D200 In an Ikelite housing with 8" port

[admin]

Well, I'm starting the first official thread of this site!

I have been a film holdout for years and finally bit the bullet and went digital when Nikon announced the D200. I needed the right camera to make the switch, and I waited for Nikon, slow as they are, to release the camera I wanted, rather than switch to Canon, as so many have done.

I have been a big fan of Ikelite housings for years and only toyed with other brands because of Ikelite's lack of a large dome for ultrawide lenses. I have always used Ikelite for macro and have been using Subal for a while now for wide angle.

With the release of the new 8" dome port from Ikelite, I finally can have an Ikelite housing and a big port. So I bought the port that Ikelite recommends for the Nikon 12-24 DX lens, and pool tested. This lens will end up being one of the most popular lenses ever underwater in my opinion because it zooms from a 99 degree wide angle to a perfect fish portrait lens. Add a macro lens and you have everything you need in just two lenses.

What I found with this port and lens was that the corners are not sharp. This is not the fault of the dome or the lens, but that the dome and lens are not matched. Because Ikelite makes so many housings for so many cameras and lenses, they do not have time to pool test and calibrate each port exactly for each lens. Other manufacturers have had issues with this lens as well. It is sharp in air, so there is no reason it can't be sharp in water with the right optics.

I talked to Ike himself about this last week and he is having a set of port extensions made for me in 1/4" increments, so I can fine tune the exact length of the port to get the lens right in the sweet spot of the dome. I will also experiment with a diopter on the lens as well to determine how sharp I can get the port/lens combo. (Many of you know that even if the lens can focus close enough for the lens to work behind the dome, a diopter often makes the corners sharper because the diopter curves the focal field of the lens in the opposite direction as the dome port. In effect, a diopter cancels the effect of the port.) My goal is to figure out exactly what needs to be done for a perfect port/lens match with this highly popular lens. When I have it all figured out, Ikelite will build and sell this exact port size for use with the lens. I'll report back.

Jonathan

:cool:

[Jonathan Bird]

Ike just e-mailed to let me know that the parts are in the mail. When I get home next week I'll be testing and reporting back!

Ike: You're the man!

Jonathan

[Warren_L]

I have an Ike housing with the Nikon 12-24 for my D70, but a 6" port. The corners are a bit soft. However, I just picked up an Aquatica housing with 8" port for my D200 and am getting good results with the 12-24. I am still considering getting a 10.5mm lens just for local diving as with the 12-24 I never really change the focal length from 12mm. the 180 degree on the 10.5mm would be nice.

[FRED DION]

I have used a +2 diopter when using a 8" port and a +4 diopter with a 6" port with good results with a Subal D70 system. Subal recommends a 50 MM extension with the larger port and a 33 MM extension with the smaller 6" port. I'm not totally sure why you used a shorter extension with a smaller port except it must match up the curvature of the lens to the curvature of the port.

[Jonathan Bird]

Fred,
Ahh! Very helpful, thanks. I was trying to decide how much of a diopter to start with. I think the general concensus is that even though this lens focuses close enough to use without a diopter, the performance behind a dome is far better with one.

Best,
Jonathan

[Sealizard]

Jonathan and/or Fred,

could you please elaborate on the idea that the 12-24 performs better behind a dome if one uses a diopter.

I'm working with: D70, Ikelite housing, 12-24 and 10.5 and the 8 inch dome with extensions for both. Having only moved to digital and a housing in the last year and a half, I'm still learning to pronounce 'diopter'. A brief, non-scientific physics lesson on the benefits would ease the learning curve. I love the 12 -24 and have been really happy with the 8 inch dome.

Thanks,

Elizabeth

[Jonathan Bird]

A dome port has almost no optical effect in air, but underwater it has a material of a different index of refraction on each side (water/air) and because it is curved, light changes direction when it p***es through the interface between the two indexes of refraction. In plain language, underwater a dome port is a lens. It is a NEGATIVE lens, meaning that parallel light rays hitting the dome with diverge as they p*** through it. The effect of this is that the dome works to increase the performance of a wide angle lens underwater over a flat port because it has less optical distortion than a flat port. However, it does have the disadvantage that it curves the focal plane.

