Sony 20 mm - 70 mm f4.0 G for UW?

[Interceptor121 765]

Despite only shooting one Sony camera ever underwater I still have an interest in UW shooting evolution and follow along....I see all manner of gear on my hosted trips so it's in my interest to continually learn from other's experience with new gear.
As to how well the new Sony 20-70mm lens may work for certain shooters I'll wait for Phil's zoom gear testing plus manufacturer's advice and real world shooting versus calculated measurements.
With decades of shooting and him generously sharing his insights he has no axe to grind and just wants people to enjoy underwater photography! We've known each other for over 30 years and is a straight shooter
I'm sure his insights will be more relevant than dry land "calculated guesses".
David Haas

Trial and error with no information basis is called guessing
Having precise information about lens design and making calculations that need to be optimised is called modelling
What Phil is doing is closer to the first description what I am suggesting is closer to the second
Food for thought


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[dhaas 33]

Interceptor121,

OK, you're right and everyone else is wrong after decades of testing that way.

I'm pretty sure actual pictorial evidence Phil will have however it works out good or bad will help anyone considering a piece of gear then spending $$$$ to travel and record their underwater moments 

Different opinions is fine but I'll wait for real world samples as I stated. 

I'm out! LOL.......

DH

[ChrisRoss 150]

15 minutes ago, dhaas said:

Interceptor121,

OK, you're right and everyone else is wrong after decades of testing that way.

I'm pretty sure actual pictorial evidence Phil will have however it works out good or bad will help anyone considering a piece of gear then spending $$$$ to travel and record their underwater moments 

Different opinions is fine but I'll wait for real world samples as I stated. 

I'm out! LOL.......

DH

Some people relate to doing calculations and that's perfectly fine - it is a way of getting in the ballpark before playing around with trial and error use of ports and extensions.  Others don't do the calculation thing and that's also fine.  Ultimately it comes down to doing both, for example you can calculate if a lens will even focus in a dome before sourcing one to test.  That's only one half of the equation getting the lens positioned properly, the other half is actually testing the lens to see if behaves well in a dome, not all of them do. 

If someone chooses not to use calculations first that's their choice and their time and effort trying out different combinations, it they are prepared to do that that's their choice.  Ultimately we all benefit from sharing of everyone's results.

[Humu797 20]

Thanks for trying to work out the kinks Phil Rudin. I just got the 20-70mm yesterday. I certainly do appreciate maths working things out, but the perfect sometimes gets in the way of good enough. That said, I rue the idea of hauling a 250 dome into the water.

[ChrisRoss 150]

11 minutes ago, Humu797 said:

Thanks for trying to work out the kinks Phil Rudin. I just got the 20-70mm yesterday. I certainly do appreciate maths working things out, but the perfect sometimes gets in the way of good enough. That said, I rue the idea of hauling a 250 dome into the water.

I doubt very much you will need a 250mm dome.  The figures indicate that the 180mm should be good enough now we await the tests to see how it goes UW.  You need to know when to stop calculating! 

 

[Phil Rudin 455]

So the manufacture supports the following lenses in the 230mm port, Sony FE 24-70 F/2.8,  24-70 F/2.8 II, 24-70 F/4 old version, 24-105, Sony 20mm F/1.8, F/4, Sigma 28-70 & 24-70 F/2.8. Port extensions for these lenses range from 50 to 90mm in 10mm increments. I think it is safe to say that if you see vignetting with 70mm of extension at 20mm it would only get worse at 80mm and 90mm, that leaves something in the 50 to 60mm range for the most likely best results. I don't own a 15mm or 25mm to try dialing in at 5mm increments. 

just to be clear I didn't just pull the 70mm first try out of my ass it was based on calculations already made by the manufacture using similar lenses. I am the first to admit that this system does not always work due to lens design. Example past Sony FE 16-35mm lenses in Nauticam housings were recommenced to have best results in a 230mm port. With the new Sony FE PZ 16-35mm F/4 Nauticam recommends the 250mm port. My guess is that most will use this lens with a 230mm port or pass on the lens all together.

