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Anyone who is considering buying one of Nauticam's outstanding wet wide optics should really download Alex Mustard's review issue #99, Nov/Dec 2017 in Underwater Photography Magazine, UWPMAG.com. This is a free PDF download and it goes into great detail as to why these wet lenses outperform rectilinear lenses behind dome ports. It also explains why you can shoot at lower F/numbers and retain the same corner sharpness as a wide lens behind a dome at higher F/numbers.

When I was given a prototype of the WWL-1 in 2015 to test with the Panasonic 14-42mm power zoom the first thing that came to mind is how can this "kit" lens possibly outperform a quality wide angle behind a large dome port. 

If you check the charts in Alex review it will be explained. 

From the many posts I have read on Wetpixel and elsewhere it is clear to me that I am not the only one who has had a hard time wrapping there head around this issue of so called "kit" lenses outperforming "pro" quality lenses behind ports. It is in fact an issue for several Nikon Z owners who find the only option for full zoom through on the Z-full frame with the WACP-1 and WACP-C is a Sony FE 28-70mm "kit" lens. 

Another issue I see raised all of the time is that the wet wide lenses in some way distorts nearly as much as a fisheye lens which I am not seeing with the lenses I have tested. If interested you can checkout my UWPMAG.com reviews of for WWL-1back issue #114 mainly using the Sony FE 28mm F/2 and back issue #120 with the WWL-1B mainly using the Sony FE 28-60mm.

This first image is full frame WACP-1 with the Sony FE 28-60mm at 28mm and F/10, looks pretty rectilinear to me.

The second with the pan fish is WWL-1 with the 28-60mm at 28mm and F/10, also looks rectilinear.

The first split shot is WACP-2 with the Tamron 17-28mm at 17mm and F/8, as Alex mentioned above at F/8 you have the same out of focus background as with a lens behind a dome. Above on Sony FF cameras 

Second split is the Olympus 7-14mm behind a dome at 7MM at F/6.3 Olympus EM-1 II.

Third split is Nikon Z-6 with 8-15mm at 15mm and F/13, what you see here is the clear difference when shooting fisheye with the bending if lines both in the foreground and the trees as you get towards the edges of the frame. 

 

 

 

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121:

I understand that you have adjudged the WACP-C useless on a cropped sensor camera.  I am not able to take a position on merits of the WACP-C nor am I trying to defend or promote the product (or the -1), although I am skeptical about your conclusion.  I am just trying to learn and evaluate as I might want to buy one if it offers enough value to me.  The problem is, I am having a hard time fitting your assessments of the worth of a WACP-C on a cropped sensor camera into my information-gathering process.

You have shot a WWL on a micro four thirds camera and felt it was inferior to your 8-18 in a 180 dome.  Fair enough.  You have presumably used both and have a basis for your opinion.  As I understand it you have never owned a crop sensor or full sensor dive camera rig and have never used a WACP.  Yet, you have very strong opinions about its value and usefulness, at least on a camera like the D500.  As far as I know, only Alex Mustard has actually used one of these optics at this point in time.  If I am correct that you never used the optic or one similar (except to the limited extent the WWL wet lens is similar) and have never used a crop sensor camera, how can you state such concrete opinions?

Your ultimate conclusions may be right, or wrong; I don’t know, as I have never used any WACP.  But I have used and owned M43 cameras and the same lenses and dome ports you have, and used the a WWL with M43 and in fact still own that stuff.  That experience allows me to form opinions about their worth to me, and compare M43 tstuff o a D500, as that is what I use now, but I do not feel my M43 and WWL experience gives me a sufficient basis to judge the merits of a WACP used with my D500. 

You also seem to place great value on the ability to shoot truly straight lines, and perhaps your area of interest is wrecks or pilings or something.  In my diving, straight lines are few and, in a situation where that was important, I would likely not use a fisheye or a WACP.  Purchasing a WACP would not mean selling my dome port and rectilinear zooms, at least not necessarily so.  For many, straight lines are only occasionally important, even if “less” fisheye distortion may be desired at other times.

