I’d love to hear any personal experience and opinions on using Sony’s 28-60mm kit lens with Nauticams wet optics — particularly the WWL-1B for wide angle and the CMC for macro.

Bonus if anyone has comparative experience on how this setup compares to using a higher-end / faster lens behind a dome, in terms of image/video quality.

 Thanks for your thoughts!

I use the WWL-1 with the 28-60mm with my A1. It works very well in my opinion no benefit for the WACP-C while the WACP-1 may have an edge but it is too heavy so not in my scope.

Instead on the macro side with CMC-1 and CMC-2 the 60mm lens is rather weak mostly because it is just 60mm so you get close like crazy and the image quality is way off a dedicated macro lens.

It does however focus faster than the 50mm macro but thats not difficult

I would say for wide angle 28-60 WWL-1 is good especially on lower megapixel camera while for macro use a dedicated port

Edited December 25, 20231 yr by Interceptor121

@Interceptor121 Super helpful, appreciate the response 🙏.

I used (for the first time) a Sony A7 IV with the 28-60 in standard port on a trip to Malapascua earlier this year. I don't have the CMC, but did use a Subsee +10 wet lens for macro. Felt that some macro images were slightly soft, but maybe as I gain experience, will learn the right combination of aperture and strobe.. You can see my images from the trip here: 

http://iez152.ieda.ust.hk/MALAPASCUA_APR23/MALAPASCUA_APR23.html

I did not use the WWL-1 B on the thresher sharks, but I will try it on (I hope) tiger and hammerheads in my planned trip to Maldives in early/mid Jan - will post images after.

Cheers,

Ajay

13 hours ago, Ajay said:

I used (for the first time) a Sony A7 IV with the 28-60 in standard port on a trip to Malapascua earlier this year. I don't have the CMC, but did use a Subsee +10 wet lens for macro. Felt that some macro images were slightly soft, but maybe as I gain experience, will learn the right combination of aperture and strobe.. You can see my images from the trip here: 

http://iez152.ieda.ust.hk/MALAPASCUA_APR23/MALAPASCUA_APR23.html

I did not use the WWL-1 B on the thresher sharks, but I will try it on (I hope) tiger and hammerheads in my planned trip to Maldives in early/mid Jan - will post images after.

Cheers,

Ajay

Thanks for sharing, and good luck on your Maldives trip 🤙

I've been wondering about the WWL-1B versus domes as well.

I have an A7RV in a Nauticam housing and can use it with either a WWL-1B / Sony 28-60 mm or a 180mm dome / Sony 20-70 mm f4 lens (I have both).

I've been comparing the two and, from a sharpness / saturation perspective I like the 20-70 more!  I realize this runs counter to much of what I've read and am wondering what other folks think - hence this post.  For those who have used both setups, which do you like more and why?

To be clear, I don't look at corners much.  My judgment is based on the center area.  I really don't mind if the corners blur as all my attention is on the central area that I'm favoring as a subject, rather than a wide area/vista.

I realize both lenses are f4 lenses, but I never plan to shoot less than F8 anyway to maintain DOF and whatever corner sharpness I am getting.

Hopefully this answers Bronson's question, in part.  I'd love to hear about how others view the tradeoffs between these two setups.  I've never done A vs. B pool tests, as Interceptor121 does, so my opinion is based on very subjective fuzzy impressions!

Gary

On 12/27/2023 at 3:55 PM, Proteus said:

I've been wondering about the WWL-1B versus domes as well.

I have an A7RV in a Nauticam housing and can use it with either a WWL-1B / Sony 28-60 mm or a 180mm dome / Sony 20-70 mm f4 lens (I have both).

I've been comparing the two and, from a sharpness / saturation perspective I like the 20-70 more!  I realize this runs counter to much of what I've read and am wondering what other folks think - hence this post.  For those who have used both setups, which do you like more and why?

To be clear, I don't look at corners much.  My judgment is based on the center area.  I really don't mind if the corners blur as all my attention is on the central area that I'm favoring as a subject, rather than a wide area/vista.

I realize both lenses are f4 lenses, but I never plan to shoot less than F8 anyway to maintain DOF and whatever corner sharpness I am getting.

Hopefully this answers Bronson's question, in part.  I'd love to hear about how others view the tradeoffs between these two setups.  I've never done A vs. B pool tests, as Interceptor121 does, so my opinion is based on very subjective fuzzy impressions!

