Ikelite 8" Dome, port bodies and the Nikon 12-24mm lens

[Hidroj]

Hy to everyone!
Ikelite says at it's website that, exclusively for Nikon's 12-24mm zoom, they have optimized their port body (the new #5510.22). I ordered, some time ago, only for this lens, the 5510.24 body (which had to be resent to Ikelite to get the newer one that provides the 60m safe operation depth limit).
What does that mean with "has been optimized"? That the 5510.24 body is not offering an increased corner sharpness? Even for the "optimized" body, the 5510.22, Ikelite says now that a +2 diopter will help.
Any idea of what shall I do with my "old" port body? Try the 5510.24 with a +2 diopter? Maybe a +4 diopter? Actually I would prefer to avoid buying the "new" 5510.22 body.

And still one question more. What about the 8" Dome shade? What happens if you use Nikon's 10,5mm Fish-Eye? Has anybody some experience with it?
Thank you very much!
Hidroj
Barcelona, Spain

 

[RonFrank]

Hy to everyone!
Ikelite says at it's website that, exclusively for Nikon's 12-24mm zoom, they have optimized their port body (the new #5510.22). I ordered, some time ago, only for this lens, the 5510.24 body (which had to be resent to Ikelite to get the newer one that provides the 60m safe operation depth limit).
What does that mean with "has been optimized"? That the 5510.24 body is not offering an increased corner sharpness? Even for the "optimized" body, the 5510.22, Ikelite says now that a +2 diopter will help.
Any idea of what shall I do with my "old" port body? Try the 5510.24 with a +2 diopter? Maybe a +4 diopter? Actually I would prefer to avoid buying the "new" 5510.22 body.

And still one question more. What about the 8" Dome shade? What happens if you use Nikon's 10,5mm Fish-Eye? Has anybody some experience with it?
Thank you very much!
Hidroj
Barcelona, Spain

Hi Hidroj,

Here is the basic answer. The 8" dome port will work for just about ANY WA lens out there. It will in fact work for any lens that will fit.

Ikelite has created several extensions for this dome. The only real requirement is that the lens fits in the dome without hitting the interior when fully zoomed. Optimally the closer the lens is to the end of the interior, the better. In some cases if the extension is too long for a given lens, some vignetting could occur, but you may want to try it out before spending the $$$ on shorter extensions.

Ikelite does not say that a +2 diopter is required for the 12-24mm lens, they say that it will increase corner sharpness. I think the requirement for using a dome port without a diopter is that the lens must be capable of focusing closer than 12". If not, no worries, just add the diopter.

I'm a little confused about what you have, what you have ordered, and what you are hoping to end up with. However my advice is to take what you have, get in the pool, and see if it works well. This assumes that your lens is not hitting the interior of the port in which case you need a longer extension.

The 24 is the longest extension, however it maybe too long for the 10.5mm as it may result in vignetting as the dome is likely in the field of view. I can not comment on the 8" dome shade as I don't have one. It may result in vignetting with the 10.5mm especially if not using the 10 extension. Ryan at Reef Photo would know the answer, and you can put an inquiry on their website at: www.reefphoto.com, and they should get back to you, or just call them.

I hope this answers some of your questions.

 

[Hidroj]

Thank you very much for your answer, Ron. I was thinking noone would say anything to my thread...
I'll try to start again, and now with two examples, let's see if it brings some more light on this subject.

I'm interested, mostly (al least until now), in Wide Angle Photography. That means that I bought a Nikon 12-24mm lens and Ikelite's 6"Dome. Not so happy with the corner sharpness I decided to buy Ikelite's 8"Dome, thinking I would improve the quality of my images. Until now, I haven't noticed a spectacular change, at least refering to corner sharpness.

Here two examples:

12-24mm at 12mm with the 6"Dome
F-Stop: 8
Shutter: 1/60s

12-24 at 12mm with the 8"Dome
F-Stop: 4
Shutter: 1/60s

When I decided to try the 8"Dome (maybe a half year ago), Ikelite was saying that the port body corresponding to the Nikon 12-24mm lens was the #5510.24 (the longest one for the 8"Dome). Now Ikelite recommends a new port body, the #5510.22, which as I see, is a little shorter, together with a +2 diopter. To increase what? Exactly what I'm interested in, the corner sharpness.

