Comparison of WACP-C with Sony 28-60mm vs. Sony 24-50mm G existing?

[Architeuthis]

The Sony 28-60mm is the standard lens for use with WACP-C for many, including me. Nauticam now lists the Sony 24-50mm G lens as also compatible with WACP-C (an additional 35mm N100 extension is required)...

 

Did someone already use both 28-60mm and 24-50mm Sony lenses with WACP-C and can say whether it is worth to switch to the (presumably) optically better 24-50mm G lens and sacrifice the 50mm-60mm range? Or is the final outcome in IQ the same and the 24-50mm lens just brings disadvantages (vignetting at 24mm, longer extension and less zoom range)?

 

Thanks, Wolfgang

[DreiFish]

Can't help with the in-water testing behind Nauticam wet optics, but you can compare land results here: https://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=1687&Camera=1538&Sample=0&FLI=0&API=4&LensComp=1525&CameraComp=1175&SampleComp=0&FLIComp=0&APIComp=3

 

At 28mm F8, it seems like the 24-50G has less chromatic aberration and better midframe and corner sharpness. Center looks pretty similar. 

 

Just for kicks, I compared the 28-60 vs the Canon RF24-50 F4.5-6.3. Chromatic aberration is similar, but the Sony lens is definitely sharper everywhere across the frame. Interestingly, the Canon shows less barrel distortion.

 

https://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=1642&Camera=1508&Sample=0&FLI=1&API=3&LensComp=1525&CameraComp=1175&SampleComp=0&FLIComp=0&APIComp=3

[Architeuthis]

4 hours ago, DreiFish said:

Can't help with the in-water testing behind Nauticam wet optics, but you can compare land results here: https://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=1687&Camera=1538&Sample=0&FLI=0&API=4&LensComp=1525&CameraComp=1175&SampleComp=0&FLIComp=0&APIComp=3

 

At 28mm F8, it seems like the 24-50G has less chromatic aberration and better midframe and corner sharpness. Center looks pretty similar. 

 

Just for kicks, I compared the 28-60 vs the Canon RF24-50 F4.5-6.3. Chromatic aberration is similar, but the Sony lens is definitely sharper everywhere across the frame. Interestingly, the Canon shows less barrel distortion.

 

https://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=1642&Camera=1508&Sample=0&FLI=1&API=3&LensComp=1525&CameraComp=1175&SampleComp=0&FLIComp=0&APIComp=3

 

The land comparison is interesting. I, personally, find the differences at comparable apertures and focal lengths between Sony 28-60 and 24-50 quite small. Sometimes the 28-60 may be even a little tack better. This is in contrast to a comparison of the Sony 28-60mm with the older 28-70mm lens that is clearly worse (same webside)...

 

=> It seems to me that the advantage of the 24-50mm lens over the 28-60mm lens for over the water use is the wider and constant f/2.8 aperture. This is, however, of little relevance for UW where smaller apertures are normally used.

 

It may, however, be that the performance of the lenses with the WACP-C is different, as a lot of optical elements are added to produce a completely different "patchwork" lens, optimized for UW...

Edited July 24 by Architeuthis

[fruehaufsteher2]

This question is really interesting. The verdict of this lens says „weak corners“ but who cares about that? 
https://www.digitalkamera.de/Zubehör-Test/Sony_FE_24-50_mm_F2_8_G_im_Test/14107.aspx

 

The large entrance pupil could be the downside if combined with WACP-C. But the constant length of the lens could be the positive aspect. 
 

I‘ll start researching and will come back to this. 

[DreiFish]

7 hours ago, Architeuthis said:

 

The land comparison is interesting. I, personally, find the differences at comparable apertures and focal lengths between Sony 28-60 and 24-50 quite small. Sometimes the 28-60 may be even a little tack better. This is in contrast to a comparison of the Sony 28-60mm with the older 28-70mm lens that is clearly worse (same webside)...

 

=> It seems to me that the advantage of the 24-50mm lens over the 28-60mm lens for over the water use is the wider and constant f/2.8 aperture. This is, however, of little relevance for UW where smaller apertures are normally used.

