Which +2 close up lens should I buy?

I just bought a nikkor 12-24mm, which I want to use in my Ikelite housing with 8" dome. I'm a little worried about soft corners, so I wanted to buy a +2 diopter. However, I'm not quite sure which one to buy. A 2-element +2 close up lens that suits a 12-24mm lens doesn't seem to exist. So, I'll probably suffer from chromatic aberrations. I was considering the B&W or Hoya, but couldn't actually find which one would be better? A camera shop told me the BW would be better due to a coating that reduces CA, but I wouldn't know of any coatings that could do that...thought there would only be an (hydrophobic) AR coating on the BW filter. Could anyone please advise me what filter I should buy? Any advise will be higly appreciated! Thanks!

Hi Clare

Welcome to Wetpixel! I hope you find this community really useful and helpful. It's certainly a great source of knowledge and advice.

I've used a Marumi +2 filter for 13-14 years on both a Nikkor DX 12-24 and now the Nikkor 16-35. No problem at all. Can't say I've seen a problem of CA - but, even if there was, this is usually removable in Lightroom or Photoshop.

Hi Tim,

Thanks for your reply! I'm really excited about learning new things from this community!

Does the Marumi give you sharp corners? And do you use it with an 8 inch dome as well? Do you see any vignetting at 12 mm?

I should look more into post processing! That's also a topic I hope to learn more about here.

And, just to check, I assume you have the single element Marumi filter, right? I know Marumi also has the achromat filters, but currently they are not available in +2.

Hi Clare

I have to be honest, I guess the Marumi is single element. I bought it as part of a set of 3 Marumi diopters, +1, +2 and +4. For the price, I doubt they were more than singles.

With the Nikkor 12-24 and a DX sensor I had sharp corners with an 8" dome with the +2.

However with the 16-35 lens and a 8" dome and the +2, I did not have sharp corners. I had to get a 9" dome and now all is well.

The sharp corner thing seems, to me, to be a bit hit or miss. Housing/port manufacturers will give their best recommendation on combinations which will (should!) deliver sharpness. But it's not always spot on - by my experience. For some people it works, for others they have to make adjustments. It's all a bit suck it and see....

I used B&W diopters which seem excellent. However, using a diopter, you lose some angle of view. You may find you get crisper results by not using a diopter but just cropping the picture to the angle of view you would get with a diopter, losing the soft corners in the process. I'm not aware that anyone has tested this definitively.

I redid my tests this weekend and I can live with the results I got at f8 (and f11 is actually pretty good). I can't access the photos now, so I'll post them later. I could also see there's a sweet spot in the zoom range. At 12 mm the results are still not great. In the end I decided to keep the Hoya HMC +2 filter, which in my case seemed slightly better than the B&W +2 (but the difference was really tiny). There was still quite a difference between with and without filter, so I'll have to live with the loss in angle of view and infinite focus.

Pete, thanks for your advice! Cropping would also work indeed, but I think in some cases just zooming in in stead of cropping also does the job.

Tim, the 9" dome will still be a better solution! But this one was a cheaper solution:-)

And I guess the Marumi filters in the set will indeed be single element. Marumi has the "achromat" filters as well, but as far as I know not in sets of 3. You'd probably also feel the difference, since the dual-element filters are quite a bit heavier. But I didn't find any dual-element filters that didn't give vignetting; they are fairly thick compared to their single-element counterparts.