Quote Originally Posted by Claire Senft
... The only reservation I would have with the collaspible model would be to see that it is still accurately focussing. Although I have not experienced myself I have read that they can need maintenance to have correct focus. Try focussing on a near object and exposing at f2 to see if the point of focus on the negative agrees with the point chosen...
Correct me if I am wrong, but I do not think that I need to check the negative to find out if the lens focuses correctly.

Let's say I measure the distance between the camera and the object. If this is the same as the number indicated on the focusing ring of the lens, then I think that no maintenance is necessary.