Extension tube or diopter?

I stopped by Samy's Camera on the way home to check on a diopter set for the 24-85mm I want to try on the S2 under the Aquatica 8" dome.

While I was there I also asked about a teleconvertor and diopter combo for the 105mm.

Long story short, I was told that a teleconvertor/diopter combination would not do any more for me than an extension tube on the 105.

I tried the setup with various tubes and it seems like I got close to 2:1 at best. Were they right or were they smoking crack? It seems to me that a 2x TC and a diopter to bring back the focus point should buy me more than what I saw with the tubes.

Also, has anyone tried the 24-85 Nikor AF-S under an 8"dome? I would rather buy one really good diopter than a cheap set of three for experimentation.

TIA!

I have tried both Nikon 24-85's behind a dome and the Tamron 28-75 behind your specific dome. They work fine.

Extension tubes should not be used with zoom lenses.

Many believe that diopters actually give better performance than extenstion tubes although many believe the opposite. Extension tubes result in loss of light, much like a teleconverter, and are harder to house.

The Nikon 105mm focuses to within 5.5" of its front element and achieves 1:1. Just tested that today. With a +1.5 diopter it becomes 4" and 4:3. Hard to believe you can use closer focus than that yet it comes nowhere close to 2:1. I believe its is practically impossible to achieve 2:1 with just a 105mm and extension tubes or diopters. If you factor in your crop factor then a +2 diopter will get it for you (about 2-3" from the port though).

Now, when you add the teleconverter it's much different. A 2x teleconvertor will give you and apparent 3:1 without diopters on your S2. No comparison between that and an extension tube.

Thanks Craig. Thought maybe I had missed something in my attempt to get educated on this stuff.

So with the 8" dome, you did not need any diopter? Should I use a "longer" extension on the dome than the 12-24 (about 5/8") extension?

I haven't used the 12-24 with an Aquatica so I don't know what it takes. I used the 17-35 extension which is about 55mm. Worked well with the 28-75 at both ends. I used it with and without a diopter. The difference is the closeness of minimum focus which, for me, was not an issue.

The D lens has a macro mode which probably would work fine without a diopter. The G lens does not and may benefit from one, say a +2. I always try going without first to see how well it works. I'd test things out for you but my Aquatica is for the Kodak and my 24-85 has some stubborn Nexus rings on it right now.