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

[Interceptor121 842]

Just now, Phil Rudin said:

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. 

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. 

The product look pretty much copies of Nauticam designs the dimensions are identical

I would not trust that port chart for any practical use it is inconsistent all over

[Phil Rudin 485]

30 minutes ago, Interceptor121 said:

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. 

The product look pretty much copies of Nauticam designs the dimensions are identical

I would not trust that port chart for any practical use it is inconsistent all over

So in am guessing that you just can't admit that you are wrong in making the assumption that I was not talking about Nauticam even though Marelux is the first word in my post and decided to instead attack Marelux products. I will not make the assumption that you have even held or seen a Marelux housing or that you any idea which Marelux housing I may have been talking about.

And just for others future reference Marelux only has one port mounting size (5 inch) for all of their current housings, further they use a bayonet port mount so a more like comparison would be housings like Aquatica, Isotta, Sea & Sea and so on. Further if you had looked closely at the Marelux port chart you would see they don't need a 35.5mm adapter because they are not moving between N100 and N120 sizes like Nauticam. You might have also noticed that the recommended Marelux flat macro port for the Sony 28-60 is a 32mm port while it is 45mm for Nauticam. Since I have actually use several Marelux and Nauticam housings I can say without reservation that they are both quality products with several differences as would be expected. 

You may also want to look at the Nauticam port charts for Sony and you will see that some lenses use the same port extension for two or three different port sizes so these recommendations are not uncommon or exclusive to Marelux.  

[Interceptor121 842]

6 minutes ago, Phil Rudin said:

So in am guessing that you just can't admit that you are wrong in making the assumption that I was not talking about Nauticam even though Marelux is the first word in my post and decided to instead attack Marelux products. I will not make the assumption that you have even held or seen a Marelux housing or that you any idea which Marelux housing I may have been talking about.

And just for others future reference Marelux only has one port mounting size (5 inch) for all of their current housings, further they use a bayonet port mount so a more like comparison would be housings like Aquatica, Isotta, Sea & Sea and so on. Further if you had looked closely at the Marelux port chart you would see they don't need a 35.5mm adapter because they are not moving between N100 and N120 sizes like Nauticam. You might have also noticed that the recommended Marelux flat macro port for the Sony 28-60 is a 32mm port while it is 45mm for Nauticam. Since I have actually use several Marelux and Nauticam housings I can say without reservation that they are both quality products with several differences as would be expected. 

You may also want to look at the Nauticam port charts for Sony and you will see that some lenses use the same port extension for two or three different port sizes so these recommendations are not uncommon or exclusive to Marelux.  

It does not matter what port system you use. You cannot have the same lens having one time a longer extension for one dome and another lens shorter it does not make any sense. Your comment about the port chart difference between the nauticaj and this one simply means the camera is more recessed indicating less precision in the manufacturing process. If Nauticam is 25mm in this one is 38mm in.

Few examples of Marelux port chart

Sigma 24-70mm lens 180mm dome 80mm extension 230mm 70mm extension

Sony 27-70 lens 180mm dome 50mm extension 230mm dome 60mm extension

Sony 24-105mm 180mm dome 70mm extension 230mm dome 70mm extension

What would be the logic to make sense of those recommendations? The ports are physically the same and based on construction either one needs longer or shorter (equal is unlikely) cannot go around like this

It just shows that there is lack of rigour here besides most of those lenses have design details available so it is relatively easy to rectify if you know how to. If someone has any logic argument to make sense of the above example I look forward to an explanation

I believe a fundamental issue with rectilinear lenses especially not too wide is that the extensions 'suggested;' are many times totally off while for fisheye lens the rule go forward until it vignettes works much better. Those few example that work well are mostly out of coincidence not choice.

 

 

 

 

[Phil Rudin 485]

For the  Sony FE 24-105mm F/4 G it does not appear that Nauticam has support for this lens but Aquatica does and it uses extension 48459 with both 8 inch and 9.5 inch glass ports, Isotta has support for 24-105 they recommend a 90mm extension for the 6 inch, 6.5 inch, 8 inch and 9 inch ports and Marelux recommends the 70mm extension for both 180 and 230mm ports. 

For the Sigma 24-70mmF/2.8  DG DN Marelux recommends the 60mm extension for both 180 and 230 ports. 

