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

[Phil Rudin 485]

On the original topic of the Sony 20-70 for U/W use a few more photos, all full frame as in no crop.

This is using the new Sony a7R V, in a Marelux housing with 180mm port and 50mm's of extension with two Backscatter MF-2 flashes.

#1 is the 20mm end about as close as the lens will AF, ISO-100, F/13, 1/500th sec.

#2 is the 70mm end ISO-320, F/16, 1/500th sec.

#3 is at 70mm as close as I could AF the lens ISO-100, F/18, 1/250th sec. The result at 70mm with closet AF is an image that is 1:4 +/- a percentage point or so. 

#4 how the equipment looks setup with a little flotation pushed onto the Flashes it handles quite well.

The Sony A7R V has a max sync speed of 1/250th sec. I used the excellent UWTechnics TTL flash converter for Sony and the also excellent MF-2 flashes set to HSS.

 

 

 

Edited March 30 by Phil Rudin

[Humu797 21]

1 hour ago, Phil Rudin said:

On the original topic of the Sony 20-70 for U/W use a few more photos, all full frame as in no crop.

This is using the new Sony a7R V, in a Marelux housing with 180mm port and 50mm's of extension with two Backscatter MF-2 flashes.

#1 is the 20mm end about as close as the lens will AF, ISO-100, F/13, 1/500th sec.

#2 is the 70mm end ISO-320, F/16, 1/500th sec.

#3 is at 70mm as close as I could AF the lens ISO-100, F/18, 1/250th sec. The result at 70mm with closet AF is an image that is 1:4 +/- a percentage point or so. 

#4 how the equipment looks setup with a little flotation pushed onto the Flashes it handles quite well.

The Sony A7R V has a max sync speed of 1/250th sec. I used the excellent UWTechnics TTL flash converter for Sony and the also excellent MF-2 flashes set to HSS.

 

 

 

 

 

 

 

Thanks for that Phil. Looks pretty good to me, but it won't make some of our forum members giddy with excitement. For those of us shooting Nauticam, better shorter or longer? I will be using the 35.5mm adapter plus extensions. 

Best,

Craig Fujii,

Waipahu, HI

[Phil Rudin 485]

9 minutes ago, Humu797 said:

Thanks for that Phil. Looks pretty good to me, but it won't make some of our forum members giddy with excitement. For those of us shooting Nauticam, better shorter or longer? I will be using the 35.5mm adapter plus extensions. 

Best,

Craig Fujii,

Waipahu, HI

Just guessing, port adapter 35.5mm plus an N120 30mm extension with 180mm dome port. 

[Interceptor121 843]

On the original topic of the Sony 20-70 for U/W use a few more photos, all full frame as in no crop.

This is using the new Sony a7R V, in a Marelux housing with 180mm port and 50mm's of extension with two Backscatter MF-2 flashes.

#1 is the 20mm end about as close as the lens will AF, ISO-100, F/13, 1/500th sec.

#2 is the 70mm end ISO-320, F/16, 1/500th sec.

#3 is at 70mm as close as I could AF the lens ISO-100, F/18, 1/250th sec. The result at 70mm with closet AF is an image that is 1:4 +/- a percentage point or so. 

#4 how the equipment looks setup with a little flotation pushed onto the Flashes it handles quite well.

The Sony A7R V has a max sync speed of 1/250th sec. I used the excellent UWTechnics TTL flash converter for Sony and the also excellent MF-2 flashes set to HSS.

 

 

 

The image at 20mm has tons of barrel distortion

Is that a jpeg of the camera or a raw processed without lens profile?

Apparently the 20-70mm has extensive barrel distortion of its own but looking at your image that is even more.

I would say your extension is way too short and the dome is incorrectly positioned generating extra barrel distortion and loosing field of view

It the housing is recessed 3.5 cm you should increase the extension to 60-65mm

On Nauticam that is 40mm

 

 

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[Phil Rudin 485]

Please describe why the lens appears to have barrel distortion at 20mm.

The camera system is a quick cell phone pic to show what the system looks like.

[Interceptor121 843]

The picture underwater number 1

The edge of the step is totally distorted and this is a rectilinear lens

When the dome center is behind the entrance pupil the image gets further distorted instead of being rectilinear

When the dome is ahead of the entrance pupil you have pincushion distortion

What you are showing there is almost a fisheye effect so the extension is too short at that focal length

Looking a bit closer the step itself may be bent but I doubt the tiles are

And also the weight looks very roundy

 

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[Phil Rudin 485]

I guess that I am not seeing what you are seeing. The "totally distorted " step or  the "tons of barrel distortion" you described above are a result of the design of the pool and the black weight not the lens. If the steps are distorted then why is the ruler not distorted using the same system.

