[namron]

Hi,

I recently got an old Rikenon P 50mm 1:1.7 from ebay. It had a little dust on one of the inside lenses.

Easy enough, I thought, let's watch some youtube videos on how to clean these old 50mm lenses. Unfortunately the closest I could find was for a Pentax 50mm 1.7.

I tried to take it apart anyway. Bad decision.

I managed to dissemble theaperture which I hope to have put together correctly, still it dosn't open completely (see picture, but I can't remember if it did before).
And I got a little spring left, which I think connects the inner ring of the aperture ring to the automatic aperture. Right now I can move the aperture only by moving the little lever you see at the 12 oclock position. I also don't know how to reattach the ring in the background which seems to be for the auto aperture.

Right now I'm at my wits end. Please bear with my. I think I learned my lesson from this.

Has anyone here disasembled one of these lenses before or could provide a schematic?

Any advice is very welcome.

Regards,

Norman

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[pschlute]

The pointy end should be going under the next blade, not over it

....and that is why the blades are not closing properly. Been there before, but not with your specific lens I am afraid.

[namron]

Thank you!

After rearranging the blades the aperture did open completely again. I then figured I could fine adjust how far it can be opened and closed with the screws it is held together and connected to the body of the lens with.

The spring was for the countertension of the upper ring which the lever, that protrudes out of the back, for the camera to operate, is part of.

I got it all back together, no peaces left over and it works.

It only doesn't snap in at the widest aperture setting, but that is a thing I can live with.

Thanks again for the quick and helpful answers.

[YamanoteE235]

You are brave. I have a Pentax 165mm for my 6x7 that I want to take apart to clean some fungus out of but I'm afraid I won't be able to get it back together. I've already tried setting it out in direct sunlight but I don't think that has helped at all.

[MysteryOnion]

I see one blade looks buckled?
If so, you may want to flatten it or it will interfere with the functioning.

If you have blue or white painter's tape, it can help with the reassembly of the blades.
If the surface is still very oily, then never mind.