180mm vs 230mm dome port with 16-35 f4 lens on FF Camera

I would like to learn more about the difference in corner sharpness between a Nauticam 180mm and 230mm dome port when using a 16-35 F4 lens on a FF mirrorless camera.  Does anyone have sample images taken with both to see what the sharpness gain gives you with a 230mm dome?

Do different camera brands and lens models perform better in a 180mm dome than others?

Any guidance or advice would be much appreciated.

There's not a lot of good examples to find on the web, the best I have found is this page:

https://uwaterphoto.com/?p=839

It has test images showing corner sharpness with a 230mm and 200mm dome at a range of apertures.  The main pic is with a 17mm at f8 and it looks pretty horrible.  Stopping to f11 would help but not a huge amount and zooming out to 16mm  would make it worse again.  The dome would be the Zen 170mm dome which I understand has the same radius of curvature as the Nauticam 180mm dome, so pretty much similar performance.

There may be some minor difference of performance among different manufacturers lenses behind smaller domes, but the problem fundamentally lies with having enough depth of field to get the corners in focus and that doesn't change with different lenses at the same image magnification and aperture they will have the same depth of field.  What may change is the field curvature of the lens at the focal plane - this might vary with different designs, but these days most lenses will have  a fairly flat field.  Also if the corner is not so sharp on land it will add to the aberrations from the dome and look worse still. 

Thanks for your reply, Chris.  I agree that the close focus wide angle reef shot looks extremely distorted in the brightly lit bottom right corner at 17mm / f8.  The other 3 corners don't stand out, so I guess it all depends on your subject and background, eh?

I noticed @Stillviking 's post "New RF 14-35 f4L, anyone tried?" after posting this one, and took a look at the ikelite review link.

Anything with sand in the corners was fine at f4, but anything with reef up close looks unacceptable to me in the corners.

I posted this thread because the nauticam charts show 230mm domes as 'preferred', but 180mm domes as an option.  I don't need tack sharp corners, but wanted to see what the tradeoff was.  I do a lot of shore diving and travel several times a year, so a 230mm glass dome is a headache. 

Sounds like @ColdDarkDiver has offered to post some test shots, which I look forward to

3 hours ago, JayceeB said:

Thanks for your reply, Chris.  I agree that the close focus wide angle reef shot looks extremely distorted in the brightly lit bottom right corner at 17mm / f8.  The other 3 corners don't stand out, so I guess it all depends on your subject and background, eh?

I noticed @Stillviking 's post "New RF 14-35 f4L, anyone tried?" after posting this one, and took a look at the ikelite review link.

Anything with sand in the corners was fine at f4, but anything with reef up close looks unacceptable to me in the corners.

I posted this thread because the nauticam charts show 230mm domes as 'preferred', but 180mm domes as an option.  I don't need tack sharp corners, but wanted to see what the tradeoff was.  I do a lot of shore diving and travel several times a year, so a 230mm glass dome is a headache. 

Sounds like @ColdDarkDiver has offered to post some test shots, which I look forward to

Everyone's standards are different and it really does depend what is in the corners.  To be clear, the corners of the shot in question are not distorted they fall outside the depth of field so are not in focus. 

Another option with a small dome is to see is you can source a S&S correction lens as it will improve performance - which is the main subject of the article of course.  Some people have posted here that they are unhappy with the corners in a 230mm dome and insist they need the S&S correction lens- which shows how much variation there are in what people find acceptable.

If you have blue water in the corners it is much less of a problem and you can always stop down more than they have in the in sample shots in the article.  The S&S correction lens and stopping down more will extend the depth of field out closer to the corners and reduce the impact on the shot.  Zooming in a little will also assist.

There is a lot of info about this here on Wetpixel! I would have a good read around.

Short answer is: It is impossible to know without trying it in the dome(s) in the water.

Longer answer is that a bigger dome will always perform better optically, the differences become more noticeable with higher resolution. Given that the very close focusing distance required to make a lens perform behind a dome port is not a typical design parameter for wide angle lens designers, many excellent topside lenses simply perform badly. Note that this is not a function of focal length, but actual design. The only way to know how your lens will work is to test it.

Housing manufacturers test lens/port combinations and then create port charts. If they recommend a given port, there is normally good reason for doing so.

The Sea&Sea correction lenses were designed for very specific lens and (Sea&Sea) port combinations. When used with other ports/lenses, they may or may not provide advantages. They are not a generic solution that improves every lens/port!

From your description, it seems like you have invested in a very powerful imaging tool. It would seem a shame to do so and then hobble it’s ability to perform at its best by choosing a dome that will give mediocre results.

13 hours ago, ChrisRoss said:

Everyone's standards are different and it really does depend what is in the corners.  To be clear, the corners of the shot in question are not distorted they fall outside the depth of field so are not in focus. 

