Hi,
Has anyone used the Seatool, D300 with 12 - 24mm, dome port combo?
My images are a little soft (although my 10.5 is tack sharp) and I figure I need to use a close up lens (say + 2) but the lens is so close to the port I doubt there's enough room between the lens and the dome.
Cheers.

The Nikon 12-24 is notorious for soft edges. I've never heard of any combo of ports and diopters that fully address the problem either. I love the 12-24 above water but long ago gave up on it underwater.

Sorry!

Dave

I am happy with the performance of the 12-24mm in my (non Seatool) system. However using this lens behind - close behind a dome without a dioptre is asking for soft corners. Ideally the lens should be used well back away from the dome - as a guide a couple of inches back and with a dioptre.

I am not familiar enough with the Seatool setup to be able to give exact recommendations. But I am sure that with the right setup you will get the results you want. These two images were taken with the 12-24mm and dioptre and I am happy with their sharpness.






Alex

The designers concentrated on producing a rectilinear lens without curvature of field. Alas, curvature of field is exactly what we want with a wide-angle lens behind a dome port so add a strong dioptre lens to bugger up the designers intentions and you'll get sharp pictures across the frame!

Alex-

which brand/model of diopter, and strength, did you use? I was very underwhelmed with the 12-24 using a B+W +2 diopter, behind a Seacam 9" dome port and 35mm extension ring. Single element diopter? Dual? Which brand?

Thanks for your input.

Brandon Cole

Hi Brandon,

In pain today, hurt back so no long replies today.

I prefer slightly stronger dioptres than theoretically ideal for a certain dome. I also use single element ones. I think that both factors help in the fight against field curvature.

I am sure that the shots above were taken with a single element +4.

Alex

Alex,
What length extension do you use?
Take care of the back. Get a good massage!

Alex,

Back pain from lifting that heavy D3 housing and your weight belt during your recent cold water trip? Seriously though, heal up quickly. Backs suck. I too have had (and no doubt will have again) back trouble for the last five years.

Thanks for your reply. I believe all of the B+W diopters I have are single element, but need to confirm. And maybe I'll try a +3 or +4 if I ever work up the guts to try the 12-24 again.

Same strategy (strong, single element) for the 17-35 2.8? I liked this lens back in the film days, then sold it, now own it again (but haven't used it underwater yet on DX) with a Nikon d300/Seacam. I've decided to confuse my life again by shooting both Nikon and Canon systems, again. I still have my aged Canon 1dsmk2/Seacam setup.

Anyhow, thanks for your help. And nice new pictures!

brandon

Thanks (everyone) sorry for the earlier bad post. I will push on with the 12 - 24 (the 10.5 is great but in clear water it is often good to get a little further away). Seatool are sending me a 30mm extension ring and I will try +3 & +4 diopters on my next trip north from Cairns to Raine is. I also hope to try out the 105micro (much further away!) Great pix Alex, no doubt with one of those very clever filters..
Cheers, Eric.

Hi all

I am also struggling with my Nikon 12-24 and soft edges. This lens cost me a lot of moola so I am determined to get it right. I have added an extension ring to my 8" dome port but this still doesn't help much. Now I want to try the diopter option. Could some one please suggest a brand of diopter and also a website where I can buy one.

Big thanks

Hi,
are you also using a nikonD300 in the seatool housing?
I haven't looked for a diopter yet, but don't expect any problems as it is not a 'special' item for u/w use. I have bought them before and pretty much any photo store will have them at reasonable prices.
I am not surprised that you have no luck with the dome and extension but no diopter.
As far as I know, the idea is that the dome creates a virtual image of the subject close to the front of the port, and it is this that the lens needs to focus on, (not the subject), so the problem is: the lens can focus down to 0.3m but the virtual image is located closer than that. So the diopter reduces the minimum focus distance to a point closer to the lens than the virtual image and presto! Well anyway when I get the extension ring and diopter I will test out that theory! My 10.5mm works just fine with the port and it has a minimum focus distance of 0.14m...
Let me know if you get a diopter and how it works out...
Cheers, E.

Nikon D300!!! Only in my wildest dreams could I afford one of those . But I persevere with my little Nikon D? (am too ashamed to admit how low that number is). I have a sea&sea housing by the way. Any way, thanks for the reply. I was told that the extension ring alone should sort out the soft edges, but clearly I need to do get the diopter too. Please post some images when you've got the extension ring + diopter set up going. I will do that same. By the way, you going to go for the +4 diopter?

Ciao

I purchased the Seatool D-300 but set it up only for macro with a 60 and AF105. I was tired of that back pain I was getting from a D-200 in an Ikelite case. I still have the D-200 setup for WA and I use a +4 diopter even with the Ike 8" dome.