QBM or C/Y Carl Zeiss Sonnar 80mm f/2.8

[caspert79]

The QBM mount and C/Y mount Sonnar 80/2.8's have different lens schemes. Any reason to chose one over the other?

[pabeu]

I guess you are talking about the 85s instead of 80.
The C/Y has an additional fifth element in the back group. From what I have read, this is for better aberration correction and corner performance.

So far I have used the QBM one on APC and it is very sharp with pleasent rendering.
Not sure if the C/Y premium is worth the extra price (they usially go for a little bit more).

The contax G 90 might be in the middle if you can live with the slightly worse haptics the fancy adapter brings.

[caspert79]

Oops, yes I mean 85mm.

I think I’d probably prefer the 85/2.8 over the 90mm for exactly the reason you mention.

[kiddo]

i dunno why, but for some reason the 85mm FL is just harder to get for good money and the fastest ones like 1.4 reach same amount (or more) as ZF or ZE mount (same aperture).

[papasito]

I use my 85/2,8 QBM with my Sony FF and it's really sharp, with nice colors and contrast.
If you can be happy with the F/2,8, I tell you, go for it.
MFD is 85 cm. Nothing special but average. I think you can live with that.
The CA is very thin wide open. I did not find any at f/4. So it's CAlo. Easy to fix anyway.
It's a little and light lens.
I compared it with the Sony 85/1,8 FE mount. The last is faster and so sharp. More contrast perhaps. But a bit more STRONG CA.

I used only one day the sonnar c/y. When I had a Sony aps-c. So I can't say anything about the corner rendering in FF.

My two cents for the QBM.

[pabeu]

There is a Rolleinar version with HFT coatings that is said to be the same as the CZ in QBM mount.

[papasito]