Gary

This tread is very interesting for me too. I have A7R5 and Tamron 17-28mm and Sony 20-70mm behind Zen DP170, but no WACP/WWL (I have Canon 8-15mm behind Nauticam 140mm for circular/180° fisheye). I am fully satisfied with IQ of the rectilinear lenses, but think about WACP-C or, as an alternative, another, bigger, domeport (my dive buddy is using most of the time the Zen DP170, so I need something in addition). If Sony 28-60mm behind WACP/WWL has less general IQ than the lenses above, I am not interested in WACPs (corners sharp at aperture wide open is fine, but if the 28-60mm is less sharp in the image center regardless of aperture... ☹️)...

=> Can someone please compare the AOVs between rectilinear 17-28mm and/or 20-70mm with WACP/WWL (I know these AOVs are not directly comparable between rectilinar and fisheye, what the WACP/WWL are in fact, but just from personal feeling: What rectilinear AOVs are comparable to WACP/WWL)?

 

Wolfgang

Edited December 28, 20231 yr by Architeuthis

Forgot to mention that I too have a Canon 8-15 that I use for wide angle, and mostly CFWA use in places like Cayman.

I'm finding that I can segment my use into use cases where the 20-70 is "good enough" for most wide angle, and the 8-15 covers the other types of use.

The big win, for me, is the flexibility to go from "wide angle" to fish portraits.  I never know what visibility I'm going to get on the bottom - especially here in North Carolina.  It's quite common to have 80 foot blue water visibility from the surface until 20 feet from the bottom, then 20 foot visibility to the bottom in green water .... or maybe .... blue water all the way down.  The 20-70 can cover both use cases.

Gary

As 121 pointed out above the higher the MP's the more noticeable the flaws in any give lens will become, this is also true for sensor size. A 33MP full frame will show more flaws than a 33mp APS-C sensor.

Regarding AOV, the 20-70 is 94 degrees at the wide end, the Tamron 17-28 is 103.48 degrees at the wide end and the WWL-1/1B, WACP-C and WACP-1 are all around 130 degrees using a lens at 28mm. Keep in mind that the wet wide lenses like WWL-1/1B add a bit of a fisheye look. Not at all like the Canon/Nikon 8-15mm Fisheye lenses but also not apples to apples compared to the Sony and Tamron rectilinear lenses. I have used all of these lenses with the respective domes and extension recommendations along with all four of the excellent Nauticam Wide Angle Conversion lenses. I have used WWL-1 and 1B, WAPC-C and WACP-1 all with the Sony FE 28-60, as well as other lenses like the Sony FE 28-70mm, Sony FE 28mm F/2, Panasonic 14-42 PZ, Tamron 28-75mm and the Tamron 17-28mm with WACP-2.

Regarding the Sony FE 20-70mm F/4 Nauticam recommend the 250mm port for best results and with the Tamron 17-28mm F/2.8 Nauticam recommends the 180mm for best results. While I have not run tests with the Nauticam 250mm port I have used the 20-70 with 230mm and 180mm ports. As you would expect at 20mm the corners become a bit soft V. larger ports but for me it was not a deal breaker because I was using the lens more often in the 50 to 70mm range while using the 17-28mm in the 180mm port for wider shots. My port extension lengths vary when testing with My Marelux A1 and A7R V housings but the 180mm and 230mm ports sizes remain the same. I also use a 12 inch (305mm) port for surface and split shots so have a very good idea how the 17-28 works in a very large port. 

For someone already shooting the Sony 20-70mm in the 170/180mm dome you may also want to consider the Tamron 17-50 for a better range or the stellar Sigma 17mm F/4 which I have used in both the 180mm and 140mm ports with excellent results. While I like the versatile of a 17 to 28/50 the Sigma 17mm prime is excellent because it will focus to 1:3.8 at 12cm (4.7 inches) this is closer than Tamron 17-28mm or Tamron 17-50mm which both focus to 19cm on the wide end of the lens. 

As has also been pointed out some favor ultimate corner sharpness while others (the lions share I believe) are willing to overlook this small detail of the total image. To prove my point you only need look at the latest photo contests like the recent DPG contest where an esteemed panel of judges have not really given a lot of weight to stellar corner sharpness but rather to the overall impact of the winning images.

You can fins reviews for several of these lenses both dry and wet in back issues at uwpmag.com by putting my name into the back issue search engine. I also intend to test the (coming soon) Venus Optic 10mm for full frame Sony cameras. This will be the first auto focus lens from the well respected lens maker and should have a very close focus distance in around the 12cm range. Venus 10mm would be a 130 degree rectilinear AOV with a 77mm filter thread which is perfect for my Sea & Sea 77mm conversion lens.

