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Ikelite 8" Dome

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Well - there is considerable (severe) vignetting on the wide open shots of the brick wall. It is reduced at f8. It looks too severe to be real, but how else would you explain it?

 

I can see from the "picture of the author" shot that you may have missed altogether with the left strobe, but even the upper rt and lower rt corners are dark - these should be in the hottest part of the image. The amount of vignetting may be caused by the lens itself based on the brick wall shots, but at f10 I wouldn't expect this.

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We have heard some less than scientific claims (Sorry Kasey, just putting the dome to the sun  and eyeballing the light, doesn't seem to drop 1/3 stop light when I look thru my dome. Could be that your eyes are more light sensitive than mine, who knows).

Marjo

 

I wouldn't make this claim looking through only glass, or only acrylic. I make it by direct comparison side by side. I could meter behind both for argument sake, but I'm not really interested in "scientifically" testing something that is so obvious to the naked eye. I thought we were beyond the glass vs acryllic arguments in this post, anyway :(

 

My challenge - find me one avid uw photographer that switched from glass to acyllic and prefers acryllic! The biggest pro-acryllic advocates haven't experienced anything else - kinda tough to be objective.

 

PS - I really wish acryllic domes met my needs, glass is heavy on the arms and on the wallet :D

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Hi,

 

I used one strobe placed about 12" above the port in the plane of the lens. Naturally, since the strobe is about 12" from the plane of the linoleum and 12" above it, it's simply not capable of lighting the whole frame - and it's not supposed to.

 

I thought I clearly stated in the review that due to the dark conditions in the pool, I used a strobe. In fact, I said I used 1 DS125 strobe. Since a number of our members were confused by the review, I'll go back and edit it to be more clear. I can see that I provided this information in a photo caption, and the caption shows me holding a housing with 2 strobes on it.

 

I stated what I did, how I set up the equipment, and the results I obtained, there's nothing ad-hoc about it. It shouldn't reflect poorly on Ikelite, if the lens has a vignetting problem in air that's not their fault...lol. The underwater portion of the review shows that the 8" dome yields sharper photos - it never mentions vignetting.

 

All I can do is tell you how I performed the test and show the results. It''s interesting to see how the members draw conclusions and what aspects y'all focus on. It teaches me a lot about my writing, and how to improve it, thanks.

 

Cheers

James

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You never mention vignetting - but your pictures show it!!! As a reader I look at the images you provide and correlate your interpretation with what I see. The Ike strobe should have been in the same position, on the same power setting for both close up pics. How do you explain the dramatic difference between the 8" dome and the 5" dome?

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Marjo,

 

I think it has been stated very clearly by James under which circumstances the shots have been made to prevent wrong interpretations. The results don’t claim any vignetting review issues. I understand the test has been focused on something different (corner performance in terms of resolution/shrpness/CA). Providing procedure details leaves the required room for readers drawing their own conclusions and priorities when choosing a certain dome for a certain lens. In my opinion the very useful information provided by James’ tryout does not draw biased conclusion for or against any brand. But it provides very valuable information you won’t get elsewhere before you buy one of the two available domes.

But if vignetting is an item to be discussed here to you - James has provided f-stop data as well.

 

Acrylic vs glass:

You have stated there would be no evidence to find when it comes to difference in terms of contrast. Well, beside optical physics (light absorption characteristics of different materials) tests have been conducted by several housing manufactures in the past. I have an old book providing information and results on this topic. If I find some time and it is of serious interest to you I can scan some stuff of it and pass you an email as I don’t want to post scanned book pages.

 

 

Julian

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Did you really really compare side galss and acryllic domes side by side Kasey... Ok you know I'm teasing you. :D

 

If the challenge was aimed at me, then forget it. I don't know, I wouldn't spend time on investigating something like that (you could just see me now, making a study, building a database...) but I doubt that someone who spent MORE money one something would go and spend LESS later. Just my guess here. And just because Johnny jumpped, doesn't mean I will. Ppl have such different motivations for buying this or that, and you know that discussion we have had on "material happiness" a few times... we'll at least in my case, not all purchases are directly correlating to real needs or real proven benefits. Sometimes we simplyl ust for gear completely irrationally. (You know when I tell I guy really I want his body, it ain't that blob under the shirt...) We like to think that more $$ is better. Or that a piece of gear in titanium/glass will somehow "perform" better than stainless steel/acryllic. Oftentimes more $$$ is somehow 'better", but not always. And in this case I am not yet convinced about the domes in question for the application were using it for.

 

It would still be interesting to hear from Ike, now that we are on the subject. From Ike's site, on the 8" dome: "We see no proof it provides sharper images with very wide angle lenses as some people contend...". I'd be interested to know what that is based on, was there some comparison etc

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I think the only way to be "convinced" would be to try it, no?

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My question is why are we looking at photos five inches from the dome with a 10-22 mm lens? Not where this lens would be used. Study the first twenty feet of a drag racer which has not "hooked up" on its way down the 1/4 mile strip.

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As I said in the review - if you shoot from further back, then the differences in image quality aren't as big. The close focus shots were taken about a foot from the test panel.

 

It depends on shooting style - most of my really good wideangle shots were taken when the subjects were VERY close, so I look for a system that can get those shots.

 

Cheers

James

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agreed!

 

For confirmation I've recently shot several extension ring combinations very close to the subject as well. Best way to confirm topside theoretical workout as differences are clearly visible. Towards infinity doesn't make sense in my opinion (starting just beyond 1 or a few meters). This also makes sense as real world wideangle shooting sometimes occurs in the same manner.

 

Friendly subject touching the glass …

 

me22.jpg

(Unfortunately not enough DOF, f8)

 

Julian

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I think the only way to be "convinced" would be to try it, no?