For the Sigma 24-70 F/2.8 ART lens Marelux recommends the 80mm extension for both 180 and 230mm ports, (I am sure that it is quite possible that for the 230 port that Marelux simply made a mistake on the single (70mm) extension because if you look below at the combination of the 40mm extension with knob and the 40mm extension that adds up to 80mm unless my math is wrong). For the Sigma 24-70 ART Nauticam recommends the 55mm extension for the 8.5 inch, 180mm and 230mm ports. Nauticam has added the asterisk to the 230mm dome as being the best but not all can afford that port.

As far as your Sony 27-70mm lens, I would not want to accuse you of making another mistake so I will wait for that lens to be released I am sure you have some inside information that we don't.

I doubt seriously that we will see extensions in 1mm increments even though they may best possession a given port for best optimal use of a given lens. Until then people have been using these combinations and producing exceptional photos for decades.    

[Interceptor121 842]

3 hours ago, Phil Rudin said:

For the  Sony FE 24-105mm F/4 G it does not appear that Nauticam has support for this lens but Aquatica does and it uses extension 48459 with both 8 inch and 9.5 inch glass ports, Isotta has support for 24-105 they recommend a 90mm extension for the 6 inch, 6.5 inch, 8 inch and 9 inch ports and Marelux recommends the 70mm extension for both 180 and 230mm ports. 

For the Sigma 24-70mmF/2.8  DG DN Marelux recommends the 60mm extension for both 180 and 230 ports. 

For the Sigma 24-70 F/2.8 ART lens Marelux recommends the 80mm extension for both 180 and 230mm ports, (I am sure that it is quite possible that for the 230 port that Marelux simply made a mistake on the single (70mm) extension because if you look below at the combination of the 40mm extension with knob and the 40mm extension that adds up to 80mm unless my math is wrong). For the Sigma 24-70 ART Nauticam recommends the 55mm extension for the 8.5 inch, 180mm and 230mm ports. Nauticam has added the asterisk to the 230mm dome as being the best but not all can afford that port.

As far as your Sony 27-70mm lens, I would not want to accuse you of making another mistake so I will wait for that lens to be released I am sure you have some inside information that we don't.

I doubt seriously that we will see extensions in 1mm increments even though they may best possession a given port for best optimal use of a given lens. Until then people have been using these combinations and producing exceptional photos for decades.    

it was a type 20-70 but again it makes no sense that port chart period

I don't need to bore you guys you are happy with what you have fine so be it

[Paul Kay 65]

On 3/13/2023 at 1:34 PM, adamhanlon said:

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've tried asking lens manufacturers for data such as the positions of Principal Points and such like useful information which would help in theoretic computations, since these may be useful in approximating requirements. Unfortunately such requests seem to disappear into a blackhole meaning that lenses would need to be tested to determine the data required. All of which makes me think that often in-water testing is just as easy as trying to check and work things out any other way ......

[Interceptor121 842]

31 minutes ago, Paul Kay said:

I've tried asking lens manufacturers for data such as the positions of Principal Points and such like useful information which would help in theoretic computations, since these may be useful in approximating requirements. Unfortunately such requests seem to disappear into a blackhole meaning that lenses would need to be tested to determine the data required. All of which makes me think that often in-water testing is just as easy as trying to check and work things out any other way ......

Patents exist as well as people that know how to present them

https://photonstophotos.net/GeneralTopics/Lenses/OpticalBench/OpticalBench.htm

Underwater manufacturers follow the same trial and error approach

When I asked Nauticam what they did they told me they use in water macro slide

In addition you can find the no parallax point of a lens using a tripod 3 posts and a slide mount

Edited March 24 by Interceptor121

[Paul Kay 65]

1 hour ago, Interceptor121 said:

Patents exist as well as people that know how to present them .....

I have a friend who is an optical designer. He uses software which can generate an enormous amount of data including predicted MTF graphs. But to do so he needs information. If you are going to waste lots of time using trial and error methods to provide such information you might as well simply use an in water macro slide in the first place. As you suggest. Its not rocket science.

[Interceptor121 842]

I have a friend who is an optical designer. He uses software which can generate an enormous amount of data including predicted MTF graphs. But to do so he needs information. If you are going to waste lots of time using trial and error methods to provide such information you might as well simply use an in water macro slide in the first place. As you suggest. Its not rocket science:rolleyes:.

