Cleaning Aperture Blades

[DraganB]

Hi Friends,

I would like to clean the Aperture Blades of this Dagor, does anybody know what Material this is and how to clean it?

 

[loccdor]

I think it's tempered blued steel (oxide coating). Naphtha has been what I've seen popularly used to clean them.

 

[DraganB]

I think it's tempered blued steel (oxide coating). Naphtha has been what I've seen popularly used to clean them.

Thanks, that would be good, hope its not paper.

 

[Harry Callahan]

It doesn`t look like paper to me, there are too many shiny/metalish spots on the blades - but if you open the lens you should be able to see what material they are made of.
This aside the opening of the aperture is not round. It looks like some blades sprung out of their mount...

 

[F4U]

Stop down the aperture with the glass removed. Hold the shutter up to a strong light. If it not metal, you will likely see faint light passing through the iris blades. Gentle swabbing with Q tip and 90+ % isopropyl ordinarily won't hurt rubber or paper iris leaves or metal ones. No acetone or MEK and the like.

 

[film4Me]

As a matter of interest, these 1909 Kodak shutter blades and the shutter's aperture blades are non metallic. Filing them in an unimportant part of the blades is like filing pencil lead, only harder. So I'm assuming they are made of a compressed carbon material, possibly the same material that dark slides were made of for plate backs in that era. The blades are flexible, but I wasn't going to find out just how flexible. They flexed a little and that was enough for me. They also clean up with lighter fluid with the cotton tip turning black, until all gunk is removed. It appears these carbon blades are very susceptible to distortion from excessive heat. The two shutter blades in the photo have circular bulges corresponding to the lens orifice in the body, presumably from the hot sunlight beating down. The red bellows of the camera also, is quite faded.

 

[Harry Callahan]

This could explain why the aperture of DraganBs lens isn`t round.

 

[F4U]

It isn't round because the blades are rubber and warped and the holes are worn. That is a very old lens and getting it to stop down nice and round is dubious. You would need to impregnate the surfaces by rubbing graphite into them. Even then they will never have a truly free action. I bet closing down the iris all the way causes it to to jam when trying to open up, or open up out of round at best. If you close it down completely I bet you have to wiggle it back and forth to get it to open without jamming. The secret to having a nice round opening is to start at the very widest opening and close down to the needed setting, Not the reverse. Never use oil. In 2025, more than a hundred years since it was made, this is a junk-grade lens. But it's still quite good if you baby it.

 

[film4Me]

The blades have pins, and if the pins dislodge from any of the blades, the opening of the aperture will become irregular. There's two pins for each blade, one is stationary, the other follows along the cam slot, and this is the one that usually dislodges. One of mine has a pin missing, it's another repair I must do, besides making new shutter blades, to completely fix the shutter. Quite often, a blade with a missing pin will still open and close due to friction alone, or there may be a burr around the hole of the missing pin, and that can be enough to "catch" the cam, and act like the pin is still there. But of course it's not, but the affected blade will be a little out of alignment, causing the aperture opening to be just that little bit out of round.

 

[F4U]

The blades have pins, and if the pins dislodge from any of the blades, the opening of the aperture will become irregular. There's two pins for each blade, one is stationary, the other follows along the cam slot, and this is the one that usually dislodges. One of mine has a pin missing, it's another repair I must do, besides making new shutter blades, to completely fix the shutter. Quite often, a blade with a missing pin will still open and close due to friction alone, or there may be a burr around the hole of the missing pin, and that can be enough to "catch" the cam, and act like the pin is still there. But of course it's not, but the affected blade will be a little out of alignment, causing the aperture opening to be just that little bit out of round.

That's one of the best answers I've seen on a forum.

 

[loccdor]

The shiny scratches the OP's len's blades have look like other metallic blades I have seen.

 

[koraks]

It isn't round because the blades are rubber and warped and the holes are worn.

The aperture doesn't seem round because the angle of incidence of the light and the shadow projected onto the white surface the lens sits on. This makes the aperture almond-shaped, but in reality, it likely isn't. I bet the actual aperture is as round as it should be.

The shiny scratches the OP's len's blades have look like other metallic blades I have seen.

Yup, looks like regular metal blades like so many.

does anybody know what Material this is and how to clean it?

I suspect there are two components to the fouling you're seeing. One is rust, the other is probably just a tiny bit of graphite that was used by means of lubrication. The graphite as such is not really an issue and can actually help. The rust is more of a problem and may not clean off with the regular naphta approach, but disassembling the aperture on a lens like this is usually not terribly difficult.

 

[nosmok]

Occasionally, after cleaning oily/dirty aperture blades with a q-tip and a small amount of 90% alcohol, I'll draw very lightly on the dry blades with a soft pencil to get some kinda lube on them that might stay put. It's not an everytime thing, and usually on larger diameter lenses.

 

[DraganB]

Hi Friends,

Thanks to everyone for the information and helpful tips regarding cleaning. I've decided to just clean the screw thread and the lenses and leave the blades alone. The lens is looking good and i am not going to risk damage and will leave it as is for now.

 

[DraganB]

The aperture doesn't seem round because the angle of incidence of the light and the shadow projected onto the white surface the lens sits on. This makes the aperture almond-shaped, but in reality, it likely isn't. I bet the actual aperture is as round as it should be.



Yup, looks like regular metal blades like so many.



I suspect there are two components to the fouling you're seeing. One is rust, the other is probably just a tiny bit of graphite that was used by means of lubrication. The graphite as such is not really an issue and can actually help. The rust is more of a problem and may not clean off with the regular naphta approach, but disassembling the aperture on a lens like this is usually not terribly difficult.

Right and very helpful, thank you much

 

[koraks]

If the aperture works and operates fairly smoothly, leaving it alone is the sensible thing to do. On modern SLRs, an aperture needs to be super smooth and quick, but on a large format lens like this one, it's OK if there's some friction. "If it ain't broken, don't fix it!"

 

[loccdor]

It looks gorgeous and clear now, good job, hope you enjoy using it.

 

[hiroko]

Just sharing, im using Automotive brake cleaner to remove the oil on the blades. I might be wrong but it works for me.

 

[jimgalli]

This stuff from Napa

https://www.napaonline.com/en/p/BK_7651322