If the WACP-C offers me performance matching what I could get from 16-35 or 17-70 in a big dome (on a crop sensor), or at least superior to what I would get in a 170 or 180, then it is appealing.  I simply can't manage a 230mm dome.  It could then be that general purpose " I don't know where we are diving today or what the conditions will be like" lens that I often wish for on recreational dive boats in unfamiliar locations.  ("Well the reef scenes are murky, the close focus options are few, but those sharks are interesting").  If it would not better those other lenses in mid-size domes, then yes, it is of little value to me.

 I doubt anyone can answer those questions based on knowledge / experience at this point, or perhaps ever.  I may need to test and decide for myself.  But in the meantime, "my lens is better than yours" arguments don't really add much.

 

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The original tests done by Nauticam compared the M43 7-14mm with a 180mm Nauticam dome against the WWL-1 using a M43 14 to 42mm "kit" lens. The result was a gaping difference in lines of resolution in favor of WWL-1 at 130 degrees and the 7-14 which is 114 degrees. The same result was observed using the WACP-1 130 degrees against the Nikon 14-24 114 degrees and Canon 11-24 126 degrees both using 230mm ports. While I am sure images taken in the field may very a bit the science here does not lie and 121's Panasonic 8-18mm would be as bad or worse in these same tests. 

Again these tests from Nauticam are all shown in the article by Alex in back issue #99 at UWPMAG.com. This is a free PDF download that everyone WACP-curious should read.

WWL-1 and WACP-1 work across format sizes from M43 to 35mm full frame. It would stand to reason that WACP-C would also work well on all formats given they are used with the recommended lenses. More format sizes from compact to video are also covered by some lenses. 

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47 minutes ago, Phil Rudin said:

 

Again these tests from Nauticam are all shown in the article by Alex in back issue #99 at UWPMAG.com. This is a free PDF download that everyone WACP-curious should read.

 

I am curious to see similar graphs on the EMWL lenses. Any out there?

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The original tests done by Nauticam compared the M43 7-14mm with a 180mm Nauticam dome against the WWL-1 using a M43 14 to 42mm "kit" lens. The result was a gaping difference in lines of resolution in favor of WWL-1 at 130 degrees and the 7-14 which is 114 degrees. The same result was observed using the WACP-1 130 degrees against the Nikon 14-24 114 degrees and Canon 11-24 126 degrees both using 230mm ports. While I am sure images taken in the field may very a bit the science here does not lie and 121's Panasonic 8-18mm would be as bad or worse in these same tests.  Again these tests from Nauticam are all shown in the article by Alex in back issue #99 at UWPMAG.com. This is a free PDF download that everyone WACP-curious should read. WWL-1 and WACP-1 work across format sizes from M43 to 35mm full frame. It would stand to reason that WACP-C would also work well on all formats given they are used with the recommended lenses. More format sizes from compact to video are also covered by some lenses. 

 

 

The 7-14mm performance is not good as the dome is too small to contain the field of view of the lens Majority of the images I have seen with that lens are in my opinion unacceptable my combination is way better in any shooting conditions and I would not recommend the 7-14mm to anyone in the 180mm dome

As far as the example you can see it yourself there no need to guess it is sharp period

A comparison should be drawn on edge sharpness only if the image is straight

None of the water contact optics are rectilinear so the comparison with a rectilinear lens doesn’t hold

You can obtain 130 degrees from a canon 8-15mm on cropped sensor that would be a more meaningful comparison as the lens and port costs more or less the same of the wacp compact

It is obvious that a fisheye lens with 180 degrees will have more distortion however a zoom fisheye on cropped at same 130

Degrees much less

An optic with 0.36x magnification will not be rectilinear someone should go and shoot a grid not take images like the examples posted which by the way show distortion

If you have the lens you can do that in your bathtub otherwise the claim that a lens has more or leas distortion have no basis

 

 Finally I am on favour of any water contact optics but I am not impressed by the marketing and the comparison with rectilinear lenses as none of those solution are rectilinear

 

Sent from my iPhone using Tapatalk

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7 hours ago, Interceptor121 said:

The actual close up examples are less sharp than my Panasonic 8-18mm with dome port in the edges. WACPClose.thumb.PNG.55e1a6f6ff32bc70e157d5a8ef7e9ccd.PNG

 

 

 

To be fair this is possibly a depth of field issue, and as Adam says we don't know the aperture.  You can see if you look at the whole image that the background is out of focus as is the rear part of the yellow sponge and the tentacles at top of frame are are also on the edge of the depth of field.

