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horvendile

WACP-2, if the WACP is too light and cheap for you

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So ok tongue-in-the-cheek subject title. You have probably seen this already, after all it's in the DEMA article on the front page, but since I don't see any thread about it: the WACP-2.

https://www.nauticam.com/collections/water-contact-optics-for-nav/products/wide-angle-conversion-port-2-wacp-2-140-deg-fov-with-compatible-14mm-lenses-incl-float-collar

Nauticam calls it a 0.8x converter, giving 140 degrees FOV with a 14 mm lens. They explicitly mention the Nikon Z 14-30/4 lens, and since I've been curious about the Z system for diving this especially caught my attention.

Well, one definite advantage with the WACP-2 is that it makes the original WACP look light and affordable. It weighs 7 kg in air and is estimated to have "an estimated MSRP of $5-7,000 USD".

On the other hand, dreaming is fun.

Tangentially, really another subject, but it would be interesting to know if anyone has tried the 14-30/4 lens with the Sea & Sea 82 mm correction lens.

Edited by horvendile

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Am not sure how this converter works it mention a low distortion but all their converters are not rectilinear so the field of view is not actually comparable

The sea and sea corrector instead IS rectilinear

 

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Yeah I shouldn't have mentioned the Sea & Sea in this thread really, apparently I just couldn't stop myself when it popped into my head. The corrector has very little to do with the WACP-2.

The relevance it does have is that it's another way, on compatible lenses, to get sharp corners without massive down-stopping.

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The sharp corners in fisheye like lenses are the result of corner compression due to barrel distortion

The corners are actually not sharp at all if you had a rectilinear image

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Did someone already test the Sea & Sea corrector lens on rectilinear WA lenses with front thread for MFT (with thread adapter, e.g. Zuiko 9-18mm, Pana 8-18mm)?

Would not be a big surprise if the lens would work equally nice and be a great solution compared to all these wet correction lenses/adapters...

In case it works in practice, the lens is certainly worth the money...

 

Wolfgang

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6 minutes ago, Architeuthis said:

Did someone already test the Sea & Sea corrector lens on rectilinear WA lenses with front thread for MFT (with thread adapter, e.g. Zuiko 9-18mm, Pana 8-18mm)?

Would not be a big surprise if the lens would work equally nice and be a great solution compared to all these wet correction lenses/adapters...

In case it works in practice, the lens is certainly worth the money...

 

Wolfgang

Wolfgang

The sea and sea lens is positive meniscus and it will work with any lens however full frame lenses have blurred corners due to depth of field while MFT due to lens correction in built for most. So the best option is to disable lens correction and is not expensive you just need to buy the software see the DxO thread in the editing subforum

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The problem with the S&S lens is it is too big for most m43 lenses.  77mm filter threads if I recall correctly.  Basically all it is doing is flattening the field, the lens is imaging a curved surface in the virtual image which means the image plane it produces is also curved.  The lens changes the focus to that the focal surface produced is flatter.  It's probably not too dissimilar to field flatteners used in astronomical imaging.  Many optical designs produce a curved focal surface and a meniscus corrector used close to the focal plane is a common solution - not practical for using in a small format camera, but the same principle seems to be applied with a correcting lens in front of the lens.  In theory you could also do it with an optic attached to the lens mount like a teleconverter, but a front mounted optic is much more universal.

Interesting that the new WACP is rectilinear, pity it's so heavy and $$$.

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@ChrisRoss is correct on what the sea and sea part does and yes it is available for 77 and 88 mm threads. The 8-18 panasonic has a 67 mm filter mount the olympus 9 - 18 is smaller all the other MFT wide angle that are housed do not take a filter
I am dubious about this WACP on both land and underwater photography I find 16-35 mm the lens that is a good compromise in terms of range and without excessive perspective distortion the sharp corners are only one consideration and frankly not a major issue at all with my Panasonic 8 - 18. If I had a full frame I would try to make a 16 - 35 mm work not necessarily I would want wider


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I am very interested in the WACP2, partly because it does split shots. There are some nice images from Alex Tattersall on Facebook this week.

As per the original WACP release it's hard to calculate what lens combinations are going to provide what equivalent to a dome setup. I don't think of my pictures in FOV and the lens distances all become irrelevant. I'm kind of glad I never got around to pulling the trigger on the WACP though as the WACP2 looks to be a better fit for what I want to shoot. Though if the WACP suddenly went to half price I would buy one in a heartbeat.

As for the weight...I'm already travelling with a rebreather, camera and six strobes. What's another 7kg??