Ultimately you can do all the calculations you want with the equipment being considered but until you try the combination in the field you won't know what works within your tolerance for IQ. Some obsess over ultimate corner sharpness while others will obsess over overall system size. 

 

[Interceptor121 765]

So the manufacture supports the following lenses in the 230mm port, Sony FE 24-70 F/2.8,  24-70 F/2.8 II, 24-70 F/4 old version, 24-105, Sony 20mm F/1.8, F/4, Sigma 28-70 & 24-70 F/2.8. Port extensions for these lenses range from 50 to 90mm in 10mm increments. I think it is safe to say that if you see vignetting with 70mm of extension at 20mm it would only get worse at 80mm and 90mm, that leaves something in the 50 to 60mm range for the most likely best results. I don't own a 15mm or 25mm to try dialing in at 5mm increments. 
just to be clear I didn't just pull the 70mm first try out of my ass it was based on calculations already made by the manufacture using similar lenses. I am the first to admit that this system does not always work due to lens design. Example past Sony FE 16-35mm lenses in Nauticam housings were recommenced to have best results in a 230mm port. With the new Sony FE PZ 16-35mm F/4 Nauticam recommends the 250mm port. My guess is that most will use this lens with a 230mm port or pass on the lens all together.
Ultimately you can do all the calculations you want with the equipment being considered but until you try the combination in the field you won't know what works within your tolerance for IQ. Some obsess over ultimate corner sharpness while others will obsess over overall system size. 
 

Assuming your lens is vignetting against the dome aperture and not the entire surface (plausible as the lens is fairly wide)
Your 70mm extension is around 20mm too long.
You can try a shorter one in a bathtub without even going to the pool and see if it is preserving or not the field of view
With this system you would have saved yourself two trips to the pool
There is more without this you will now go back with 60mm and conclude that works because it doesn’t vignette but that is incorrect too and your angle of view will be reduced
You can keep doing the same things for any number if years you want but ultimately this is physics
Even in physics you do observation but the purpose of theory and model is to reduce them to the minimum so you don’t have to go back to the drawing board every time
Of course is your prerogative to use your own time as you wish as well as define your own level of quality you are satisfied
For clarity once you know the lens design you need trigonometry which is year 11 in UK 10th grade in US
This is not advanced science


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[Paul Kay 62]

20 hours ago, Interceptor121 said:

Trial and error with no information basis is called guessing
Having precise information about lens design and making calculations that need to be optimised is called modelling

Reality requires a bit of both. Lens manufacturer's rarely supply the sort of information required for any really precise calculations and when working at close focus many parameters can shift (like focal length for example) which can cause 'modelling' problems. So in my experience calculations should really be used to provide a reasonable starting point for fine tuning by trial and error. This has always been how I have optimised my set ups and its worked well enough for me.

[Interceptor121 765]

Reality requires a bit of both. Lens manufacturer's rarely supply the sort of information required for any really precise calculations and when working at close focus many parameters can shift (like focal length for example) which can cause 'modelling' problems. So in my experience calculations should really be used to provide a reasonable starting point for fine tuning by trial and error. This has always been how I have optimised my set ups and its worked well enough for me.

There are detailed simulator that even include focus breathing
But focus breathing doesn’t change entrance pupil position anyway
Check the optical bench on photonstophotos to have an idea what is available for most lenses
Even without a model you can calculate with good precision the position of the entrance pupil either starting from angle of view and filter size or put the lens on a tripod and find the position yourself
As of now the error margin I have had is less than 5mm so depending on what data you have you can reduce your error margin a lot
On top not everyone has all parts to play with so having your own method is a way to save money

When I asked nauticam how they make they evaluations i was told they use a macro slider which means they do this is a little tank
Having to take a lens at sea to determine the correct extension would be very inefficient so the manufacturers themselves don’t do that
Yet in some cases I am not totally sure of the consistency of port charts and there are cases where things don’t get the asterisk blessing and still work fine

I think knowledge helps matters and knowing how things work is a good thing it makes the process efficient and you have a solution before the manufacturer makes the test which is useful to check of a lens is even worth a focus gear that you can also 3D print

The idea that we should dismiss knowledge and just jump in the water slapping what we think may work may work if you have a lot of time on your hands but no doubt is inefficient and potentially inaccurate

It may give someone a headache to know someone else has a grip on those concepts without even having the lens but that’s pretty much a reality
We can then disagree on what is ideal for two different people but dismissing the fact one may have a method that produces results quickly seems illogical

Besides even from the datapoint provided by Phil you can work out how to make a correction isn’t that a good thing?