If you look at this link you can see the corners look reasonable and not a great deal different to the rocks texture across the frame, I lifted a direct link from the page so you can see a full size image:

https://cdn.shopify.com/s/files/1/2599/6382/files/SOC-2656340_2048x2048.jpg?v=1579543265

It's displayed as a link so you can open it in a new tab and see it full size.

This is a problem with reef images, the 3D arrangement is usually not apparent so you can't really tell if the corners and the subject are at the same distance.

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23 hours ago, Ryanrod said:

Were you able to get any clarification from Nauticam?

I had a chat and was told that the 28-75 had indeed been tested and didn't make the cut with the WACP-C.

We were not able to determine if this was due to it physically not fitting or optically not making the grade - either way the answer was pretty definitive. WACP-1 is the recommendation for that particular lens.

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It says Canon 18-55mm has a range of 130-46 degrees. Would this be the lens of choose if you want the most zoom range.

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37 minutes ago, Glasshouse said:

I had a chat and was told that the 28-75 had indeed been tested and didn't make the cut with the WACP-C.

We were not able to determine if this was due to it physically not fitting or optically not making the grade - either way the answer was pretty definitive. WACP-1 is the recommendation for that particular lens.

Thank you for the answer

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10 hours ago, Draq said:

121:

I understand that you have adjudged the WACP-C useless on a cropped sensor camera.  I am not able to take a position on merits of the WACP-C nor am I trying to defend or promote the product (or the -1), although I am skeptical about your conclusion.  I am just trying to learn and evaluate as I might want to buy one if it offers enough value to me.  The problem is, I am having a hard time fitting your assessments of the worth of a WACP-C on a cropped sensor camera into my information-gathering process.

 

You have shot a WWL on a micro four thirds camera and felt it was inferior to your 8-18 in a 180 dome.  Fair enough.  You have presumably used both and have a basis for your opinion.  As I understand it you have never owned a crop sensor or full sensor dive camera rig and have never used a WACP.  Yet, you have very strong opinions about its value and usefulness, at least on a camera like the D500.  As far as I know, only Alex Mustard has actually used one of these optics at this point in time.  If I am correct that you never used the optic or one similar (except to the limited extent the WWL wet lens is similar) and have never used a crop sensor camera, how can you state such concrete opinions?

 

Your ultimate conclusions may be right, or wrong; I don’t know, as I have never used any WACP.  But I have used and owned M43 cameras and the same lenses and dome ports you have, and used the a WWL with M43 and in fact still own that stuff.  That experience allows me to form opinions about their worth to me, and compare M43 tstuff o a D500, as that is what I use now, but I do not feel my M43 and WWL experience gives me a sufficient basis to judge the merits of a WACP used with my D500. 

 

You also seem to place great value on the ability to shoot truly straight lines, and perhaps your area of interest is wrecks or pilings or something.  In my diving, straight lines are few and, in a situation where that was important, I would likely not use a fisheye or a WACP.  Purchasing a WACP would not mean selling my dome port and rectilinear zooms, at least not necessarily so.  For many, straight lines are only occasionally important, even if “less” fisheye distortion may be desired at other times.

 

If the WACP-C offers me performance matching what I could get from 16-35 or 17-70 in a big dome (on a crop sensor), or at least superior to what I would get in a 170 or 180, then it is appealing.  I simply can't manage a 230mm dome.  It could then be that general purpose " I don't know where we are diving today or what the conditions will be like" lens that I often wish for on recreational dive boats in unfamiliar locations.  ("Well the reef scenes are murky, the close focus options are few, but those sharks are interesting").  If it would not better those other lenses in mid-size domes, then yes, it is of little value to me.

 I doubt anyone can answer those questions based on knowledge / experience at this point, or perhaps ever.  I may need to test and decide for myself.  But in the meantime, "my lens is better than yours" arguments don't really add much.

 

 

 

@Draq

Well stated... to your statement "my lens is better than yours" - that's not really 121's point (but it does come across that way). There tends to be a lot of posturing and opinions thrown around on topics like this -ultimately it comes down to either hearing from experts or peers that have shot the combo you are thinking about, or have some level of indepth knowledge on how they may work.

