John E

So what is the real world interpretation? If one has the choice between Sony 26-60mm + WWL-1, the Canon 8-15mm, Sony 14mm or Sony 16-35mm at it's widest, and is taking the same type of shot such as a reef scene, which would be the better option for overall sharpness? Assuming the correct extensions are used and the appropriate dome size, is the fisheye the worst option unless the specific style is needed, or does the close working distance reducing the amount of water in front of the camera offset any drawbacks and mean it is the best option?

Maybe it is worth a test in a pool and have the same composition i.e backed off on the non-fisheye - this would better reflect real world use - as Chris H points out about the shooting distance for a given subject. For the Canon 8-15mm fisheye, if you are talking about an APS-C crop wouldn't it also be relevant to try it wider than 15mm? (noting the Sony A7Rv has the same pixel density as the A6700). i.e. I wonder what is the fisheye pictures edge difference between the APS-C crop at around 10mm (or whatever is the exact equivalent) to full frame at 15mm? Then there is the question of the view at the fisheye edge being so oblique anyway.

This is an example of using the Canon 8-15mm fisheye plus 1.4 Kenko with a Sony A7Rv but doing some partial de-fishing in Lightroom just because of the straight lines on the coral nursery. This happens to be with an 8 inch dome as that is what I had.

Olympus 7-14mm now sold Olympus 60mm now sold

I haven't used Weefine but have used AOI wet lenses. I have found the quality absolutely fine - but I now would avoid lower cost wet lenses that have a polycarbonate front element. Whereas it is possible to polish a dome port, to my knowledge the coatings on the polycarbonate front elements on wet lenses mean they can't really be polished, say if they get a scratch from a slight misjudgement when doing CFWA Getting a front element replaced then costs quite close to a replacement wet lens.

Housing now sold, camera and lenses still available.

I have for sale an Isotta housing + Olympus OM-D E-M1 Mark ii camera + some lenses. Other than the 12-40 mm lens, all items were bought new in 2022. Everything is in very good condition and fully functional. Comes with original boxes except for Olympus 12-40mm lens. Camera and lenses stored in a dehumidified cabinet. Camera only used in the housing. Items are in Queensland, Australia. Parcel post can be arranged. Isotta housing for Olympus OM-D E-M1 Mark II + Vivid Sentinel V5 plus manual pump (Asking AUD $1200) Olympus OM-D E-M1 Mark II body + Olympus FL-LM3 compact flash + 2 genuine batteries + Olympus charger (18,256 shutter count) (Asking AUD $700) Olympus 7-14mm f2.8 PRO lens (Asking AUD $850) Olympus 8mm f1.8 PRO Fisheye lens (Asking AUD $790) Olympus 12-40 f 2.8 PRO lens (Asking AUD $480) Isotta Olympus 7-14 zoom gear (Asking AUD $70)

I am a huge fan of the fish identification photographs of Gerald Allen, Roger Steen, Paul Humann and Ned DeLoach in books like Reef Fish Identification Tropical Pacific. I wonder if anyone knows what focal lengths they used. It strikes me that if you want longer reach MFT or APS-C is much more manageable and the amount of water you are shooting through is going to have a big impact on image quality and lighting anyway. (OM 90mm sounds appealing here) Another question is don't the 20-70 and 70-200 lenses extend a lot? Doesn't that effect image quality due to finding the best port extension length... eg difficult to get the right dome position on the 20-70 or vignetting at 70mm on the 70-200?

And you have to love the fish that need a fisheye lens. This reticulated whipray photo was taken on an EM 1ii with the Olympus 8mm.

I had (have) an EM1 ii i and now a Sony A7Rv. I just intended to sell the Olympus but have been hesitating. Both are really good but it is easy to underappreciate the Olympus. I have an Isotta housing and last year there was not a confirmation from them that they would make a housing for the OM1. (They do now.) I also wanted as high a resolution as possible as I am trying to take survey pictures of substrate and count coral recruitment. Hence my change to Sony. I can't see much benefit in the Sony in your circumstances except for the ability to crop, which could be significant. I am not sure about Nauticam but with the 102mm diameter port system on Olympus in Isotta I never have to remove a port to get the camera out of the housing even if using larger diameter lenses. I have found the 12-40 pro (thanks Chris Ross for the prompt) really good to use for medium size fish. I was using it with a flat port and extension that I had anyway and just the range from 40mm down to about 25 to 30mm. I assume it is considerably sharper than the 12-50. I was also using the 60mm macro. For me I really like versatility of the A7Rv (in APSC mode it has the same pixel pitch and resolution as the A6700). The autofocus is better but I didn't find it an issue on the EM 1ii. I tend to use back button and spot focus a lot as I am worried the focus will jump off my target. I've not found the AI on the Sony useful for fish so far. I have the 90mm and Canon 8-15mm fisheye and the Sony 28-60 which is probably not great for fish on its own (I have only tried it once - am waiting for a WWL-1 to arrive). I have not looked at the spec but assume the 28-60 has too long a minimum focus distance to be fun to use on its own. The viewfinder is very good. I have a 45 degree viewfinder on the EM 1 ii housing but haven't bothered using it yet on the Sony housing ( I very rarely use the LCD due to bright sunlight) The smaller and lighter lenses are something I miss when handling the camera on a boat. When I look back through my fish photos I can't tell by looking which ones are taken with the Olympus and which ones with the Sony. One thing about the Sony A7Rv is that, if I take a photo and it is not as sharp or detailed as I want, I now know it is is my fault and not the camera!

Thanks Whiskeyjack, I have the EM-1 ii. Interesting to know what Isotta recommended for you although the EM1 series and EM5 have different port charts (EM1 extensions being shorter) and the EM1 has the zoom cog is on the housing.

