Sony A7RIII with flat port and UWL-400F feasible ?

Hello all, I have been shooting  wih a pretty basic Sony RX100V plus Sony housing. Bought a AOI UWL-400F for it but thanks to Covid have never used it. 
 

Wanting to step up my gear I am a little overwhelmed by all the possibilities. I have bought a Sony A7RIII with the Zeiss 24-70 f4 lens and am looking to house it somehow. 
I am also planning to buy a macro lens, the shots I am seeing here are just incredible. Probably will go with the Sony 90mm Macro. 
 

In general I like to dive in the Caribbean, reef diving mostly, have not really ever done any big fish diving. Above water I mostly do landscapes and such and that also is what I like to do underwater. 
 

My question now: Is it feasible to have the Sony/Zeiss 24-70 behind a flat port and use the UWL-400F with it ? Could I get away without a big dome port ? Anybody ever try this ? 

Which housing system?  the key to be able to use it it is the housing system having a port that fits the 24-70 - the key being the front element must be very close to the port glass.   The port charts don't generally make a recommendation for a flat port for the 24-70 so you are on your own trying to work out the right port and extension to use.  There does not seem to be any published info about the UWL-400F lenses compatibility with any full frame lenses, the Fantasea compatibility table only covers compatibility with the 16-50 lens  and Sony A6xxx series cameras.  The fact that it's an M52 thread suggests that it might struggle with a full frame sensor?

The problem you'll run into with housing the 24-70 in a conventional dome  (assume it's the f4) is the 40cm minimum focus distance which depending on the port arrangement may limit how close you can focus or even prevent focus and require you to use a diopter.  The 24mm focal length is not that wide and a 180-200mm port would be fine, but 24mm is not really wide enough for reef scenics. 

Thanks for the reply - have not decided on a housing yet, leaning towards the Isotta for size reasons.

I picked the 24-70 f4 but am by no means wedded to it and still within range to return it. The 28-60 f4-5.6 might be a better option ? Or should I just forget about the AOI wet lens and accept that I will need a flat port for macro and a dome for all the other stuff ? 

Really depends on what you want to shoot, if it's reef scenics, the classic lens to use is a fisheye which means an adapted Canon or sigma lens and you can use them in smaller domes.  Nauticam lists all of this on their port charts and has a system to adapt any Canon mount lens to Sony  and use the canon zoom or focus gear and I see Isotta lists the adapted Canon 8-15 as well. 

Your other option is the WWL which gives very nice optics in a small package.  The 28-60 really would only make sense when mated with a WWL as by itself it's not that wide and doesn't focus that close at the long end.  With that you are really stuck with Nauticam, Isotta I don't believe make a suitable flat port, I recall someone asking a question around that before and their shortest port leaves a large gap to the lens meaning you would lose field of view going that way. 

As for the AOI lens, you would be on your own figuring out a port combination that would fit your chosen lens and then you'd have to test it.  Nauticam certainly has the biggest range of ports that will fit lenses that MIGHT work with the AOI lens.  When I say might you'll certainly be able to form an image but you might lose field of view if the port doesn't fit as well as it should and you might not be happy with the corner sharpness.  If you went with Isotta I don't believe there are suitable flat ports for the smaller kit lenses typically used with wet lenses.  You might be able to fit the 24-70, it needs about 25-30mm less extension than the 90mm macro lens but it may or may not work well with the AOI lens and and the extra port/extensions would possibly be a regret investment.  If it was me I would forget about it.

I strongly doubt that 24-70mm f/4 will work with a wet lens. It has a large front element, suggesting an entrance pupil that is set deep inside the lens. Imagine the cone of light that it gathers, but in reverse - it starts at a point inside the lens, goes out through that large front element, and keeps widening - by the time it reaches the rear element of your UWL-400F, it is considerably wider than its ~60mm diameter, so everything outside that area will be vignetting. Worse yet, this lens extends a considerable distance in order to zoom, so if your flat port accommodates that, it gets even further from the front element in its zoomed-out 24mm position, at which point a considerable portion of your frame is likely to feature the port interior.

