UKC

I bought a Yashica Electro-AX yesterday, with a Yashinon-DS 50mm f/1.7 lens.
One of the odd things about this camera (certainly to someone like me, more accustomed to slightly more modern cameras) is that it doesn't have an auto-diaphragm mechanism, i.e. when you stop down the lens, that's what you see through the viewfinder - the f/8 image or whatever. Fine. Except there is a facility to quickly open up the aperture (it's kind of like a reverse of a DOF preview) - you hold a button and it opens to f/1.7 to aid composing and focusing, then let go again in order to shoot. However, the blades must be a bit clogged because this action is really slow. Odd, because changing the actualy aperture using the ring, is quite smooth (indeed in practice maybe I'll just fully open it up and reclose, rather than going for the one-button click.

However it to me to wondering - how do you clean aperture blades? I've never had to, indeed I've never dismantled a lens. I see three tiny screws near the aperture ring, they're the only visible screws so I guess that's my starting point. Happy to give it a go.

Waiting for the battery to arrive in the post anyway so this'll while away the waiting time

In reply to Blue Straggler:

How long since it has been used, if a long time it may just be sticky. Use the button several times to see if it frees up.

Also run through the shutter speeds several times. They may be running slow as well. When you put a film in it, use all combinations of shutter speed and apertures to see if anything is fast or slow, shooting the same subject like a test card or newspaper or scene with no moving things on a tripod.

In reply to sutty:

Thanks sutty. That's my usual procedure with new-old acquisitions. As I said, turning the aperture ring opens and closes the aperture cleanly enough, the button opens it slowly. I can't test the shutter speeds until the battery arrives - it seems that without the battery (£9! from smallbattery.company.org.uk), it sticks on one speed (the manual I got from the butkus.org site doesn't say anything about this), even on Bulb mode! I have some cheap colour neg film that I use as test rolls.
The camera body looks clean and well looked after apart from the lever on the self-timer has snapped off (no big deal, I never use self-timers)

In reply to Blue Straggler:

It sounds like the stickiness could be in the button-spring mechanism rather than the iris or iris springs themself. I've taken the back off a Praktica lens before and the first point of access didn't disturb the lens cluster or anything critical, so (on your own head...) you could try opening up the back and seeing what's in there.

In reply to Blue Straggler:

http://www.maplin.co.uk/Search.aspx?criteria=switch%20cleaner&source=15

This page may have some useful information for you, save links you like;
http://www.google.co.uk/search?hl=en&q=cleaning+camera+leaf+shutter+bla...

In reply to Blue Straggler:

I once cleaned an old lens where the blades had stuck because oil from the zoom mechanism had clogged them... I only could shoot wide-open, as the spring wasn't strong enough to close the aperture when closed.

I just carefully opened the lens from the back and removed everything piece-by-piece until I got to the aperture thing itself, took it apart and cleaned the blades with pure ethanol (methylated spirits work too). Put everything back together, and it works again.
It was a lot easier than I thought, it took me a few hours and I literally knew absolutely nothing about lenses at the time. The people in the camera shop told me that it wasn't really worth it to repair it, so I didn't really had anything to lose.

My dad saw the mess half-way and didn't believe that I'd ever get it back together.
(there's only one flaw now, I managed to send the little steel ball (<0.2mm diameter) that makes the aperture ring go 'click' across my room in some corner, so now I have a perfectly smooth aperture- and I think I left a fingerprint on one of the elements, but that could have been avoided by wearing gloves...)

In reply to Arjen:

Thanks. I'll wait for the battery to arrive and see if this is even going to be a problem. Because of the way this camera works, I won't be restricted to shooting at a given aperture like you were - my only disadvantage would be that it might be a dark view in the viewfinder when I'm stopped down. however I mostly shoot wide open anyway! I'll have the "problem" with all my other M42 lenses anyway as they don't have the coupling, so maybe I should just get used to it? (I intend to use this camera mostly with my Zeiss 50mm f/2.8 anyway)

thanks again sutty, and thanks John