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It is not difficult the WACP is a zoom fisheye effect the equivalent for full frame is an 8-15 mm lens with a 1.4 teleconverter. The WACP has more zoom range though
For the WACP-2 there is only the canon 11-24 am not aware of any Nikon optics that wide. This takes the 230 mm fisheye dome and most likely will have worse performance of WACP-2 plus 16-35 mm
However I would never shoot a rectilinear lens wider than 16 mm anyway


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There are some test shots on facebook of the WACP 2

First I am confused by the specs it says with a 14 mm lens the field of view is 140 degrees and the magnification is 0.8x

14x0.8=11.2 mm field of view at full frame 125 degrees. To get 140 I need 0.57x

Looking at the images they are not rectilinear so this is not a rectilinear lens is just a less distorted lens

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On ‎1‎/‎28‎/‎2020 at 11:00 PM, Interceptor121 said:

There are some test shots on facebook of the WACP 2

First I am confused by the specs it says with a 14 mm lens the field of view is 140 degrees and the magnification is 0.8x

14x0.8=11.2 mm field of view at full frame 125 degrees. To get 140 I need 0.57x

Looking at the images they are not rectilinear so this is not a rectilinear lens is just a less distorted lens

Hi Interceptor,

Thank you for pointing out the discrepancy here.

Our colleague used a rough ratio of the difference of the angle of view between 114° and 140°, which is the amount of the increase of diagonal angle of view using the Nikon 14-30mm lens at 14mm with WACP-2, while rushing out the initial release.

I agree that we should use the conventional way of calculation for the magnification ratio, as the market has been doing for a long time:

Original angle of view and focal length of the lens:   114° at 14mm

Resultant angle of view by using the WACP-2:           140° which is equivalent to the AOV of a full frame 8mm rectilinear wide angle lenses.

Hence the magnification ratio should be:   8mm/14mm = 0.57X

By the way, we have the privilege of inviting Dr. Alex Mustard to experience the WACP-2 during his workshop in the Cayman Islands in January, you may find some very nice pictures and his initial opinion here: https://www.facebook.com/amustard/media_set?set=a.10163542674385713&type=3

Best regards,

Edward

Edited by Edward Lai
added missing words

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Hi Interceptor,
Thank you for pointing out the discrepancy here.
Our colleague used a rough ratio of the difference of the angle of view between 114° and 140°, which is the amount of the increase of diagonal angle of view using the Nikon 14-30mm lens at 14mm with WACP-2, while rushing out the initial release.
I agree that we should use the conventional way of calculation for the magnification ratio, as the market has been doing for a long time:
Original angle of view and focal length of the lens:   114° at 14mm
Resultant angle of view by using the WACP-2:           140° which is equivalent to the AOV of a full frame 8mm rectilinear wide angle lenses.
Hence the magnification ratio should be:   8mm/14mm = 0.57X
By the way, we have the privilege of inviting Dr. Alex Mustard to experience the WACP-2 during his workshop in the Cayman Islands in January, you may find some very nice pictures and his initial opinion here: https://www.facebook.com/amustard/media_set?set=a.10163542674385713&type=3
Best regards,
Edward

Thanks Edward
As far as I can see this lens is not rectilinear and it still has barrel distortion and therefore is not an alternative to a dome+rectilinear lens
Seems just another wet adapter that works with wider lenses and has more field of view achieving a zoom quasi fisheye effect not available on full frame and 0.57x magnification as I calculated
Is the optic afocal?


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1 hour ago, Interceptor121 said:


Thanks Edward
As far as I can see this lens is not rectilinear and it still has barrel distortion and therefore is not an alternative to a dome+rectilinear lens
Seems just another wet adapter that works with wider lenses and has more field of view achieving a zoom quasi fisheye effect not available on full frame and 0.57x magnification as I calculated
Is the optic afocal?


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Thank you Interceptor,

We build the WACP-1 and WACP-2 for underwater photographers who demand superior image quality at larger apertures, such as f/5.6 or even f/4.  While the WACP-2 in combination with the Nikon 14-30mm results with 140° AOF images with quite low distortion, and very good image quality across the frame, our main objective is not aiming for zero distortion.

First of all, zero distortion doesn't exist at all for any lens in the wide angle range of 130° to 140°.  For example, the Canon 11-24mm (max AOV 126°), the Nikon 12-24mm (max AOV 122°) and the Nikon 14-30mm (max AOV 114°) all have certain amount of barrel distortion at the wide end.  Naturally, the WACP-2 as an afocal add-on lens mounted in front of a lens having barrel distortion, it will be not able to eliminate the inherent barrel distortion.