You can shoot this lens in a dome - Nauticam recommends a 180mm one, and Isotta offers a range from six to ten inches, but as Chris says, 24mm is not especially wide. I have shot reef scenics with a Sony 16-50mm on APS-C behind a dome, which is pretty much the same zoom range, and it's a very versatile setup, but it requires very clear water and lots of strobe power - I use a pair of Retra Pros with reflectors.

If you want to try to use the wet lens, the compact 28-60mm is probably your best bet. Isotta doesn't have it on their port charts yet, but Nauticam does, and if it works with Nauticam's WWL-1/B, there's a reasonable chance it will work with your UWL-400F as well.

46 minutes ago, Barmaglot said:

If you want to try to use the wet lens, the compact 28-60mm is probably your best bet. Isotta doesn't have it on their port charts yet, but Nauticam does, and if it works with Nauticam's WWL-1/B, there's a reasonable chance it will work with your UWL-400F as well.

Only problem is you've already lost 4mm of focal length, the UWL-400 is designed for 24mm lenses.  So you go from roughly 12mm equivalent focal length(full frame terms) to 14mm if you can use it in a port that doesn't vignette and that's currently only with Nauticam .

Yes, but the OP already has the UWL-400F. As far as I can tell, his choices amount to:

• Buy a big dome and use it with 24-70mm f/4 - widest FoV is 84 degrees at 24mm. Total cost in parts (Nauticam, not including housing) - $2569
• Buy a 28-60mm + flat port and use it with UWL-400F - widest FoV is 114 degrees at 28mm x 0.5 (if it works). Total cost in parts (again, Nauticam, not including housing) - $1196, plus another $207 if you want manual focus capability
• Buy a 16-35mm + big dome - widest FoV is 107 degrees at 16mm. Total cost in parts (assuming Nauticam 180mm dome option) - $3218
• Buy a 28-60mm + flat port + WWL-1/B - widest FoV is 130 degrees at 28mm. Total cost in parts - $2756, plus another $207 for focus gear

There's also the option to use Sony 12-24mm, or Canon 8-15 fisheye, or any number of other options, but pairing the existing UWL-400F with 28-60mm, if it works, looks like the most economical option while producing a field of view that is plenty wide enough for most applications.

2 hours ago, Barmaglot said:

There's also the option to use Sony 12-24mm, or Canon 8-15 fisheye, or any number of other options, but pairing the existing UWL-400F with 28-60mm, if it works, looks like the most economical option while producing a field of view that is plenty wide enough for most applications. 

The key is if it works, My guess would be centre sharpness should be OK and equivalent to using it on an A6400 or similar camera out to an APS-C size crop, but outside that is purely a guess, the fact it has a 52mm mount says to me it's designed for smaller sensors and a lot of reviews are on the TG-6 or similar, generally it would be designed on purpose to cover full frame - extending the coverage into the corners is the hard part and if it was I'd expect it to have a 67mm mount. Fantasea and AOI don't seem to make housings for full frame cameras.

It seems like an expensive experiment to try it out.

Possibly, yes, but UWL-400 is qualified to work with A6xxx cameras using 16-50mm lens, with a footnote that you need to zoom to 19mm to avoid vignetting. 16-50mm and 28-60mm use the same 40.5mm filter size, and 28mm is just about the equivalent of 19mm on APS-C. I'm actually getting tempted to get a UWL-400F for my own A6300 setup - it looks like by far the smallest and least expensive 'real' wet wide lens that works with this platform, and it should give me about the same FoV on the wide end that I get with my 10-18mm behind a dome, as well as allow me to zoom in further than the 18mm permits, and frame things tighter still by taking the lens off and parking it on a strobe arm - something that would be difficult to do with a WWL-1 or even a WWL-C, and I wouldn't need to worry about packing the dome.

@VOL - does the UWL-400F have a protruding rear element when used with 67mm step-up ring? I can't find good images of its mounting end online.

