The C-Sonnar is sharper at the edges, has less field-curvature. The J-3+ will focus to 0.7m, the C-Sonnar to 0.9m.
This is my Jupiter-3+, wide-open on the M8. Between 0.7m close focus and the crop factor- it is a great combo. I have two of these lenses. I like it- the choice of material and construction is the best of any J-3 or original LTM Zeiss Sonnar I've seen.
Secret Garden, Occoquan by fiftyonepointsix, on Flickr
I bought one, might have been the first in the US- SN 200. I did a write-up about it, the company has it on their website. Didn't know I was an expert till they told me so...
https://www.lomography.com/magazine...-of-the-new-jupiter-3-plus-with-brian-sweeney
The J-3 and CZJ 5cm F1.5 Sonnar: My Favorite.
Jupiters by fiftyonepointsix, on Flickr
Eight is Enough by fiftyonepointsix, on Flickr
Full Disclosure: I'm a sucker for a Sonnar.
This is my Jupiter-3+, wide-open on the M8. Between 0.7m close focus and the crop factor- it is a great combo. I have two of these lenses. I like it- the choice of material and construction is the best of any J-3 or original LTM Zeiss Sonnar I've seen.

I bought one, might have been the first in the US- SN 200. I did a write-up about it, the company has it on their website. Didn't know I was an expert till they told me so...
https://www.lomography.com/magazine...-of-the-new-jupiter-3-plus-with-brian-sweeney
The J-3 and CZJ 5cm F1.5 Sonnar: My Favorite.


Full Disclosure: I'm a sucker for a Sonnar.