77 replies to this topic

[TomStack]

Paul,

Thank you for a wonderful explanation! Extremely informative!

Best,

Tom

[Viz'art]

Also good to remember is that apart from Macro lens, most lens are not at their best behaviour when focusing at their minimum distance (hence the use for the diopter), I believe in Diopter when they make a diference, alas the only way to know is to get in the water and try it on you kit. well worth the effort if only to know that your equipment is used to its fullest.

Also slapping a close up lens is to simple, one should care to find out the proper strenght for his/her dome diameter.

[craig]

an interesting comparison of the first generation 16-35L and the Nikon 17-35 using a Canon mount adapter

Not that using an adapter and using all manual controls is practical underwater, but according to this tester the Nikon outperforms the older 16-35 even on Canon bodies. It would be a huge disappointment if the new generation didn't fix that. It should be clear that we are not at a point where FF Canon wide zooms can't be improved and if a lens gives poor edge performance outside a dome we should have every reason to expect improvements underwater from the new version. A lens that is soft is unlikely to be sharpened by a dome.

[StephenFrink]

A lens that is soft is unlikely to be sharpened by a dome.

Craig is absolutely right! I think many lose track of that in evaluating dome performance.

I'm out of town tomorrow and can't do the UW test quite yet, but the 16-35 L II arrived this afternoon and I did a very quick test. Tripod mounted with focus on the part of the board in the center that said "Church". Center point AF fell right there, and it had enough contrast to pop focus. Note that the other two boards are positioned at the lower left and right, far from the central focus and about the hardest test of corner sharpness a wide angle will ever have. F-5.6 @ 1/125th second at ISO 100 for both shots.

Here is the 16-35 L II:

Here's the 17-40. Not massive difference in angle of coverage, certainly not enough to justify trading lenses on that criteria alone.

[StephenFrink]

Here's a screen grab for the corner comparison. Both at "Actual Pixels", 100% enlargement in Photoshop, no sharpening, or any other adjustments for that matter. From JPG, quality "L".

Based on this I'd say that the 16-35 L II is greatly improved over the 17-40. Going back to Craig's original assertion, the dome is not going to improve the performance of what a lens does in the air, I am optimistic indeed that I can do better than the 17-40 by using the 16-35 L II underwater. Having good glass to begin with is a very big part of the battle!

The performance of this lens in the first topside test certainly justifies the time spent dialing in the ideal port and port enxtension combination. 16-35 is on the left and 17-40 is on the right. You may not be able to tell much from this small JPG, but seen large on my 23" monitor the difference is significant.

[StephenFrink]

Note also the contrast appears to be improved in the 16-35, the 17-40 looking a bit muddy in comparison. Shot is open shade, both 1/125th second at F-5.6.

My first 10 minutes of testing likely cost me $1500 for a new lens. Damn

[bmyates]

My first 10 minutes of testing likely cost me $1500 for a new lens. Damn

Well, take comfort in the fact that, in addition to the results you've already mentioned, your quick backyard test scores high on the "rationalizometer," an important instrument for those of us with the "buy first/ask questions later" approach to new gear...

[Paul Kay]

This is just a thought, but, as wide-angle zoom designs get better one of the areas in which their design might improve is in their quality at close focus settings. It would be well worth checking out a new 16~35 against an old version and also the 17~40 at their closest focus as this is where designs used to show up flaws significantly, and is also the area of interest to underwater photographers not wanting to use a diopter - I find the 24/1.4 pretty good close up and very usable with Canon's 500D.

[Alex_Mustard]

Coincidently, there are a couple of articles by Pete Atkinson in the latest issue of UWP Mag, that I have just downloaded, with good info on using wide angle zooms behind domes that is relevant to some of the discussion above.

Alex

[bmyates]

...I find the 24/1.4 pretty good close up and very usable with Canon's 500D.

Paul, not to sidetrack this thread too much (and sorry if my questions all seem elementary ), but it never occured to me to use the 500D with the 24/1.4 - what exactly do you accomplish vs. using the 24/1.4 by itself? Shorter minimum focus distance? Sharper corners?

