Chris Ross

Hi Chip, by removing the mount, you mean the tripod mount attached to the Metabones? Good information that a standard zoom gear works with this setup. Does that mesh with the adapter gear or the housing gear? Not doubting what you observed at all, but it does seems odd that your setup vignettes at 60mm plus 35.5mm adapter but Wolfgang reports he uses 60mm total extension with the 35.5mm adapter, the fact some of the extension is on the other side of the adapter should make no difference.

As I understand only the mKV works if you want to use it with the TC, the ID of the MkV adapter is bigger so the nose of the teleconverter fits through.

You would expect that with less extension you would not run into vignetting, what this does is move the centre of curvature back behind the entrance pupil of the lens, so it's no longer optimally placed. This will cause I believe a bit more barrel distortion and a slight loss of field of view. Having said all that it seems Fisheye optics are less sensitive to the exact placement of the dome compared to rectilinear lenses in my view, though there are some who will argue this point. It's good to see the performance looked good when you tested it. It seems to be a great very flexible solution. On Wolfwangs's point about zoom gears - I'm not sure I got the meaning exactly, however changing the extension tube in front of the N100-N120 adapter has no impact upon the the zoom gear fit. On the topic of zoom gears I used Wolfgang's adapter solution to get my zoom gear matching the knob in my N85-N120 adapter, but found it would lose mesh when turned unless i provided inward force on the knob. It prompted me to change over to a zoom gear that uses the housing zoom knob and I find that a lot easier to use.

So it appears that this port was designed to work with a couple of Sony cameras using a 1/2.3" sensor which is 6.2 x 4.5, so quite small. Typically UW ports are designed around a specific field of view on a particular sensor size, so it might struggle on larger sensors. Only way to find out is probably to try it.

I would agree, though I have an 8-15 fisheye on m43 and it's effectively a fisheye and the first 2/3 of the range of a WWL/WACP and it can do the job of both. In Sony you can get this with the Sony 2x with metabones and 8-15.

Decent quality cards are reasonably priced these days as long as you are not at top tier speed, though i notice they have gone up along with many computer items recently. The bonus for faster cards is they will download faster if you have the right card reader. I've been using 200GB/sec sandisk SD cards and have 2 128GB cards and back up to a laptop daily. I could write to both cards in camera but generally don't bother and just keep some backup copies. You only need the really fast cards for high frame/sec shooting of full res images, even video is not that demanding in comparison, not likely to need it UW. My raw files are about 17MB (20MP m43 camera) and I can fit over 4000 images on one card.

You are referring to the USB-C bulkhead? The Nauticam right angle plug only just fits through the special M16-M24 adapter, it has to be angled through, If you had a right angle USB plug you could see if you can squeeze it through the M16 on your housing, bearing in mind that . The Kraken bulkhead might be a safer bet as you plug the cable in from inside the housing and it doesn't need to go through the m16 hole.

Actually quoting diagonal fields of view is a bit misleading when comparing rectilinear lenses to barrel distorted wet optics as with barrel distortion the corners are stretched the most. It would be quite rare to place a subject like a whale, a shark or even a wreck along the diagonal axis, rather they are placed along the horizontal axis typically, so in my view comparing the horizontal fields gives a truer picture of the difference in subject size they can accommodate. The horizontal field of a 16mm rectilinear is 96 degrees, while a WWL at the widest is about 106 degrees in the horizontal axis, which is about a 13.5mm rectilinear lens horizontal field. so the horizontal field of view is only 10 degrees wider not 25 degrees wider. All that said I wouldn't take a bit dome down to shoot whales if i Could get similar fields from the smaller wet optics. A fisheye has a 144 degree horizontal field in comparison so is significantly wider.

I use the neoprene bag that came with the MFO3 to protect mine during shore entries. Cinch down the cord on the cloure to keep it on. Take it off in the water and clip it off and reapply during the safety stop. Just don't let go of it as it will float away. An alternative might be a beer cooler used to keep bottled beer cold while drinking, probably widely available. You might find one around the right size. The advantage for me is it keeps the lens wet till I can soak it in fresh water after the dive. You could probably do something similar for your macro port.

