Stuck Aperture Blades

[randerson07]

The aperture blades in my 55mm 1.8 Petri lens have stuck at around f11. When going down to f/16 the blades move, then back to 11 they move but after that they stick.

Once I have this lens apart what is the procedure for unsticking? I can see some sort of lube on the blades themselves do I need more? is there a particular lube that works well?

thanks in advance
Ryan

 

[KD5NRH]

You need less, if you can actually see it there. Google "sticky aperture blades" and you'll see some articles on it. You might get temporary relief from running it on continuous drive at f/22 for a few seconds, but you'll eventually need to get that cleaned up. I've got a sticky Sigma that gets a little better each time I do the "dry run," but it doesn't have any oil showing on the blades.

I've thought about experimenting with some of the high-tech non-gumming lubes, but I'll have to find a cheap lens that I don't care too much about first. The trick to relubing them would be first cleaning all the old lube off, then gettting an even and extremely light coat of whatever on there. AFAICT, most folks settle for cleaning them, which unless you're soaking them in acetone or something, probably leaves about the right amount of lube behind.

 

[Overkill-F1]

KD5NRH, I'm quessing that you are kidding when you mentioned acetone. It will soften or eat most paints.
...Terry

 

[KD5NRH]

KD5NRH, I'm quessing that you are kidding when you mentioned acetone. It will soften or eat most paints.

Well, some people will try to clean anything with anything, but yeah, I'd stick to denatured alcohol for pretty much any cleaning inside optics. I'd hate to see what a stray drop of acetone would do to the various glues and sealers in some lenses.

 

[Mitica100]

The aperture blades in my 55mm 1.8 Petri lens have stuck at around f11. When going down to f/16 the blades move, then back to 11 they move but after that they stick.

Once I have this lens apart what is the procedure for unsticking? I can see some sort of lube on the blades themselves do I need more? is there a particular lube that works well?

thanks in advance
Ryan

Ryan, if you manage to take the lens cells apart and have the aperture blades in the open, I would get some Naphta or Ronsonol, dip a piece of microfiber in it, squeeze the excess and start wiping veeeeeery gently untill all of the oil comes off from the aperture blades. No lens in this world has been made to function with lubrication on its aperture, someone goofed and added that so the lens 'functions' better. Unfortunately, it doesn't. It makes the blades stick more.

Note: You might have to spend a few good hours at this until you are going to see a noticeable difference. Be patient...

 

[randerson07]

Im going to give it a go this weekend, when I have time to sit down for a while and get it done.

Ive got two 55mm lens so at least I can still use the camera.

Thanks for the help guys.

 

[yellowjeep]

I had the same problem with my S2. It really was alot simpler than I thought. Like Mitica said, use lighter fluid with naphtha. When I did mine I let a little fluid sit on the blades for a minute or two. Then I set it on the widest aperture, and very (very very) gently applied pressure to blades until they snapped open and out of the way. Then I repeated the process again. Then I left it alone over night with the lens apart to let the naphtha evaporate. It works great now.

IMO cleaning the blades was easier than redoing the light seals.