  

16 hours ago, Architeuthis said:

 

=> Can someone please compare the AOVs between rectilinear 17-28mm and/or 20-70mm with WACP/WWL (I know these AOVs are not directly comparable between rectilinar and fisheye, what the WACP/WWL are in fact, but just from personal feeling: What rectilinear AOVs are comparable to WACP/WWL)?

 

Wolfgang

 

This table shows calculated values for fields of view diagonal/vertical/horizontal.  If you want to compare coverage or reach I would suggest comparing horizontal fields is probably best .  Not the same picture of course but is probably best for comparing how the lenses would go for example shooting a shark.

The top 4 lines are rectilinear lenses.  Then follows 5 ways of calculating the WWL coverage with a 28-60 lens.  Stereographic projection seems closest to right as using a constant focal length multiplier to get the fisheye equivalent focal length it comes closest to predicting the full zoom diagonal field from the widest field multiplier.  The equivalent focal length I'm using is adjusted to get the formulas to match Nauticam's figures for the WWL diagonal field from their port charts.

Equisolid, equidistant and stereographic projections are reasonably close together predicting the horizontal field while Orthoganal and rectilinear are much further apart.  T

To demonstrate how far out the rectilinear formula is, I used the 0.36x factor for wide and full zoom it while it predicts the wide zoom it is 30° out on full zoom.

I think the Sterographic projection is probably reasonable to predict the reach of the WWL to compare with the rectilinear lenses.  Various caveats apply such as field being reduced at min focus distance etc, but it should be good enough to compare the reach of the various lenses.

This graph shows the (rough) coverage of angles of view of WWL1/WACP with Sony 28-60mm compared to the rectilinear lenses discussed, based on Chris's suggestion to take the horizontal angle of view as a criterion (The WACP/28-60mm combination covers an angle of view comparable to a 13-33mm rectilinear lens)...

=> It seems the WWL1/WACP would be a good substitute for the Tamron 17-28mm, but Sony 20-70mm is something special.

=> I did not find a careful review of the Sony 28-60mm lens yet, where the actual resolution has been measured. I guess it would be not quite as good as the Tamron 17-28mm and Sony 20-70mm (over the water). I wonder whether there could be a difference spotted in real life when comparing UW photos (most reviewers say that IQ of WWL1/WACP with 28-60mm is excellent)?

 

Wolfgang

 

 

 

 

 

Edited December 29, 20231 yr by Architeuthis

I'm glad we're having this discussion, because I could "swear" that I'm getting better images from the 20-70!  And yes, I understand the AOV and corner compromises.

There is no "science" behind my impression.  Given that I've never done side by side, or equivalent settings comparisons I would be the first to defer to those that have done that kind of work.  That said, I am really liking the 20-70 and am thinking that it may become my "go-to" lens, especially in uncertain visibilities.  I had planned to use the 28-60 / WWL-1B for this, but now I'm wondering ...

Gary

I owned the Sony A7C + 28-60+WWL1B and my unscientific perception was that the sharpness of subjects 10’ and further was not as crisp as I was previously getting with my Oly MFT 12-40 in a dome.  I often shoot dolphins and sharks that are not always close.  I ended up switching to Canon, but when I did, I opted for the 14-35mm in a 230mm dome instead of water contact optics.  I prefer this setup over the 28-60+WWL-1B.  Also interesting, is that I find myself using the 35mm end of my 14-35mm far more often than the wide end, and am considering adding a 24-70mm lens +180mm dome as my standard setup.  I would sacrifice corner sharpness for the smaller/lighter dome, as most of my dives are shore diving.  I think this zoom range is overlooked by many as we tend to be taught that fisheye/wide-angle + macro are the two setups you should ‘focus’ on.  I also own the 8-15 fisheye, and love this lens, but it is only brought out for special occasions like CFWA on colorful reef scenes, or if I’m traveling and need to lighten my kit weight.

-Jaycee

5 hours ago, Architeuthis said:

This graph shows the (rough) coverage of angles of view of WWL1/WACP with Sony 28-60mm compared to the rectilinear lenses discussed, based on Chris's suggestion to take the horizontal angle of view as a criterion (The WACP/28-60mm combination covers an angle of view comparable to a 13-33mm rectilinear lens)...

=> It seems the WWL1/WACP would be a good substitute for the Tamron 17-28mm, but Sony 20-70mm is something special.

