lubricate iris

[mylek]

Hello,

is there a way to loosen an old iris on a Petzval lens?
Is dry graphite a good way of dealing with this sticky iris.

Regards!

[Sevo]

First of all, clean it, or better yet, have it cleaned, as that will mean complete dis- and reassembly. Adding anything more to the goo that makes them stick will not improve matters.

Dry lubricants have the advantage of no creep, but they shed dust. If the blades are in a good shape, they may need no lubrication. If they do, I'd go with minimal amounts of a surface adhesive PTFE lubricant rather than with graphite.

[alex from holland]

Most of the time it aren't the blades itself but only the aparture ring.
Try to use only a few drops of siliconspray on the outside of the lens at that ring.
ONLY A FEW DROPS. I got several lenses working again that way.
On the blades itsl i only use very little graphite powder.

[John Koehrer]

First of all, clean it, or better yet, have it cleaned, as that will mean complete dis- and reassembly. Adding anything more to the goo that makes them stick will not improve matters.

Dry lubricants have the advantage of no creep, but they shed dust. If the blades are in a good shape, they may need no lubrication. If they do, I'd go with minimal amounts of a surface adhesive PTFE lubricant rather than with graphite.

What he said. blades should be dry. Any old lube will be on the aperture ring but normally there's no lube used there.
Stay away from powdered lubricants too.