Diopter for Canon 16-35; Schneider or Aquaphot?

The minimum focusing distance of the Canon 16-35 is about 11 inches so I'm probably going to add a +2 diopter. The options appear to either the Schneinder diopter at $187 from Backscatter (plus shipping and taxes to the UK) or Aquaphot's 'no name' diopter at a far more competitive price - http://www.aquaphot.com/ShopFiles/Canon%2016-35mm%20F2.8%20+2%20dioptre%20filter.htm

I'd be grateful for any feedback on the performance of the Aquaphot offering especially if directly compared with the Schneider.

Am I being ignorant if I ask what is the problem with a B+W diopter? The Aquaphot doesn't look like an achromat, so what's the benefit? Why is the Schneider so expensive, even before import duty? It is an achromat, but even so...

... Marumi make achromats (i think the weakest is about +3D and retails for about £88 in the UK). I've used a +5D with a 105mm macro lens with some good results, although the lens is a bit chunky which may not be so good with a medium-wide lens.

Used Canon and Nikon achromats, sadly, are like gold dust, only more so...

For those that are not familiar with the term achromatic lens:

http://www.edmundoptics.com/learning-and-support/technical/learning-center/application-notes/optics/why-use-an-achromatic-lens/

http://en.wikipedia.org/wiki/Achromatic_lens

The Meltdownman

Does B+W make an 82 mm diopter? B&H doesn't show it and Marumi also shows no 82 mm lenses. For a few bucks, you can try out some cheap chinese versions on ebay. There are of course Canon versions but the largest I can find is only 77 mm so you would need to use and adapter that might not be the best course.

Bill

do you need achromats for a +2 diopter?

For that lens, I think an achromat will do much better than a plain magnifier. The lens is really nice so I would put the best diopter I could on it. But there are precious few good ones in 82mm.

Bill

Are you shooting FF? I would think it would vignette a lot at 16mm. You could go even bigger and use a step down ring. If your shooting cropped it's probably not an issue.

B&W = Schneider and if they make an 82mm it should be available here in the UK as there is a B&W importer (you could try SpeedGraphic. FWIW I've tried using achromat diopters and none achromats and have found little difference in actual performance. 11" is pretty good as a close focus distance especially behind a large dome (its measured from the focal plane don't forget) and the reduced angle of view, increased aberrations and lack of infinity focus make me wonder if its worth bothering.....

I have tested the Schneider 82mm (B+W is distributed by Schneider in North America, but these are separate manufacturers). It definitely did not improve image quality in my opinion, and actually decreased corner sharpness to my eye. 16-35 /2.8L II in Zen 230 is pretty good with no diopter.

B+W is distributed by Schneider in North America, but these are separate manufacturers.

FWIW. From Schneider's website: "The B+W filter manufacturing company was founded in Berlin in 1947 by business partners Biermann and Weber. In 1985 the merger with the Jos. Schneider Optical Works in Bad Kreuznach expanded the B+W line of products with optical filters for science and technology."

Just a trading name now.

B&W = Schneider and if they make an 82mm it should be available here in the UK as there is a B&W importer (you could try SpeedGraphic. FWIW I've tried using achromat diopters and none achromats and have found little difference in actual performance. 11" is pretty good as a close focus distance especially behind a large dome (its measured from the focal plane don't forget) and the reduced angle of view, increased aberrations and lack of infinity focus make me wonder if its worth bothering.....

You don't need infinity focus with the dome lens, so that is not an issue. Close focus would be the issue since the focus of a subject would be squeezed within the range of 3x dome radius to dome tip (for subject stuck right to the front of dome lens. If the camera film plane to dome tip of is greater than 11", then there would be no focus issues. If it is less, then you might have trouble focusing on subject close to the dome lens.

If the camera film plane to dome tip of is greater than 11", then there would be no focus issues. If it is less, then you might have trouble focusing on subject close to the dome lens.

Absolutely. BUT just where it is most needed is where performance drops away due to pushing all optical considerations to the limit.

Using the 70mm extension recommended by Nauticam the distance for focal plane to the tip of the dome is about 10" so indeed there could be issues with CFWA shots. But for me the 5D3, 16-35mm and Zen 230 combination is all about pelagics. For CFWA I'll continue to shoot with a 7D, Tokina / Kenko and DP-100 which does that job very well.

Thank you for your valued opinions Ryan, Paul, Tim and Lwang. I'll probably be happy to shoot this glass bare of a diopter but I may just take a test chart along and shoot a few 'corners'...