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Ikelite 8" Dome

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Didn't know the page was public yet! Have to post on the front page. :blink:

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I got one last week and will be using it on the Wetpixel Shark trip at the end of this month....early testing looks positive for the 12-24 :blink:

 

Hopefully, I'll have some Hammerhead shots to post when we get back April 4 :):)

 

Karl

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It looks hot! :blink:

 

Can it be used with the 12-24 and the 18-70? That alone might make it worth the price of admission. Ummm, assuming I sell my other 2 ports.

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This is a great step in the right direction for Ikelite. I think their housings are nice but the port system leaves something to be desired. I hope to see more flexible port systems (ie macroport/systemport) and an extension system from ike in the future.

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It looks hot!  :blink:

 

Can it be used with the 12-24 and the 18-70?  That alone might make it worth the price of admission.  Ummm, assuming I sell my other 2 ports.

 

Hi Jim....yes, the 18-70 w/+ 4 diopter works with the same dome.....the 10.5 does not work....massive vignetting

 

Karl

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Karl - What is the minimum focus distance for the 18-70? I would have hoped that an 8" dome would not require such a powerful diopter.

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Kasey comment indicates unfortunate perceived opinion. The existing Ikelite dome and port system have always been as optically superb as ANYTHING money can buy. The only limitation remains with a few isolated lens combinations and testing with these domes confirms this.

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Good news about the 8" dome. I will probably get this because I have wanted to do split shots. However, personally, I wouldn't want to have just one dome and a bunch of extenders. What's the upside with that? Sounds like more potential for failiure.

 

I like having the right port for each lens. I think its is a benefit to have each port being optically correct for each lens.

 

I like not having to mess with extenders.

 

I like that the ports are light, sturdy and inexpensive too.

 

Someone mailed me the other week telling me they think maybe ikes polycarbonate willmake the picture "soft". Well, I say thats BS. I highly doubt that there is anyone who could tell the difference between a picture taken thru a glass vs a polycarbonate dome, especially in natural environment of ocean (salt) water, where the effects of natural elements (particulate matter in water, light absorption etc) far outweigh any supposed effects of the PC material.

 

I dare anyone to show some scientific proof that the differenece between glass and PC dome is significant to a level where the human eye can tell a difference in a image photographed uw thru one or the other... until such time I will be considering that type of comments "polycarbonate bashing" and "glass snobbery". :blink:

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Kasey comment indicates unfortunate perceived opinion.  The existing Ikelite dome and port system have always been as optically superb as ANYTHING money can buy.  The only limitation remains with a few isolated lens combinations and testing with these domes confirms this.

 

My comments were meant as a compliment. My knowledge of Ikelite dSLR systems is limited to briefly handling housings of people I've dived with. In some cases, the domes were sub-optimally matched to the ports. For example, a local instructor used the setup recommended by Ike for his digital rebel + kit lens, and the diopter recommended by Ike was scratching the dome as it hunted for focus. I don't see why a WA lens should ever be that close to the port optic.

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I highly doubt that there is anyone who could tell the difference between a picture taken thru a glass vs a polycarbonate dome, especially in natural environment of ocean (salt) water, where the effects of natural elements (particulate matter in water, light absorption etc) far outweigh any supposed effects of the PC material.

 

 

Regardless of material - just putting a diopter (especially a single element diopter) in front of a wide angle lens causes significant softening in the corners. This is VERY apparent on land and no less so underwater. For my purposes, I am MUCH happier with a big dome that doesn't need diopters. For some lenses this is more of a hassle than others - ie the Nikon 12-24.

 

As far as PC vs glass - Ask anyone that has put 100+ dives on a PC port which they prefer. Swirls and fogging on PC domes is a pain in the butt. Optically, a brand new PC dome may be indistinguishable from glass, but keeping them clean and scratch free is nearly impossible.

 

KC

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For example, a local instructor used the setup recommended by Ike for his digital rebel + kit lens, and the diopter recommended by Ike was scratching the dome as it hunted for focus.

I guarentee he was using the wrong port, much like if you use the 12-24 port with the 18-70mm kit lens, the diopter will touch the port.

Regardless of material - just putting a diopter (especially a single element diopter) in front of a wide angle lens causes significant softening in the corners.  This is VERY apparent on land and no less so underwater.  For my purposes, I am MUCH happier with a big dome that doesn't need diopters.  For some lenses this is more of a hassle than others - ie the Nikon 12-24.