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[Paul Kay 62]

7 minutes ago, Interceptor121 said:

There are detailed simulator that even include focus breathing
But focus breathing doesn’t change entrance pupil position anyway
Check the optical bench on photonstophotos to have an idea what is available for most lenses

None can deal with the interaction of a simple lens (dome port) of unknown refractive index and thickness, working within and environment of differing refractive indices, and its interaction with a camera lens. I have a friend who is an optical designer and given sufficient appropriate input data he can provide extraordinary amounts of information including theoretical MTF details. But underwater photography  is often undertaken at settings which are neither easy to pre-determine nor as staigntforward as might be preferred andas a result its difficult to provide good theoretical data. A 20~70 lens used at close focus distances behind a dome will have compromises and working out which set of compromises is optimal (for each individual photographer) really does require rough calculation followed by practical trial and error. As extension tubes for ports are usually in 5mm increments at best this should tell us something about the tolerances accepted by the manufacturers. Photography is actually a highly practical application of technology.

[Interceptor121 765]

None can deal with the interaction of a simple lens (dome port) of unknown refractive index and thickness, working within and environment of differing refractive indices, and its interaction with a camera lens. I have a friend who is an optical designer and given sufficient appropriate input data he can provide extraordinary amounts of information including theoretical MTF details. But underwater photography  is often undertaken at settings which are neither easy to pre-determine nor as staigntforward as might be preferred andas a result its difficult to provide good theoretical data. A 20~70 lens used at close focus distances behind a dome will have compromises and working out which set of compromises is optimal (for each individual photographer) really does require rough calculation followed by practical trial and error. As extension tubes for ports are usually in 5mm increments at best this should tell us something about the tolerances accepted by the manufacturers. Photography is actually a highly practical application of technology.

Paul
You are saying the same thing
I never said you don’t need any verification but the error margin is low
And am not talking about MTF etc this is simply positioning
As the extension is fixed if the entrance pupil moves performance will change so it won’t work well at all focal length
This is not fixable by any fixed port system
With regards to refractive index that alters the visual image but again matters nothing to the positioning of the port related to the entrance pupil refractive index is not part of the formula
Anyway this is going wildly off topic

I have asked nauticam if they will make a zoom gear for this lens and I am still considering if this is worth it myself


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[JYk 20]

I will just stay here and follow the topic. Personal I would love to see if this might be a good setup with a "smaller" 180cm or 8 inch dome port. Could be a perfect travel setup. The lens also has a 0,39 maximum magnification at 70mm, so I think it could work for some bigger marco subjects. Well lets see when we got the port list from the vendors. 

[Interceptor121 765]

43 minutes ago, JYk said:

I will just stay here and follow the topic. Personal I would love to see if this might be a good setup with a "smaller" 180cm or 8 inch dome port. Could be a perfect travel setup. The lens also has a 0,39 maximum magnification at 70mm, so I think it could work for some bigger marco subjects. Well lets see when we got the port list from the vendors. 

The 180mm has a 11 cm radius the 230 has a 12cm radius the difference is the field of view. I see almost zero benefit using the 230 dome with this lens. Is either the 180mm for a smaller set up or the 250mm port for the most ideal set up

The disbenefit of the smaller port is that you will loose the close focus as explained by @ChrisRoss you will give up on 8cm.

So while the 250mm port would offer you 48cm range the 180mm will offer you 25cm focus range resulting in a more compressed depth of field. You will not gain anything from the smaller port as the camera will not focus right on it so you will only gain on weight and cost.

