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WSDiver

Domeport for Ikelite & Canon 16-35mm?

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I'm getting ready to order the Ikelite housing for my Canon 5D and I've got a question with regards to the domeport I should get. I currently have the 16-35 Canon lens, and will start with that (I'm already way over budget with regards to toys!). Most of my diving is on wrecks in the St Lawrence River, and very soon I'll get the Canon 14mm wide angle. According to the Ikelite website, the 16-35mm can use:

 

- 6" domeport (#5503.55)

or

- 8" domeport (#5510.81)

neither is listed as "recommended"

 

Now that putative 14mm can also use

- 6" (#5503.50 - note the difference in part number!)

or

-8" (#5510.82 ) which is recommended.

 

I'm inclined to go for the 8" dome port. The difference between 5510.81 and .82 is the body. Therefore, my questions are basically:

 

- which is the better domeport for the 16-35? The 6" or 8"?

- can I get away with using the same 8" domeport body for the two lenses or will I need one of each?

 

WSDiver

Pointe des Cascades, Quebec, CANADA

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While I have haven't tested this, based on inferences from other manufacturers port charts, I think both lenses may work behind 5510.82, and if that combination doesn't vignette w/ the 14, I would assume it yields better optics.

 

It might be a good idea to buy both extensions and test them out in a pool. A +2 diopter also sharpens up the corners on the 16-35, but isn't required.

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Don’t know about Ikelite port length and what port combination physically fits that lens. But from optical point of view, I would definitely go with the 8†dome for such a wide lens because it is the better optical match. James has done pool testing with a Canon 10-22 and 8â€/6†domes:

 

http://wetpixel.com/i.php/full/canon-10-22...te-8-dome-port/

 

16-35 on 50D is as wide as the 10-22 on a 20D.

 

Julian

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After extensive testing with the 16-35 on the 5D with various combinations of both the 6" and 8" domes with +2 and +4 diopters, I have concluded the following:

 

Optically, the 6" and 8" are similar, with the 6" causing more barrelling. Also, adding a +2 diopter helps a bit on both ports. The 8" is great for over-under shots.

 

I have found the 16-35 to be a very difficult lens to house. Even at it's best, the outer 10-20% on the long edges are blurred. Has anyone found a way to get sharp edges with the 16-35 on a full frame camera (with any housing/port)? I'm not certain if it's worth housing it...

 

I am seriously considering trying a 17-40 as I have heard people get better results underwater with that lens. Another item which is high on my 'must get' list is a 15FE which I have also heard produces excellent results.

 

(A quick note for 1.5 crop camera users, the crop will resolve the blur issue.)

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The 16-35L easily produces sharp images on a full frame camera. What you are likely seeing is not lens softness but DOF issues. When you shoot the 16-35, what do you focus on? The subject or the closet object in the frame? Depending on your lens' aperture, and due to the huge angle of view of the 16-35, you may get items in the frame that are simply beyond that given aperture's DOF...

 

I use a +4 diopter on mine with a 6" port with excellent results.

 

I'll post some pool shots tomorrow.

 

s.

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The 16-35 does produce good edge to edge results on land. Underwater, I'm seeing refraction blurring at the edges. It is not DOF blurring.

 

The +4 on the 6" does produce the sharpest results, but I didn't like the barrelling it added. Admittedly, barrelling isn't much of an issue underwater.

 

This picture is an example of the blurring that I'm referring to

(16mm, f/5.6, 8" dome w/+2 diopter):

post-1996-1152307452_thumb.jpg

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Well, your corners definitely look softer than the ones I got with my 16-35L with a 6" Subal dome and +4 diopter.

 

S.

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