 

It may, however, be that the performance of the lenses with the WACP-C is different, as a lot of optical elements are added to produce a completely different "patchwork" lens, optimized for UW...

 

The water contact optics only perform as well as the 'taking' lens used behind them. Their main purpose is to neutralize the virtual image otherwise created by the water to air interface. As far as I know, they can't make a lens that's bad on land perform better underwater than it does on land. What they can do is minimize the image quality loss from being in water that you would otherwise get with a dome port.

[Chris Ross]

2 hours ago, DreiFish said:

 

The water contact optics only perform as well as the 'taking' lens used behind them. Their main purpose is to neutralize the virtual image otherwise created by the water to air interface. As far as I know, they can't make a lens that's bad on land perform better underwater than it does on land. What they can do is minimize the image quality loss from being in water that you would otherwise get with a dome port.

In general yes, but in trying to deal with the virtual image they create in effect a flattened version of it and also increase the field coverage.  The net impact likely depends on how the lens in question copes with the new image being fed into it by the wet lens.  One example is field curvature in the base lens may cancel out some of the curvature of the virtual image or is the curvature is in the opposite direction may make it worse.

 

The original premise when the WWL was first created was that the dome optics degraded the image to an extent that the properly corrected kit lens could out perform a premium lens like a 16-35 f2.8 optic when it is placed behind a dome.   Some of the analysis done on these forums indicates however that this is not always the case it seems.   The de-magnification done by the wet lens also shrinks the image scale which also means the aberrations are also shrunk along with the image so become less noticeable.  Of course depending on how the lens interacts with the wet lens it may introduce its own abberations.

[Architeuthis]

11 hours ago, fruehaufsteher2 said:

This question is really interesting. The verdict of this lens says „weak corners“ but who cares about that? 
https://www.digitalkamera.de/Zubehör-Test/Sony_FE_24-50_mm_F2_8_G_im_Test/14107.aspx

 

The large entrance pupil could be the downside if combined with WACP-C. But the constant length of the lens could be the positive aspect. 
 

I‘ll start researching and will come back to this. 

 

This is another interesting test side, as they have tested both the 24-50mm and the 28-60mm Sony lenses...

 

An extract for non-native German speakers: Interestingly the resolution measurements show that both lenses are very good (around 85 - 90 lp/mm at moderate apertures (for 24-50mm at all focal length, for the 28-60mm lens only values for 28mm are given), similar results to what is visible from the test images linked by Dreifish. Both lenses suffer from 50%-60% degradation of resolution towards the corners and both also from longitudinal chromatic aberration. Certainly the 28-60mm does not need to hide when it is compared to the 24-50mm, when over the water performance is considered (the constant f/2.8 aperture of the 24-50mm seems irrelevant for UW use)...

 

Of course it is impossible to predict how well a lens will work together with WACP-C, but I agree with Dreifish that a bad lens is normally not a good starting point (but both 28-60mm and 24-50mm Sony lenses are good, but not excellent, performers)...

 

 

Wolfgang

Edited July 25 by Architeuthis

[fruehaufsteher2]

When I thought about testing the lens I noticed that the FOV would not increase despite the shorter lower end of the zoom range. Additionally I would need to buy another 35mm Nauticam extension. I think it's not worth the effort as the 28-60 performs extremely well.

null

[ChipBPhoto]

As it was explained to me by those in the know, the simpler the lens design, the better the water specific correction ability.  (Ie think contact lenses specifically for water correction). That is why we normally see mid-grade lenses recommended with WACP/WWL solutions.  (Sony 28-60, etc.). Not bad lenses, but simple “kit” lenses.
 

Better quality G / GM / L lenses perform better in standard domes due to no water correction built into the dome glass.  The dome solution relies much more heavily on the lens optics quality than the water contact options. 
 

From what I’ve seen and used the 28-60 seems to be the best option with the WACP-C.  I personally don’t believe you will see any benefit uw adapting the 24-50 G lens for use with the WACP-C.
 

[DreiFish]

4 hours ago, ChipBPhoto said:

As it was explained to me by those in the know, the simpler the lens design, the better the water specific correction ability.  (Ie think contact lenses specifically for water correction). That is why we normally see mid-grade lenses recommended with WACP/WWL solutions.  (Sony 28-60, etc.). Not bad lenses, but simple “kit” lenses.
 