My questions around all this subject are two:

-Is there any system to increase the corner sharpness (using the 6” or the 8” Dome), without buying this new port body?

-Has anyone used Nikon's 12-24mm lens, inside Ikelite's 8"Dome, with the 5510.22 Body and the +2 diopter, who could share his experience? Does this combination achieve a substantial improvement?

Thank you very much to everybody!

Hidroj
Barcelona, Spain

PS: Maybe you think the blurring at the corners has more to do with focus distance and my position while I was taking the picture. Probably there's a part of truth. As Ron says, the best will be going to the pool and testing again with the two ports. I'll do it and hope to post the results as soon as possible.

 

[RonFrank]

Hi Hidroj,

I now understand what you are asking. Unfortunately, I can not give you a good answer based on experience as I don't own the 6" port, or all the other extensions.

One comment I will make is that in the two examples you proved, the top example with the 6" port appears that the reef is not as close as the example with the 8" dome. I'm not sure if in the lower example if the reef is soft because of corner softness, or because of focus.

If you really want to test all this out, the pool is the solution. Ideally you should shoot stuff with lines, and a constant spot at a consistent focus distance and settings to determine if the results are similar. You may want to just put a diopter on your current setup, and see if it improves.

As an aside, while we all want perfection in our images, a bit of corner softness is not going to destroy an otherwise great shot.

Good luck, and post your findings when you are done. Also if you want to sell one of your extensions, like the 24, PM me, I maybe interested.

 

[MarkH]

I've had the same problem with my Ikelite 6" dome and 17mm (film) SLR lens. The corners are almost ok at f16, but become extremely soft at larger aperatures. I tried using larger domes (home-made 8" and 10"), but although the corners became a bit sharper, the problem was still very noticeable. The large domes were also more bouyant so I went back to the 6". From what I understand, this is a problem with aligning the nodal point of the lens (where the light rays converge to a point, somewhere along the middle of the lens) with the center of the sphere of the dome. With a 6" dome, this would be 6" behind the front of the dome. The problem is that most housing manufacturers have the lens too far into the dome. If you move the lens back to where it should be for perfect optics, you will have vignetting from the dome shade or housing body. The answer is to have a more complete dome (the full half-sphere), but I'm guessing this would be too bulky and bouyant. You could use a smaller sphere, but then the dome curvature would be too small and the virtual image would be too close. I'm also guessing that Ikelite's dome extensions are an attempt to place the lenses' nodal point as close to an ideal spot as possible without having vignetting. It's a compromise that works better for some lenses than others. All this is my understanding of dome port optics and may be B.S.

 

[Cacia]

oh...my head hurts.

Wish I could follow this. I have the 6" and the 8"...but what is the port body? The fat ring? I have the 8" because I want to shoot tight wreck interiors with the 10.5.

The softness in your shots doesn't bother me, especially if there was a subject.

How does one "make" a dome port, out of curiosity?

 

[MarkH]

I think the "port body" is what I am thinking of as the port extension. I made my own by ordering a couple custom domes (about $30 each) from a specialty plastics place. This is the company I used:http://www.globalplastics.ca/domes.htm
I attached this to the mounting system from an old Ikelite port that I cut off.

 

[Hidroj]

Swankenstein, and how do your domes look like?
Just curious about that.... maybe you even could show us some pictures of your "new" port?
Thank you very much!

 

[RonFrank]

I have the IKE 8" dome port with the extension that they recommend for the Tokina 12~24mm lens, the 5510.16. My buddy has the 12~24mm Nikon, and after reviewing the lens spec, I am completely at a loss as to why the 16 would not be recommended for both the Nikon and the Tokina. The lenses are the same dia, length, focal length, and even share the same minimum focus distance. That said, why the two different extensions? I think we have tried the Nikon in the 5510.16, and it appeared to work fine. Next time I hook up with Kevin, we will make sure the 12~24mm Nikon works in that port, and report the findings.

 

[MarkH]

Swankenstein, and how do your domes look like?
Just curious about that.... maybe you even could show us some pictures of your "new" port?
Thank you very much!

They actually looked pretty bad. Here's a photo of what's left of the 10" dome:

I broke off the Ikelite mount to use it on the 8", then I cut the 8" down to use on my video camera:

Most of the wide angle photos at the bottom of the following page were taken with the 10" dome thing:http://victoriadiving.awardspace.com/mcneillbay.html