6 replies to this topic

[Rick]

I’m in the process of upgrading my camera and have narrowed it down to either the Nikon D100 or the Fuji S2 Pro. In looking at the different housings for these cameras, I ran across a note on the Ikelite web site that says a +4 diopter is required for zoom lenses. None of the other housings that I’ve looked at seem to have this as a requirement. I’ve never used diopters before and was wondering what if anything this does to image quality, depth of field, etc. Also, I’m curious why it’s needed.

[scottyb]

I think it is due to the fact that, with Ikelite housings, you are using a dome port and most zooms do not focus close enough without the diopter

[jimbo1946]

The diopter would only be required for lenses shooting through a dome port. My guess is that a micro/macro zoom lens would probably not require a diopter. I mostly shoot 60mm and 105mm through a flat port, and I haven't really done much through a dome port. Some of the folks who use the zoom lenses behind a dome port can give you a better answer, however.

[ikelite]

Postings by jimbo1946 and scottyb are correct. Diopter is not needed for a flat port. Following link explains:

http://www.ikelite.c...s/qdiopter.html

[Rick]

Ike, thanks for the reference - that explained it very well.

For wide angle, I am considering the 18-35mm f/3.5-4.5D AF Zoom-Nikkor. Comments about image quality, depth of field, etc. from anyone who has used this lens with a diopter would be greatly appreciated. Also, since the minimum focus distance for the lens is 1 foot, it seems to be right on the edge of whether or not the diopter is required. Again, any comments would be appreciated.

[james]

This is funny - I just answered this question on the uw-photo list for another D100 user last week.

The 18-35 requires a +4 diopter when used in the Ikelite housing. The filter ring size is 77mm and I bought a B&W diopter at David Haas's recommendation. It is good glass and doesn't degrade the image quality as far as I can tell.

Here are some shots from a winter trip to the Flowergardens (50' viz):

http://www.reefpix.o...showgall&gid=58



For topsides use the 18-35 is my workhorse lens. On the S2/D100 it has a field of view of a 28-56mm lens. It's also lightweight and not prone to flare.

HTH
James Wiseman

[Rick]

James:

Thanks. Your recommendation regarding the brand of diopter answered my final question.