=> I did not find a careful review of the Sony 28-60mm lens yet, where the actual resolution has been measured. I guess it would be not quite as good as the Tamron 17-28mm and Sony 20-70mm (over the water). I wonder whether there could be a difference spotted in real life when comparing UW photos (most reviewers say that IQ of WWL1/WACP with 28-60mm is excellent)?

 

Wolfgang

 

 

 

 

 

The rectilinear competitor of a WACP/WWL is a 16-35mm lens it gives you a taller frame a bit narrower on the sides

Lots of people do not like the natural look of rectilinear lenses

The 16-35mm lenses that focus very close work in the 180mm wide angle port from Nauticam without need for larger optics. Note that the 230mm dome is just 1 cm longer in terms of curvature radius, the largest benefit of that dome is the field of view to accommodate up to 11mm lenses but the dome itself is not that big in the end

The 180mm port has a curvature radiuse of 11cm but a smaller field of view which means you cannot use lenses wider than 16mm performance wise though is almost identical 1cm is not much to go about

In terms of bulk the 180mm dome is bigger than the WWL-1 but identical to a WACP-1

Many people go about comparing the 230mm dome but this is only required for 12-24 or 14mm lenses. 12mm lenses are in fact horizontally wider than the WACP-1

Edited December 29, 20231 yr by Interceptor121

I think we would agree that with rectilinear lenses and with any given dome port (180/230) that within reason the the amount of extension used can change corner sharpness but not the AOV of the lens.

This is not necesarily the case with the wet wide lenses like WACP-C/WACP-1. Changing the extension length can widen or narrow AOV and also change corner sharpness. So none of the calculations for the 28-60 lens are necessarily correct in the example above. 

4 hours ago, Phil Rudin said:

I think we would agree that with rectilinear lenses and with any given dome port (180/230) that within reason the the amount of extension used can change corner sharpness but not the AOV of the lens.

This is not necesarily the case with the wet wide lenses like WACP-C/WACP-1. Changing the extension length can widen or narrow AOV and also change corner sharpness. So none of the calculations for the 28-60 lens are necessarily correct in the example above. 

The calculations are based upon the Nauticam port chart and the diagonal field of view they list.  All the calculations do is estimate the horizontal and vertical field of view based upon the reported diagonal field of view.   So on this basis the calculations are only as good as the fields provided in the port charts.  The calculations are done for a number of projections as the horizontal and vertical fields are different in those projections at the same diagonal field and we don't what projection the Wet lenses are.  This happens because the corners are stretched more or less in the various types of projections.  

 

The short version is if the calculations are incorrect, so are the port charts, but they are only applicable to the port/extension combination used in the port charts.

 

A complication is that some domes are not full hemispheres.  As Massimo points out the maximum field of view of the 180mm dome based upon geometry is that of a 16mm lens, however if you look in the port charts this dome is recommended for the Olympus 7-14mm, a 14mm full frame equivalent lens.  The only way you do this and not vignette is to place the entrance pupil forward of the optimal position.

 

In fact the issue of correct extensions is a bit of a red herring herring for the purposes here.  What we are trying to do is compare reach of different combinations.  Reach for example is about whether or not you can fill the frame with a shark that doesn't let you get closer than 3m for example.  You don't need calculations done to 3 decimal places to check this, what you need is consistent calculations and in the case of not knowing the projection a way of cross checking.  We can't compare every combination of extension and port size all we can do reasonably is compare recommended dome/wet lens/extension.  

 

Even if you are out a bit in extension it's not going to really change the answer as we are doing a relative comparison and extension change that still has reasonable image quality is not going change the field enough for you to decide differently which lens has enough reach for you. 

 

As Alex Mustard has pointed out before, this is only part of the equation - a fisheye projection provides a different impact to the image with close focus on the central subject causing it pop out and causing sharks to look fatter as examples.  However if the shark is too small in the frame that's all moot, when you need reach you really need it and this discussion is about getting that reach while minimizing the loss of field of view if you also want to take some wide shots on the same dive.

7 hours ago, JayceeB said:

I owned the Sony A7C + 28-60+WWL1B and my unscientific perception was that the sharpness of subjects 10’ and further was not as crisp as I was previously getting with my Oly MFT 12-40 in a dome.  I often shoot dolphins and sharks that are not always close.  I ended up switching to Canon, but when I did, I opted for the 14-35mm in a 230mm dome instead of water contact optics.  I prefer this setup over the 28-60+WWL-1B.  Also interesting, is that I find myself using the 35mm end of my 14-35mm far more often than the wide end, and am considering adding a 24-70mm lens +180mm dome as my standard setup.  I would sacrifice corner sharpness for the smaller/lighter dome, as most of my dives are shore diving.  I think this zoom range is overlooked by many as we tend to be taught that fisheye/wide-angle + macro are the two setups you should ‘focus’ on.  I also own the 8-15 fisheye, and love this lens, but it is only brought out for special occasions like CFWA on colorful reef scenes, or if I’m traveling and need to lighten my kit weight.