Hi Whiskeyjack, would you be able to provide the port extension length you use with the Canon fisheye lens Thanks. John

Glad to hear that is possible. I use Canon 8-15 with Sony. I have both Olympus and Sony Isotta housings but do not have the EF to MfT metabones adapter. Was planning on selling the Olympus but also thinking about keeping it. I use the B120 to B102 adapter so extensions and ports are interchangeable. For Canon on Sony they list zoom gears for use with an adapter only, and with adaptor plus teleconverter. I expect the part is like those gears with the different length to match the zoom cog in the housing body? They don’t seem to list the extension length on their port chart but have a wide range, so sounds like that would be simple. I doubt any custom parts would be needed.

Thanks. I hadn't noticed the two different 6.5 inch ports.

With this set up in an Isotta housing I am trying to find out what (if any) the sharpness compromises are on a smaller (4.5 inch fisheye dome) versus a 6 inch dome, and if small apertures and no need for circular fisheye, or absolute 180 degree coverage, mean the 4.5 inch is fine. I notice Zen have a 100mm fisheye port for the Canon 8-15..... a European company gives diameter in inches and an American company in mm ¯\_(ツ)_/¯

Thankyou Massimo. Your tests were a big help in me choosing the Canon 8-15 and newer Kenko 1.4 on Sony A7Rv. On this camera there is also the versatility of using APS-C mode and getting a good zoom range with the same image quality as the A6700, but having both options works well.

Hi Sundeep, I also learnt a lot from Massimo, Wolfgang and also Chris Ross. I'm not sure if Massimo is referring to Nauticam ports? I have Isotta and OM-D EM 1 ii (also now a Sony in Isotta). The 102mm port diameter is a bonus with Isotta. I have the 8mm with the 4.5 inch glass dome and the 7-14 with the 8 inch dome. Both really good, although as Chris says there is also now the OM system 8-25mm which sounds a good range but it's minimum focusing distance is still 23cm so not sure how that effects things with a 6.5 inch dome? If you don't mind a change, the Tokina with an adaptor sounds like a great zoomable solution to cover both lenses, but as Chris says the Isotta port chart doesn't cover it so you would have to figure the extension out, or maybe Isotta can tell you. Check the thread about the advantages of fisheye zooms, there is a chart with the zoom ranges of different options.

If they are about the same price the Metabones would be a safer bet than the Sigma. In Australia the Sigma is about half the price. I have a Sigma MC-11 on Sony A7Rv ... works great on photos, doesn't focus on video.

Hi Phil, It is true Isotta's port charts list the options but don't say which is the optimum image-quality solution for each lens, which would be better, but that is easy to find out when purchasing form a dealer. (I think naïve is not a fair description.) The same thing seems common practice with other manufacturers. From what I can see, Marelux lists their 7 inch and 9 inch domes as being suitable for wide rectilinear lenses. They even have a 5.5 inch fisheye port listed for the Nikon 14-24 F mount lens (minimum focus 28cm at 18-24mm), but not 14-24 Z mount (minimum focus 28cm at all zoom positions) along with the 7 inch and 9 inch domes, but no information on which is optimum.

Just to avoid possible confusion, the current "premium" quality Kenko 1.4x tele-converters are called "Teleplus HD Pro 1.4X DGX". There isn't "premium" in the name. The other cheaper current model is the Teleplus HD 1.4X DGX

As interceptor121 says the current model is called Kenko Teleplus HD Pro 1.4X DGX. By the way, as you mention you are figuring out about the adaptor, my Sigma MC-11 does not focus at all on my Sony A7Rv when the top stills/video dial is set to video. To focus I need to move that dial to stills, then focus, then back to video for single focus. But far from ideal if you do much video, in which case the Metabones is better. And then apparently the Metabones version 5 has a slightly larger internal diameter than the version 4. So that means it can work with the Sony 1.4X teleconverter, but that is placed behind the converter rather than in front of it (not sure what impact that has). So an alternative solution to the Kenko... Maybe others can confirm... I just picked this info up from other posts (old Wetpixel site) before I bought mine.

In case it is of interest, I am planning on putting my Olympus OMD EM 1 ii with Isotta housing up for sale and will be looking for around 60% retail value for the housing and AU$850 (440 pounds sterling) for the camera plus extra battery. I'll be selling the Olympus 8mm fisheye, 7-14mm with Isotta gear, 12-40 Pro and 60mm macro lenses too. The gear is all in excellent condition with original boxes and around two years old. I needed high resolution (research and coral recruitment monitoring zooming in lots to see small coral recruits) so ended up with a Sony A7RV. But.... I am in Australia, although I have relatives visiting from UK in Feb March who could bring the housing to the UK and post locally. I have a reef tour business called Wavelength Reef Cruises so that could handle payment transaction. I was planning on posting in the classifieds here when I get round to it.

Not stopping you ! These photos show how Sony full frame is not necessarily much bigger than M43....

I'm an Isotta user rather than Nauticam. I changed to Sony from an Olympus with an 8mm fisheye (4.5 inch dome) and a 7-14mm lens (8 inch dome +60mm extension). I opted for the Canon 8-15 plus Sigma MC11 + Kenko which also uses the 60mm extension and 8 inch dome. II have so far just been using the 8 inch dome port . would need to get a 50mm extension to use the 4.5 inch. As I have a 102mm diameter port on the Olympus Isotta housing and 120mm on the Sony I just needed to buy the B120 to B102 converter. The zoom range is not very large but I am very happy - including not having to buy a new port or extension with the 8 inch. I am also getting a WWL-1. The focus for stills with the Sigma is fine but not for video.

For reference - I have an Inon 45 degree X-2 (for Inon and Isotta) and that mount is 33mm diameter and 16mm deep (just measured with a ruler so not exact to a fraction of a mm)