2 hours ago, Barmaglot said:

Possibly, yes, but UWL-400 is qualified to work with A6xxx cameras using 16-50mm lens, with a footnote that you need to zoom to 19mm to avoid vignetting. 16-50mm and 28-60mm use the same 40.5mm filter size, and 28mm is just about the equivalent of 19mm on APS-C. I'm actually getting tempted to get a UWL-400F for my own A6300 setup - it looks like by far the smallest and least expensive 'real' wet wide lens that works with this platform, and it should give me about the same FoV on the wide end that I get with my 10-18mm behind a dome, as well as allow me to zoom in further than the 18mm permits, and frame things tighter still by taking the lens off and parking it on a strobe arm - something that would be difficult to do with a WWL-1 or even a WWL-C, and I wouldn't need to worry about packing the dome.

@VOL - does the UWL-400F have a protruding rear element when used with 67mm step-up ring? I can't find good images of its mounting end online.

My biggest concern would be I can't find any reviews with that lens on a A6xxx camera anywhere, only a review with a TG camera.  The lens is the same as the backscatter 0.5x M52 lens they sell for the TG cameras and they only push it for TG cameras.  Closest I could find was this which had a sample shot of the 400 on on an RX100, but it did have a bunch of posts with good size sample images of the UWL-09F and Sony A6xxx cameras and the 16-50 and those look pretty Ok, just very slightly  soft in the corners. 

https://www.housingcamera.com/blog/product-reviews/the-ultimate-wet-lens-sample-post

The shots have EXIF data embedded so you can pick that up, there's only one shot at 19mm and f9, the last one.

3 hours ago, Barmaglot said:

Possibly, yes, but UWL-400 is qualified to work with A6xxx cameras using 16-50mm lens, with a footnote that you need to zoom to 19mm to avoid vignetting. 16-50mm and 28-60mm use the same 40.5mm filter size, and 28mm is just about the equivalent of 19mm on APS-C. I'm actually getting tempted to get a UWL-400F for my own A6300 setup - it looks like by far the smallest and least expensive 'real' wet wide lens that works with this platform, and it should give me about the same FoV on the wide end that I get with my 10-18mm behind a dome, as well as allow me to zoom in further than the 18mm permits, and frame things tighter still by taking the lens off and parking it on a strobe arm - something that would be difficult to do with a WWL-1 or even a WWL-C, and I wouldn't need to worry about packing the dome.

@VOL - does the UWL-400F have a protruding rear element when used with 67mm step-up ring? I can't find good images of its mounting end online.

Thank you both for the discussion ! I will order the parts and give it a try since I already habe the UEL-400F. @Barmaglot here are some pictures for you. The first is without the step up ring ans you can see nothing protrudes. Second is a picture next to a chapstick for size and the third with the step-up ring. 

Thank you for the photos, but are you sure that step-up ring is not mounted in reverse? The knurled section seems to be wider than the M67 threaded part, so there is no way it could fit into a port.

Still, the rear element looks to be flush with the threading, which means that if I mount it in a magnetic adapter, there will be extra distance between port glass and lens, and that will shrink the FoV. So much for that idea

You are right - I turned the ring around and updated the photo. 

Thank you - yes, it's a flush rear element, good for screwing directly into a port, not so much for quick-detach adapters. Maybe I should look for a used Inon UWL-H100 Type1.

9 minutes ago, Barmaglot said:

Thank you - yes, it's a flush rear element, good for screwing directly into a port, not so much for quick-detach adapters. Maybe I should look for a used Inon UWL-H100 Type1.

Have a look here - they mention a quick release adapter. 
 

https://www.aoi-uw.com/products/wet-lenses/aoi-uwl-400a.html

Thanks... that quick release adapter is for their own proprietary bayonet, but judging by the photos, it does have a protruding rear element, so an M52-M67 step-up ring should be good enough to put it into a magnetic ring.

Sorry about hijacking your thread.