 

As far as PC vs glass - Ask anyone that has put 100+ dives on a PC port which they prefer.  Swirls and fogging on PC domes is a pain in the butt.  Optically, a brand new PC dome may be indistinguishable from glass, but keeping them clean and scratch free is nearly impossible. 

 

KC

A diopter on a wide angle lens does not cause corner softning so much as it causes light fall off. A big dome will not always cause you to not need a diopter, as is the case with the 18-70 Nikon. The 12-24 doesn't need a diopter in a big or small dome port. I personally don't know of any Nikon lens that needs a diopter with a small dome, but not a larger one. Although one may exist.

 

I also disagree with you about PC vs Glass. Try buffing a light scratch out of a PC dome, then try doing the same thing on glass.

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With glass it is much easier to clean and use safely, without scratching it in the 1st place! I have used PC and glass ports extensively, and the choice is clear (no pun intended) to me. Do you have experience with glass ports? As so many discussions on this forum, people jump in to defend what they own over other products that they have minimal experience with. I still own a few PC ports, and they function just fine, but I can never get them as clean as I would like, and I'm always holding them up to the light to see that smudge or scratch. My oldest glass ports are much easier to get spotless!

 

I'd love to hear from someone that switched from glass to PC and prefers PC!

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I guarentee he was using the wrong port, much like if you use the 12-24 port with the 18-70mm kit lens, the diopter will touch the port.

 

A big dome will not always cause you to not need a diopter, as is the case with the 18-70 Nikon.  The 12-24 doesn't need a diopter in a big or small dome port.  I personally don't know of any Nikon lens that needs a diopter with a small dome, but not a larger one.  Although one may exist.

 

The port was the one recommended by Ikelite. I believe Marjo had the same experience.

 

The nikon 17-35 needs a diopter with a small dome but not with the 8"Aquatica or Seacam SD. The Nikon 12-24 doesn't work well with diopters, so manufacturers have revised their recommendations. Initially, based on the MFD of the lens, diopters were recommended when used with small ports. In fact, diopter/MFD issues resulted in initial problems with the use of that lens underwater. One of the reasons I bought Aquatica over Subal was that Subal recommended a diopter in front of the 12-24, but the Aquatica dome was big enough not to need it. Subal has since changed its recommendation for housing that lens. Others would be more informed as to what those recommendations are at this time.

 

KC

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I'm excited to try one of these underwater, but now a little disappointed to hear that it won't work with the 10.5 since that was the main justification. I guess the adapter puts the dome too far out to avoid vigenetting? Bummer.

 

How does the port system work with multiple lenses? Do you use extension rings on top of the port adapter?

 

What will I need to use the 12-24mm 15mm FE (sigma) and the 60mm behind this port?

 

I already own ports for all of these so the next biggest justification would be less ports to travel with and split level shots.

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One of my first wetpixel posts was driven by a closer look at the Ikelite D60 housing. I have found Ikelite’s quick response to new released camera models and affordable housings matching the short lasting DSLR camera generations very well. It’s funny because I had asked Ike what he does think about a real and big fisheye dome in the future. But the Ikelite 200% German price philosophy and the absence of a bigger dome for fisheye (split) work weakened my interest and I kept using my film camera with the Seacam port system a little longer.

 

Based on information given by Ike earlier in this board the smaller Ikelite dome glass provides radius just a bit less than the new 8“ dome assuming ~ 4†as the effective outer radius (roughly a hemisphere with 8†glass diameter?).

 

Assuming the smaller dome glass is positioned according optical requirements the difference would be small for lenses with smaller field of view because the radius is not that different. Also a possible dioptre requirement would not be influenced (again: if the small dome is setup correctly). In other words: only a small part of the 8†dome curvature would be used with a lens with less field of view.

 

This would require:

- small dome is setup correctly and not to close

- the lens field of view is equal or smaller than the Ikelite small dome glass’ field of view

 

Based on information in this board the second item has not been the case with extremely wide lenses and/or fisheyes. In order to avoid vignetting (as the dome curvature doesn’t cover the lens’ field of view) the small dome glass is placed closer to the lens different to an optical correct setup. While covering the complete filed of view the dome is positioned too close, degrading close focus ability and corner performance. I see the 8†dome addressing this issue for very wide and fisheye lenses.

 

That’s why I would prefer to accept Kasey’s compliment. The greater curvature provides the opportunity to house super wideangles and fisheyes properly. I would not reduce the 8†dome usefulness to split level work only.