For me, I'm already committed to getting a WACP-C for my D850, which I will end up sharing with my daughter who shoots a Sony A7R4. Both are FF, so not a helpful comparison... I also have a D500, and may try that pairing as well (I often travel with both cameras & housings, limiting to 1 port to be shared between the two for w/a would be helpful).


 

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7 hours ago, ChrisRoss said:

To be fair this is possibly a depth of field issue, and as Adam says we don't know the aperture.  You can see if you look at the whole image that the background is out of focus as is the rear part of the yellow sponge and the tentacles at top of frame are are also on the edge of the depth of field.

If you look at this link you can see the corners look reasonable and not a great deal different to the rocks texture across the frame, I lifted a direct link from the page so you can see a full size image:

https://cdn.shopify.com/s/files/1/2599/6382/files/SOC-2656340_2048x2048.jpg?v=1579543265

It's displayed as a link so you can open it in a new tab and see it full size.

This is a problem with reef images, the 3D arrangement is usually not apparent so you can't really tell if the corners and the subject are at the same distance.

Reasonable does not make it 4 stops better

The wet optics are normally afocal they do not feel depth of field as a dome so there would not be a lot of difference between details that are one foot distant in the frame.

Even if it was shot at f/4 it should be equivalent to f/16 and it would have plenty if the claims are true

I just think that measuring those lenses against the edges of a rectilinear lens is not meaningful as you would not take almost any of the test shots with a rectilinear lens anyway so what is the point?

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2 hours ago, oneyellowtang said:

@Draq

Well stated... to your statement "my lens is better than yours" - that's not really 121's point (but it does come across that way). There tends to be a lot of posturing and opinions thrown around on topics like this -ultimately it comes down to either hearing from experts or peers that have shot the combo you are thinking about, or have some level of indepth knowledge on how they may work.

For me, I'm already committed to getting a WACP-C for my D850, which I will end up sharing with my daughter who shoots a Sony A7R4. Both are FF, so not a helpful comparison... I also have a D500, and may try that pairing as well (I often travel with both cameras & housings, limiting to 1 port to be shared between the two for w/a would be helpful).


 

Yes that was not my point

My point is that using a measure of sharpness vs a rectilinear lens is not a good benchmark if you compare shots that do not require a rectilinear lens to start with.

If you instead were shooting some nice straight lines then you would say ok it is not straight (none of those lenses are) but it is sharp throughout. Then the other topic is on cropped sensor you have zoom fisheye that have similar distortion at 130 degrees or less and that are normally less bulky and do not have such a gap in sharpness at the edges.

Then of course each person has to look at their use case and where does this fit but the reference to edges etc for me is not good marketing

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I don't follow the idea of "compare shots that do not require a rectilinear lens to start with" 

Surely, this is a creative decision? I often prefer the look of a more rectilinear lens , while others may prefer fisheye. I chose lenses based on my creative vision, not because one is "necessary?"

No "water contact" or "wet lens" system is afocal in practice. Image focus and depth of field is produced by using the respective camera lens' focus and the light path from the lens onto the sensor.  Depth of field is still an issue with these lenses. 


 

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3 minutes ago, adamhanlon said:

ThI don't follow the idea of "compare shots that do not require a rectilinear lens to start with" 

Surely, this is a creative decision? I often prefer the look of a more rectilinear lens , while others may prefer fisheye. I chose lenses based on my creative vision, not because one is "necessary?"

No "water contact" or "wet lens" system is afocal in practice. Image focus and depth of field is produced by using the respective camera lens' focus and the light path from the lens onto the sensor.  Depth of field is still an issue with these lenses. 


 

Water contact optics are afocal on their own hence the wording on nauticam specification focal distance from front of the lens to infinity

The other point to be noted is that the magnification of 0.36x is only achieved in the corners not horizontally or vertically and in that regard those lenses are similar to a fisheye

So the WWL-1 0.36x has a similar behaviour of the WACP 0.36x the difference is that the mount allows the lens to work as there is no flat port that would take the zoom but the technical specifications are the same

When I compared the WWL-1 to a rectilinear lens I discovered that while the diagonal field of view is wider and the lens has more depth of field, in terms of actual field of view compared to my 8mm on the horizontal and vertical the difference was very small. Still it is easier to work with an afocal wet lens than a lens behind a dome where the focus range is limited and depth of field is lacking. When you shoot video and you crop the diagonal the lens looks even more straight so that works very well

But if you think that those optics make your 28mm lens a 10mm on all axis that is not the case normally the horizontal magnification changes to around 0.5x and vertical can go close to 0.7x

Which in turn makes the idea of comparing with a rectilinear lens not really appropriate because from a creative point of view those two options do not produce the same result.