For what concerns the macro idea again you are not going to get that close to be able to focus consider that the 180mm port is not that small definitely not a macro device but can be used for close up of a moray eel or similar

Edited March 9 by Interceptor121

[adamhanlon 0]

On 3/8/2023 at 6:55 AM, Interceptor121 said:

For clarity once you know the lens design you need trigonometry which is year 11 in UK 10th grade in US
This is not advanced science

Once again @Interceptor121, your point comes across as overly aggressive and argumentative.

Perhaps (for those of us that never understood or can't remember trigonometry) rather than point out that we "should" all be able to be as clever as you, you should actually set out how to do this and explain why the theory works. To suggest that those of us that can't remember what we learnt in school are in some way deficient is borderline ad hominem and insulting.

The goal in this community is not to try and show how clever you are, but to help others to understand. 

For what it is worth, my experience is that lens performance behind dome ports is serendipitous rather than by design. I have not been able to discern from specifications whether a lens will work well or not, and have found that in-water testing is the only way to actually find out how lenses perform and to figure out extension lengths. In part, wide angle lens designers tend not to prioritise close focus performance.

[Interceptor121 765]

1 hour ago, adamhanlon said:

Once again @Interceptor121, your point comes across as overly aggressive and argumentative.

Perhaps (for those of us that never understood or can't remember trigonometry) rather than point out that we "should" all be able to be as clever as you, you should actually set out how to do this and explain why the theory works. To suggest that those of us that can't remember what we learnt in school are in some way deficient is borderline ad hominem and insulting.

The goal in this community is not to try and show how clever you are, but to help others to understand. 

For what it is worth, my experience is that lens performance behind dome ports is serendipitous rather than by design. I have not been able to discern from specifications whether a lens will work well or not, and have found that in-water testing is the only way to actually find out how lenses perform and to figure out extension lengths. In part, wide angle lens designers tend not to prioritise close focus performance.

I was not intending to offend anyone I was reacting to this rather unconventional statement from David Haas which I think is dismissive and diminishing of who tries to do an effort for the benefit of others.

As to how well the new Sony 20-70mm lens may work for certain shooters I'll wait for Phil's zoom gear testing plus manufacturer's advice and real world shooting versus calculated measurements.

My point is that in the largest majority of cases lens design is known or can be calculated quite easily for what is needed to implement the correct dome port. As I said it requires basic trigonometry to know which dome can fit what even without having the lens design.

I am growing increasingly skeptical of the lack of rigour that there is in the sector despite the high value of the items involved that generate costly mistakes. In order not to make those mistakes I have developed my own method that works well. So far there have been a number of solutions not on the chart that have proved to work without being officially supported.

With few parameters available is entirely possible to calculate what a combination can or not do and the idea that we need to wait some advice from real world shooting (besides I do my test in a pool it is still underwater after I have done a model) and nothing can be said is a very extreme view and to dismiss who tries to put some order into this is in my view a mistake

Perhaps going forward I should just keep my considerations to myself as otherwise there is a risk that this is not even welcome simply because someone can't understand the logic and neither I want things to become a lecture and spend to much time explaining myself

[adamhanlon 0]

I can see nothing unconventional or even contentious in the following statement. I read that he is simply stating that he wants to see how the lens works in "real world" conditions before making a decision. It also stated as an opinion, so cannot be seen as "unconventional," "dismissive" or in any way "diminishing." He is simply disagreeing with you, not stating that you are wrong....

1 hour ago, Interceptor121 said:

As to how well the new Sony 20-70mm lens may work for certain shooters I'll wait for Phil's zoom gear testing plus manufacturer's advice and real world shooting versus calculated measurements.

 

1 hour ago, Interceptor121 said:

Perhaps going forward I should just keep my considerations to myself as otherwise there is a risk that this is not even welcome simply because someone can't understand the logic and neither I want things to become a lecture and spend to much time explaining myself

Kind of sums up the issue. I am truly sorry that you feel the Wetpixel community is unable to "understand" your logic. If this is the way you feel, perhaps your insights might be better shared in a venue that can do so. 

Your decision.