(BTW, James and I determined in our informal Bahama pool test that the 24/1.4 works best in the Superdome with a 25mm ext. ring. Is that the same configuration you use, or have you found something else to work better?)

[StephenFrink]

Coincidently, there are a couple of articles by Pete Atkinson in the latest issue of UWP Mag, that I have just downloaded, with good info on using wide angle zooms behind domes that is relevant to some of the discussion above.

Alex

While I haven't personally shot a 12-24 for a while, I did so a lot when it first came out; and I did it with a D1X, Seacam superdome, and a PVL 35. Pete was very unhappy with that combination. But, my recollection was that it was pretty nice, so I went back to my post from that era to look at some of the images in the gallery I'd posted. See http://www.seacamusa.../1224zoom.shtml.

Looks like the corners are fine in retrospect, and I have had dozens of other shooters with me on live-aboards and in my classes shooting the same and I recall their corners holding up just fine. I'd have to go back to the original images to pull the EXIF, but at ISO 100 I expect I was working around F-8 for most of the shots.

Pete is very knowledgeable, and I don't argue with his observations. It is just that mine have not been the same. If you look at the link above you'll see some of my thoughts regarding diopters with this lens as well. Also, we've been having good luck with the wide port and a +3 with the 12-24 for situations where the shooter may not want the expense, mass, or water resistance of the superdome. The wide port has to have a diopter to function. The superdome may or may not require one, depending on subject and personal taste.

[Paul Kay]

Stephen

I used the 12~24 on an S2Pro with wideport and a +4 (and I think I used 35mm extension). Results were fine for subjects at reasonable distances of say 1.5m+ (I've just had one of the images used as a 6 foot high display image - not bad for 6MPixels!) but not so good at closer distances. Its a lens with a mixed reputation above water and I know photographers who won't use it. My personal opinion of the lens was that it was adequate rather than anything else.

Pete's article covers much of what has been stated already but it is worth realising that being over precise is pointless as extenders are only available in 5mm increments, diopters may change the optics and this needs to be taken into account, and so on - even subject distance will adjust the optics slightly. 5mm is close enough generally speaking, but this may need to be the nearest 5mm to the equipment/style you shoot for 'optimum' results. Hard and fast rules are tricky, recommendations are a better way of looking at things!

[StephenFrink]

I'm back in the studio now, thinking about getting in the water with the new 16-35 II and playing around with the housing. Interesting to note that the zoom gear for my 17-40, which is the same as one would use on the old 16-35, also fits the new 16-35 II.

I can't speak for all housings, but at least for Seacam, the existing zoom gear works for the new lens.

[StephenFrink]

Interesting to note that the zoom gear for my 17-40, which is the same as one would use on the old 16-35, also fits the new 16-35 II.

Did my pool tests today. Seacam housing, swivel 45 viewfinder (so I did not have to get my head wet during testing protocol and it would go faster), superdome and fisheye port, and the following port combinations with each port:
no extension, PVL20, 25, 30, 35, 40, 45, 50, 55, and 60

Lenses tested: 16-35mm II, 17-40, 15mm with Tamron 1.4 teleconverter

As with topside test, I provided an impossible test on the lens. I set one of the exposure slates in the background center, and that's where the lens focused. I then put two more exposure slates at right and left upper corners, about 2 1/2 feet closer to the lens than the point of focus, and worked at only F-5.6 (aperture priority). Hard to imagine any lens being stellar in the corners under those conditions.

Why? That can happen on the reef. You have a central area of focus and reef rising on the periphery in the foreground. Had I chosen to shoot across a flat plane, the results would have been dramatically different. The lens would have performed far better focusing along a flat plane.

But, how often does that come up in normal UW imaging? Right now I only cared about what port extension would give the best results for the way I would likely shoot on a reef.

OK, here's the quick and dirty on what is a pretty interesting comparison. First, here is the 16-35 with no port extension and the superdome. THIS IS WHY WE TEST. It is horrible. Note also that it is not as wide as the later tests with a properly matched port extension. That was actually a surprise to me. (All distances were the same).