Lenses are designed to keep a flat plane in focus. Meaning, if you point your camera at a large, flat wall, the center and the corners should both be in focus at the same time, even though with a wide angle lens, the distance to the wall will be closer to the camera in the center than at the corners.

A dome port messes this up. It tends to curve the focal plane so that the lens can no longer keep the center and the corners in focus at the same time. The result is that you point your camera at a reef and focus (in the center) and the corners are soft. It is the natural result of a dome port.

The other thing a dome port does is requires the lens behind it to think it is focusing on something much closer than it is. Since it diverges the light rays that p*** through it, it fools the lens behind it into thinking that the light rays are come from much closer. So maybe you you shooting a subject that is 6 feet away, but the lens must focus on an "apparent image" through the dome that is much closer, perhaps 12"-16" depending on the radius of the dome. Some lenses cannot focus this close. So in many cases you need a diopter lens threaded onto the camera lens just to allow the lens to focus on the apparent image. A diopter is a positive lens, meaning it causes light rays that p*** through it to converge, not diverge. It is the opposite of a negative lens. It is commonly referred to as a magnifying gl***!

Many people think that a diopter is only used on a lens to allow it to focus closer and has no function behind the dome port if the lens can focus close enough without the diopter. But the side benefit of a diopter is that since it is a positive lens, it counteracts the effects of the dome port being a negative lens to a degree. You still get the dome port's advantages over a flat port, but the diopter attempts to curve the focal plane in the opposite direction than the dome port curves it. In effect, they cancel each other out. If you get the right diopter and the right dome and everything is all lined up right, you should be able to keep that reef in focus from the center all the way to the corners. This is the reason that the Nikonos 15 was always so darned sharp, because it was designed from the start to be used underwater and the optics are corrected for the little dome port on the front.

Getting a sharp image means not just getting a sharp lens and the right port, but matching them well. Think of the diopter as the "coupler" between the two.

Some manufacturers provide careful instructions for the popular underwater wide angle lenses of which dome to use, which port extension AND which diopter, for best results. My N90 with a Subal housing and a 20 mm lens is SHARP all the way to the corners, even wide open. It seems counter-intuitive that putting an additional piece of gl*** in the image path (the diopter lens) can actually IMPROVE the picture quality but it does.

Jonathan

I just re-read that and I'm not sure I even understand it....hope I didn't confuse you more!

[Jonathan Bird]

OK, I big giant pile of dome extension ports showed up the other day (thanks Ike!) and I'm about ready to start some pool testing!

Ike had them make me the extensions in 1/8" increments, which is probably too much precision for this application, but it never hurts to have choices!

Jonathan

[Sealizard]

Jonathan,

thanks for the *valiant* attempt to explain the diopter concept to me. It's still a bit convoluted, but I did carry away the following thoughts:

1. The best we can do today is to use the Ikelite 8" dome port with the extension (collar/stalk - whatever one calls it) designed for the lens being used. For example the 10.5mm lens is sold with an extension that is shorter than the one used for the 12 -24mm lens.
2. You will test new extensions to further define the precise height needed in order for the 12-24 to be able to produce corner to corner sharpness with the 8-inch dome. If you're successful, at some point Ikelite will market those.
3. In the meantime, a diopter properly matched (Fred suggested +2 for the 8-inch dome and a +4 for the 6-inch dome - Subal) might also make the difference or at least help.

Did I get the strategy right if not the math?

Thanks again for the reply - that was a lot of work! You deserve a dip in the pool!

[Jonathan Bird]

1. The best we can do today is to use the Ikelite 8" dome port with the extension (collar/stalk - whatever one calls it) designed for the lens being used.

Yes. Judging by how fast Ikelite turned around some prototype extension rings for me, I expect that they will have "production" versions available VERY soon after I complete pool testing this week.


2. You will test new extensions to further define the precise height needed in order for the 12-24 to be able to produce corner to corner sharpness with the 8-inch dome. If you're successful, at some point Ikelite will market those.