Also please forgive me for not using profiles in the cell phone images taken above water.

Edited March 31 by Phil Rudin

[Draq 135]

That is one powerful lens!  It somehow managed to bend the concrete steps into having their own barrel distortion.

 Don't let that thing near me!  I already suffer from barrel distortion in the stomach area.

If you have the same thing in a pincushion version, I might like to borrow it.

[Interceptor121 843]

2 hours ago, Phil Rudin said:

I guess that I am not seeing what you are seeing. The "totally distorted " step or  the "tons of barrel distortion" you described above are a result of the design of the pool and the black weight not the lens. If the steps are distorted then why is the ruler not distorted using the same system.

Also please forgive me for not using profiles in the cell phone images taken above water.

Lol had not worked out that the steps were that bent

I can't comment on the rules as the image look a bit coarse and it is at an angle maybe if it was straight

It was a funny mistake, yet I do not like those images not if this is the resolution or what but they are gritty

[Davide DB 595]

Ping pong ping pong...

[Interceptor121 843]

As comparison those are screenshots from 4K video of the Sony 24-70 GM2 not even scaled from the full 50 megapixels

At f/8...

[hyp 115]

Using images posted on here to check the quality of a Setup is dubious at best considering the low resolution wetpixel allows. Things like distortion not withstanding but we’ve already figured out those steps are always „distorted“. 

[Interceptor121 843]

13 minutes ago, hyp said:

Using images posted on here to check the quality of a Setup is dubious at best considering the low resolution wetpixel allows. Things like distortion not withstanding but we’ve already figured out those steps are always „distorted“. 

Photography competitions are for most 1600x1200 pixels

The images posted by Phil are 1200x800 which is way low 

Mine are 3840x2160

Facebook are 2048 wide which is plenty

You can tell the difference from a facebook picture if a image is sharp or not. 1200x800 is too low though

[Phil Rudin 485]

See if this is sharp enough for you.

[Paul Kay 65]

On 3/31/2023 at 9:44 PM, Draq said:

That is one powerful lens!  It somehow managed to bend the concrete steps into having their own barrel distortion.

I'm sold on it. I must get me one of those.

[Architeuthis 182]

I just got news from Phil Burghard at Nauticam. He writes that they have finished testing the 20mm-70mm lens. The ideal extension (Nauticam) is 35mm for the 180 domeport and 40mm for both the 230 and 250 domeports...

The not so good news is that they found the lens to optically perform best behind the 250mm domeport (as Massimo was already suspecting). After asking about smaller domeports, Phil writes, however: "...I personally feel the 24-70mm and the newer 20-70mm will perform very well behind the 180mm dome. Since the field of view at 20 or 24mm is not so wide, the corner sharpness to me is very acceptable..."

=> I did not go for the lens yet (the only native Sony lenses I own, at present, are the Tamron 17mm-28mm and a 50mm prime), I am still building a system. I will wait, test what I have and reconsider. Currently my plan is to go for the 20mm-70mm f4.0 as standard/travel zoom lens and to supplement this lens by really good prime lenses...

 

Wolfgang

[Interceptor121 843]

47 minutes ago, Architeuthis said:

I just got news from Phil Burghard at Nauticam. He writes that they have finished testing the 20mm-70mm lens. The ideal extension (Nauticam) is 35mm for the 180 domeport and 40mm for both the 230 and 250 domeports...

The not so good news is that they found the lens to optically perform best behind the 250mm domeport (as Massimo was already suspecting). After asking about smaller domeports, Phil writes, however: "...I personally feel the 24-70mm and the newer 20-70mm will perform very well behind the 180mm dome. Since the field of view at 20 or 24mm is not so wide, the corner sharpness to me is very acceptable..."

=> I did not go for the lens yet (the only native Sony lenses I own, at present, are the Tamron 17mm-28mm and a 50mm prime), I am still building a system. I will wait, test what I have and reconsider. Currently my plan is to go for the 20mm-70mm f4.0 as standard/travel zoom lens and to supplement this lens by really good prime lenses...

 

Wolfgang

I own the Sony 24-70mm GM2 I have tested it for video. The lens focuses at 21 cm therefore it works perfectly with the 180mm dome

I recommend a shorter extension that what Nauticam proposes for best results it sharp across the whole range

The 20-70mm has a longer working distance and the lens extends a lot in addition to needing a large dome due to the working distance it will have less consistency as you zoom in from 20 to 24 because it is wider

Performance of lenses behind domes depends a lot from the construction which is normally optimised for topside use so may not always be ideal underwater

[hellhole 26]

It makes sense as the 180 dome works for a 16-35. With the right extension. It will work well too at 20mm

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[Interceptor121 843]

12 minutes ago, hellhole said:

It makes sense as the 180 dome works for a 16-35. With the right extension. It will work well too at 20mm

Sent from my SM-S908E using Tapatalk
 

In order to pick up a wide angle port you need two ingredients

1. The right field of view. 

2. The appropriate radius 

This lens has a narrow field of view so any of the 3 Nauticam glass wide angle port will work

The lens construction however is such that a large radius is required so the performance will be sensibily better with the 250mm wide angle port. Then the 230 and 180 in order.