[Phil Rudin 455]

On 3/8/2023 at 1:55 AM, Interceptor121 said:

Images do not look good at all

I think your extension is way too long the 230 port has a field of view of 140 degrees while the lens has 94 degree using vignetting as a criteria is not going to help

#1-THIS RESPONSE IS LIKELY BASED ON AN ASSUMPTION AS 121 HAD NO IDEA WHAT HOUSING BRAND, PORT BRAND OR EXTENSION BRAND I WAS USING. SO I WOULD ADD MAKING ASSUMPTIONS TO ADAM'S LIST.  

You can try a shorter one in a bathtub without even going to the pool and see if it is preserving or not the field of view
With this system you would have saved yourself two trips to the pool

#2-MANSPLAYING (A TERM GENERALLY USE WHEN A MAN IS TAKING TO A WOMEN) 121 HAS MANSPLAINED TO ME THAT I CAN AVOID GOING TWICE TO THE POOL BY TESTING MY EQUIPMENT IN A BATHTUB AS IF HE KNOWS ME.

FIRST I HAVEN'T USED A BATHTUB SINCE I WAS A CHILD AND SECOND I HAVE A POOL IN MY BACKYARD ABOUT 30 FEET FROM MY OFFICE. TODAY THE WATER TEMPERATURE IS 82 DEGREES FAHRENHEIT AND THE AIR TEMP IS 86 DEGREES. SECOND I THOROUGHLY ENJOY MY POOL AND USE IT SEVERAL DAYS A WEEK. I CAN ALSO WALK TO THE INTRACOASTAL  WATERWAY FROM MY HOUSE OR DRIVE TO THE BLUE HERON BRIDGE IN ABOUT FIVE MINUTES FOR TESTING SO WHY WOULD I WANT TO WASTE WATER FILLING A BATHTUB.     

There is more without this you will now go back with 60mm and conclude that works because it doesn’t vignette but that is incorrect too and your angle of view will be reduced

#3 121 HAS ALSO ASSUMED A CONCLUSION FOR ME ABOUT WHAT I THINK WILL OR WON'T WORK WITH THIS LENS.

You can keep doing the same things for any number if years you want but ultimately this is physics
Even in physics you do observation but the purpose of theory and model is to reduce them to the minimum so you don’t have to go back to the drawing board every time

#4 IT APPEARS IN THIS STATEMENT THAT 121 AGAIN ASSUMES THAT I AM NOT AWARE THAT PHYSICS ARE INVOLVED IN THIS PROCESS.

Of course is your prerogative to use your own time as you wish as well as define your own level of quality you are satisfied

#5 THANK YOU 121  FOR ACKNOWLEDGING THAT I AM ALLOWED TO USE MY TIME ANYWAY I LIKE.

 
For clarity once you know the lens design you need trigonometry which is year 11 in UK 10th grade in US
This is not advanced science

#6 121 IS CORRECT THIS IS NOT ADVANCED SCIENCE AND THE POSSIBILITIES ARE LIMITED TO WHAT PORT YOU CHOSE FOR THIS LENS AND A CHOICE OF EXTENSIONS THAT AT BEST ARE IN 5MM INCREMENTS. NOT THAT ITS ANYONES BUSINESS BUT I NEVER LIKED MATH DURING MY SCHOOL YEARS AND NEVER WENT BEYOND ALGEBRA MUCH TO THE CHAGRIN OF MY PARENTS WHO WERE BOTH ENGINEERS MY THREE SISTERS AND I ALL HATTED MATH. THIS IS WHY I DON'T HAVE ANY INTENTION TO USE TRIGONOMETRY AND WHY IT GIVES ME A MIGRAINE. I APPLAD THOSE WHO FIND TRIGONOMETRY INTERESTING BUT I AM NOT ONE OF THEM AND HAVE GOTTON ON FIND WITHOUT USING IT AS A TESTING RESOURCE.     


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Since most of the comments in question were in my posts I would just like followup with a response since my friend David Haas and Adam have gotten involved in one way or another. In this thread and another I did not post in Adam pointed out that 121's remarks were overly aggressive, argumentative, dogmatic and hectoring. To me they make several unfounded assumptions and and give the impression 121 knows me in some way which could not be further from the truth. 