Yes, I expect they will introduce an extension for the 8" port that is EXACTLY right for the 12-24 based on my tests. I will also recommend a diopter for it which will be included with the instructions on the port.


3. In the meantime, a diopter properly matched (Fred suggested +2 for the 8-inch dome and a +4 for the 6-inch dome - Subal) might also make the difference or at least help.


I expect that the diopter will help a lot. I agree with Fred's assessment of the +2 for the 8" dome and the +4 for the 6" dome. I will also try a +3 with the 8" dome though because I think a tad more correction at the corners may be beneficial. Either way, the diopter will help a lot.

Stand by for results soon!

Jonathan

[Jonathan Bird]

Well, I began phase 1 of the pool testing today. Man, it can get confusing trying all these different combinations of port extensions and keeping track of all the pictures. My dad was the stenographer on dry land as I froze my butt off in the pool which was 68 degrees. Pretty lame, I had to wear a 5 mm suit just to get in the pool! Here are the results.

Ike had a set of extensions made for me. The "starter" extension is P/N 5510.16 which is the one they recommend for this lens on their website. This recommendation is just a ballpark guess. Ike made me 4 more, each 1/8" longer. So I call them:

5510.16+1/8
5510.16+1/4
5510.16+3/8
5510.16+1/2

Ikelite also makes a P/N 5510.24 which is about 5510.16+3/4 or about 1/4" longer than the longest one I had to test.

I got in the pool and did test shots with each of these extensions on the 8" Ikelite port, using a B+W +3 diopter 77 mm close-up lens on the Nikon 12-24 mm DX zoom set at 12 mm (widest setting) at f/4. I wanted to also test a +2 but as it turns out I didn't have one in the right thread diameter. (I thought I did, DAMN. Will try to get and test in the Galapagos. I leave Thursday!) I think the +2 might be better.

To sum it up, the longest extension that Ike made me was the best (5510.16+1/2) but I am still not happy with the corner sharpness. It may be that the dioper is too strong. It may be that the port still needs to be longer. I have ordered the longer port (5510.24) and hope to have in time for the Galapagos. It has been on back order for weeks.

The pics I'm about to show were shot using high quality jpeg (raw is overkill here) and I have posted them un-tweaked, right as they came from the camera. No sharpening, no level correction. Dowload from camera-->open in photoshop-->crop (or resize)-->save

I did the tests both close up (about 18" from the side of the pool) and medium distance (about 4 feet from the side of the pool) and shot the images holding the camera at an angle so the tile would go diagonally across the frame, giving a center and corner reference for sharpness. All the images are razor sharp in the center, as that is where I set the focus point in the image. All images were shot at 12 mm (widest setting) as this is where the corner sharpness is worst because it demands the most of the lens/port combination. Also, please note that in order to make this as easy as possible to judge, everything was shot wide open at F/4. Nobody will really shoot images like this at f/4 if they can help it. But this minimizes the depth of field and makes the corners as soft as they are going to get, so we are judging absolute worst case.

The first image here shows a reduction of the full frame to 640 pixels wide and shows the image from which the enlargements come from. (The steps of the pool, from about 18" away).

[Jonathan Bird]

These next two images show the center of the frame for comparison with the sharpness at the corner. Please note that this is with the longest port, which was the sharpest in the corner.

Pic 1: center of frame
Pic 2: lower left corner

[Jonathan Bird]

This next one shows the sharpness in the corner of the standard Ikelite port (5510.16). You can see that it is slightly softer than the longer port (+1/2)above. You can also see that all of these corner shots show a fair amount of chromatic aberration, which looks like red and blue halos around highlights. This is a refraction issue, which is partly caused by the diopter (meaning, you will see it even in air with no port when you shoot through a diopter with a wide angle lens) and partly by port mis-match. When the port is well matched, you will minimize this aberation, but you will still have it because of the diopter. Note that as you zoom the lens in, you will have A LOT sharper corners and MUCH less aberation. Remember, this whole test is being done at the absolute worst case settings (as wide as it goes, wide open aperture).