With the 180mm port the lens will not focus on the dome and performance will be affected

It is one of those cases where a lens is not built for ideal underwater use

[hellhole 26]

Issit that about how far you put the lens to the dome? And for such..what extension you use?

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[Interceptor121 843]

Issit that about how far you put the lens to the dome? And for such..what extension you use?

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No it is not just like that
If you use a smaller radius than needed the lens focuses away from the dome but the infinity point doesn’t change
So your too small dome eats away the focus range eating away the image quality
Better to get a lens that fits better in the 180mm dome if that is what you want
The tamron 17-28 and Sony 24-70GM2 work well the latter doesn’t need 55mm extension in my view 50mm is sufficient and the 250mm port is not required


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[Phil Rudin 485]

The new issue #132 of UWPMAG.com posted yesterday with my review of the Sony FE 20 to 70mm F/4 zoom using the Sony A7R V camera with the Marelux MX-A7RV housing, 180mm dome port and two Backscatter MF-2 flashes. I also did a review for outfitting your housing with a verity of accessorizes including the new Marelux Flexbuoy buoyancy compensation device.

[Architeuthis 182]

I did not have time yet to test my Sony 20-70mm UW (the DP170 is occupied most of the time by my wife ). But here I saw another review by Opticallimits: https://www.opticallimits.com/sonyalphaff/1169-sony2070f4g

=> similar to the lenstip review they find the lens is excellent, except bokeh and (uncorrected) distortion at 20mm (both issues not very relevant for UW use)...

 

Wolfgang

Edited June 5 by Architeuthis

[Interceptor121 843]

1 hour ago, Architeuthis said:

I did not have time yet to test my Sony 20-70mm UW (the DP170 is occupied most of the time by my wife ). But here I saw another review by Opticallimits: https://www.opticallimits.com/sonyalphaff/1169-sony2070f4g

=> similar to the lenstip review they find the lens is excellent, except bokeh and (uncorrected) distortion at 20mm (both issues not very relevant for UW use)...

 

Wolfgang

Nauticam has a zoom gear on their website but the port chart not updated yet

As previously discussed the relative short length of this lens combined with the working distance of 30cm means a very large radius is required. There will be a good distance close to the 180mm/DP170 dome where the lens will not be able to focus and I am not clear what the impact will be on IQ but I am not over confident that this will work well

The Sony 24-70GM2 can focus right on the 180mm dome but yet it is not marked as optimal while the 250 port is. As as I can see the 24-70gm2 works really well. Yes 24mm is not as wide as you would want

I have now a Tamron 20-40mm that works perfectly with the 180mm dome and I have no plans to invest in the 20-70mm G lens

[Phil Rudin 485]

On 6/5/2023 at 6:53 AM, Architeuthis said:

I did not have time yet to test my Sony 20-70mm UW (the DP170 is occupied most of the time by my wife ). But here I saw another review by Opticallimits: https://www.opticallimits.com/sonyalphaff/1169-sony2070f4g

=> similar to the lenstip review they find the lens is excellent, except bokeh and (uncorrected) distortion at 20mm (both issues not very relevant for UW use)...

 

Wolfgang

Fear not Wolfgang I am sure you will be pleased with the results behind the 170/180mm dome. The fact is that you can easily focus down to about 2 to 3cm in the 180mmm port. This zoom lens will get you a bit closer on the 70mm end with about a 1cm difference on the wide end. While I own several lenses that will focus all the way to the glass I can't ever remember wanting to ram my expensive port glass into the subject I am photographing. If you were to choose the 230mm option then it will be focusing inside the glass. I use the light in my pool to test close focus, it is 15cm (6 inches) across so you can get an idea of how close you can get at both ends of the lens.

I have used the Marelux Sony A7R V housing for these photos with the MX-180mm dome and 50mm of extension. The conversion for the Nauticam housing with the N100 to N120 35.5 port adapter would be an extension around 30mm with 180mm port.

Since the $1100.00US Sony FE 20-70mm F/4 covers the zoom range of both the $2300.00US Sony FE 24-70mm F/2.8 II and the $700.00US Tamron 20-40mm F/2.8 I will not be investing in either of these lenses nor do I believe the F/2.8 aperture adds any value for U/W work.

Images both at F/13 AV light, #1 at 20mm and #2 at 70mm.

 

Edited June 6 by Phil Rudin