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

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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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.

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.

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

Ping pong ping pong...

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...

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“. 

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

See if this is sharp enough for you.

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.

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

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

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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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

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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

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

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

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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.

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

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

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.