX lens at any zoom power.

Thanks for the responses. Yes I was asking about blurring and not vignetting . And your responses are encouraging.

It looks like the lens will be fine unless the Ikelite housing/port combination results in blurring in which case I will have blurring over the total zoom range of the lens.

It also looks like a number of you got good results with the Subal housing.

James, what housing were you using in your pool test?

Also, as an aside, if you haven't seen this angle of view calculator, check it out. While these are angles of view in air, I assume they would be the same in water with a dome and thus the D70 with the Nikkor 12 - 24 lens will have an 89 degree angle of view at the wide end. Not as much as the 128 degrees I get with my INON WAL with a dome. But probably as much as I need.

http://www.sweeting.org/mark/lenses/nikon.php

Edited for some spelling.

Ikelite D100.

Cheers

James

Hi Peter,

I use the 12-24 DX lens on my Fuji S2 behind an Aquatica 8 inch dome, and I am getting incredibly sharp results edge to edge at all zoom settings. I don't know if Ikelite makes an 8 inch dome, but I believe its true that "the bigger the dome the sharper the image". Also, I do not need to use a diopter with this setup.

Say Hi to Lynn for me.

Bruce Dickson