Hi all

As always, every time I go on another dive trip, I find the urge to change something in my setup.

I currently shoot w Sony A7R5 in Nautical housing - for wide angle I use the kit 28-60mm lens w Nautical WACP-C. I am mostly very happy but find myself constantly struggling with the weight and going over the 10kg hand carry limit (w only WACP-C, camera, lenses, macro port, and SMC-1). On my current trip to Halmahera I also found it not wide enough to capture the big schools of barracuda and jacks in Tifore - cannot get close enough for strobes to light while still capturing the full ball in the frame.

I previously used the 28-60mm w WWL-1B, and before that with the MWL-1, and before that had a Nikon APS-C which I used w Tokina 10-17mm and 4.33m mini dome. I find myself missing the 150 degree effect fov of the MWL-1 and the Tokina, and really miss the light weight of the Tokina set up. I sold the MWL-1 because I wasn't happy w the image quality, everything had a distorted feel to it especially in the corners.

So upon doing some research, I have stumbled upon the Canon 8-15mm fisheye in either 140mm glass dome or the 4.33" mini dome as another option. I already have the metabones V adapter and the 30mm extension, so would need to buy the lens, N100-120 port adapter, new zoom ring, and one of the domes. On the other hand I can sell my 28-60, the zoom ring, and the WACP-C -> so net net I don't think it will be a big cash outlay.

I have a few questions:

1) will changing to this be a dent on image quality?

2) is the mini dome viable and a decent option? Primary consideration is the weight savings. However I do see the 140mm glass dome recommended more.

3) what is the equivalent field of view at the 15mm end? can I still get normal rectilinear wide angle shots? I know the 8mm end is a full circular fish eye.

4) anything else I should consider?

Many thanks!

1 hour ago, jjmochi said:

3) what is the equivalent field of view at the 15mm end? can I still get normal rectilinear wide angle shots? I know the 8mm end is a full circular fish eye.

The 15mm end is an approximately 180 degree diagonal fisheye, similar to the 10mm end of Tokina 10-17mm on APS-C. Positions between 8mm and 15mm give you various degrees of corner vignetting. If you want a usable zoom range, you need to add a teleconverter - a 1.4x moves the 180-degree fisheye to 11mm, whereas a 2x gives turns 8mm into a diagonal fisheye and zooms in from there. Older 2x TCs produced significant degradation in image quality, but new Kenko HD PRO models are said to be fine in that regard. Sony TCs (with Metabones V adapter to accommodate the protruding elements) are possible too, albeit more expensive. You can find some sample shots here:

And here:

Edited 4 hours ago4 hr by Barmaglot

3 hours ago, jjmochi said:

1) will changing to this be a dent on image quality?

2) is the mini dome viable and a decent option? Primary consideration is the weight savings. However I do see the 140mm glass dome recommended more.

3) what is the equivalent field of view at the 15mm end? can I still get normal rectilinear wide angle shots? I know the 8mm end is a full circular fish eye.

4) anything else I should consider?

Many thanks!

Barmaglot has already linked treads with plenty of information...

I have Sony A7R5 and use it with 28-60mm/WACP-C, Canon 8-15mm (with and w/o Kenko and Sony 1.4x and 2x TCs; now I use it predominantly with Sony 2x TC when longer focal lengths are needed) and can say something, but it is from from my subjective experience, I do not make optical benchmark tests UW:

"1) will changing to this be a dent on image quality?":

IQ of the pure Canon 8-15mm fisheye lens is at least as good as the 28-60/WACP-C combo, even a bit sharper. Together with the 2x Sony TC the Canon 8-15mm provides very similar IQ, compared to the 28-60/WACP-C combo (maybe WACP-C is a bit better at 28mm, but gets a bit less sharp at 60mm).

"2) is the mini dome viable and a decent option? Primary consideration is the weight savings. However I do see the 140mm glass dome recommended more.":

I just used 140mm glass dome on FF. My wife is using 100mm glass dome together with the Tokina 10-17mm/0.71x speedbooster on MFT (Oly EM1II). Both give very good results in IQ. I did not use 100mm glass on FF, but several people write that this is a bad compromise for FF (most use it just for specialiced photis as very CFWA, but I find 140mm also very good for this). The acryl dome should not be different from glass, just the radius matters, except some flair when photos are made against the sun and acryl is much more prone to scratching (one does not see minimal scratches in most pohotos, but when photos are made against the sun these minimal scratches can show up without mercy).

"3) what is the equivalent field of view at the 15mm end? can I still get normal rectilinear wide angle shots? I know the 8mm end is a full circular fish eye.": At 15mm you get 180° diagonal FOV with a fisheye on FF. When using the 2x Sony TC, you start with 16mm (approx. 170°, what is pretty wide) and end with 30mm (approx. 85°). This compares to 130° at 28mm up to 68° at 60mm for the WACP-C combo. I, personally, do not miss the 85°-68° range of the WACP-C, since the working distance is already often too large to give good IQ at this long range. On the other side, I permanently miss the range wider than 130° when I am with the WACP-C combo.

The WACP-C does not give rectilinear optics, but it gives fisheye look. Just more moderate fisheye look, just as longer focal length fisheye lenses do. I, personally, do not like extreme rectilinear WA UW. The Sony 20-70mm in 170mm WA dome is enough for me regarding rectilinear WA (Tamron 17-28mm is also very good, but zoom range is limited). When wider, rectilinear lenses produce extreme elongations towards the edges that I do not like at all (I also have Laowa 10mm that behaves o.k. behind the 140mm glass dome, but used it only for two dives, I really dislike the optics towards the edges)...

"4) anything else I should consider?": you could also consider the FCP-1 that gives similar FOVs as the Canon 8-15mm with 2x Sony TC behind 140mm dome, but I am not aware about strict tests that compare the optical IQ of both FCP-1/28-60mm and 8-15mm/2x SonyTC/140mm domeport (I believe the difference in IQ must be small, since some professionals still prefer the WACP-1 over the FCP-1 (because of IQ), when FOVs wider than 130° are not required)...

Wolfgang

Edited 1 hour ago1 hr by Architeuthis

13 minutes ago, Architeuthis said:

you could also consider the FCP-1 that gives similar FOVs as the Canon 8-15mm with 2x Sony TC behind 140mm dome

She's looking to reduce her travel weight; FCP-1 is a full kilo heavier than WACP-C.

25 minutes ago, Barmaglot said:

She's looking to reduce her travel weight; FCP-1 is a full kilo heavier than WACP-C.

Also the option with 140mm dome is not really cutting down from WACP-C (2.5kg with lens).

1.5kg 140mm glass dome

0.5kg 8-15mm

0.2kg Monster adapter

0.2kg TC

0.3kg N100-N120 adapter

39 minutes ago, Sokrates said:

Also the option with 140mm dome is not really cutting down from WACP-C (2.5kg with lens).

1.5kg 140mm glass dome

0.5kg 8-15mm

0.2kg Monster adapter

0.2kg TC

0.3kg N100-N120 adapter

Yeah, good point... that glass dome is no featherweight. Perhaps look at an acrylic dome option?