-Jaycee

This is not surprising as if you look at tests you'd find the Oly 12-40 would be crisper in the centre than the 28-60 kit lens.  Also a 24mm equivalent lens is not that much of a test of dome port optics. 

 

The WWL is not going to make the centre sharper, but provides better edges at wider f-stops than you could get in a dome.  For shooting sharks the edge sharpness is less important.  I use the 12-40 in a Zen 170mm dome and really like it for temperate water diving, what I really wish for would be a 10-40mm lens with same close focus performance. 

This is a great subject. I’m currently using the Sony 28-60mm with my WACP-1 and have considered getting a 28-70mm but just never did because I didn’t want to add the extra extension even though I travel with it for my 230 dome. 
 

has anyone shot both the 28-60mm and the 28-70mm and have real world results?

I shoot the 28-60 + WWL 1. I'm very happy with the combination. Would be interested in the new fisheye conversion port if I ever get my hands on it, but only for the additional field of view.

 

To be honest at the apertures that we generally use underwater the differences between any modern lens formulas is going to be a figment of our imagination.

On 12/30/2023 at 12:39 AM, Chris Ross said:

This is not surprising as if you look at tests you'd find the Oly 12-40 would be crisper in the centre than the 28-60 kit lens.  Also a 24mm equivalent lens is not that much of a test of dome port optics. 

 

The WWL is not going to make the centre sharper, but provides better edges at wider f-stops than you could get in a dome.  For shooting sharks the edge sharpness is less important.  I use the 12-40 in a Zen 170mm dome and really like it for temperate water diving, what I really wish for would be a 10-40mm lens with same close focus performance. 

I want to relate my experience from Malpelo

 

When you have a lot of current and you need to swim a 180mm dome means 30 bars gone compared to a smaller WWL-1 set up. 

When you dive in a comfortable location you make different choices than if you need maximum agility

Which is the reason why WACP-1/WACP-2 230mm 250mm ports really don't interest me that much

 

The WACP-C is as far as I would go however it does not provide any benefit that I could see on the WWL-1 so an still hanging there. 

With regards to centre sharpness if you can bear a dome my Sony 24-70 Tamron 17-28 all eat the Sony 28-60 for lunch 

We have Sony 16-35 f/2,8 in Nauticam 180mm dome (with A7R2).

As Interceptor121 pointed out, WWL is near 16-35 at wide side, even if second one is rectilinear.

Has someone doing some comparison between both setup ?

I have found here a site that has over the water test images of a test chart from the different lenses in discussion, made with similar sensor (from A7R3 to A1) on display: https://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=1525&Camera=1175&Sample=0&FLI=0&API=0&LensComp=1646&CameraComp=1538&SampleComp=0&FLIComp=2&APIComp=0

 

When viewing these images, I would say that the over water performance of the Sony 20-70mm is very similar to the Sony 28-60mm (maybe a tick better at f4 in the center), Sony 24-70mm GM II is a tick better (both at 28mm and 60m and at f/4 (f5.6) and f8, both center and periphery), Sony 16-35mm GM II is slightly better at 28mm (both f4 and f8) and Tamron 17-28mm is almost the same IQ (28mm both f/4 and f/8).

The lenses above seem to have pretty similar performance at the focal lengths and apertures viewed. Only the Sony 28-70mm is outstanding (only 50mm or 70mm are available for this lens, but results are similar), as IQ is clearly and much worse compared to the 28-60mm.

 

Here a table of the result of my subjective judgements (but have a view on your own):

 

=> These results suggest to me that IQ in the center will be pretty similar between Sony 20-70mm and Tamron 17-28mm behind domeports and Sony 28-60mm behind WWL/WACP (provided the Nauticam optics maintains the IQ).

=> It also explains why most prefer the 28-60mm over the 28-70mm, that is recommended by Nauticam as "best" solution...