You are talking about two opposite

Someone that is trying too much to simulate stuff

And someone else who has nothing better than using a tool designed for macro to test domes whose only benefit is not to go in the water

It is clear that the results are suboptimal when I said they use a macro slide (for wide angle) doesn’t mean I think they are doing the right thing the opposite

Clearly when there is a competence gap it is difficult to appraise the difference between astrophysics and trigonometry so all sounds alien

But this is not astrophysics or quantum mechanics and many topside photographers have worked out how to overcome the lack of documentation it takes 20’ to work out. Panorama photographer do this since ever

If you know how to

 

 

Sent from my iPhone using Tapatalk

[Paul Kay 65]

23 hours ago, Interceptor121 said:

You are talking about two opposite ......... If you know how to

 

I'm sorry but your post makes no snese to me. Perhaps someone else would like to explain it?

[adamhanlon 0]

Using a macro slide in this instance simply allows housing and port designers to vary the distance of the dome from the lens, and hence determine the correct amount of extension to use for a given lens. Given that the vagaries of actual lens design suggest that theoretical testing is limited, this seems a simple and effective way of doing so?

Nauticam uses Zemax lens design software to specify and design their water contact optics. It is very powerful, but is susceptible to human error. It can produce solutions that are practically impossible (due to cost or element size). Anecdotally, I know the solutions take large amounts of time and computer power, with the software running for 36 hours or more to produce a solution. The macro slide technique seem quite elegant and efficient by comparison!

[Davide DB 583]

59 minutes ago, adamhanlon said:

The macro slide technique seem quite elegant and efficient by comparison!

Does exist a photo of this setup?

[adamhanlon 0]

Hmmm.

I have seen a picture of Seacam's set up, but don't have a copy of it.

Imagine a large rectangular fish tank, with a bayonet/port mount and a macro slide mounted on the base. A lens target is located in front of the port.  The "tank " is immersed within the water (in Seacam's case in a swimming pool) but as it is open topped, the operator can still adjust the camera's position and exposure settings. A sequence of images is then shot with the camera position being moved using the slide. The resulting images are then studied, and the optimal lens to port distance established.

 

[Interceptor121 842]

2 minutes ago, Davide DB said:

Does exist a photo of this setup?

Do not want to post affiliate links but there are plenty of those on google lol

In essence you need to adopt the slider to eliminate the need for all extensions test so it is much quicker than trying

The dome part goes underwater and the rest is outiside the water

The problem of this set up is that it depends on the outcome

If you are looking for the longest extension for no vignetting this works amazingly well

If you are trying to ascertain if the field of view is preserved or if the performance is the best this is not good unless you have wet MTF charts take all shots and then compared them with analysis software which is not what is getting done here

In practical terms the approach extend as much as you can works very well for fisheye lenses with 180 degrees field of view and very bad for rectilinear lenses that do not have a very wide field of view

This is one of the reason why fisheye lenses look better simply because the simple technique works for those lenses and not for others

As an example I have here a lens 24-70mm that has suggested extension of 90mm with the 180mm dome however doing some quick calculations the lens only need 75mm 

You put your 90mm on try the lens and end up with horrible pincushion distortion and spherical aberrations so you dismiss the lens while in fact you had the wrong extension

The simple technique of go until vignetting only works when the lens field of view is equal or very near to the port field of view otherwise it is flawed

Then there are other situations for example your port field of view is less than your lens field of view you need to push the lens inside the port this generates barrel distortion and spherical aberration....

[Davide DB 583]

Ok thanks

[Paul Kay 65]

19 minutes ago, Interceptor121 said:

The problem of this set up is that it depends on the outcome

I hate to tell you this but, unless you are carrying out quantitative technical or scientific photography (my background), photography relies entirely on visual assessment. When reality and theory don't coincide it is rarely (as in never) reality which has got it wrong.

I would add that chasing your tail over absolutes in photography (let alone underwater photography) is never going to work. One way or another photography almost always relies on compromises.

Edited March 26 by Paul Kay

[Interceptor121 842]

I hate to tell you this but, unless you are carrying out quantitative technical or scientific photography (my background), photography relies entirely on visual assessment. When reality and theory don't coincide it is rarely (as in never) reality which has got it wrong.