It looks like the turtle manual talks to the camera as it says it automatically switches to HSS if the SS goes over max sync speed, which you would need to configure to 1/250 in the trigger, the default seems to be 1/160. You would also need to confirm the HSS will work with your Retras as it doesn't mention strobe compatability on the website. Your alternative is the Nauticam trigger which doesn't register with the camera and will sync to 1/400 without HSS. This will give you more flash power at 1/400 than a HSS trigger will deliver. It a purely manual trigger. It should be able to rear curtain sync as well as this is set in the camera and I can set it in my camera without a flash attached. I'm pretty sure it will fit, it mentions it is OM-1 compatible.

Quiet a few people here use the Canon fisheye with Metabones adapter, it's well established solution as Sony does not have a native fisheye. On the topic of 16-35, some reach is helpful however I really don't think you want to be using a big dome when chasing whales. If you look at the WACP and 28-60 and the horizontal field of view - which shows approximately how big a subject will fit in the frame, it goes from about the field of a 13-14mm lens through about the the reach of a 29mm lens, so it terms of horizontal field it is like a 14-29mm lens and compare this to a 16-35 mm lens it's more or less the same, but with better corners of the frame in the WACP and better ability to shoot wider apertures. The combination of a Canon 8-15 and a Sony/metabones on the other hand goes from a 180° diagonal fisheye with about 144° horizontal field of view through to a 28mm rectilinear lens, it's about equivalent to a 7-28mm rectilinear lens if you could get one. It's reported to have equivalent sharpness to a WACP/Sony 28-60 setup. I would suggest the 28-35mm range won't be too useful for whales, at that focal length to fit in the frame a whale would be on the deg of visibility. This post is a good one on the Sony 2x/metabones/140mm dome combination: I have an OM-1 with Canon 8-15 on metabones and that is what I would be taking if going to shoot whales.

I believe you are talking about different lenses. @dentrock is talking about the Sony 16-25, you are talking about the 16-35 II. I think the issue with the 230mm dome is living with it for travel, the size and weight when diving with it, including the drag when trying to swim with it.This is as much or more of a concern than the expense. With whales you are jumping off a boat and swimming around trying to get in position - a 230mm dome is not going to make that easy. you are also asking about flare, and mentioned problems with your ikelite port with reflections - these are different issues and causes. Acrylic ports are known to cause reflection issues and glass domes are less prone to this. Unless you are going for artistic effects flare is probably best dealt with by planning to be dropped on the sunny side of the whales and good operators will try to achieve this. If I were doing it I'd want to be using a fisheye lens, they work well in small ports and are quite sharp, you do need to pay attention to corners as they can be easy to include stray fins and other distractions on the edge of the frame. The WACP will certainly work, it's just not quite as wide.

Yes that's right, one of our members here, Wolfgang ( @Architeuthis ) uses the 8-15 with the Sony 2x and likes the setup. The downside is it's not as sharp as the bare lens, but if I recall it is about as sharp as a WACP-C, there's a thread on here about using this setup. You mount Sony 2x on body, then Metabones then the 8-15. Very flexible. I use an OM-1 in combination with a Canon 8-15, with the crop factor there is no teleconverter and I get the same zoom range.

So you are saying pressing the AF point button outside the housing activates display off, but inside the housing it won't work, but other functions assigned to that button work inside the housing? Maybe there is a eye detection function in the camera viewfinder and inside the housing it thinks there is an eye at the viewfinder and won't activate the function, because it thinks you are still using the viewfinder? You could test by covering the eye sensor to see if it stops activation outside the housing?

Fair enough, though I would add that ports for Isotta seem to be a quite a bit cheaper and particularly extension rings when you look at the prices for the type II rings from Nauticam - that's a long term cost if you add more lenses later. The Canon 8-15 with metabones and Sony 2x is also a fine option, about as good a quality as WACP-C according to posts on here and combines a 180° diagonal fisheye, the field of a 14-28 rectilinear and the wider end of the WACP. You can use it behind a Nauticam 140mm dome among other options such as Nauticam 4.33"acrylic dome and even the tiny Zen 100mm dome (at the cost of some corner performance). In Isotta you don't need the N100-N120 adapter and you could use it with the 4.5"glass dome.