Which Ike port for Canon 17-40 and 5d?

I know, I know, another post on corner sharpness. I just want to find somebody who got it to work and copy what they did. :-)

I've read the threads on acceptable sharpness, and Synthetic's thread about his results with the 8" dome.

Currently using: 5d. Canon 17-40. Ike 5503.50 6" port. No diopters. (The 5503.50 is supposed to have the same placement as the currently recommended 5503.51 port, just is a little snug around the barrel, per Ryan at Reef Photo.)

I'm not that big on wide angle, but would like to make some improvement on the current setup. I understand from prior posts that decreasing aperture and adding a +2 or +4 (which should I get?) diopter would help corner sharpness. Anything else?

Is anybody using the 6" dome with this lense/housing combo with any success? I know the 8" is probably preferred.

Extension tubes?

Assume I can't afford and don't want to lug the 8" dome (all pennies being saved for Raja Ampat/Lembeh trip!). Not selling these photos, so I don't want/need to break the bank to make it perfect, but am interested in whether there is a cost effective way to get a measurable improvement.

Thanks!

Taxgeek/Susan

I have found through my own experience with both Canon 17-40L and 5D, this combo a bit hard to please when it comes to corner sharpness, which I indicate in my write up in the Underwater Journal, www.underwaterjournal.com (shameless plug, I know) on Subal’s CD5 housing for this system.

Having said that, from my own as well as Stephen Frink and Brandon Cole’s testing/toying around with this lens and Canon’s full frame DSLR bodies the eight-inch port. Even with it, you most likely still need to experiment with various diopters and extension rings to see what works. Every housing design has its own, and often-different story as to what port, extension ring, and sometimes diopter combination works with that particular lens and camera body.

As for me, I have given up using wide angle zooms like the 17-40 or 16-35 for serious wide angle scenic work and have instead resorted to doing such work with my Canon 15mm fisheye both alone and with a Tameron 1.4 telaconverter on the back.

With the telaconverter, and, 15 fisheye gives similar field of coverage with much more satisfactory corner sharpness, even at F4, than my 17-40 (at focal length of 17) could below F8. The only piece of additional hardware needed (in the case of the Subal housing and FE DP2 dome port) is a 20mm extension ring.

For me, this has worked out to be a wonderful, inexpensive (around $140 for the Teleconverter) option that works well.

Going with this option will likely allow you to go with the 6-inch dome over the 8-inch based on the more forgiving nature of full frame fisheye lens for retaining corner sharpness.

Walt,

Sounds like a great solution! I, too have gone back to fixed focal length fisheye lenses on my cropped sensor Canon dSLR cameras. Software can fix the very slight curvature produced with these cropped sensor models, although in many photos it's almost impossibe to tell a fisheye was used. But on the Canon 5D it is very apparent.

Any noticeable change if AF speed of the fixed focal length fisheye lens?

Plus did you try various brand televconvertors before settling on the Tamron? I know Tokina, Sigma and Canon (the priciest!) make nice 1.4X ones...

Any info appreciated...

dhaas

Thanks Walt! I will look into a fixed focal length lense maybe.

Susan

The main reason I chose the Tamron 1.4x (http://www.tamron.com/lenses/prod/teles.asp) is it has only 4 elements total. The Kenko 1.4 and Tamron 1.4x SP AF Pro both are comprised of 5 Lens elements in 4 groups, with the Sigma 1.4x DG consisting of 5/3. Where as Canon’s, take one look at how the lens protrudes out from the coupler will tell you why.

What I found interesting with the Tamron 1.4x model is that in addition to no apparent reduction in focusing speed, the lens also did not experience any loss in aperture value.