As part of my quest to determine viability of adapting 8-15 on my Sony A1 I made a series of shots which I thought could be of interest. I would also appreciate if current owners of this setup could answer certain concerns as far as chromatic aberration .

 

Testing setup was Sony A1 + Tokina TA-019 + (Kenko Teleplus HDpro 2x) + Canon 8-15 F4  taking picture of improvised lens resolution chart setup under simple LED light. Magnifications are 300% on a 50MPix sensor with ISO of around 2000 but you can see this on screenshots. White rectangle in left corner thumbnail shows magnified position.

 

First image the full view. 15mm is at 15 without tele, 16mm is at 8mm with 2x tele

 

zoomed in 300%

 

 

 

 

 

 

 

Underwater images without teleconverter at 15mm behind 180mm glass dome with 20mm port extension - too short (would need 15mm for this test, without the extension the CA was even worse in other pictures) but good for test and also a show a problem with chromatic aberration.

 

 

 

 

 

 

 

What I would like to see if any users of 8-15  have any sort of test images with 140mm dome and proper extension which could demonstrate chromatic aberration issue or lack of it. With 180mm glass the CA is absent only at the very center and starts showing quickly towards the corners.

 

Other then CA I am happy with corners and off center sharpness and resolution and micro contrast  of adapted 8-15. Much better then WWL and perhaps WACPs, also Kenko 2x show no degradation of image whatsoever including color rendition so I think if I could tackle CA or it would show no issue in post the 8-15 with 2xKenko is great combo even for 50Mpix sensor adapted on A1. Tokina AF works flawlessly in photo mode including tracking and animal AF, also good in video mode that that has to be selected topside.

 

I switched from Kenko 2x HD to the Sony 2x TC and think the results are a tick better and also the required extension is shorter (Canon 8-15mm, Metabones V adapter, A7R5, Nauticam 140mm fisheye dome). I do not observe significant increase of CA, compared to the pure 8-15mm fisheye, when I use the 2x TC.

 

I have posted full resolution UW photos here. Canon 8-15mm with and w/o 2x Sony TC and WACP-C/Sony 28-60mm are compared (real images, no test screens):

 

https://www.dpreview.com/forums/thread/4779356

https://www.dpreview.com/forums/thread/4779452

https://www.dpreview.com/forums/thread/4779455

 

My personal judgement was that regarding sharpness/microcontrast in the center, the pure 8-15mm is better, while WACP-C/28-60 and 8-15mm/2xTC perform similar (maybe WACP-C a tick better @28mm, but a tick worse @60mm when compared to 8-15mm/2xTC). I think your test images show similar findings: the 2x TC softens the images to some extend...

All combinations loose IQ towards the edges, I was unable to find a difference, worth mentioning, between combinations in this aspect (I consider the IQ in the edges as secondary, as long as IQ there is reasonably o.k.)...

 

=> Of course the FOVs of 8-15mm/2xTC and WACP/28-60mm are only overlapping and not the same, but when I read in reviews that IQ of WACP-C and FCP-1 are similar, I have no urge to buy FCP and test it out (for sure I can make photos with 8-15mm/2x TC at apertures much wider as f/13 (f/13 appears to be the limit for FCP))...

 

=> I personally have ordered now a Sony 1.4x TC and plan to use the 1.4x by default, just to be on the safe side when IQ is concerned...

 

 

Wolfgang

 

 

Thanks for the reaction, I've spent quite some time reading yours and @DreiFish posts recently 🥵.

 

I have both Sony and Kenko 2x - unfortunately neither Tokina or MC11 accept Sony 2x so I couldn't compare.  I am not impressed with Sony 2x neither with 70-200 F4 GII or 200-600 so I think they will be same, the performance penalty is there but unless zoomed in 300% on 50Mp file one can't really notice it seems. 

 

I am more concerned with CA when using 180mm dome and would like to see uncorrected 140mm samples with contrast subjects. I didn't see any CA with 140mm dome but I did see CA with 17inch dome at @DreiFish thread which made me wonder... 

 

I wonder whether I could get satisfactory performance from 180mm dome and 8-15 w/2x to have one dome when traveling. I am quite OK with corner sharpness and micro contrast which in my opinion quite a bit surpasses that of WWL1 28-60 combo but that CA makes me wonder.

 

 

Edited January 16Jan 16 by RomiK