[StephenFrink]

16-35mm II, best results with Seacam Superdome and PVL 60. Note that there is distortion in the corners. That is to be expected, but note also that there is no vignetting like you'll see on the 17-40 sample in the next post. The 16-35 II has much better color and contrast as well. The lens is very sharp in the center.

[StephenFrink]

17-40, best results with Seacam Superdome and PVL55. Note that this trumps my previous testing where I have recommended either a PVL 30 or PVL35. This camera and lens have recently been sent back to Canon for precise calibration for a back-focusing problem. It is now very sharp with all topside tests, with all my lenses. I deduce this is the more accurate test, and the way I will shoot moving forward. Your personal cameras may differ and you should do your own tests.







You won't see massive differences from these small thumbnail images. In reality, I did not see massive differences between the 100% enlarged view in the corners of the UW shots with the 17-40 and 16-35 II either, even in PS on a 23" monitor working from the RAW images. Here's how I see it:

1. 16-35 II is definitely sharper than 17-40 topside. This is evident in the topside tests, both center and corners. The 16-35 II is significantly improved over the old 16-35 and 17-40.
2. 17-40 has issues with vignetting and is rather flat in terms of contrast and somewhat muted in terms of native color rendition (both easily tweaked in Photoshop).
3. 16-35 II is sharper in the center, even underwater.
4. If you think the 16-35 II is going to give substantially better corner resolution in a housing you'll likely be disappointed. This is a dome issue, rather than a lens issue.
5. Is the 16-35 II worth it? For me yes. For topside resolution, for color and contrast purity, and for the slightly wider angle of view. But, don't expect miracles in corner resolution when used with a housing. Future testing will have to look into how a diopter might affect performance.
6. Corner performance will be significantly enhanced by working at smaller apertures.
7. As expected, superdome was better for these lenses than the fisheye port.
8. Optimal resolution in the corners remains a dome issue, with refraction and virtual image making corner performance an ongoing challenge.

[StephenFrink]

15mm and Tamron 1.4 teleconverter. Superdome and PVL 20. This is an interesting concept, suggested to me by Walt Stearns. I love the angle of view and comparative lack of distortion, but find it soft.





I suspect the Tamron glass is the culprit. Canon does not make a teleconverter that would work for this application.

This is a very promising direction, using a fisheye lens with a teleconverter. Alex Mustard has been doing quite a bit of this with Nikon glass I think. Maybe he can offer some insights there. However, for my tests with Canon and Tamron, the results are borderline.

If anyone finds a better teleconverter for this aplication, let me know.

[StephenFrink]

OK, here's the quick and dirty on what is a pretty interesting comparison. First, here is the 16-35 with no port extension and the superdome. THIS IS WHY WE TEST. It is horrible. Note also that it is not as wide as the later tests with a properly matched port extension. That was actually a surprise to me. (All distances were the same).

Final test was with no port extension, admittedly the worst combination for the 16-35 II and superdome, but at 2 different apertures. Look at the difference F-stop makes in terms of 100% view of the corner.

Here is F-5:



Here is F-9:



Clearly, aperture is critical in working with all of the lenses tested. I predict that at F-8 and smaller, the 16-35 II will do just fine, in the centers and in the corners, for most UW imaging applications. Real in-water testing, on a coral reef, needs to be the next step. But these tests reveal the start point.

[Aquatic]

15mm and Tamron 1.4 teleconverter. Superdome and PVL 20. This is an interesting concept, suggested to me by Walt Stearns. I love the angle of view and comparative lack of distortion, but find it soft.





I suspect the Tamron glass is the culprit. Canon does not make a teleconverter that would work for this application.

This is a very promising direction, using a fisheye lens with a teleconverter. Alex Mustard has been doing quite a bit of this with Nikon glass I think. Maybe he can offer some insights there. However, for my tests with Canon and Tamron, the results are borderline.

If anyone finds a better teleconverter for this aplication, let me know.

Stephen,

You might want to try the Canon EF Life Size converter for the EF 50mm Macro.



Dan

[Paul Kay]

"You might want to try the Canon EF Life Size converter for the EF 50mm Macro."

Whilst these physically fit together, they wont focus!