Better quality G / GM / L lenses perform better in standard domes due to no water correction built into the dome glass.  The dome solution relies much more heavily on the lens optics quality than the water contact options. 
 

From what I’ve seen and used the 28-60 seems to be the best option with the WACP-C.  I personally don’t believe you will see any benefit uw adapting the 24-50 G lens for use with the WACP-C.
 

This explanation seems dangerously simplistic -- first, Nauticam has designed the WACP-2 (which is a water correction optic specifically for modern lenses with larger front elements that couldn't be accommodated on the WACP-1. These lenses also tend to have more complex optical formulas.

 

I don't see why there would be something in the more complex designs that would make them perform worse with nauticam's water contact optics than older more simple lens designs. In fact, my experience is the direct opposite -- I've used both an old EF 28-70F3.5-4.5 zoom lens and a modern RF 14-35L lens with the WACP-1 on Canon R5C, and the RF 14-35L  produced noticably better image quality in terms of resolution and contrast (in the 28-35mm limited range).

 

So I don't think you're right that using a better taking lens behind the WACP-C is not going to lead to better image quality. To my knowledge, all the WACP-C/1/L is doing is (a) demagnifying and (b) taking what would be a curved image because of the water-air interface and rendering it flatter for the taking lens to more easily cope with. It's a bit wishful thinking to believe it somehow interacts with older lenses to produce better image quality than you can get from more complex modern lenses. 

[Chris Ross]

52 minutes ago, DreiFish said:

So I don't think you're right that using a better taking lens behind the WACP-C is not going to lead to better image quality. To my knowledge, all the WACP-C/1/L is doing is (a) demagnifying and (b) taking what would be a curved image because of the water-air interface and rendering it flatter for the taking lens to more easily cope with. It's a bit wishful thinking to believe it somehow interacts with older lenses to produce better image quality than you can get from more complex modern lenses. 

I agree however the biggest issue is that the more complex lenses tend to be fast, with big front elements and the manufacturers don't make versions of them that have the entrance pupil in the range where it is compatible with the WWL/WACP series of wet optics.

 

An additional consideration is that to achieve the resolution some of these newer wide angle lenses are capable of everything needs to be near perfect, and this would include not stopped down too much, good entrance pupil position in the case of domes and not shooting through too much water. 

[DreiFish]

2 hours ago, Chris Ross said:

I agree however the biggest issue is that the more complex lenses tend to be fast, with big front elements and the manufacturers don't make versions of them that have the entrance pupil in the range where it is compatible with the WWL/WACP series of wet optics.

 

An additional consideration is that to achieve the resolution some of these newer wide angle lenses are capable of everything needs to be near perfect, and this would include not stopped down too much, good entrance pupil position in the case of domes and not shooting through too much water. 

 

Hey Chris,

 

I agree that the big front elements are the biggest limiting factor in terms of which taking lens can work with which Nauticam wet contact optic. Filter thread size is not a perfect proxy for this, but it's a reasonable one. So with that in mind:

 

WWL-C seem limited to ~60mm filter size (Reference point: Canon RF 24-50F4.5-6.3 is a 58mm filter thread)

WWL-1/1B seem limited to ~60mm filter size (Reference point: Sony 28-60 has a 41mm filter size, Sony 28mmF2.8 prime is 49mm filter size -- but I imagine it can use lenses with a front element at least as big as the WWL-C)

WACP-C seems limited to 67mm filter size or smaller (reference point is that you can used the new Sony 24-50F2.8 G, with a 67mm filter size)

WACP-1 seems to be limited to 77mm filter size or smaller? (reference point is that I've used the Canon RF 14-3F4 L lens, which has a 77mm filter size) 

WACP-2 seems to be able to use at least 82mm filter sizes (reference poin is the Canon RF 15-35F2.8 L lens

 

One other important limiting factor is how much the lens moves in and out during zooming and focusing, which impacts what extension rings are needed and whether the full focal range can be used. Lenses that extend furthest at the widest focal range (or zoom internally) are the ideal candidates here.