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WA + EOS 5D: which dome/diopter?


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#1 don2008

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Posted 26 January 2008 - 04:34 PM

I'm the not so prout owner of a new - and long desired for - Ikelite housing for my 5D.

I’ve just pool-tested the Ikelite 6’ dome (5503) with my EOS 5D and EF 28/1.8 and i regret to say that i'm not too enthusiastic about the results...(cornersharpnes - sigh!).

So now i’m browsing the web realizing that maybe i need diopters?

In an effort to get more satisfying results with the 5D i consider the 8’dome (w. 5510.10) for my EF’s 15/2.8, 20/2.8, 24/2.8 and 28/1.8 respectively.

Has anyone tested what diopter + Ikelite-port for the 5D with the above mentionend three non-fisheye lenses will perform the best?

Thanks
Steen

#2 Walt Stearns

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Posted 28 January 2008 - 06:24 AM

Sheen, Canon’s 5D is a fantastic camera. I own two, which I use almost exclusively for commercial work. However, there is one hindrance about Canon’s 5D and 1D’s series full frame camera bodies, and I sure Nikon’s new D3 will prove to be no exception, is that they are tough customers when comes to getting images with decent corner sharpness out of wide angle lenses.

From own experience, the lenses that I have had the most success with has been from a full frame fisheye with a Tamron 1.4x teleconverter. Matched with a Subal FE2 (7.5 inch) domeport and 10mm extension ring, corner sharpness was excellent all the way down to f3.5 in some cases. Where as shooting reef/wreck scenes 17-40 (at 17 to 24) behind even a wider port like Seacam’s 9-inch superdome, the corners really start going south below f8.

I wish could provide you with a silver bullet fix, but I think we are all still looking for that fix ourselves. Stephen Frink has had his share of struggles in regards to finding wide-angle lenses/port combinations that will deliver desirable corner sharpness with his Canon 1Ds/Seacam system.

Here is a couple threads covering the subject.
http://wetpixel.com/...topic=17980&hl=
http://wetpixel.com/...topic=18678&hl=

The one overlying fact with these lenses is wider and larger dome ports appear to be our best work around. So with that in mind, moving up from the 6-inch port to their 8-inch dome port, with either a #5510.10 port extension ring or a +1 to +2 diopter (B&W make some really good ones), I can assure you will see a marked improvement in corner detail.


Walt Stearns
www.underwaterjournal.com

#3 james

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Posted 28 January 2008 - 10:53 AM

I agree that an 8" port with +2 diopter would be a good place to start. The reason that Walt's fisheye lens performs so well is that it projects a curved image - which makes the VIRTUAL image easier for the camera to get all within the depth of field of the picture.

Cheers
James
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#4 don2008

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Posted 03 February 2008 - 08:10 AM

Thank's for all the valuable input (Q...
I will get an 8' dome.
/S