Nauticam WACP-C test shots

Maybe there is something similar at work like with the EMWL where the focus point is different at different apertures (and cameras usually focus at the widest aperture) and while that difference is negligible on land it gets emphasized with wet lenses.

59 minutes ago, gcachon said:

It may be the case that the WACP produces sharp corners at f/5.6 for subjects far away. However, those don't tend to be the subjects that I get to shoot. The subject positioning in this pool test replicates a primary use scenario of me. Hence the interest in what aperture I need to use.  

I do not think you will get amazing results at close range at those apertures. I believe you need to look at f/11 and smaller and with that sensor size and distance you won't have too much trouble with strobes

The truth is that other than a fisheye lens with teleconverter you don't have other options. I have the canon 8-15mm it is an amazing lens you should get for your R5 if you don't have it. I think you can put a kenko teleconverter on it 1.4x and then you may end up having good enough results compared to the 28-70mm lens and WACP although what it will do is to range from 170 to 130 degrees not cover the 80-130. For what I shoot this is more interesting actually for photos but not so much for video

8 hours ago, gcachon said:

Interesting! For me the sharpness test is still valid because I want the subject that I focus on to be in focus, not something 30cm behind it. In other words, how sharp will the pictures that I actually take be. But this is a very useful comment because now I will do some more tests specifically on this issue. 

For sure! My point is that if there is focus error then you are no longer really comparing the sharpness of the two setups but more so the focus accuracy. Perhaps in your mind I’m splitting hairs, but for me it’s an important distinction to make. Keep in mind that other people are likely to be influenced by your post when they’re considering the WACP-C, yet their setups (different cameras/lenses) may behave very differently with it in terms of focus accuracy. But I completely agree with you that if there’s a consistent backfocus error with your setup then it’s not a very viable option no matter how sharp it is.

7 hours ago, hyp said:

Maybe there is something similar at work like with the EMWL where the focus point is different at different apertures (and cameras usually focus at the widest aperture) and while that difference is negligible on land it gets emphasized with wet lenses.

Could be. Would require some more rigorous testing to be sure. 

10 hours ago, gcachon said:

While that might work, I don't want to have to rely on that technique, especially with subjects that move (turtles, rays, eels, etc.) Also, it isn't clear to me that would fix the corners. Even on land, the 28-70 is not great in the corners at 28mm. Plus, I don't know how the focal plane bends for this lens - it might bend forward or backward with this lens. If backward, your approach would help. If forward, then it would make it even worse. Fortunately, I am not so picky about sharp corners. I just don't want them to be so blurry that they become a distraction to the overall image. 

It was mainly a suggestion for the testing to get maximum depth of field coverage and answer the question about corner sharpness, you certainly wouldn't want to be using it for moving subjects, but it's good to be aware of the issue.  Some situations like diving along walls will have one side of the frame physically a lot closer and moving the focal point may help to pull the corner in to focus.

Quality post! APS-C + Fisheye seems a great option for a MUCH LOWER PRICE to be honest.

On 10/30/2022 at 4:35 PM, Isaac Szabo said:

Obviously, the focus plane is behind the subject, rendering the sharpness comparison invalid. You would have to do more testing to figure out if backfocus is a consistent problem with the WACP-C setup, but if it is then that would be a strike against it.

So I ran more tests and posted the images in the same folder (see first post for the link). To my surprise, it does seem that the WACP-C with the 28-70 is back focusing at the open apertures. If you look at the f/5.6 file (https://www.dropbox.com/s/vh273ajh0igzyy3/WACP-C 28-70 f%3A5.6.jpg?dl=0) the camera was focused on the cressi box in the middle (about 100cm on the measuring tape, the sticker with "focus" written on it), like I did for all of the shots. But the objects on the back wall appear to be better in focus. Not surprisingly, then, the corners are a mush mess. 

I don't know if this is an issue with the WACP-C, my R5, or my EF28-70 lens copy. I was using spot focus and very careful to make sure it was focusing where I thought it was focusing. I did tests with a EF 28-80ii and the same thing happens. 

If pool tests are not your thing, I posted two samples of the WACP-C from a reef (uncropped and only shadows lifted a bit to be better able to see the corners). Both were taken at f/14. One is a bit further back (the elephant ear sponge) and one is closer (anemone and moray) because there was mention that the effect could be due to distance to subject. (These are the shooting distances for my typical subject.) 