To compare these, you can open multiple windows in your browser and position the images next to each other.

[Jonathan Bird]

The babysitter just showed up, I gotta run out for dinner! More to come later tonight....stay tuned!

Jonathan

[Jonathan Bird]

OK, I'm back!

So where were we?

This shot shows the standard port with no diopter at all. You can see that the corner sharpness is CRAPOLA! You really need the diopter if you want the corners to be sharp!

[Jonathan Bird]

Here are the same series of pictures with the subject at about 4 feet instead of 18".

1. The full frame shrunk to 640 pixels wide
2. close up of corner, with 5510.16+1/2" extension
3. Close up of corner with normal 5510.16 extension
4. Close up of corner with normal 5510.16 extension NO DIOPTER

Yes, the diopter REALLY makes a lot of difference.

[Jonathan Bird]

Ok, the last two examples. These are shot at f/8 instead of f/4. You will notice that while they are a bit sharper, they still have the chromatic aberration, as this will not be reduced by stopping down and gaining depth of field. At this point, the chromatic aberration is what limits the apparent sharpness. I am thinking at this point that I need to test a port extension that is a little bit longer, just to be sure I have the lens in the sweet spot, and I also need to drop the diopter power to a +2. I might have too much diopter on there, introducing a lot of chromatic aberration.

Pic 1: f/8 with the 5510.16+1/2 extension at 18"
Pic 2: f/8 with the 5510.16+1/2 extension at 4 feet

I think it's worth pointing out that Ikelite's "seat of the pants" suggested port extension length for this lens is within about 1/2" of perfect. Not bad for no pool testing, especially considering that the tests above show it is the diopter that makes about 95% of the difference in the corner sharpness, not the exactness of the port length.

Ike is working on getting me the slightly longer 5510.24 port to test in the Galapagos, and I'm working on getting my hands on a 77mm +2 diopter before I leave. Who woulda thunk....B&H and Adorama are both out of stock on 77mm +2 diopters right now. I have e-mailed Fred (where are ya Fred!?) and will call around to some local camera places on Monday. Why is it that no matter how far in advance I plan, I still end up having stuff FedEx'd to me at the last minute before a trip? Is it just me, or does everyone have this problem? ;)

Jonathan

[Clay Coleman]

Excellent stuff, Jonathan. Not only are your results applicable to many of us, but your method is a great example as well. Now I'd like for you to start over with a Tokina (just kidding). -Clay

[Jonathan Bird]

Actually, I have offered to assist Ikelite in fine tuning the ports for the more popular underwater lenses, so you never know...

Jonathan

[Jonathan Bird]

Here is a shot of the port and extensions in question, in case anyone is wondering what they look like.

My +2 diopter is on the way (thanks Fred!) and I'll do the last pool test on Wednesday--the day before I depart for the Galapagos. Nothing like a little last-minute testing!

Jonathan

[Jonathan Bird]

I just got some HOT new info from Ikelite concerning an upcoming product. I am waiting to hear from Ike if it's OK to spill the beans. This is nothing that is going to change the world, but you Ikelite guys are all going to want it....

Stand by....:D

Yes, I'm taunting you all.....:p

Jonathan
:cool:

[Jonathan Bird]

Ok, turns out they just posted it on the Ikelite website, so I'm not breaking any major secret news here, but they are releasing a dome shade for the 8" port.

Jonathan

[Jonathan Bird]

Thanks to Larry at Ikelite, I have a hot new 8" dome shade in my possession right now....very cool. This is one accessory that you will want to get in order to reduce those port reflections.

Ok, so with a few more extension lengths turned out by Larry at Ikelite for me at the last minute, plus a +2 diopter from Fred, plus a bunch of FedEx, I was able to pool test with a +2 diopter and a few more extension lengths. Yes, I was in the pool today, 66 friggin' degrees, freezing my butt off, the day before my trip, just to fine tune this rig.

Today I tried a 5510.16+5/8" and a 5510.24, which is the standard Ike stock number for what could be called a 5510.15+3/4".

What I discovered is that the sharpest combo I tested was the 5510.16+5/8 plus a +2 diopter. (Seen below).