It would be ideal if someone who has those optics goes in a pool and tries this in quick succession as I have done with the WWL-1. Alternatively if someone sends me the equipment I will be more than happy to run such tests myself!

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1 hour ago, Interceptor121 said:

Reasonable does not make it 4 stops better

The wet optics are normally afocal they do not feel depth of field as a dome so there would not be a lot of difference between details that are one foot distant in the frame.

Even if it was shot at f/4 it should be equivalent to f/16 and it would have plenty if the claims are true

I just think that measuring those lenses against the edges of a rectilinear lens is not meaningful as you would not take almost any of the test shots with a rectilinear lens anyway so what is the point?

I'm not talking about depth of field in terms of corner sharpness due to dome port optics, this is pure depth of field as in only the polyps and front half of the sponge is in focus.  If that rock in the corner is too close or too far away from the camera it will also be out of focus.  The depth of field is low because the magnification is high due to being right on top of the subject for CFWA and/or the aperture is fairly wide.  You need to look at the entire image to discern this.

The point about the shark shot is that the corners there do not seem any worse than the edges, it is a more conventional shot where corner sharpness could impact.  It's a pity they don't have EXIF data in the images or posted in that ReefPhoto post, but the inference is it was taken on APS-C and I'd expect there to be no corner issues on smaller formats with a WACP and appropriate lens.  There's something funky about the way they have posted the images and I couldn't convince the browser to load a 100% view from the files stored, there's some sort of scalable view being used so it's hard to judge absolute image quality even though they seem to be large pixel dimension images.

 

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5 minutes ago, ChrisRoss said:

I'm not talking about depth of field in terms of corner sharpness due to dome port optics, this is pure depth of field as in only the polyps and front half of the sponge is in focus.  If that rock in the corner is too close or too far away from the camera it will also be out of focus.  The depth of field is low because the magnification is high due to being right on top of the subject for CFWA and/or the aperture is fairly wide.  You need to look at the entire image to discern this.

The point about the shark shot is that the corners there do not seem any worse than the edges, it is a more conventional shot where corner sharpness could impact.  It's a pity they don't have EXIF data in the images or posted in that ReefPhoto post, but the inference is it was taken on APS-C and I'd expect there to be no corner issues on smaller formats with a WACP and appropriate lens.  There's something funky about the way they have posted the images and I couldn't convince the browser to load a 100% view from the files stored, there's some sort of scalable view being used so it's hard to judge absolute image quality even though they seem to be large pixel dimension images.

 

For an article that is supposed to review a lens it lacks some pretty fundamental data for sure

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25 minutes ago, Interceptor121 said:

For an article that is supposed to review a lens it lacks some pretty fundamental data for sure 

Well, there is a pretty blurry line between ad copy and a meaningful review when created by a manufacturer or retailer and featured on their retail website.  A big difference from something Adam or Alex would do.  I thought it was worth mentioning, which is why I refereed to it only as a data point..

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Just a more critical question, do we really have some testing of these kinds of setup that would be in the same ballpark as Christopher Frost photography for example? What we got most times is a text and a few pictures from a dive, but at this point I don't see any real testing methodologies created for underwater gear. The only thing that came close was the test from Wie Domeports, Vorsatzlinsen und Korrektivports wirken - UWFoto.net (its in german) and even they lacked so many data points that I can't really judge anything from these short articles. 

I have the feeling, we just have to try out for our own. But who wants to sink that much money into the hobby...

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Just now, Draq said:

Well, there is a pretty blurry line between ad copy and a meaningful review when created by a manufacturer or retailer and featured on their retail website.  A big difference from something Adam or Alex would do.  I thought it was worth mentioning, which is why I refereed to it only as a data point..