My conclusion is that at 28mm, with my setup of the WACP-C, I should go with f/14.

On 11/2/2022 at 9:08 AM, stillviking said:

Quality post! APS-C + Fisheye seems a great option for a MUCH LOWER PRICE to be honest.

I agree that there is a case for the APS-C + Fisheye. 

If you like really wide, as in 100-180 degree FOV, then APS-C + Fisheye looks very good. That is actually wider than I usually like to go, which is why the "narrower" FOV of the WACP-C (60-130 degree FOV) is attractive to me. 

I posted some more samples from the R5 WACP-C 28-70 at 28mm f/5.6-f/14 and the 7Dii Tokina 13mm at f/11. The latest samples should all have the same pixel dimensions for comparison. Uncropped, exposures slightly adjusted, as before. The 7Dii/Tokina is better in the corners, but not as good in the center (when compared to the WACP-C at f/14) 

I would love to see the R7 with the Tokina. My hunch is that it would be fantastic. Folder link is here ... https://www.dropbox.com/sh/wc8u0jvg0ns2o8k/AABy8geIDmsE4XBXV0ac9ODKa?dl=0

On 10/31/2022 at 6:10 PM, ChrisRoss said:

It was mainly a suggestion for the testing to get maximum depth of field coverage and answer the question about corner sharpness, you certainly wouldn't want to be using it for moving subjects, but it's good to be aware of the issue.  Some situations like diving along walls will have one side of the frame physically a lot closer and moving the focal point may help to pull the corner in to focus.

Agreed. I just posted more test shots. It does seem that that WACP-C is backfocusing at the wider apertures. Short of using backbutton focus (or manual focus), I am not sure how to deal with this issue. Even those solutions are irritating. 

On 10/31/2022 at 3:12 PM, Isaac Szabo said:

Keep in mind that other people are likely to be influenced by your post when they’re considering the WACP-C, yet their setups (different cameras/lenses) may behave very differently with it in terms of focus accuracy. But I completely agree with you that if there’s a consistent backfocus error with your setup then it’s not a very viable option no matter how sharp it is.

Right - I am posting these images so that if someone is considering this option, they can use them in their decision. A frustrating thing about buying underwater equipment is that there are so few actual samples from sources other than the company selling the product. 

If you have a suggestion for how to test if this is "just" a focus accuracy issue or something else, let me know. I would especially be interested if this is something that I can modify with my setup. 

On a related point to the value of posting actual samples, I would love to see a comparison between the WACP-C and a modern lens behind a good dome. Topside, the modern lens is definitely much sharper than the lens compatible with the WACP-C. Dome optics degrades the quality of the image (narrower apertures are needed to get corner sharpness because of the curve of the image).  But if the WACP-C is limited to f/14, there might not be an aperture advantage to the WACP-C. So, in the end, how do they compare in center sharpness and corner sharpness at similar apertures (say f/14)? I don't own a dome, so I can't do the test. 

6 hours ago, gcachon said:

So I ran more tests and posted the images in the same folder (see first post for the link). To my surprise, it does seem that the WACP-C with the 28-70 is back focusing at the open apertures. If you look at the f/5.6 file (https://www.dropbox.com/s/vh273ajh0igzyy3/WACP-C 28-70 f%3A5.6.jpg?dl=0) the camera was focused on the cressi box in the middle (about 100cm on the measuring tape, the sticker with "focus" written on it), like I did for all of the shots. But the objects on the back wall appear to be better in focus. Not surprisingly, then, the corners are a mush mess. 

I don't know if this is an issue with the WACP-C, my R5, or my EF28-70 lens copy. I was using spot focus and very careful to make sure it was focusing where I thought it was focusing. I did tests with a EF 28-80ii and the same thing happens. 

It could be similar to the situation with the Nauticam EMWL where the lens on its own has a small amount of aperture-related focus shift that is usually unnoticed but is amplified by the Nauticam optic to the point that it's problematic. If that's the case, then you could see if there's a setting to force the camera to focus at the shooting aperture instead of wide open. Or you could see if there's a different lens that's compatible with the R5 and WACP-C. Or you could just live with the issue by trying to focus at the very front of subjects and stopping down enough to largely mask the backfocus error. 

7 hours ago, gcachon said:

If you have a suggestion for how to test if this is "just" a focus accuracy issue or something else, let me know. I would especially be interested if this is something that I can modify with my setup. 

