12-24MM Nikon

Got a good deal on the Nikon 12-24mm lens so I bought it. In the Subal housing (ND2) Subal say a 50 extension ring is to be used and some say a +2 or +4 diopter. Getting the camera ready I used the 50 extension and a +4 dipoter. Testing it before I packed it away I noticed that using a +4 gave it a huge rounding effect when looking through the viewfinder, so I put the +2 on and still the same effect but not as much, next I took off the 50 extension ring and used a 20 that I have, still the same. So I ended up shooting with no diopter, only the 20 extension (because it don't stick out as much) and the having very sharp pictures through the whole range, which made me happy I bought it. So a couple of questions I hope someone can answer:

1, Would that rounding effect have been canceled out in the water? )I think not)

2, The diopters, why? oh and the +4 cut my focal distance right down.

3, The extension ring, why would they say 50 if the 20 worked fine?

Thanks

Subal nowadays suggests using a 50 ring without a diopter. But I havent been able to get really good results with the 12-24. I rarely use it anymore, favoring my 10.5 instead. If you get good results with the 20 ring, please post some here.

Cor

As a Subal user I disagree with Subal's official line. Although I am very happy with the setup I use, which is a 30 or 33mm (don't remember which) ext ring and a strong dioptre (+4) with the 12-24mm behind the FE2 dome. Initally I didn't like this lens, but since switching to this set up I am now very pleased with the image quality and corner sharpness.

I'll try and post some 100% crops so you can examine image quality. But in the mean time here are a couple of examples from January (these are uncropped):

Alex

Hmm, ive got a few 33 ERs and a +4 diopter, so I think I'll give that a go today or tommorow

Cor

I use a 12-24 a lot. With my 50mm extension and the Titan 8-inch port, I got horrible edges. When I dumped the port, I got the Subal FE. Now I get real good pics still using the 50 mm extension ring. I have always shot with a +2 diopter because I love CFWA and believe that I get sharper, crisper results. Here are a couple of shots taken with my D100 and L&M Titan set-up. I'm pretty happy with it.

Alex, i assume you're using the DP-FE2, any chance you can check your ring? Im using the 33 now with a +4. Taking it to the water now.

Cor

Well I tried it and was quite happy using it this way, I did see slight blur on the corner of one but the rest looked fine, I'll try a few different ways with diopters and extention rings to see which looks the best. Here are a few from today with this lens using the 20mm extention ring and no dipoter.

12-24 @12MM

12-24 @12MM

12-24@24MM

That second shot is fantastic. Nice job.

Joe

I really like that hogfish too. You should enter that one in a few competitions. Colourful Caribbean wide angle, without divers and with such an personality filled subject are rare.

Actually send it to What's Hot - they'd love that one I'm sure!

Alex

I use the FE2 super dome with the 50 mm ring and a +2 diopter. Seems to work well.

Cor.....how was your dive with the +4?

Karl

The 12-24 with a 33mm ring and a +4 seems to be working a bit better than a 50mm ring without a diopter, but im still seeing a bit of radial distortion, most noticable in the corners. Alex, in the images you posted in this thread, did you do any lens correction in photoshop? If not, then I dont understand what im doing wrong to get that distortion. If you did, then I understand, after a minor lens correction in CS2 its mostly gone.

Cor

Hi Cor,

I didn't do any correction in my camera. But I guess as you get used to this lens you tend to frame subjects to hide the stretchy corners effect.

Alex

Alex, were the shots posted above taken at 12mm? They look more like 24mm?

Karl

Good point, Karl. I hadn't thought of that when choosing them. I suspect that they were.

Alex