Jonah Housing Question

Gentlemen,

I have read your review/posts of the Jonah d100 housing and have a question about the port/lens combinations you used.

James/Craig: One of the pictures in your review has a caption under it suggesting that it may be possible to use the 4 inch dome with extension for both the 60mm macro and the 24-85 zoom. Do you think that port/extension would work with the 17-35?

The reason I'm asking is because I am considering the Jonah for my 10d and will be using the 50mm macro and 17-40 zoom. Can I use one port for both or do I need to buy the flat port and a dome to accomodate both lenses.

Andi: In one of your posts you say under a picture of the Jonah system that you have the nikon 12-24 housed in the four inch port with and extender. Test shots showed no vingetting (SP?). Based upon this am I safe making the above assumption about the canon 17-40 in the same port set up? What port did you use to house your 15-30 Sigma? Results? Did you have to use diopters?

I would prefer not to have to buy, pack, haul, and then push the 8 inch port through the water if the 4 inch will do the trick...what do you guys think?

Thanks,

Not having the parts to test, my feeling is that the 17-35 would be too long to fit in that combination of port and extender. I use a 60mm extender for that lens with my 4" Nexus dome.

Optically, my smaller dome is fine with the 17-35 and the cropped sensor. That's not true of the 12-24 though. I'd work with Jonah to get different length extensions. I'm sure that's on their list to provide.

In general I recommend a flat port for macro and a dome port for wide angle shooting. You will get "compromise" results if you try to compromise. Meaning not much magnification using your macro lens.

You will need to ask Jonah about the ports and extensions. As I remember, the 17-40 does not focus as close as other lenses, so a diopter will be necessary (probably). You will also need the appropriate extension rings or the corners will not be sharp in your wide angle shots.

Also, don't confuse yourself trying to compare Nikon lenses and ports to Canon. All of those combinations have factors that make them completely different.

The only way to find the right combination of dome/extension/diopter for your wide angle lens is to try them underwater and take test shots. Usually the manufacturer does this and settles on a preferred combo. Or some helpful hobbyists do it.

Cheers

James

Just an FYI, the 17-40 focuses to 11", the same as the Canon 16-35.