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View Full Version : What to think of edge separation of old Petzval lens?



erian
24-Oct-2019, 19:12
Should I be concerned when it is on the rear lens?

paulbarden
24-Oct-2019, 19:51
Should I be concerned when it is on the rear lens?

It depends on how severe it is, and how far into the center of the lens it goes. Balsam separation can be pretty severe and yet not affect image quality very much.

Steven Tribe
25-Oct-2019, 09:53
Should I be concerned when it is on the rear lens?

Yes,you should be very concerned!

The rear lens cell contains two separate lenses, neither of which is an achromat.

Your lens is either not a Petzval or the front and rear cells have been swapped around.

Minor breakdown around the edges is of no consequence.

erian
26-Oct-2019, 05:02
Yes,you should be very concerned!

The rear lens cell contains two separate lenses, neither of which is an achromat.

Your lens is either not a Petzval or the front and rear cells have been swapped around.

Minor breakdown around the edges is of no consequence.

Good point. Fortunately not my lens, just an offer. I think that I got confused by the orientation of the pictures and it is indeed the front lens that has separation.