Unfortunately, until I knew the sharpest combination with the +2 and the longer ports, I didn't know which ones to compare it with from the previous tests while I was still at the pool. (I had to come home, evaluate the images, then decide one last comparo). My second sharpest combo was the 5510.16+1/2" with the +3. But remember that I did not have a 5510.16+5/8 with me at the time I did that test, so it may be that the +3 diopter with the +5/8 extension is sharper than the +2 diopter with the same extension. I am taking that extension on my Galapagos trip and I will test the +2 versus the +3 on the dives and see.

Talk to ya'all when I get back!

Jonathan

[chris bangs]

Did you test the extensions without the diopter as well?

CB

[Jonathan Bird]

Not the longer ones. The experiments showed that the diopter was VERY important, and in fact made a larger difference in image quality than the length of the extension. I'm going to speculate that as long as the port extension is in the ballpark, the diopter contributes 90% of the corner sharpness and the extension is only 10%.

Jonathan

[FLEETHAM]

Hey guys,

Fred Bavendam turned me onto diopters on wide angle lenses 25 years ago in British Columbia and I've been using them ever since. I agree with the increase in lens sharpness, but also it allows you to focus much closer than the standard set-up...and it was this reason he was so adamant about using them. The only lens I can't get one on is a full frame fisheye. I'm on the fence about jumping to a Canon 5D. I've heard mixed reports about Canon's 15mm fisheye behind Ike's big dome. Some are not happy with the corners...although some are. It seems sigma's fisheye might yield better corners. I wish Sigma would get it together and copy Nikon's 10.5 for the smaller chip and make it in a Canon mount.

David Fleetham
http://www.davidfleetham.com

[Jonathan Bird]

One of the interesting things about fisheye lenses for underwater work is that fisheye lenses are by their very nature designed to focus on a curved field. A rectilinear wide angle lens is designed to focus on a flat plane and keep the whole thing in focus (a very difficult task in lens design). More simple optics focus on a curved field, meaning they focus at the same distance from the lens across the field, which results in an arced focus, like a piece of pie. This is easier to obtain and thus fisheye lenses are simpler and cheaper than rectilinear lenses. (Ever wonder why the Nikon 14 mm rectilinear wide angle is twice the price of the Nikon 16 mm full frame fisheye? That's why).


Anywho, the curved field produced by a dome port is a perfect match to the curved field of focus of a fisheye. That's why, even though you couldn't put a diopter on a fisheye if you wanted to, you don't need one. This makes fisheye lenses natural behind dome ports and often a lot sharper than a rectilinear lens. I have never been much of a fisheye guy, but I just bought a 16 mm fisheye to use on my D200. It will give me 107 degrees on a DX sensor, rather than 180 degrees on a film camera. But since it's a fisheye lens (i.e. has a curved focal field), it should be VERY sharp in the corners. I used to like my 14 mm rectilinear lens (114 degrees on a film camera) but I could never get it sharp in the corners underwater.

I agree about the close focus being a benefit of diopters. The problem is that most people think the diopter should only be used on a lens that can't focus close enough behind a dome. The way a diopter curves the field of focus in the opposite direction of the dome, thereby "canceling" its effect, is the true reason one should use a diopter. The closer focusing ability is just gravy. In my opinion, any lens wider than 28 mm (on a film cam) or wider than 18 mm (on a DX sized sensor digital camera) should have a diopter to mate it to the port. Rule of thumb that seems to work is +2 diopter for an 8" port and +4 diopter for a 6" port.

I finally decided, by the way, that I like the +2 diopter more than the +3 on the Ikelite with the 12-24 and the 8" dome. Final answer on the port is: 5510.16+5/8" extender with the +2 diopter on the 8" port. Also, that new lens shade was simply fabulous!

Jonathan

[Mike Veitch]

Ya, i have finally decided to go with the +2 on my 12-24 as well.. (but am too cheap to pay the shipping to Yap so will wait till i need to order something big! haha)
i don't shoot it as much as i do the 10.5 but the corner softness really noticeable when i try CFWA... thankfully most of the time i use it i am shooting blue water so don't notice it too much...

