Of course, I can read the specs and I understand that there are physical differences and the T-stop vs F-stop thing and round(er) iris

I have (for example) an 18mm Zeiss prime that I use on my 5D mk I (stills only) as well as on my EF mount video cams. I love the lens and am thinking of adding a couple of more focal lengths. But since I wind up using it more for video than for stills I do think about getting one of the compact video primes - at least until I think about the price difference!

So what I'm trying to understand is what advantage (if any) in optical performance/picture quality I'd see for the extra $$$. Or is it all about usability (like more precise focus pulling) rather than optical performance?

(I'm thinking of upgrading to the new 5D with a 50MP sensor and have been thinking about getting one of the Zeiss OTUS lenses with it so I'm really thinking hard about the whole lens thing right now)

Thanks

You won't notice much difference optically between the stills version and the Compact Primes. it's the mechanics that cost the money, with the stretched focus scales etc.

This article goes into the differences. https://matthewduclos.wordpress.com/2011/11/02/cp2vszf2/

Which you go for would depend on how you work, although I'm not sure the cost of the CPs for use with a 5D makes much sense, there are better cameras for shooting video which perhaps should be considered before buying these lenses.

Thanks for the link. It was pretty well written.

In addition to the 5D I also have a C-100 and a BMCC (and a couple of BMPCC's with Metabones EF Speed Boosters) and I use pretty much all my lenses on all the cameras. so I was thinking primarily of using the CP for video but after reading the article I think I'll stick with stills lenses. The new Zeiss OTUS lenses are optically amazing and still less expensive than the CP's, but I think overkill unless I do go for the 50MP Canon.