Zeiss c/y 50mm 1.7 won't reach infinity

[dust'n the callipygous]

Just like it sounds. Tried it on two 5Ds and a 7D. I'm using a cheap eBay adapter from big_is, which is supposed to work fine. When set to infinity, focus is actually around 20ft. Any ideas?

 

[Kholi]

it's your adapter. Trust.

 

[Kin Lau]

The adapter is too thick. Try another one... cheap adapters sometimes have QC problems and you only need to be off by fractions of a mm.

 

[dust'n the callipygous]

That was my suspicion. Guess I'll be ordering a new one.

 

[thekreative]

I couldn't believe I hadn't tested my 50mm at infinity until I had a paying gig that needed it. Everyone should double-check to make sure they have the right thickness before it bites them.

 

[Samuel H]

out of 11 vintage lenses I have bought, 3 were wrongly assembled and could not focus at infinity, even using the same adapters that allow me to focus at infinity with my other lenses (another 2 had other serious issues)

and when a lens is not correctly assembled, you lose more than infinity focus: it becomes softer, and bokeh can also get uglier:
http://www.similaar.com/foto/lenstests/lenstestsc.html

also: I haven't had better luck on reputable sellers than on ebay; I had to send back to the reputable seller my elmarit-R 180mm f/2.8, and it came home again wrongly assembled (I reassembled it myself, just as I have done with all the other problematic ones, and it's working perfectly now, but this one was real tough)

 

[Gene Sung]

Are you sure it doesn't focus to infinity? Or do you mean, infinity does not fall on the infinity mark? Those are 2 different things. I have a set of Zeiss ZFs 50mm and 85mm in Nikon Mount. I use a Fotodiox Pro adopter $85. It focuses to infinity, but comes a few millimeters before the infinity mark. The guy at Fotodiox explained that they have to do that because there are so many Nikon mount lenses that the only way to insure that it can achieve Infinity Focus is if it fall a few millimeters before the mark.

That is a disadvantage of using adapters. I have yet to find an adapter for any lens where infinity fell exactly on the mark. DigLloyd, the guy who runs the Zeiss lens test website (and trust me, he would know), says that the best adapter and the one that falls nearest to the infinity mark are the adapters sold by Camera Quest. But they are really expensive, about $200 or so.

 

[Samuel H]

what I was talking about is "can't focus at infinity, no matter how much you play with the focus ring" (the farthest they could get was usually somewhere around 20-30m) (the 180mm couldn't take a sharp picture of the moon even at f/16: it fell out of the DoF)