It seems there is a lot of fisheye questions right now, but I have been wondering why most of the Port Charts either list a 140mm or 230mm port for use with the 8-15mm Canon (Nauticam/Marelux).While it seems that the fisheye would make a 180mm dome a nice solution with sharp corners in a reasonable travel package.Is there a reason why 180mm are avoided with this fisheye lens?
I am specifically asking about the 15mm focal length – not when shooting at 8mm (i.e. not going to remove the shades).
If anyone has experience using this lens on an RF mount, I also am confused why on the RF port charts there is no extra extension to make up for the RF-EF adaptor.
Assuming you're referring to Nauticam 180mm dome SKU #37129, it's a wide-angle dome rather than fisheye - i.e. it's a shallow dome with a larger radius of curvature that doesn't cover a whole hemisphere. The 8-15mm @ 15mm still gives you a 180 degree FoV corner-to-corner, so you need a hemisphere dome to run it. 140mm is good for CFWA type shots, while 230mm is more suited for over/under splits.
Also the benefits of a large dome are less with fisheye lenses compared to rectilinear. On full frame a 100mm dome might be seeing some more obvious corner issues. To be clear you could use a 180mm dome with the fisheyem you would have to place it it well forward of the optimum point and image quality will suffer a little. This is what ikelite does with their compact 8" dome. However I believe the likes of Nauticam have found a 140mm dome a better solution. in terms of small size for CFWA and image quality and mark it as the most optimised solution with the 8-15mm.
On the EF-RF adapter, I believe what Nauticam has done is move the camera back in the housing so that the EF-RF adapter flange is at the same position relative to the lens that the EF camera flange was in their EF housings. This means that the EF zoom/focus gears automatically fit when used in an RF housing and the with the EF-RF adapter the EF port chart automatically applies. If you did it with extension rings you would have to make a whole new set of zoom gears. Nauticam has done the same thing for the Nikon Z housings.
23 hours ago, ColdDarkDiver said:
It seems there is a lot of fisheye questions right now, but I have been wondering why most of the Port Charts either list a 140mm or 230mm port for use with the 8-15mm Canon (Nauticam/Marelux).While it seems that the fisheye would make a 180mm dome a nice solution with sharp corners in a reasonable travel package.Is there a reason why 180mm are avoided with this fisheye lens?
I am specifically asking about the 15mm focal length – not when shooting at 8mm (i.e. not going to remove the shades).
If anyone has experience using this lens on an RF mount, I also am confused why on the RF port charts there is no extra extension to make up for the RF-EF adaptor.
I have used the Canon 8-15mm fisheye on both Canon R and Sony Cameras with a verity of housings. I did a review on a Canon R housing for UWPMAG.com issue #106 a free PDF download. With both Nauticam and Marelux housings the extension needed is the 30mm using Canon EOS R cameras. I have also used both the 140mm and 230mm dome ports and as stated above the 230 works best for splits while the 140mm works best for just about everything else. I have a Nauticam 140mm port for sale in Wetpixel classifieds if you decide to go that way.