Dave F.- I had a chance to shoot the 5D a while back under same conditions as my D70.. and i tell ya, wow on the sunball!... no comparison whatsoever. I take it you are on the 20D? if you get a chance to just try someone elses rig try a few sun shots, i can tell you i was jealous....

[chris bangs]

Not the longer ones. The experiments showed that the diopter was VERY important, and in fact made a larger difference in image quality than the length of the extension. I'm going to speculate that as long as the port extension is in the ballpark, the diopter contributes 90% of the corner sharpness and the extension is only 10%.

Jonathan

Thanks Jonathan

I will be in Japan at the end of the month and pick up a Hoya +2.

[chris bangs]

Dave F.- I had a chance to shoot the 5D a while back under same conditions as my D70.. and i tell ya, wow on the sunball!... no comparison whatsoever. I take it you are on the 20D? if you get a chance to just try someone elses rig try a few sun shots, i can tell you i was jealous....[/QUOTE]

No Comparison in price too:eek:

Mike, have you compared the 200D to the D70 on sunball images?

Also if you want to get the +2, Have fred at UWphoto.com send it to MDA. I can have one of our customers bring it to you.

[Mike Veitch]

Mike, have you compared the 200D to the D70 on sunball images?

Also if you want to get the +2, Have fred at UWphoto.com send it to MDA. I can have one of our customers bring it to you.

No one has shown up with a D200 and housing yet for me to steal off the camera table.... :D

On the filter, good thinking Chris, i just may do that! Thanks

[Sealizard]

and pick up a Hoya +2.

Is there a significant difference in the quality of different brands of diopters?

Any preferences in addition to the Hoya?

[Jonathan Bird]

I feel that the B+W brand (which is German) is the best filter on the market but Hoya (Japan) is highly regarded as well. Tiffen is probably decent but is considered a budget brand.

Jonathan

[tarczy]

The experiments showed that the diopter was VERY important, and in fact made a larger difference in image quality than the length of the extension. I'm going to speculate that as long as the port extension is in the ballpark, the diopter contributes 90% of the corner sharpness and the extension is only 10%.

Final answer on the port is: 5510.16+5/8" extender with the +2 diopter on the 8" port.

Jonathan

Sooooo . . . does that mean the if I use the 5510.16 port extender I'm probably good to go?

If not, I'm probably gonna have to find an underwater photo chat board with a bunch of Canon photo pros on it. You Nikon guys are killin' me.

:( :( :( :(

[Jonathan Bird]

Sooooo . . . does that mean the if I use the 5510.16 port extender I'm probably good to go?

I would wait for Ike to start making the one for the Nikon 12-24 (5510.16+5/8) and use that one. It's gonna be close. The diopter makes the biggest difference.

Jonathan

[tarczy]

I would wait for Ike to start making the one for the Nikon 12-24 (5510.16+5/8) and use that one. It's gonna be close. The diopter makes the biggest difference.

Jonathan

Just to be clear for all those (current and future) following this thread, Ikelite has manufactured a Port Body http://www.ikelite.com/web_pages/dabigadoma.html (http://www.ikelite.com/web_pages/dabigadoma.html) that is tuned for the Nikon 12 -24mm lens. The Ike part number is #5510.22 and lists for $150 (Jonathan - are you getting any royalty payments for all the work you did? :) )

Ike's description for the 5510.22 port body is as follows . . .

"The #5510.22 has been optimized to operate with the Nikon 12-24mm zoom lens. Addition of a +2 diopter close-up lens to the camera enhances corner sharpness."

Since the +2 Diopter fixes 90% of the problem and the port body takes care of the other 10%, the assumption is that the same port body (#5510.22) and 8" Dome combination will work equally well with the Canon EF-S 10-22mm lens. Since I seem to be the only clown on this board shooting Canon, I'll try out the combination on my next Turks & Caicos trip in December and post the results.