 

Julian

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Julian, Re"While covering the complete filed of view the [small ] dome is positioned too close [for the 10.5 ], degrading close focus ability and corner performance."

 

I don't agree with your statement.

 

Pool tests I conducted a while back indicate very good performance with the Nikkor 10.5mm lens behind the Ikelite #5503.15 port.

 

http://www.peterpeterpeter.com/ikelite/10-...tests/index.htm

 

And calculations I did indicate that the center of the radius of curvature of the #5503.15 port is at the entrance pupil of the lens.

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Pool tests I conducted a while back indicate very good performance with the Nikkor 10.5mm lens behind the Ikelite #5503.15 port.

 

http://www.peterpeterpeter.com/ikelite/10-...tests/index.htm

 

 

I would have considered the corner in your closeup example very soft - look at the N compared to the O.

Difficult to say without it being side - by -side with another combo. I would hardly call those corners sharp.

 

Just measurebating I guess, but remember that the 10.5 should be less affected by a small dome than a zoom,.

 

KC

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I have used PC and glass ports extensively, and the choice is clear (no pun intended) to me.

Please post some examples.

 

Much like the glass vs PC debate, there has been no evidence provided that Glass is better than PC, or that a larger dome is sharper than a smaller dome.

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Pool tests I conducted a while back indicate very good performance with the Nikkor 10.5mm lens behind the Ikelite #5503.15 port.

Does not have anything to do with this.

Please understand that this is not about how good your fisheye lens performs behind your dome (by the way, why did you stop down several steps when doing such a test?).

 

You have to distinguish between two basic dome problems causing image quality issues:

 

1. Improper dome setup

2. rectliner lenses focus on a flat surface. The dome’s virtual image is curved.

 

Item 2 is much worse for rectlinear wideangle lenses. Fisheye lenses focus in a matter the virtual image is shaped (curved, closer edges). Therefore they perform much better behind dome ports in general. Getting a good corners performance with a fisheye in comparison to a wide rectlinear lens does not say anything about item 1.

 

And calculations I did indicate that the center of the radius of curvature of the #5503.15 port is at the entrance pupil of the lens.

 

Where does that come from? I really wonder how you can confirm by calculation that the centre of curvature matches the entrance pupil when the dome curvature is smaller than the lens field of view. That would mean your fisheye dome is a 100% true 180° hemisphere? I don’t doubt you have calculated something. Maybe the information in this board about Ikelite’s fisheye dome being not a hemisphere was wrong? Have a pic of it?

 

Julian

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Just measurebating I guess, but remember that the 10.5 should be less affected by a small dome than a zoom

Definitely. Wider reclinear glass works better with dome glass matching the field of view.

 

Much like the glass vs PC debate, there has been no evidence provided that Glass is better than PC, or that a larger dome is sharper than a smaller dome.

 

I think glass vs. PC debate is meaningless as a general discussion which is better.

From my understanding:

 

glass:

+ better contrast

+ more resistant against flare / reflections

+ more resistant against scratches

- if scratched, more difficult to polish

- refraction index differs from water

 

PC:

- easily scratched

+ more easy to remove scratches

+ refraction index more close to water

- less resistant against flare/reflections

 

 

@Peter

I want to add that UK-Germany,Sealux and Subal put fisheyes behind dome glass with less than 180° coverage as well (and the curvature centre doesn't meet the entrance pupil). Fisheyes are not that critical as super wideangles (see point above). But the glass is still big enough for split shots and maintaing a certain radius. This is where the 8" Dome comes in from Ikelite. And for super wideangles it provides the appropiate coverage allowing the usage of the full radius.

 

Julian

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Please post some examples.

 

You want examples of me cleaning my domes? <_<

 

I have not stated that new PC is optically inferior! Please reread my post - I've stated that I prefer glass because it is less prone to scratching, and much easier to get clean and smudge free.

 

On the dome size issue - I don't own a small port and therefore cannot provide examples, but the softness I referred to above speaks for itself. I think Julian stated well the reasons for the lens being so close to the dome in these setups - for ultrawide (weitwinkel) lenses it is not optimal!

 

I've yet to be impressed by the sharpness of any test of ultrawides behind a small dome. Nor have I seen many great underwater wide-angle shots captured behind Ike small domes - while I don't imply that to be a function of the equipment, it does imply that WA enthusiasts tend to lean elsewhere.

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Nor have I seen many great underwater wide-angle shots captured behind Ike small domes...
Guess the challenge has been laid down, no? :blink:

 

~Matt Segal

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