I use the megadap etz pro with no issues except for the shadow wavelike banding, which is caused by the filter. Megadap does not respond to this. yet otherwise great, no optical problems. Sigma Art 14mm f/1.4 superb with it (astro)...
Really? This here suggests pretty severe problems in the corners when adapting that lens:
https://photographylife.com/reviews/sigma-14mm-f-1-4-dg-dn-art/2
well they are wrong. I am an astrophotographer and the 14mm is the best wide angle I have used and seen. superb at f/1.4. Coma etc are at f/1.4 the same like with the nikon 14-24 G lens at f/4.
Could be sample variation too. My first 14mm was trash in one corner, star trails looked like they were drawn with a highlighter. Second was uniform across corners but still not amazing.
Possible, but rather unlikely, especially as it is likely to have at least comparable problems on the native filter stack when decentered.
Then the problems came from the lens, but photographylife clearly shows that the problem only occurs when adapting to the Z-mount and not natively.
The same thing happened in the review of the 14/1.8 GM, only worse, heavy Coma problems in the corners only when adapting.
So that doesn't speak for sample variation.
The problem of different filter stacks is nothing new.
With the Sony FE 14/.8 GM, the problem is even more serious when adapting to Nikon Z and such demanding scenarios as astro in the outermost peripheral areas.
https://photographylife.com/reviews/sony-fe-14mm-f-1-8-gm/2
There are also clear user reports on the Sony FE 20mm f/1.8 G when adapted to Z.
https://www.fredmiranda.com/forum/topic/1845120/
Philipreeve.net has also addressed this topic, and here too there are clear differences depending on the filter stack, not only when adapting M-mount to Sony E or Nikon Z, the main topic of the article, but also when adapting E-mount to Z-mount.
https://phillipreeve.net/blog/diffe...mean-for-us-sony-e-nikon-z-leica-m-kolari-ut/
https://www.lensrentals.com/blog/2014/06/the-glass-in-the-path-sensor-stacks-and-adapted-lenses/
For me it makes more sense that the reviewers who take the trouble to make such comparisons simply look much more closely than the normal user who of course prefers to classify his expensive G-Master on his Z-body as absolutely flawless.
Especially since it is rarely as obvious as with such astro shots wide open in the outermost corner areas and this filter stack topic seems to be particularly problematic in the wide-angle/super-wide-angle range with deep rear elements.
In practice it is usually much more subtle and only becomes really obvious in corresponding torture scenarios.
The basic problem as such does exist and has now been documented several times.
It's just that few people make the effort to carry out such comparisons.
For me, the work that sites like photographylife, phillipreeve or the Lens rental blog do on the subject of filter stack problems is more convincing than a "Well they are wrong."