Do I need a dome port? I think so but for what?

Hi There,

Just a quick introduction for you to understand my question. Underwater I used to shot with a G11 and out of the water with a D700 (with 14-24mm and 24-70mm). Before putting the D700 underwater I am looking for some basic information and my first question is about dome port. With each housing there are a lot of dome ports (6", 8" or 9.25" and even more). Do you have an explanation for dummy?

Thanks
Yvan

Decide on what lens you want with your underwater camera, then the port choice will become more obvious.

A bigger dome port is easier to scratch, better for over-under shots.
A smaller dome port is harder to scratch (less surface area at risk) and easier for travel (smaller).

For each camera/lens/housing combination, there are only a certain number of port options. Decide on your camera/lens/housing and the port choices will be obvious.

Specific details, I know not.

A flat port does not correct for the magnification factor caused by water. So for any given lens angle it acts like magnifying glass, reducing your angle of view. That's also why you see a narrower angle of view with your mask underwater vs. at the surface.

A dome port gives you a wider angle view because it is itself a lens. It compensates for the magnification of the water column you are looking through. This results in more light getting to your lens as well.

The chief factor I think you want to consider is if you shoot macro subjects or prefer wide angle images.

Then decide which lens you want to use, macro or wide angle. Then you will have to purchase the proper length and diameter port body and the desired port itself, dome or flat, to use with your lens.

By and large one does not use much zoom with underwater photography.

A smaller dome might be the best compromise if you you want both macro and wide angle capability. Especially taking into consideration what Doc Harry wrote. A flat port with a wet mount wide angle accessory lens may the another option.

exposure:

Hi There,

Just a quick introduction for you to understand my question. Underwater I used to shot with a G11 and out of the water with a D700 (with 14-24mm and 24-70mm). Before putting the D700 underwater I am looking for some basic information and my first question is about dome port. With each housing there are a lot of dome ports (6", 8" or 9.25" and even more). Do you have an explanation for dummy?

Thanks
Yvan

Click to expand...

Hi Yvan,

Hopefully you havnt bought an Ikelite housing as your lenses will not fit into any of their dome ports. They are either took wide or too long.

Which housing do you have for the D700? I am presuming an Aquatica as they make the 9.25 inch mega dome.

Choosing a dome size can come down a few choices. Cost, suitability to your lens/es, travel, under/overs, and generally how you shoot.

Here is a review i quickly found on the internet to give you more of an idea: Cameras Underwater: Interchangeable Lens Ports.

I love my 8 inch Acrylic dome as it suits my shooting. I will get the 9.25 one day but it cost like $1500. I also am currently playing with the 4 inch (100mm) Aqautica mini dome but unfortunately its only suited to DX fisheyes like Nikon 10.5mm and Tokina 10-17mm.

Hope this helps,

Mark

The big reason for using a dome port isn't wideness but rather
sharpness. When looking at an air/glass/water interface at an
angle there's a lot of chromatic aberration, which makes the corners
really fuzzy. Looking straight through, you don't have the problem.
With a dome port PROPERLY PLACED, the front entrance pupil of
the lens is at the center of radius of the port, and so the lens looks
straight out through all parts of the port.

Longer lenses (e.g. 60 mm macro, etc.) are close enought to
looking straight through that the chromatic aberration isn't a problem.

That, and the metal part that holds the class would get in the way
of wideness with a reasonably wide-angle lens.


Chuck

People often get smaller ports for fisheye lenses so they can approach subjects closer for close-focus wide-angle photography. Larger domes are often used with non-fisheye wide-angle lenses, for sharper corners and better over/under shots. Hope this helps, good luck! There's a couple great underwater camera stores in Singapore, you should stop in one of them and say hi.

I would concur with Chuck. The issue with the larger dome port is to get better corner sharpness. I also have the 14-24mm and the 24-70mm. My absolute favourite lens is the 14-24mm for shooting out of the water. Tack sharp and there's so much I can do with it (I shoot with both a D3 and D3X). However, I have tried to put the 14-24mm underwater with my Aquatica housing using the 9.25in megadome, however, it is still not enough to give me sharp corners, which is a real shame. That's just the nature of matching a rectilinear lens like the 14-24mm with a semi-spherical virtual image produced by a dome port.

I'd suspect you'd want to get a fisheye like the Nikon 16mm fisheye. I had this at one point (it is an outdated lens) and was not satisfied with the sharpness, so I went with the sigma 15mm fisheye, which I really like. I've heard good things about the Tokina 10-17mm fisheye, which may give you a bit more flexibility, but I don't have any first hand experience with this so I would hesitate recommending it.

Tokina 10-17 is a Dx lens and not suited to the D700. Great for Dx cameras as you can mount one behind a 4 inch mini dome.

Regards Mark

Thanks to all of you to clarify me the use of dome ports. I didn't buy yet the housing but was interesting by the Aquatica. Like Warren I love the 14-24 out of the water and it is sad to read that I'll loose sharpness underwater. The current alternative could be the 14mm/2.8 or to wait for a 8-15mm like Canon... Like Mark said the 10-17mm doesn't really fit to the FX format and it will crop your images with a ratio of 1.5 for of 5Millions pix.

To begin, I think I'll go to use the 14-24mm and a 8" Dome port then later a 60mm or 105mm macro. Not sure about the 24-70 underwater but it can be another post.

Yvan

exposure:

Thanks to all of you to clarify me the use of dome ports. I didn't buy yet the housing but was interesting by the Aquatica. Like Warren I love the 14-24 out of the water and it is sad to read that I'll loose sharpness underwater. The current alternative could be the 14mm/2.8 or to wait for a 8-15mm like Canon... Like Mark said the 10-17mm doesn't really fit to the FX format and it will crop your images with a ratio of 1.5 for of 5Millions pix.

To begin, I think I'll go to use the 14-24mm and a 8" Dome port then later a 60mm or 105mm macro. Not sure about the 24-70 underwater but it can be another post.

Yvan

Click to expand...

I would be careful of getting your hopes up too high with the 14mm f/2.8 as that is also a rectilinear lens and will likely have similar results to the 14-24mm f/2.8. The issue is using a wide rectilinear lens behind a dome port. The one thing that you can do to help correct the corner sharpness issue is the use of a diopter, probably a +2 or +3. Since the 14-24mm cannot accecpt front mount filters, it is not a viable solution. Looking at the 14mm, it appears it cannot accept front mounted filters as well.

I have had the 24-70mm underwater and it is much better as far as corner sharpness is concerned. However, I find that this has somewhat limited use (at least for me).

Oh, one thing I forgot to mention was that the corner sharpness issue tends to disappear with the 14-24 at about 18-19mm, but that kind of defeats the purpose of having the 14-24mm in the first place.