Wolfang, I was not aware I could sue a tokina or canon fisheye zooms, I would really like to try these lenses, what adapteur do you use for these lenses on micro 4/3 system.
I have decribed it already here, both with Zen DP170N120 and the Nauticam N120 140 minidome:
I prefer now to use the Metabones 1x Smart adapter with Canon 8-15mm over the 0.71x speedbooster. The angle of view at 8mm is like the Zuiko 8mm fisheye (Subjectively, I cannot see a difference in image quality between the Zuiko 8mm and the Canon 8-15mm when used at 8mm either with the DP170 or the Nauticam 140mm minidome), but when you zoom out to 15mm the diagonal angle is approx. 85 degree, similar to a rectilinear lens at 12mm. While the 34.7mm extension works as it is with the 0.71x speedbooster, using the 1x adapter requires a 3D printed extension collar for the Nauticam Zoomgear - in case you want to use it, I will send you the files (for 1x adapter and also 1x adapter plus 1.4x Kenko teleconverter).
I regard this the perfect WA solution for MFT camera, but of course this is a matter of taste and people have different preferences.
I have tested the 30mm extension form Unterwassercamera.at with the Zuiko 8mm and was very satisfied (Actually this extension was custom made for me by Manfred Werner, the owner of this shop). I did not test the Nauticam 34.7mm extension with Zuiko 8mm underwater yet, because the Canon 8-15mm became my favorite WA lens and I did not use the Zuiko 8mm (and also the rectilinear Pana 7-14mm that I used quite often) since then (but above the water there is no vignetting - difficult to imagine how vignetting would be produced upon submerging...).
I do not have much experience with split shots so far, so cannot comment this issue. I guess whether rectilinear or fisheye is also a matter of personal preferences and the situation...
P.S.: I have a used Tokina 10-17mm for sale at a good price, extension collars for Zoomgear for using with 34.7mm extension and Metabones 1x on MFT camera are included: http://wetpixel.com/...topic=62911&hl=
Edited by Architeuthis, 15 May 2019 - 12:23 AM.