:p :p :p

[Sealizard]

[

the assumption is that the same port body (#5510.22) and 8" Dome combination will work equally well with the Canon EF-S 10-22mm lens. Since I seem to be the only clown on this board shooting Canon, I'll try out the combination on my next Turks & Caicos trip in December and post the results.

:p :p :p

Tarczy - haven't looked at the Ikelite site, but I am curious if simliar lens lengths in Canon and Nikon lenses use the same ports and port bodies (collars, stalks, whatever!) or if there is any difference in how they're manufactured. I take it you will test to see if the 2mm difference in the 10 -20mm Canon and the 12-24mm Nikon lens make any difference.

Looking forward to your report.

[Jonathan Bird]

Mark,
Cool update. I had not noticed that they had updated the page and started manufacturing the port length that we worked out for the 12-24. Unfortunately, no royalties on it for me ;) but at least I have a nice sharp lens to show for the effort!

The only way to fine tune it to the Canon system is to do what I did and test. However, if you measure the length of the Canon zoom, from the front element to the camera mounting plane, we can compare the lengths of the Canon and Nikon zooms. Given that they are roughly the same focal length, if they are abou the same physical length, we can probably be 90% certain that the same port extensions are right.

Again, I would like to emphasize that the port length was fine tuning. If you take the diopter off and shoot with the right extension, but compare it to shots with the diopter on but the wrong extension, the shots with the diopter will be sharper. The diopter makes MUCH more difference in the corner sharpness than the port extension.

They also have announced the D-80 housing (with the supercool TTL diddle knob):
http://www.ikelite.com/web_pages/2dslr_dttl80.html

They also have some of my Galapagos shots with the new port:
http://www.ikelite.com/web_two/triv_jbird.html

Ike cropped and re-saved some of the shots with higher compression making them look a little too compressed, but you get the idea. All those shots were done with the 12-24 except the batfish.

Jonathan

[tarczy]

For the Canon EF-S 10-22mm zoom lens, the distance from the front lens element to the lens/camera mounting plane is roughly 3.25 inches.

How does that compare to the Nikon 12-24mm zoom?

[tarczy]

Tarczy - haven't looked at the Ikelite site, but I am curious if simliar lens lengths in Canon and Nikon lenses use the same ports and port bodies (collars, stalks, whatever!) or if there is any difference in how they're manufactured. I take it you will test to see if the 2mm difference in the 10 -20mm Canon and the 12-24mm Nikon lens make any difference.

Looking forward to your report.

The Ikelite Port system for SLR's is pretty much the same for Canon and Nikon as it relates to diameter. I believe that in some instances the length of a Nikon port may vary when compared to a similar Canon lens. This has to do with differences in lens design between the two manufacturers.

In the case of the 8" Dome port, the Canon wide angle zoom and the Nikon wide angle zoom are very similar in terms of exterior dimensions. Hence, the Nikon port extensions are interchangeable with the Canon port extensions.

I'll let you know my findings in January when I'm back from my trip. Sorry, but I refuse to go through the heroic effort that Jonathan went through. Since Ike ain't payin' royalties, I'll just be satisfied if my pics turn out reasonably sharp without using sharpening software.

:D :D :D

[Jonathan Bird]

Mark,
Later tonight when the kids are in bed I'll go measure the 12-24 to compare.

As a side note, since Larry at Ikelite made me a complete set of port extensions in 1/8" increments to test the 12-24, there is a full set of testers available, should some individual like to use them to do some lens tests and find the best extension for another lens. When I was done, I sent the whole set back to Larry so they could be used to test other lenses. I'm sure Ike could be convinced to loan them to qualified individuals to tune other lenses! HINT HINT! You Canon guys out there.....who are you? Now is your chance!

Jonathan

[Ryan]

Canon full-frame options are currently being evaluated by someone, and EF-S would logically follow.