First I will go back to my original comments meant for the original poster who was interested to know it anyone had used this lens. My response was yes I am in the process of testing the lens with a 230mm port and 70mm of extension. I also described what I thought the advantages of the 20-70 over the more common 24-70 and 28-70 loses could be. Above in all caps are my responses to 121 some of which are the subject of Adam's post above..

 

 

Edited March 13 by Phil Rudin

[ajay 13]

@Interceptor121 thanks for the reference to photonstophotos -- I have only had a chance to browse it for a few minutes, and it seems to be a treasure trove. Appreciate it.

Apropos to the debate here, I haven't too much insightful to add - having been in the education field for a long time, I am finding that many humans respond better to an approach that we call the experiential learning model. Here the idea is to first "just do it" (a quick and rough prototype), and then, when the design fails (and it does, haha), analyse the failure, look up the theory, make a model, solve it and use the solution to drive the next iteration.. I feel like I could see shades of this approach (as contrasted to the purely liberal approach used in most of our universities today) in this discussion. Just my two cents,

Kind regards

Ajay 

[ChrisRoss 150]

9 hours ago, Phil Rudin said:

 

Since most of the comments in question were in my posts I would just like followup with a response since my friend David Haas and Adam have gotten involved in one way or another. In this thread and another I did not post in Adam pointed out that 121's remarks were overly aggressive, argumentative, dogmatic and hectoring. To me they make several unfounded assumptions and and give the impression 121 knows me in some way which could not be further from the truth. 

First I will go back to my original comments meant for the original poster who was interested to know it anyone had used this lens. My response was yes I am in the process of testing the lens with a 230mm port and 70mm of extension. I also described what I thought the advantages of the 20-70 over the more common 24-70 and 28-70 loses could be. Above in all caps are my responses to 121 some of which are the subject of Adam's post above..

 

 

Re maths, exactly, some people prefer to relate to problems from a theoretical perspective other like to test things in a practical manner.    Both approaches are fine and each to their own preference.  In the end it will need to be tested anyway.  I have found vendors deviate from the theoretical positioning for some lenses and my understanding is that at least some vendors are setup with macro sliders where they can test the lens to come up with the final positioning.  

If someone is prepared to take the time to try out these new lenses and share the results we should all be thankful no matter which approach they take to get there.  Ideally in this forum we can all can learn from both approaches by considering the views of everyone without any form of finger pointing

[Interceptor121 765]

[mention=34353]Interceptor121[/mention] thanks for the reference to photonstophotos -- I have only had a chance to browse it for a few minutes, and it seems to be a treasure trove. Appreciate it.

Apropos to the debate here, I haven't too much insightful to add - having been in the education field for a long time, I am finding that many humans respond better to an approach that we call the experiential learning model. Here the idea is to first "just do it" (a quick and rough prototype), and then, when the design fails (and it does, haha), analyse the failure, look up the theory, make a model, solve it and use the solution to drive the next iteration.. I feel like I could see shades of this approach (as contrasted to the purely liberal approach used in most of our universities today) in this discussion. Just my two cents,
Kind regards
Ajay 

I guess some subjects are fairly simple take a cooking class you learn by doing
But you wouldn’t leave someone to experiment chemistry without any learning before hitting the lab
The recurring theme with wide angle lenses is something new comes up and people who don’t have the lens and do not own the underwater parts are curious to know if this combination is going to work
Generally there are things you should be looking for but it really helps to know the lens construction as that will give you an almost accurate idea of the behaviour of the lens
The other complexity are the underwater ports only few of them are complete hemispheres the others are cuts with smaller angle of view and they are also built differently one another
With that in mind it is clear that two ports of this nature should require different extension but in most cases you look at the port chart and that’s not the case. You know then that the manufacturer hasn’t actually tried too hard the compatibility
When you don’t have all those parts available it really helps to know how things work to optimise your spend
One thing that is apparent is that the prevailing empirical approach which is find the longest extension until you see vignetting and then step back produces good results only when the lens field of view is very similar to the port field of view
In the case mentioned here the lens has 94 degrees while the port has 143
They are far apart so the extension when the lens vignette is far away from the ideal placement point and they empirical approach becomes suboptimal


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[Phil Rudin 455]

Marelux has now updated the port chart for Sony lenses and added the Sony FE 20-70mm F/4 with zoom gear #51109. With the 230mm port they have recommended a 60 extension and a 50 extension with the 180mm dome port. I have now tried both and I really like the 180mm port for my local diving. Marelux has sent me a 15mm extension which arrive next week so I may try 5mm over/under just for fun.