It was not meant to be a critique to you. It looks like am bashing this lens any of the wet optics and whoever is interested in it which is not the case considering I reviewed the original WWL-1 when it came out and have always been a supporter

However this whole idea of comparison with rectilinear lenses has bugged me since the start and I have wrote Nauticam about it. None of those adapters is rectilinear the WACP-2 is likely to be the least distorted but that does not make it a rectilinear lens. None of those wet optics are a real proxy for a focal reducer like those made by metabones for example that preserve geometry. 

The key benefit of those adapter is the higher depth of field that they have due to the near afocal construction and the elimination of chromatic aberrations compared so a simple dome port. This means you can shoot at wider aperture than you would do otherwise which in turn means less strobe power required in return for carrying the bulk.

I would be very interested in comparing those lenses to a fisheye zoom on APSC as an academic exercise what I can say is that on MFT the canon 8-15mm is sharper than the WWL-1 and 14-42mm in the overlapping focal range and can get to 180 degrees if you need to. The Tokina 10-17mm is not as good as optic but it is very compact with its acrylic mini dome that would be a good benchmark for this WACP-C as the Tokina covers 180-100 degrees. The WACP-C covers 130-60 degrees so a Tokina shot at 14mm is probably a good proxy. 

One of the things that I have been saying here is that the distortion of such lenses is reduced as you zoom in for example the Tokina distortion goes from 28% to 12% 

https://www.lenstip.com/19.6-Lens_review-Tokina_AT-X_107_DX_AF_Fish-Eye_10-17_mm_f_3.5-4.5_Distortion.html

So at 14mm with an 18% distortion may be not that different from a WACP-C at 130 degrees which based on my experience with nauticam wet optics may have quite a bit of distortion and for me is very similar to the tokina at 14mm

14mm-wwl-1-original-20190426.jpg

I have no doubt that for full frame those adapters are worthy in fact the only solution to have certain type of shots as zoom fisheye do not exist however the use case on DX and MFT for both dry and wet mount really depends on your use case. Does the range between 60 and 100 degrees matter to you more than 180-130? How about weight? Even the WAPC-C is heavier than Canon 8-15mm with 140mm dome and far more bulky than the tokina solution

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43 minutes ago, Interceptor121 said:

It was not meant to be a critique to you. It looks like am bashing this lens any of the wet optics and whoever is interested in it which is not the case considering I reviewed the original WWL-1 when it came out and have always been a supporter

However this whole idea of comparison with rectilinear lenses has bugged me since the start and I have wrote Nauticam about it. None of those adapters is rectilinear the WACP-2 is likely to be the least distorted but that does not make it a rectilinear lens. None of those wet optics are a real proxy for a focal reducer like those made by metabones for example that preserve geometry. 

The key benefit of those adapter is the higher depth of field that they have due to the near afocal construction and the elimination of chromatic aberrations compared so a simple dome port. This means you can shoot at wider aperture than you would do otherwise which in turn means less strobe power required in return for carrying the bulk.

 

 

 

The other benefit to these lenses is that they flatten the field so you  can shoot at wider apertures.  On full frame people are shooting at f13-16 with 14-16mm range lenses and adding a S&S correction lens and still complaining about corners.  You could go to wider rectilinear lenses but you are fundamentally limited by the necessity of focusing on the virtual image due to dome port optics.  I don't know how the WACP style optics deal with the virtual image but they do not have this limitation. 

I suspect there are fundamental limitations which prevent you from staying rectilinear as you go wider.  At the limit a 180° rectilinear lens is impossible - the corners that are at 180° would be at infinity as rectilinear lenses take straight lines and convert them to straight lines i the image.  Fisheyes get around this as they don't attempt to keep straight lines straight - they are basically designed to focus on an annular semi-circular band symmetrical to the the lens which is ideal as that is exactly what a virtual image is.

While it is true that you can get better results out of a fisheye zoom - they don't exist for full frame (as full frame fisheye zooms)  and there are limited options for crop sensors with the best seemingly an adapted Canon 8-15 on m43.   You can do various kludges on full frame like add a 3rd party 1.4x but the optics seem to suffer.  Apart from that Canon and Nikon users can use the 8-15 zooms between 10/11mm and 15mm and the Tokina 10-17 is another option, though now discontinued.