[octopulse]

Hi Johnathan et al,:) thanks for the great information and all the work that went into the revisions of the Ikelite Dome ports for the Nikon 12-24.:D I just picked up my ikelite housing for the D200 and am having a few dilemmas over the choice of ports to purchase. Money IS an object hence I want to try and make sure that I get a pretty versatile balance whilst minimising $.:confused:

At present I have a sigma 50mm macro, Tokina 12-24 and a Nikon 18-200VR. I need to be able to shoot both wide angle and macro shots and know that I will probably need to get another longer macro in the next while for some of the shyer critters. I have potentially dumb question about macro ports: Does anyone know if the 5505.5 port that fits the nikon 105 macro will also work with my Sigma 50mm without causing a great deal of vignetting? The Sigma port should be #5505 and hte difference in length is 2.6 cm (1 inch). Should I be considering using close up lens filters on my macro lens anyway? If so will they foul the 5505 port?

I would also really appreciate advice on a more important decision: I am trying to decide between the 4 inch 5503.51 which is apparently specific to the Tokina 12-24 :confused: and the 8 inch Dome with the appropriate extension mount. Given Johnathan's extensive tests that demonstrated the need for customisation of the Nikon 12-24 dome port extension I was wondering whether this was likely to be similar with the Tokina lens? I am pretty convinced from reading this thread that I should get a 77mm +2 diopter no matter what but I wanted to pole people's opinions on the various merits of the 4" and 8" domes for use with this lens?

Bit long for a first post I know but I would really appreciate any guideance as I have a pending order in with Adorama that will need to be altered on Monday pending these decisions! Can't wait to get this rig in the water....

Cheers

Roger over n out

[Jonathan Bird]

Roger,
It has been my experience that the Ike 5" ports (which are 3" radius and therefore would be 6" ports if they were a full hemisphere, the way the 8" port is) would be fine with the wider lenses except that since they are NOT a full hemisphere, they vignette when they are the right distance from the lens. I know that sounds confusing, but basically, if you put the port close enough to a 12 mm lens that it won't vignette, the port is TOO close for good corner sharpness. This could be fixed with a full hemisphere, but they only give you a section of the hemisphere on the 5" port. If you do decide to use a 5" port on that lens, be sure to use a +4 diopter, not a +2. A smaller dome needs a significantly stronger diopter to keep the corners sharp. I would recommend the 8" port though. It WILL be sharper at the corners. It also makes the housing closer to neutrally buoyant!

As for the flat port, I use different ports for the 50 and the 105. I find it interesting that you use a 50 mm Sigma. I do too, and so does Doug Perrine. I always liked it better than the 60 Nikon because it was just a little shorter and made it possible to shoot things that were a little larger (fish portraits) but still go down to 1:1. It's EVERY bit as sharp as the Nikon. On a DX sensor digital cam, it becomes a 75mm effectively (with the 1.5 x crop factor) rather than a 90, which makes a big difference. The only problem with that lens is that for the really small stuff, you have even less working distance than the 60 mm, which makes it hard to light stuff. But in that case, you are really better off with the 105 anyway. (Which becomes an ungainly 160 mm on a DX cam!! egads!)

I would use seperate ports for these two lenses. The thing is, with the 50 mm and the longer port, you limit how close you can get to the subject even MORE because the port gets in the way. Also, the flat ports from Ikelite are so cheap that they are almost disposible. I replace mine annually just because they are cheap and why deal with the little scratches? Furthermore, having one for each lens means you always have a spare on a dive trip if you goof and gouge the sucker by accident. Just my $.02.

Anyway, I just explained to you a reason to spend all your money on new ports and I know that is NOT what you wanted to hear, so I apologize for that! But honestly, the lenses are so much more expensive than the ports. Once you have gone and paid good money for sharp lenses, why spoil the results with the wrong ports? The port is more than just a way to keep the water out. It's a very important part of the optical path underwater and becomes basically a lens in front of your lens. You're 90% of the way there, so might as well go the whole way.

Best,
Jonathan

[octopulse]

Hi Johnathan,

I appreciate that insight re: the macro and dome ports. Your comments were exactly what I needed; I will bite the bullet and go with the 8" as it makes more sense for corner sharpness and for future acquisitions (10.5mm.....:) )

I'll post a few shots once the rig is finally in the water! I will be shooting coral spawning experiments early in November hence the lust for good macro!

cheers :D

Roger