Another option with a small dome is to see is you can source a S&S correction lens as it will improve performance - which is the main subject of the article of course.  Some people have posted here that they are unhappy with the corners in a 230mm dome and insist they need the S&S correction lens- which shows how much variation there are in what people find acceptable.

If you have blue water in the corners it is much less of a problem and you can always stop down more than they have in the in sample shots in the article.  The S&S correction lens and stopping down more will extend the depth of field out closer to the corners and reduce the impact on the shot.  Zooming in a little will also assist.

I would like to avoid a specialized corrective lens.  Stopping down for wide open for reef background shots would probably be my choice.  Thanks again for your help.

1 hour ago, adamhanlon said:

There is a lot of info about this here on Wetpixel! I would have a good read around.

Short answer is: It is impossible to know without trying it in the dome(s) in the water.

Longer answer is that a bigger dome will always perform better optically, the differences become more noticeable with higher resolution. Given that the very close focusing distance required to make a lens perform behind a dome port is not a typical design parameter for wide angle lens designers, many excellent topside lenses simply perform badly. Note that this is not a function of focal length, but actual design. The only way to know how your lens will work is to test it.

Housing manufacturers test lens/port combinations and then create port charts. If they recommend a given port, there is normally good reason for doing so.

The Sea&Sea correction lenses were designed for very specific lens and (Sea&Sea) port combinations. When used with other ports/lenses, they may or may not provide advantages. They are not a generic solution that improves every lens/port!

From your description, it seems like you have invested in a very powerful imaging tool. It would seem a shame to do so and then hobble it’s ability to perform at its best by choosing a dome that will give mediocre results.

 

Sage advice, Adam.  Thank you.  I will begin mining the forum for info on this topic now.  

10 hours ago, JayceeB said:

Stopping down for wide open for reef background shots would probably be my choice.

Again - have a read about. With any full frame camera and a rectilinear wide angle lens (even one that works well behind a dome), a large dome (say 230mm), you will see serious corner softness at apertures larger than f/11 or so. This is a function of physics and optical theory, not lens/port design and is hence unavoidable!

17 hours ago, JayceeB said:

Sage advice, Adam.  Thank you.  I will begin mining the forum for info on this topic now.  

You should also check out some Wetpixel Live segments, perhaps look at Alex Mustard's book and do some internet searches for articles on the topic by Alex and others.  Older issues of UWPmag have some articles on this.

I struggled with the same issues when i decided to move from M43 to full frame.  And got a D500 instead.

By the way, since I gather you already have a D850 and housing, unless you can determine that the S&S correction lens does much for the 16-35 in a 180, you could consider getting a 17-70 instead.  It has a shorter minimum focus distance, which can help, but I believe you might need to restrict yourself to DX format when using that lens.  Not sure.

2 hours ago, Draq said:

You should also check out some Wetpixel Live segments, perhaps look at Alex Mustard's book and do some internet searches for articles on the topic by Alex and others.  Older issues of UWPmag have some articles on this.

I struggled with the same issues when i decided to move from M43 to full frame.  And got a D500 instead.

By the way, since I gather you already have a D850 and housing, unless you can determine that the S&S correction lens does much for the 16-35 in a 180, you could consider getting a 17-70 instead.  It has a shorter minimum focus distance, which can help, but I believe you might need to restrict yourself to DX format when using that lens.  Not sure.

Thanks @Draq.

I will look.  I have a Sony A7C+28-60+WWL1.  Works great for CFWA, but lacks the reach of a 16-35.  Considering a 16-35 + dome, but trying to understand what will be gained and lost in this trade.  Definitely no decisions made at this point.

13 hours ago, JayceeB said:

I have a Sony A7C+28-60+WWL1.  Works great for CFWA, but lacks the reach of a 16-35

What do you mean by reach? Too wide for smaller subjects? Why not just take off the WWL, park it, and shoot those through bare port? Nauticam's port chart lists converted FoV for your combination as 130-69 degrees, and lens FoV as 75-40 degrees, so a fully zoomed out lens with bare port is just a bit narrower than a fully zoomed in one with WWL. You'll have a bit of pincushion distortion on the wide end, but it will go away as you zoom in.

JayceeB: For some reason I thought you were using a D850 and the Nikon 16-35.  I have no idea whether Sony allows you to set for APS-C mode, so some of my comments above are likely irrelevant.  Sorry about that.

FWIW, I did a little looking and came upon a thread where Phil Rudin stated a 170/180 port does work well with the Sony 16-35.  He quoted Zen as saying " The Sony 16-35mm f/4 is a pretty unique rectilinear lens in that it performs very well behind smaller domes like the Zen DP-170 or the Nauticam 180mm dome."

You may want to explore this further.

