ileiman

Here is a link to small selection of photos I shot with the Canon 7D on a two week liveaboard trip on MSY Seahorse, March 2011. The route we took was from Ambon to Sorong: Nusa Laut, Banda Islands, Pulau Koon, Misool, Waigeo, Dampier Strait. A total of 38 dives.
We saw practically everything from Pygmy Seahorses to Manta Rays, and soft corals of every possible color and form.



The 7D was in Ikelite housing, I had two Ikelite DS161 strobes with 12+12 inch Stix buoyancy arms, and the following set of lenses:

• Sigma 17-70 mm DC Macro OSHSM
• Tokina 10-17mm fisheye
• Canon EF-S 60mm macro

The majority of dives I ended up using my new Sigma 17-70 mm lens due to its versatility. At 17mm it is a quite a decent wide-angle, even for shooting Mantas - and at 70mm you can do some sort of macro, even pygmy seahorses are doable. With this lens I had the Ikelite 8" dome, which gives a very good image quality but is of course huge. Before this trip I shot only with the Tokina fisheye, but now I found that to be almost too wide angle and suitable only for special occasions. With the 60mm lens I didn't like at all to be forced to shoot only macro for an entire dive, when there was always the possibility to see almost anything.

Most of the time I shot with Manual exposure at ISO 100.

Has anyone used the "Sigma 17-70mm F2.8-4 DC Macro OS HSM" lens
with Ikelite dSRL housing? Any suggestions what port to use?
Note, this is the new OS-version of the lens!

The lens is 89 mm long at wide, and 131 mm when zoomed all the way out.
This would suggest that the standard dome-port #5503.80 might just work, but does it vignette at the wide?
Or the #5510.28 modular port body might just work with 8" dome?

Has anyone tried?

And yes, I do know that the official Ikelite port chart says:
"Lens diameter too large to operate in port system." But this is not entirely true. The usual zoom gear clamp doesn't work, but with little tweaking with velcro-tape you can get the zoom gear working. There are some posts in wetpixel about how to do this for the HSM non-OS version.
Diopters with Sigma 17-70
Sigma 17-70 HSM with the velcro strap
I tried this with my OS-version, and the same trick works as well.
Unfortunately the ports I have are not long enough to allow zooming the lens to 70mm, so I can't try out myself how it works, and would hate to buy a port that doesn't work properly.

I have a Canon 7D in Ikelite housing, with 2x Ikelite DS161 strobes on the Ikelite 6" strobe arms.
I do a lot of wide angle photography with a Tokina 10-17 fisheye, and have found the 6" arms to be too short. Even in clear waters it is too easy to get flare to the dome, and in dirtier waters there is always some amount of backscatter no matter how you position the strobes.
I also would like to get better buoyancy to the system. One Ike DS-161 strobe is 200 g negative in water, and the camera in housing about 1 kg, so camera plus two stobes and Ike arms have a total negative buoyancy of almost 2 kg. So far I have been using DIY floaters on the rig. The longest Ikelite arms are 9" and don't add that much to the reach.

The new ULCS (Ultralight) 2" thick buoyancy arms (DB-BL series) look like an interesting solution. However, it seems that to get any meaningful amount of buoyancy out of these arms, you would need really long arms, like 16"+16" arms on one strobe would give 0.7 kg positive buoyancy and with two such arms I would get +1.4 kg that would almost make my rig neutral. But, then with 16+16 arms I get a whopping reach of 38" = 97 cm on one side. Maybe that is already too much? What do you think?. Has anyone experience with arms of this size? I would think that adjusting arms this long would be difficult and create a lot of drag?
And then with arms this long, I would need also extension sync cords, which aren't exactly cheap either...

However with shorter arm segments you get much less buoyancy, and the arm length affects the price very little.

I would appreciate any comments and ideas.