 

You are sooo Bad! Please don't make me do that, you know i'll be in trouble the moment I touch something "cool"! No tempting, please. The hubby is already convinced that you are a bad influence!

 

Ike's metafor is excellent! Ever looked at an uw image and said "hmmm... that must have been taken thru an acryllic port!" Well, I haven't at least.

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My question is why are we looking at photos five inches from the dome with a 10-22 mm lens?  Not where this lens would be used.  Study the first twenty feet of a drag racer which has not "hooked up" on its way down the 1/4 mile strip.

 

I love to shoot WA with a foreground subject inside 12"

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Ike's metafor is excellent! Ever looked at an uw image and said "hmmm... that must have been taken thru an acryllic port!" Well, I haven't at least.

 

1)Ever look at a closely focused shot and thought the corners were just a little soft for your taste? Happens to me all the time and I like to know that I've done all that I can before the dive to minimize it.

 

2) Ever wish you had just a tad more light underwater :D

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Kasey:

 

1. No, my corners are plenty sharp.

 

2. Yes, all the time. But not still not convinced that cool new port will give me more light. But if you could show me that I could go with f22 over f16, well, I might look again.

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Say.....you two aren't married are you....LOL.....ya'll sound like my wife and I :D:(:(

 

Karl

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My "questions" were meant to be rhetorical! If you've never had a soft corner you need to get CLOSER! With any wide angle zoom I've ever shot I occasionally get a corner inside the minimum focus distance of the lens.

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Hi guys,

 

Just for the record, I never said there was anything wrong with the standard 5" Ikelite acrylic wide port. I looked at a bunch of the photos taken with the smaller port and they look just fine. For the review, I didn't provide a lot of photos taken using this port, as I figured Wetpixel members would already have some real-world photos taken with the smaller port.

 

So c'mon folks, cough Marjo cough - let's see some!

 

I pushed the the two different ports to the extreme limit for the review, just so that I could see if there were any differences. That was the only way that I could make them show - which says a lot.

 

Is there a difference? Yes. Is it important to you? That's for you to decide.

 

And if you young lovers :-) want to argue about acrylic vs glass, how about starting another thread? Both of the ports I tested are acrylic, so for this test it's a moot point.

 

Cheers

James

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Horror!!! Nope, were not married or anything like that as far as I know! We hang out at the same dive deck and under the same pier once in a while tho. Neither one of us is especailly known for keeping our opinions to ourselves :D

 

 

So c'mon folks, cough Marjo cough - let's see some!

 

Oh, I will have to work up some serious courage for this one...

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Our ports are acrylic, not polycarbonate for the confused experts.  I polled several National Geo photographers about material choice and was surprised to find glass is not always preferred.  One comment was "I'm not a big fan of glass domes

since they are heavy and get streaking that never disappears."  We chose to attach Aquatica domes because of their stellar reputation.  What would you pay for glass.  I have a source, but believe complete dome would be at least six hundred dollars.

 

E-mail me at <ike@ikelite.com> if you want to avoid cluttering the forum..............

 

I would only like to by 2 ports for a housed 20D. One for the 10-22mm and one for the 100mm macro. If acrylic is the best choice, then this is fine for me. But if glass is the way to go, then I'm in for any reasonably priced option. How many buyers would be needed to make glass a reasonable option? Can we form a Wetpixel Power Buy?

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I think for a $1,500 camera like the 20D, acrylic is just fine. I've used and like the 8" acrylic domes out there. Results with the Nikon 12-24 were good, and now it looks like results w/ the 10-22 are good as well.

 

The big glass domes start at over $1,000 - so probably return on investment for glass is not worth it. Better to spend money elsewhere (lenses), but that's just my opinion.

 

Cheers

James

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Ok, one more comment on the Ike materials... the housing itself IS made out of Polycarbonate, not acryllic. Ports apparently different matter. I don't find a mention in the Ike port chart that the ports are made of acryllic, that's why I originally used the the PC term. Well now I know better.

 

Also, rather interesting confusion with the material of the new 8" dome. I somehow assumed that this one would automatically be glass (thnking that "genuine Aquatica domes surely must be made of glass), but reading the ike site, there is actually no mention of the material. My bad. But my guess is that I'm not the only one assuming it was a glass dome! :D

 

I'll give it a rest

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I think for a $1,500 camera like the 20D, acrylic is just fine.  I've used and like the 8" acrylic domes out there.  Results with the Nikon 12-24 were good, and now it looks like results w/ the 10-22 are good as well.

 

The big glass domes start at over $1,000 - so probably return on investment for glass is not worth it.  Better to spend money elsewhere (lenses), but that's just my opinion.

 

Cheers

James

 

Ike said ealier in the post that the glass port would be around $600. For the longevity of glass at that price - no brainer I think!

 

I was mostly satisfied with the performance of the Aquatica acryllic domes on the fisheye - less so with the 12-24 - soft corners inside 12" - hopefully the SD is better - it is so far great with the 17-35 on FF.

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I tried the 8 " dome with Canon 20D and Sigma 15mm fisheye this evening. I used the same extension ring as Ike provided for the 10-22 lens, and the Sigma 15mm doesn't quite stick out into the dome port, so the extension ring may be a few mm too long,

 

But that doesn't seem to affect image quality at all, the image looks good and it doesn't vignette:

 

sigma15mm.jpg

 

f5.6 @ 1/60th

 

Cheers

James

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My understanding is this port also works with the 18-55mm kit lens....

 

Which from what I can tell, means this port and the 100mm macro port will cover all of the Canon lenses I want to use with the 20D housing ...

that would be the 10-22mm the 18-55mm and the 100mm macro.

now I just need to get the port... :)

 

its on order :D

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