Nauticam updated the Sony chart on 3/14 and while the 20-70 has not been added they have added the WACP-1 with the new Sony FE PZ 16-35mm F/4. This allows a zoom from 28-35 for a converted FOV from 130-109 for those who think the  28-60, 28-70 and 28mm F/2 don't have good enough IQ. The combination requires the N120 10mm/10mm II extension. Prior Sony 16-35 lenses only worked with the expensive and heavy WACP-II.

[Interceptor121 765]

22 minutes ago, Phil Rudin said:

Marelux has now updated the port chart for Sony lenses and added the Sony FE 20-70mm F/4 with zoom gear #51109. With the 230mm port they have recommended a 60 extension and a 50 extension with the 180mm dome port. I have now tried both and I really like the 180mm port for my local diving. Marelux has sent me a 15mm extension which arrive next week so I may try 5mm over/under just for fun.

Nauticam updated the Sony chart on 3/14 and while the 20-70 has not been added they have added the WACP-1 with the new Sony FE PZ 16-35mm F/4. This allows a zoom from 28-35 for a converted FOV from 130-109 for those who think the  28-60, 28-70 and 28mm F/2 don't have good enough IQ. The combination requires the N120 10mm/10mm II extension. Prior Sony 16-35 lenses only worked with the expensive and heavy WACP-II.

those recommendations make no sense.

the 230 port is almost an hemisphere while the 180mm port has an angle of view that is reduced the port is 83mm tall requiring always 2 cm more compared to the 230mm port

It looks like they are continuing to use vignetting as a criteria so of the two the 180mm port extension is the one that is nearer what is required. The 230 port should be 20mm shorter and 60mm is possibly way too long 30mm would be a better option if you had that port

Of course manufacturers know better except when they don't!

[Phil Rudin 455]

First of all I am just the messenger and secondly while I am sure you used advanced trigonometry to calculate the 30mm extension for the 230mm dome the lens approaching the 70mm end hits the back of the port glass. It seems to me that would be a bad thing so you may want to recalculate.    

[Interceptor121 765]

1 hour ago, Phil Rudin said:

First of all I am just the messenger and secondly while I am sure you used advanced trigonometry to calculate the 30mm extension for the 230mm dome the lens approaching the 70mm end hits the back of the port glass. It seems to me that would be a bad thing so you may want to recalculate.    

180mm port depth 83 mm 230mm port depth 112 mm

83+50=133

112+30=142

I do not see how the lens would hit the 230 port before it hits the 180mm port

Besides both need the 35.5mm N100 to N120 port so add 35.5 and 25mm the port is recessed in the housing you get

133+35+25=193

142+35+25=202

Both dimensions are far away from the lenght of the lens fully extended

The 230 port is always deeper and physics normally works well and the reason why the 230 port needs to be longer is because the radius is 1cm longer however if this was 60 cm the combination would go to a whopping 232mm which is not required and will induce pincushion distortion

Edit I am now looking at the marelux port chart there is no 35mm port adapter in the port chart and the extensions look all over the place in some cases the two ports take the same extension in others one is longer than the other and then viceversa. Ouch!

Edited March 17 by Interceptor121

[Phil Rudin 455]

Once again it does not appear that you bothered to read my post or even be in the ballpark because I was talking about the Marelux port chart not the Nauticam port chart. Nauticam posted new updates on 3/14 and they have not listed the Sony 20-70mm F/4.

If you are unaware Nauticam and Marelux are not the same company and they don't use the same extension lengths.