Canon 10-22 Soft edge

[kriptap 0]

I use the Canon 10-22 and at it's widest I get soft edges, it's behind an 8inch dome port and is about 5mm from the glass, I used an extention ring once but that pushes the dome to far out and I see the dome shade in the images, does anyone know if their is something I can try to correct this, apart from not shooting at 10MM that is. Thx.

[StephenFrink 9]

Before you go crazy trying to correct perceived flaws in the underwater image, you may wish to thoroughly test the lens topside. You may find the same soft edges occur, in which case there is no possibility of underwater correction with normal port configurations.

 

My inital tests with 10-22 indicated it is fairly soft at wide apertures, a similar artifact to that I've observed with Nikkor 12-24, and Canon 16-20 on full frame.

 

A lot of wide zoom work UW is shot at wider apertures such as F-5.6, and many of the set-ups include reef in the foreground, but behind the primary central plane of focus. Both factors will make lens performance issues more evident.

[james 0]

I agree with Steve - you may never get a "perfect" image from a wide-angle zoom like this. But you still need to configure your setup so that you get the best possible with what you are shooting.

 

To do this, you need to use the right combination of dome port and extension ring. With the Nikkor 12-24 and the Aquatica 8" dome, I tested 5 extension rings and found that the best one was a 15mm ring. I would use that as a starting point for the Canon 10-22 as it is a very similar lens. It's important to use the right extension so as to match the entrance pupil of the lens with the radius of the dome port.

 

Cheers

James

[UWPhotoTech 0]

What housing are you using this with? Once this is known an extension ring recommendation can be made.

[kriptap 0]

I'm using the Aquatica A20 and the 8 inch dome. No extention ring as when I add one the dome shade gets in the image. Above the water the lens is very sharp al round, but below the corners are soft.

[Paul Kay 65]

Most lenses with a field of view of in excess of 90 degrees wil exhibit some corner softenss underwater. In general a larger dome port diameter reduces this problem but there will still be some degree of softness in the corners and this may be exacerbated by the subject matter and placement.

 

I have an optical engineer working on this problem (at least I'll have a more definitive explanation if he can get computer time on it) but as it is a purely optical problem there does not seem to be a simple work around.

[kelpthrasher 0]

I haven't had a chance to test my Canon 10-22 lens with the 8in. dome yet due to unfavorable water conditions locally, but I've been told that 1) the extension ring is essential, and 2) it's recommended to go without even the smallest lens shade, or vignetting will occur with the lens set at 10mm. Of course, going without a lens shade could potentially cause sunburst problems in very shallow water situations.

[UWPhotoTech 0]

You should be using Extension Ring 18461 and the 18480 Fisheye Dome Shade. If you still vignet with the 18480 Dome Shade then remove the shade. The extension ring is absolutely necessary. You may also wish to consider a +2 Diopter Lens. As Stephen mentioned you will obtain the best results with smaller apertures.

[TomStack 0]

I can certainly agree with Stephen and Dave. The Aquatica Extension Ring 18461 Dave lists

is optimal, BUT we've found you MUST shoot at f11 or smaller to eliminate corner softness. The slower shutter speeds, even at ISO 100, required to do this are usually acceptable as camera

shake is minimized at 10mm. We're usually shooting at a shutter speed of 1/60.

 

Tom Stack

 

http://www.tomstackphoto.com

[TomStack 0]

Yo James!

 

I thought you got married this weekend, what are you doing posting on Wetpixel???

 

Thought you would be "honeymooning"!!!

 

Tom

[Jolly 3]

it's behind an 8inch dome port and is about 5mm from the glass

 

just to confirm: you have an 8" dome and the distance between lens front element and dome glass is just 5mm?

 

Julian

[richorn 0]

I know we are discussing the Canon here, but on my S2, with the Aquatica and 8" dome, 12-24 lens, I MUST use an extension, and no diopter.

 

The only lens that uses the dome (in my bag) without an extension is the 10.5 FE.

 

I was under the impression the two setups were VERY similar.

[UWPhotoTech 0]

I know we are discussing the Canon here, but on my S2, with the Aquatica and 8" dome, 12-24 lens, I MUST use an extension, and no diopter. The only lens that uses the dome (in my bag) without an extension is the 10.5 FE. I was under the impression the two setups were VERY similar.

<{POST_SNAPBACK}>

 

You are of course correct, if my memory serves the extension ring for the 10-22 is slightly shorter than the 12-24 ring. But when the 10-22 first started shipping we were setting up with the 12-24 extension ring AND also using the 12-24 zoom gear and getting excellent results.