The 35mm Summicron Asph. is of course the cats meow but as has been previously stated don't discount the Summaron (2.8 or even 3.5) under the right conditions it has pretty much the Summicron look and is a lot cheaper to buy.
I just purchased a used Carl Zeiss 35/2 Biogon ZM T*. I figure the extra stop of speed could be beneficial if it's my only lens. I've heard reports of the f/2 being slightly soft wide open, but to me getting the shot and it being a little soft is better than not being able to get the shot at all.
Now you have to go make pictures.
Put all the opinions out of your mind. You have an excellent lens and don't need to be curious about other opinions.
Enjoy the lens and don't fret the details.
Thanks so much guys. I'm excited! I should have the camera and lens next week. I was just metering some scenes around the house, one of my girlfriend in the living room with one lamp on, not very bright. Reading with simply the reflected light from the lamp onto her I got 1/30 at f/2 at ISO 1600. Perfect! Hopefully that extra stop will be worth it!
I'm pretty sure you'll like the lens. My only quibble with it is the size, but it's worth it for the speed I think.
I couldn't decide between the 2.8 and 2.0 Biogons so I purchased both and shot with them for a while. I decided to keep the 2.0, but that 2.8C is a fine and small lens. The 2.0 does intrude into the 35mm framelines on the Ikon, but I actually had to go and check to be sure; it's quite minor.
Anyway I wanted to share a few comparison shots for you, but you already went and bought one. :-) Perhaps someone else will find them of interest. These images are bigger than I remember so sorry for the size. I shot these last year as I was deciding between lenses. Both lenses performed well for casual photography but I wanted to see if a noticeable difference would emerge if I (for once) used a tripod and took identical photos. The first two are at f2.8 and the last two are with the Biogon 2.0 exposed at f5.6.
I scanned them on a Nikon Coolscan - this one is a full size crop of the one above.
Enjoy your new lens!
I think you made the right choice Brian. If I am not mistaken, the f/2 Biogon has less distortion than the f/2.8. It really is a great lens.
One last shot, showing the 2.8 attached to the camera and the 2.0 next to it. Not a small lens (it's bigger than my 50mm 1.5 Sonnar) but I quickly got used to the size. The filter and caps make the 2.0 look bigger in this image than it is.