Using any of these wide angle zoom lenses behind a dome port also doesn't help with barrel distortion.  Until now we haven't seen anyone to be able to produce perfect zero distortion images using one of these wide angle lenses behind a dome port.  Of course, the normal dome port theory applies here!  People can't achieve relatively good sharp corners until closing down the apertures to around f/14, and a dome port could actually induce more barrel distortion to the system.  Adding a corrective lens in front of the camera lens may further complicate the issue because it introduces another type of distortion to the system.

There is now a 12mm (AOV 122°) lens in the market that claims to have zero distortion, at the price of heavily and unnaturally stretching the images at the corners.  It is fine for shooting buildings, but any subject, in particular people, will look extremely unpleasant if placed near the corners.  The result of using this lens behind a dome port is yet to be found out.

Best regards,

Edward

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Edward
In no means am criticising the lens or the optical quality although as you know I prefer to test this stuff myself as most people out there have a creative approach and not engineering approach and this ends up with incorrect information leading to wrong expectations
The question about afocal is important in the computation of depth of field for video use is not relevant to the quality question
From a marketing point of view I would say that the correct positioning of this optic is as an alternative to prime fisheye not to rectilinear zoom lenses with the benefit of wider aperture

Regarding the comment on dome distortion firstly lenses are never zero distortion they have as minimum 2-3% barrel distortion this is accepted
With regards to dome obviously this is a single element and the key issue is field of curvature again this issue already exists on land and is magnified by the dome however as of today there is no other solution if you want to have distortion below 5% I think here the issue is more to understand if you really need straight lines or not
Since Nauticam introduced the WWL-1 I have been shooting micro four thirds and I do not have issues major issues with rectilinear lenses within the limits of dome ports due to the crop factor
Some of the issues the WACP 1/2 resolve are purely for full frame users but I am interested in the technology development anyway
To that extent I would recommend performing rigorous test shots with grids and calculate distortion at least on one or two lenses and publish the details.
If nobody knows how to do it or want to do it I will do it just send me a test rig


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Massimo...

The test shot data for the WACP 1 is here: https://wetpixel.com/articles/review-nauticam-wide-angle-corrector-port (including the Zemax data).

I would expect that we will be running a review of the WACP 2 soon too :)

Someone on another venue suggested that the barrel distortion on the WACP was awful. My response was "compared to what?" He is a video shooter using Digital Cinema Gear and seemed to think that he could get better results with a PL lens behind dome port. Once I explained a little optical theory, he realized that his results were based on the way he had set up the WACP and his lens choice (and the combination of both).

@Edward Lai's point is well made however. No wide angle lens can eliminate barrel distortion. What is unique about the water contact optics is how little of it they have, particularly when compared with conventional dome/land combinations. When this is combined with the option of using the lenses at large apertures, this makes them a very attractive option.

Of course, whether an individual feels that the quality is worth paying (large) amount of money for is very much a personal decision. :)

 

 

 

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Massimo...

The test shot data for the WACP 1 is here: https://wetpixel.com/articles/review-nauticam-wide-angle-corrector-port (including the Zemax data).

 

I would expect that we will be running a review of the WACP 2 soon too

 

Someone on another venue suggested that the barrel distortion on the WACP was awful. My response was "compared to what?" He is a video shooter using Digital Cinema Gear and seemed to think that he could get better results with a PL lens behind dome port. Once I explained a little optical theory, he realized that his results were based on the way he had set up the WACP and his lens choice (and the combination of both).

[mention=21179]Edward Lai[/mention]'s point is well made however. No wide angle lens can eliminate barrel distortion. What is unique about the water contact optics is how little of it they have, particularly when compared with conventional dome/land combinations. When this is combined with the option of using the lenses at large apertures, this makes them a very attractive option.

Of course, whether an individual feels that the quality is worth paying (large) amount of money for is very much a personal decision. 

 

 

 

I don’t have an issue with distortion but I do not like incorrect specifications (0.8x vs 0.57x) and statements like they have appeared elsewhere that the lens is rectilinear

 

I also believe that testing lenses on reefs is not actually sufficient as those have no geometry anyway and real conditions mask the real optical performance

There should be both a pool/controlled environment test as well as open water test

 

I don’t make comment on the cost va value that is subjective but on the focal range for sure the WACP-1 is more useful than WACP-2 for video users

 

 

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To add on the zemax testing that is not a fair comparative as distorted lenses compress corners while rectilinear most time enlarged them and dome has field of curvature of course
Wacp and the likes should be compared with fisheye zooms (when available and in full frame I think not available)
The only meaningful comparison possible today is tokina on Sony A6X vs WWL-1 or same or canon 8-15 on MFT vs WWL-1
Hence the need to clearly declare the distortion so that you know what’s the price to pay for sharpness
Rectilinear lenses behind well designed dome ports have distortion less than 3% fisheye like are well above 10%


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