5D Lens suggestions

[Hammerhead]

I've already got it, but managed decent results using the 10-22 in the 6". Just asking for a bit of Ike-specific feedback....

 

[MarkH]

Anyone shot a 15mm fisheye in the 6" Dome? Any comments? Basically it would be a PITA to pack both ports if not necessary...

I have a 16mm fisheye behind the 6" dome, but it's on a cropped sensor so the angle of view is more like a 20mm on a full-frame sensor. A fisheye on a full-frame sensor behind a 6" dome would probably have some serious edge/corner sharpness issues. That's why I don't see the point of buying the most expensive/sharp wide lens, since as soon as you put it behind a dome port, you lose all that extra sharpness that you paid for. Most of the extra quality in high-cost lenses is in the sharpness and reduced chromatic abberations in the corners, which is then destroyed when you put it behind a dome anyways. I have a $120 Russian fisheye (Zenitar) that I use underwater and I don't think I would get much better results with a Canon that cost 10X that.

 

[f3nikon]

I have a 16mm fisheye behind the 6" dome, but it's on a cropped sensor so the angle of view is more like a 20mm on a full-frame sensor. A fisheye on a full-frame sensor behind a 6" dome would probably have some serious edge/corner sharpness issues. That's why I don't see the point of buying the most expensive/sharp wide lens, since as soon as you put it behind a dome port, you lose all that extra sharpness that you paid for. Most of the extra quality in high-cost lenses is in the sharpness and reduced chromatic abberations in the corners, which is then destroyed when you put it behind a dome anyways. I have a $120 Russian fisheye (Zenitar) that I use underwater and I don't think I would get much better results with a Canon that cost 10X that.

Finally someone who knows what they are talking about, very good input. My comments about matching the dome ports with the camera's lens fell on deaf ears.

The point being that a high quality wide-angle lens on land, will lose its value when place behind the wrong type of dome port underwater.

I myself would have a very bad day if I found out that all that money was wasted on distorted images.

http://www.scubaboard.com/forums/underwater-photography/211651-some-photos-all-c-c.html

 

[f3nikon]

Just so you know, you can't use the 24-105 F4L lens underwater. It is too wide. If you use it in with a flat port, it will vignette on the 24mm end. Its effective focal point moves too much to put it in a dome. If you use an extension to push it out so that it won't hit the dome, the focal point won't be centered on the center of the dome. This will lead to lots of distortion. I have this lens and I love, it, but it is strictly for topside use. For wide angle underwater I use the Canon 24-70 WA zoom and a Sigma 15mm fisheye under a dome port. For macro, I use the Canon 100mm macro under a flat port with a Macromate wet diopter. This covers pretty much the whole range for me.

Another very good set of information.

 

[spt29970]

I think I muddied the waters a little by not pointing out that I use my 17-40mm with an Aquatica housing and a 9" Dome. I didn't realize that it won't fit the Ike housing, which is too bad since the 17-40 is one of my favorite lenses.

On the topic of CA and soft corners, it is important to note that the biggest factor is the accuracy of the centration of the effective focal point (EFP) of the lens with the center of the dome. This can be tricky since the EFP moves when you adjust the zoom. It even moves a little as adjust the focus, which affect primes as well as zooms.

The effect of these shifts gets relatively smaller, when the lens is behind a bigger dome. That is one reason, that all things being equal, bigger domes have less aberration than smaller ones.

 

[f3nikon]

I think I muddied the waters a little by not pointing out that I use my 17-40mm with an Aquatica housing and a 9" Dome. I didn't realize that it won't fit the Ike housing, which is too bad since the 17-40 is one of my favorite lenses.

On the topic of CA and soft corners, it is important to note that the biggest factor is the accuracy of the centration of the effective focal point (EFP) of the lens with the center of the dome. This can be tricky since the EFP moves when you adjust the zoom. It even moves a little as adjust the focus, which affect primes as well as zooms.

The effect of these shifts gets relatively smaller, when the lens is behind a bigger dome. That is one reason, that all things being equal, bigger domes have less aberration than smaller ones.

So true...and this is the reason that the Nikonos 15mm lens is a tough act to follow. The Nikonos dome is a part of the 15mm lens, the dome moves in reference to the other lens elements, so the "centration" as you called, it is under Nikon's design control.

With the housed DSLR the dome is stationary and the camera's lens is moving in and out changing the focal point edge to edge. Oh boy I think another can of worms has just opened up on this taking a DSLR U/W issue.

 

[pakman]

I think I muddied the waters a little by not pointing out that I use my 17-40mm with an Aquatica housing and a 9" Dome. I didn't realize that it won't fit the Ike housing, which is too bad since the 17-40 is one of my favorite lenses.

I think Larry thought you were using your 24-70L in your housing as per your earlier post.

For wide angle underwater I use the Canon 24-70 WA zoom and a Sigma 15mm fisheye under a dome port.

 

[bigfrog23]

hay spt29970 what port extension do you use with the 24-70 2.8 L i did not think that it would work very.

 

[spt29970]

hay spt29970 what port extension do you use with the 24-70 2.8 L i did not think that it would work very.

I owe everyone a big apology. I mistyped my original post. I use the 17-40mm f/4L with a 18457 extension ring. I don't have a 24-70mm f/2.8L

The results are very good for UW imaging, but nothing compared to the sharp corners you get in terrestrial photography. Here are a few samples from my flickr page

I see fields of green, and skys of blue... on Flickr - Photo Sharing!
Jacks at Mamsa Point II on Flickr - Photo Sharing!
Manta and Diver on Flickr - Photo Sharing!
and here is my rig.
Black Lobster with Floats on Flickr - Photo Sharing!

 

[bigfrog23]

sorry to get off topic but what zoom gear do you use with the 24-70 did you make it your self or get it from aquatica. i also noticed that you are using the 9 inch dome instead of the 8 inch dome. Have you had the chance to use the 8 inch dome and is there a big difference between the two in your opinion. Besides the fact that the 9 inch dome is made out of glass instead of acrylic.