Visual assessment confirms the vignetting method is wrong because it is not aligned with dome port theory
You don’t need quantitative method unless you want to measure how much is wrong


Sent from my iPhone using Tapatalk

[Paul Kay 65]

1 hour ago, adamhanlon said:

Using a macro slide in this instance simply allows housing and port designers to vary the distance of the dome from the lens, and hence determine the correct amount of extension to use for a given lens. Given that the vagaries of actual lens design suggest that theoretical testing is limited, this seems a simple and effective way of doing so?

I seem to remember reading about the results of moving a port in or out a few mm and the results being very difficult to distinguish. Many housing manufacturers seem to provide extenders in 5mm increments and this is  probably for very good practical reasons. Certainly I've use a 5mm too long port extension and not really noticed the difference although no doubt for some lenses some shift in image 'quality' (whatever that is) might just be visible.

[Interceptor121 842]

I seem to remember reading about the results of moving a port in or out a few mm and the results being very difficult to distinguish. Many housing manufacturers seem to provide extenders in 5mm increments and this is  probably for very good practical reasons. Certainly I've use a 5mm too long port extension and not really noticed the difference although no doubt for some lenses some shift in image 'quality' (whatever that is) might just be visible.

It is visible at the edges of the frame if you look for it
The key issue is that nobody tests the lens on land first so without knowing your starting point it is difficult
The worst offenders are domes with large field of view but relatively small in radius which are badly affected


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[Architeuthis 179]

2 hours ago, adamhanlon said:

Hmmm.

I have seen a picture of Seacam's set up, but don't have a copy of it.

Imagine a large rectangular fish tank, with a bayonet/port mount and a macro slide mounted on the base. A lens target is located in front of the port.  The "tank " is immersed within the water (in Seacam's case in a swimming pool) but as it is open topped, the operator can still adjust the camera's position and exposure settings. A sequence of images is then shot with the camera position being moved using the slide. The resulting images are then studied, and the optimal lens to port distance established.

 

I also remember i have seen such a port testing "aquarium" in the Internet. Here I have found an image (last image in this article "Port testing chamber"): https://underwatervisions.wordpress.com/2010/05/16/an-interview-with-mr-nauticam/

Wolfgang

[Interceptor121 842]

9 minutes ago, Architeuthis said:

I also remember i have seen such a port testing "aquarium" in the Internet. Here I have found an image (last image in this article "Port testing chamber"): https://underwatervisions.wordpress.com/2010/05/16/an-interview-with-mr-nauticam/

Wolfgang

Very nice it does have resolution charts but only at the edges?

There are distance markings on the flat plane 180x80 presumably 80 deep 

So that would be more or less a 20mm lens to fill up the entire field of view which is not that wide

I see there is another hole on the short side perhaps for flat ports or maintenance

It is also interesting to see that the aspect ratio is 2.25 so clearly not for classic 3:2

Edited March 26 by Interceptor121

[Davide DB 583]

Keep in mind the article is 13 years old

 

Edited March 26 by Davide DB

[Interceptor121 842]

Keep in mind the article is 13 years old
 

You don’t build things like those any other day of the week


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[Davide DB 583]

Look, before Adam mentioned this tool, I didn't even suspect its existence, but since you started to analyse the photo, I just specified that it is an article from 13 years ago.

None of us know if they still use that one or they have ten new ones.

We are in the realm of speculation.

[Interceptor121 842]

27 minutes ago, Davide DB said:

Look, before Adam mentioned this tool, I didn't even suspect its existence, but since you started to analyse the photo, I just specified that it is an article from 13 years ago.

None of us know if they still use that one or they have ten new ones.

We are in the realm of speculation.

Not really

There is a macro slider right there where you rig camera and lens.

Inside the glass tank there is a dome port

you move the macro slider until you get what you think is the best distance -> extension ring is measured

Limitations:

1. Each dome has a given field of view. If the field of view of the lens is larger than the dome any solution determined is not ideal anyway

2. The target is 80 cm away from the camera this is not where you see the most severe issues. Look at my tests when you are at 30 cm situation changes as distance does play a role

3. The size of the tank is 180 cm which means it is more suited to focal length of 20mm and wider

Other than that this is exactly how it should be done. Perhaps you can find a way to move the resolution targets closer for a more severe test