Diglloyd also compared the two lenses and his findings are somewhat different, but he sees the Sigma as a reference for some types of photography.
The Sigma would be the choice for weddings, etc., with a lot of action and moments to be captured, due to its AF.
The Zeiss would be the choice for nature and perhaps model-like portraiture, where you have time to compose (esp. nature when you can compose in Live View).
I don't like the way Diglloyd tested compared to Dustin Abbot. I believe testing at the different ranges (close, mid, and far), and providing the Lightroom examples
by video was more helpful than using still photos and written opinions.
Not just 'discussing,' but
showing the difference between 'sharpness' and
micro-contrast was also quite helpful in understanding the enormous advantage of the Zeiss.
Upclose the Zeiss is better. Both are outstanding.
Yes, up-close, they're not even in the same league.
Farther away, the Zeiss still has far better micro-detail, but the vignetting hurts it (wide-open). I thought the Sigma looked better in the corners, but not in the same league as far as micro-contrast. Still, I would never shoot a long-range shot at f/2; any landscape-type shot would typically be shot at f/8 or so, where the vignetting isn't a problem. I found the Zeiss best at f/4 up close, where it still handily trounces the Sigma in micro-contrast and color detail.
Again, I think differentiating between 'global sharpness" and micro-contrast was helpful in understanding the difference between the two.
I always thought the 85 mm was the easiest lens to produce into perfection but now it seems to be the 135mm.
My first 135 mm lens was a nikkor Ai 135mm f3.5 and it was really soft.
Both lenses are far from perfect IMO, though I believe the Zeiss is closer to perfection.
The Zeiss has a 1:4 reproduction ratio; the Sigma a 1:5 ratio.
If they had a 1:1 reproduction ratio, they'd be perfect (for me).
Both are weak in the min. focus distance department: the Zeiss 2.62' (80 cm); the Sigma 2.87' (87.5 cm).
If they had a 9-12" min. focus distance, they'd be perfect.
The Zeiss would be anyway. I don't think the Sigma is anywhere near as close to perfection.