While the WWL-WACP etc are not rectilinear it mostly doesn't matter they are not fully fisheye distorted either and the comparison to rectilinear lenses is just a convenient way to convey the concept to people without detailed optical knowledge.  For most purposes underwater apart from pool shots and some work with wrecks the amount of distortion they have is acceptable and for these purposes are a more versatile alternative to 16-35mm class lenses with mostly a wider zoom range and at the wide end can do CFWA work quite well and are optically superior in many cases.

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The other benefit to these lenses is that they flatten the field so you  can shoot at wider apertures.  On full frame people are shooting at f13-16 with 14-16mm range lenses and adding a S&S correction lens and still complaining about corners.  You could go to wider rectilinear lenses but you are fundamentally limited by the necessity of focusing on the virtual image due to dome port optics.  I don't know how the WACP style optics deal with the virtual image but they do not have this limitation. 
I suspect there are fundamental limitations which prevent you from staying rectilinear as you go wider.  At the limit a 180° rectilinear lens is impossible - the corners that are at 180° would be at infinity as rectilinear lenses take straight lines and convert them to straight lines i the image.  Fisheyes get around this as they don't attempt to keep straight lines straight - they are basically designed to focus on an annular semi-circular band symmetrical to the the lens which is ideal as that is exactly what a virtual image is.
While it is true that you can get better results out of a fisheye zoom - they don't exist for full frame (as full frame fisheye zooms)  and there are limited options for crop sensors with the best seemingly an adapted Canon 8-15 on m43.   You can do various kludges on full frame like add a 3rd party 1.4x but the optics seem to suffer.  Apart from that Canon and Nikon users can use the 8-15 zooms between 10/11mm and 15mm and the Tokina 10-17 is another option, though now discontinued.
While the WWL-WACP etc are not rectilinear it mostly doesn't matter they are not fully fisheye distorted either and the comparison to rectilinear lenses is just a convenient way to convey the concept to people without detailed optical knowledge.  For most purposes underwater apart from pool shots and some work with wrecks the amount of distortion they have is acceptable and for these purposes are a more versatile alternative to 16-35mm class lenses with mostly a wider zoom range and at the wide end can do CFWA work quite well and are optically superior in many cases.

The issue with rectilinear lenses is the virtual image of the dome limits the useful working distance of the lens you need to close the aperture to get sufficient depth of field so you don’t see substantial blurring of the edges
With fisheye lenses and water contact optics the field of view in the corners is enlarged and then compressed into the frame so apparently the edges are sharper
However if you defish the image you see that the edges are not so sharp after all
Personally I think that the issue with rectilinear lenses and domes is greatly reduced with cropped sensor and very small frames on micro four thirds as long as port design is optimised
In terms of using a rectilinear lens I tend to use it for wrecks and shots with people in it. There is an increasing trend shooting images with diver or a freediver in the picture and fisheye like lenses make those look funny so there is still a place for rectilinear lenses
To shoot reefs and close focus those lenses were never a primary choice as there is lack of straight lines plus you want to get closer
At the end what matters is that if you really need straight lines you need a rectilinear lens. In addition a lot of shots midwater have nothing in the corners so who cares if they are blurred?


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Sorry to take the conversation in a new direction (but I’ve not read all the posts to stay on topic!).

I thought I’d share some WACP shots. Afterall the view and zoom range of an lens set-up will determine the type of shots it can produce underwater. And the best way to judge is a lens would be suited to what you need is to look at the types of underwater images it can produce. Ultimately this is far more important than arguing whether you prefer the corners of the frame squished in or stretched out.

I have 500+ WACP images on my website now - which give a very wide range of examples of the types of images that these optics produce. These are mostly taken with the WACP-1 - but they will give a good idea of how the WACP-C - which has the same FOV.

https://www.amustard.com/library/page/search/"28.0"/1/

(note that I can’t search WACP in the EXIF, so this is just a search of images taken with the 28-70mm lens). So there are a few non-WACP images in the mix (topsides or old pictures taken pre-WACP). But at least 500+ WACP pix to browse.

Alex

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1 hour ago, Alex_Mustard said:

Sorry to take the conversation in a new direction (but I’ve not read all the posts to stay on topic!).

