60mm Macro lens with Dome Port

I couldn't find another thread on this… I am thinking of using my Nikon 60mm macro lens with a Zen 230 dome port, just for a little test. My thinking is that, for a full frame camera, the result might be the equivalent of a 47º - 50º lens. I have no idea what the corners might look like.

I think that Stephen Frink experimented with this. I was thinking that this might fill the gap I have between a 17-35 lens and the 60. Has anyone tried this and what were the results?

Fletcher

A very long time ago, Nikon F3/Aquatica, I had a special dome lens for the 60 mm port.

IIRC it droped the 60 to about 45/50 mm equivalent.

The dome radius was greater than your mini.

I never liked it as it was a pain to install.

Dinner next week? "The Globe"?

I have a 230mm dome port that I was planning to use for this experiment. I'm thinking that I don't need a port extension for a 60mm lens. Can't think why it might be a pain to install.

We leave for Yap & Truk this Friday. If this works, I may use it for some of the smaller rooms in the wrecks, like the machine rooms.

Warm water, woohoo! Love California diving but… warm water is mighty nice!

It's silly: the dome pushes small subjects away and makes them very difficult to light. Using a very large dome is optically similar to using a flat port.

I've tried a 60mm micro-Nikkor with the discontinued Nexus dome designed for the Nikon 12-24mm DX lens, which is only a small segment of a bigger dome, and it's OK, but still not as easy to light as with a macro port.

I'm travelling to Truk in a few months, and plan to use a Sigma 15mm with a teleconverter for tighter spaces behind the same old Nexus dome. I might bring a 60mm and use the same port to avoid carrying a macro port as my memory of the life on the wrecks suggests that the odd macro image would be interesting.

Fletcher:

This will work OK, but you might need a +3 diopter to get reasonable corners. I have shot the Canon version of this with a tiny dome and while lighting was a pain, the results were interesting. With a very big dome like yours I think the effect will be smaller.

Enjoy Yap and Truk, we want to see pictures when you get back.

Bill

I wonder if a flat port will be better

It's silly: the dome pushes small subjects away and makes them very difficult to light. Using a very large dome is optically similar to using a flat port.

...... I might bring a 60mm and use the same port to avoid carrying a macro port as my memory of the life on the wrecks suggests that the odd macro image would be interesting.

Hi Tim,

A couple of questions: what makes lighting harder when using this lens with a dome instead of flat? Why would using a longer lens be better in a tight space- my instinct was that the smaller the space, the wider the lens ought to be?

Charles

Charles: When you shoot a dome port, you are shooting a virtual image (not the real thing) which is smaller than the image in a flat port, (not the real thing) and this virtual image will be quite close to the front of the dome. Your working distance is small, you need to put the light where the object really is (not where it appears in the dome) so you often end with very strange strobe positions.

Bill

If you can code Fortran (or translate to matlab or excel), Keri Wilks' dad (I think) has an analysis of dome ports here

http://scubageek.com/articles/wwwdome.html

which will explain the optics.

Bill