I think you're already on the right track. What I would do is setup the camera so that it is fixed in position and cannot move at all. And shoot at a high contrast focus target that includes something like a yardstick at an angle. Something similar to this setup. Setup fairly close to the target since that will reduce depth of field and make focus errors more apparent. Set the camera to back button focus. Focus on the target with the aperture wide open and take a shot. Then stop down the aperture in steps and take a shot each time without refocusing until you reach f/16 or so. You will then have a set of images that will show whether or not the focus shifted when the aperture was stopped down. You can also rerun the test but this time refocusing with each shot to see if that changes anything. And taking multiple shots at the same aperture but refocusing each time would give a better understanding of focus consistency. 

8 hours ago, gcachon said:

Right - I am posting these images so that if someone is considering this option, they can use them in their decision. A frustrating thing about buying underwater equipment is that there are so few actual samples from sources other than the company selling the product. 

I agree - except neither the companies selling these products nor the main people reviewing them release full resolution example images. It really makes it difficult for us customers. So yes, I'm thankful for your efforts here.

2 hours ago, Isaac Szabo said:

It could be similar to the situation with the Nauticam EMWL where the lens on its own has a small amount of aperture-related focus shift that is usually unnoticed but is amplified by the Nauticam optic to the point that it's problematic. If that's the case, then you could see if there's a setting to force the camera to focus at the shooting aperture instead of wide open. Or you could see if there's a different lens that's compatible with the R5 and WACP-C. Or you could just live with the issue by trying to focus at the very front of subjects and stopping down enough to largely mask the backfocus error. 

I think you're already on the right track. What I would do is setup the camera so that it is fixed in position and cannot move at all. And shoot at a high contrast focus target that includes something like a yardstick at an angle. Something similar to this setup. Setup fairly close to the target since that will reduce depth of field and make focus errors more apparent. Set the camera to back button focus. Focus on the target with the aperture wide open and take a shot. Then stop down the aperture in steps and take a shot each time without refocusing until you reach f/16 or so. You will then have a set of images that will show whether or not the focus shifted when the aperture was stopped down. You can also rerun the test but this time refocusing with each shot to see if that changes anything. And taking multiple shots at the same aperture but refocusing each time would give a better understanding of focus consistency. 

Well, the plot thickens. Tested the EF 28-70 R5 on land using a computer keyboard for my sloped test target. No apparent focus shift at all. Clearly the depth of field is very narrow at the open end. And much deeper at f/16. But the midpoint of the focus area remains on the same key (ie at the same point). So it has something to do with this setup with the WACP-C underwater. I have replicated all of the tests with the EF28-80 ii. It isn’t as sharp as the EF28-70  but it does the same thing (poor results with open apertures). There is only one other lens on the nautical port chart for the canon r5 but it is a EF 28-28iv. I doubt that will be different. Of course results for non canon brands could be different, unless it is something about the WACP-C. 

4 hours ago, gcachon said:

Well, the plot thickens. Tested the EF 28-70 R5 on land using a computer keyboard for my sloped test target. No apparent focus shift at all. Clearly the depth of field is very narrow at the open end. And much deeper at f/16. But the midpoint of the focus area remains on the same key (ie at the same point). So it has something to do with this setup with the WACP-C underwater. I have replicated all of the tests with the EF28-80 ii. It isn’t as sharp as the EF28-70  but it does the same thing (poor results with open apertures). There is only one other lens on the nautical port chart for the canon r5 but it is a EF 28-28iv. I doubt that will be different. Of course results for non canon brands could be different, unless it is something about the WACP-C. 

To clarify, what I meant was to perform the test underwater with the WACP-C on (like your other tests). It's not surprising that you didn't detect a focus shift above water. The way it works with the EMWL is that the focus shift with just the macro lens is so small that it's very difficult to detect, but when you add on the EMWL it's greatly amplified and becomes very problematic (It's more severe than your backfocus issue). So while it's good to know that the 28-70 by itself doesn't have significant focus shift, I think a more controlled underwater test is what's needed if you really want to pin down the nature of the issue. 

5 hours ago, Isaac Szabo said:

To clarify, what I meant was to perform the test underwater with the WACP-C on (like your other tests). ... I think a more controlled underwater test is what's needed if you really want to pin down the nature of the issue. 

Understood. A land test rules out the camera and lens as the primary culprit. Rather than go through the hassle of another water test, I'll probably take a few more reef shots at f/14, f/9, f/5.6 to see how this plays out in practice.