I thought I’d share some WACP shots. Afterall the view and zoom range of an lens set-up will determine the type of shots it can produce underwater. And the best way to judge is a lens would be suited to what you need is to look at the types of underwater images it can produce. Ultimately this is far more important than arguing whether you prefer the corners of the frame squished in or stretched out.

I have 500+ WACP images on my website now - which give a very wide range of examples of the types of images that these optics produce. These are mostly taken with the WACP-1 - but they will give a good idea of how the WACP-C - which has the same FOV.

https://www.amustard.com/library/page/search/"28.0"/1/

(note that I can’t search WACP in the EXIF, so this is just a search of images taken with the 28-70mm lens). So there are a few non-WACP images in the mix (topsides or old pictures taken pre-WACP). But at least 500+ WACP pix to browse.

Alex

Hi Alex

There is no doubt that those optics produce fine images and for full frame cameras give access to a focal range that is not really covered (if you exclude various set up with teleconverter that I have actually tried on someone else camera and they are suboptimal) and therefore you can take images otherwise not possible to shoot. In addition lighter options are surely welcome considering the weight of the previous ones.

However your own book underwater master class has many examples of tokina 10-17mm shot between 13 and 17mm which look pretty good to me in the corners. Today you can already take such shots on APSC and my view is that none of those water contact lenses add much that is not already there for those formats. 

I really don't believe that this idea of edge sharpness improvement is helping the case for selling those lenses and neither the idea that they are almost rectilinear when in most cases they are far from it. They can make shots like yours possible for full frame users that are not avaialble with other optics that is a fact regardless of how the edges are looking.

On this note I will exit this thread as I have already created enough stir I guess

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Posted (edited)
14 hours ago, Interceptor121 said:

I would be very interested in comparing those lenses to a fisheye zoom on APSC as an academic exercise what I can say is that on MFT the canon 8-15mm is sharper than the WWL-1 and 14-42mm in the overlapping focal range and can get to 180 degrees if you need to.

This has been my impression as well comparing the Canon 8-15 (behind a 140mm dome) with the WWL-1 14-42mm combo. The fisheye is.. sharper and more importantly, has better contrast.

But where the situation get muddy is the conclusion that the distortion is the same between a zoomed fisheye and the WWL-1. I think this is not exactly true. Subjectively at least, they have different renditions. And I would venture a 'feeling' that the WWL-1 has less barrel distortion than the zoomed-in Canon 8-15 at similar fields of view. 

A fisheye renders an image according to an equisolid projection, but interestingly enough, the exact formula differs between different fisheye lenses. So the Lumix 8mm fisheye doesn't distort quite the same way as the Olympus 8mm fisheye or the Canon 8-15...

image.thumb.png.3e711c6aa360b2e8bdff92dd2032f18e.png

 

 

A rectilinear lens renders an image according to a rectilinear projection. And the WWL-1 and presumably the WACP-1/2/C? Probably a different projection function than either the fisheye or rectilinear lenses. The end result is that I don't think you can conclude that the rendering of a fisheye like the 8-15 and nauticam's wet lens range is exactly the same for the same field of view. 

But what is true is that all of these projection functions should be more similar than different at tighter angles of view. It's at wider angles of view that the distortion really differs. Take a look at this graph from the paper linked below. The closer you are to the center of the image, the less pronounced the differences between rectilinear and equisolid angle projection. 

 

image.thumb.png.4d7a1877628f58c9dcf63fc1e2ba30f5.png 

For those technically minded, this paper might be a good starting point: http://michel.thoby.free.fr/Fisheye_history_short/Projections/Models_of_classical_projections.html

Ultimately, what we need is for someone to test the WACP-1/2/C against a fisheye lens like the 8-15 at tighter angles of view. I will do just that using APS-C and m4/3 crop on the R5 C once I get my WACP-1.. or WACP-C.. whichever ships sooner.

But what I will say is that in m4/3 crop, I find that the canon 8-15 even at 15mm still has too much barrel distortion to look natural in video. This was not at all the case with the WWL-1 even at 130*. So no, Massimo.. I don't think the zoom fisheye lenses are a 1:1 substitute for Nauticam's wet optics on APS-C or m4/3 sensors. 

Edited by dreifish
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