10 hours ago, Barmaglot said:

What do you mean by reach? Too wide for smaller subjects? Why not just take off the WWL, park it, and shoot those through bare port? Nauticam's port chart lists converted FoV for your combination as 130-69 degrees, and lens FoV as 75-40 degrees, so a fully zoomed out lens with bare port is just a bit narrower than a fully zoomed in one with WWL. You'll have a bit of pincushion distortion on the wide end, but it will go away as you zoom in.

Thanks, @Barmaglot .  I have actually played around a bit with this.  The ability to pull on/off the WWL multiple times on a dive sounds good on paper, but in actuality, for me at least, the activity of taking it off, parking it, then un-parking and re-installing takes some time and isn't something I really even like doing once on a dive

4 hours ago, Draq said:

JayceeB: For some reason I thought you were using a D850 and the Nikon 16-35.  I have no idea whether Sony allows you to set for APS-C mode, so some of my comments above are likely irrelevant.  Sorry about that.

FWIW, I did a little looking and came upon a thread where Phil Rudin stated a 170/180 port does work well with the Sony 16-35.  He quoted Zen as saying " The Sony 16-35mm f/4 is a pretty unique rectilinear lens in that it performs very well behind smaller domes like the Zen DP-170 or the Nauticam 180mm dome."

You may want to explore this further.

Thanks, @Draq. I read through Phil Rudin's review on the 16-35 + Nauticam 180.  https://www.uwpmag.com/?download=88

Let me check for the Zen content.

57 minutes ago, JayceeB said:

Thanks, @Barmaglot .  I have actually played around a bit with this.  The ability to pull on/off the WWL multiple times on a dive sounds good on paper, but in actuality, for me at least, the activity of taking it off, parking it, then un-parking and re-installing takes some time and isn't something I really even like doing once on a dive

Do you have it on a threaded mount or on a bayonet? I use a diopter on magnetic rings, and attaching/detaching it is no problem at all. Obviously a WWL is larger, but on a quick-disconnect bayonet it shouldn't be much of a problem.

1 hour ago, Barmaglot said:

Do you have it on a threaded mount or on a bayonet? I use a diopter on magnetic rings, and attaching/detaching it is no problem at all. Obviously a WWL is larger, but on a quick-disconnect bayonet it shouldn't be much of a problem.

I have the WWL-1B mounted with bayonet.  The 28-60 port has a focus knob on the left side that prevents the release toggle on the bayonet mount to be installed normally.  As a workaround, the bayonet mount, on the port, must be installed upside-down, so the toggle ends up on the right side of the port.  The WWL-1B is installed upside down as well.  I painted a small white dot on the bottom of the WWL-1B (which faces up) to let me know approximately where to align it when securing the WWL1-B.  It takes a bit of time to get it right and secure.  You need to do that exercise twice since you take it off the camera, then secure it on a bayonet on the arm.  And twice again when you re-install the WWL-1B.  I also carry the CMC-1 on the other arm.  So to swap CMC-1 for WWL-1B, it takes 4 steps.  Remove WWL-1B from port.  Install WWL-1B on right arm.  Remove CMC-1 from left arm.  Install CMC-1 on port.  I absolutely make use of this on some dives where I have large sharks and nudibranchs on the same dive, but the nudi has to be outstanding before i'll make this switch.

23 hours ago, JayceeB said:

Thanks, @Draq. I read through Phil Rudin's review on the 16-35 + Nauticam 180.  https://www.uwpmag.com/?download=88

Let me check for the Zen content.

Jaycee, This review is now over six years old and times have changed. The WWL-1 was just announced in that issue and WACP was not available until much later. Next at the time I was shooting a 24MP A7 II, the A7R IV at 61MP will reveal more lens flaws both above and below water.

While the 180mm port is more than adequate for most uses with a 24MP camera the 230mm will be the gold standard even with high MP cameras if you shoot above F/11/13. Next issue is that corner sharpness is much more important to some than it is to all. As Adam has noted in other threads many U/W photo contests have been won by images with poor corner sharpness, in other words they are not just trashed because of the corners. 

Last the new Sony FE PZ 16-35mm F/4 coming at the end of June in the US is going to be a much better lens than the over six year old Zeiss branded lens. It is smaller, the power zoom can be assigned to a camera control button so it can be operated from the housing without the expense of a gear and it cost $1200.00, the old lens cost $1350.00 on release close to seven years ago.

Last I use the 16-35 for split images and the 230mm dome is the much better choice than the 180mm.    

Well, I was trying to help, but I guess I steered you down the wrong path.

Thanks for your response, Phil.

I did see the new 16-35 Sony lens announcement, and it’s great news to hear you mention it will be a good one.

So far I have not taken split shots, but that might be something I experiment with later on.

The A7C I have been shooting for the past year is serving me well so far, but I know one day an upgrade will occur and that will surely be higher resolution.

1 hour ago, Draq said:

Well, I was trying to help, but I guess I steered you down the wrong path.

Appreciate your help, @Draq ...I guess i went off on a tangent on that response