 

Wolfgang

Edited January 1, 20241 yr by Architeuthis

When  you shoot at f/11 the gap between lenses is very small and most of the resolution is gone even a 24 and 50 megapixel sensor start to look the same

As long as underwater photography remains a game of f/11 and smaller (which is still is despite the claims of f/5.6 on newer water contact optics nobody shoots f/5.6) things level and SNR and color response become more important than resolution and dynamic range

Only at close up range, but not as close as macro, you see real resolution differences

I try to shoot f/8 to f/11 even on full frame. At f/16 you get the depth of field but the detail in the centre is for most gone

Edited January 1, 20241 yr by Interceptor121

On 12/29/2023 at 7:07 PM, Chris Ross said:

The calculations are based upon the Nauticam port chart and the diagonal field of view they list.  All the calculations do is estimate the horizontal and vertical field of view based upon the reported diagonal field of view.   So on this basis the calculations are only as good as the fields provided in the port charts.  The calculations are done for a number of projections as the horizontal and vertical fields are different in those projections at the same diagonal field and we don't what projection the Wet lenses are.  This happens because the corners are stretched more or less in the various types of projections.  

 

The short version is if the calculations are incorrect, so are the port charts, but they are only applicable to the port/extension combination used in the port charts.

 

A complication is that some domes are not full hemispheres.  As Massimo points out the maximum field of view of the 180mm dome based upon geometry is that of a 16mm lens, however if you look in the port charts this dome is recommended for the Olympus 7-14mm, a 14mm full frame equivalent lens.  The only way you do this and not vignette is to place the entrance pupil forward of the optimal position.

 

In fact the issue of correct extensions is a bit of a red herring herring for the purposes here.  What we are trying to do is compare reach of different combinations.  Reach for example is about whether or not you can fill the frame with a shark that doesn't let you get closer than 3m for example.  You don't need calculations done to 3 decimal places to check this, what you need is consistent calculations and in the case of not knowing the projection a way of cross checking.  We can't compare every combination of extension and port size all we can do reasonably is compare recommended dome/wet lens/extension.  

 

Even if you are out a bit in extension it's not going to really change the answer as we are doing a relative comparison and extension change that still has reasonable image quality is not going change the field enough for you to decide differently which lens has enough reach for you. 

 

As Alex Mustard has pointed out before, this is only part of the equation - a fisheye projection provides a different impact to the image with close focus on the central subject causing it pop out and causing sharks to look fatter as examples.  However if the shark is too small in the frame that's all moot, when you need reach you really need it and this discussion is about getting that reach while minimizing the loss of field of view if you also want to take some wide shots on the same dive.

Chris, These are not things I don't already know, all I said is that with wet lenses extension can change the AOV. If you have 4mm of difference between a macro lens front element and a +15 wet closeup lens you get more magnification (Narrower view) than if you have 8mm of difference.

 

Same is true for the Recommended N100 30mm on a Nauticam housing for the WACP-C. Change the extension length and you change the AOV. Plenty of other housings can support WACP-C, WACP-C, WWL-! and so on but not all have exactly the same length from the front of the 28-60 lens.

 

Attached photos, first 28mm with Nauticam Sony A1 housing with N100/30 extension, second Marelux A1 housing with recommended 17mm extension, third Tamron 28-75mm at 28mm. AOV is different with each land lens.

 

 

3 hours ago, Phil Rudin said:

Chris, These are not things I don't already know, all I said is that with wet lenses extension can change the AOV. If you have 4mm of difference between a macro lens front element and a +15 wet closeup lens you get more magnification (Narrower view) than if you have 8mm of difference.

 

Same is true for the Recommended N100 30mm on a Nauticam housing for the WACP-C. Change the extension length and you change the AOV. Plenty of other housings can support WACP-C, WACP-C, WWL-! and so on but not all have exactly the same length from the front of the 28-60 lens.

 

Attached photos, first 28mm with Nauticam Sony A1 housing with N100/30 extension, second Marelux A1 housing with recommended 17mm extension, third Tamron 28-75mm at 28mm. AOV is different with each land lens.

 

 

Thanks Phil, there is indeed some variation, but I think that is a seperate problem if you get into all the possible variations of different manufacturers ports  you come up with too large a comparison.  On a relative basis (not an absolute basis) you still should be able to compare coverage horizontal differences between a rectilinear and the wet optics.   The calculations are mainly to calculate the horizontal coverage from the diagonal.  The diagonal coverage can be misleading as the the corners stretch so much due to barrel distortion in fisheye lenses and wet optics.

 

Just to clarify the photos are 28-60 at 28mm for first two and Tamron 28-75 at 28mm for the last and they are all behind a WACP or WWL optic at varying extensions taken from a fixed location in the pool?