a setting on an A50mm f/1.7

Hi,

I recently picked up an ME Super, partially because I wanted to play with film and partially because it came with an A-50mm lens and I was planning to swap it for the M-50mm I currently use with my K20D. It turns out that while the aperture ring will turn to the A setting (on both cameras) if you push down the little button, it doesn't stay there. The button doesn't pop back up to lock it into A mode like on other lenses, and the K20D doesn't recognise it as being in A mode.

Is this normal? Am I missing some trick? Or is there something wrong with the lens?

Thanks!

You're not missing anything, it should work like other lenses as you describe. It sounds like there's something wrong with this lens unfortunately.

Bad luck!

My 50mmA 1.7 does the same thing. I believe it was forced at some time and the locking pin broken off inside.
Does it rattle when you shake it:

Unfortunately the 50mm A 1.7 does have a history of aperture ring problems

Doesn't particulaly bother me though.

Yes, it does rattle... that's probably a bad sign

Any idea if this sort of thing is repairable, or would it cost me more than the lens is worth?

Yes, I've seen this as well.
The repair is quite easy, but becarefull putting the lens back together again, because of the small parts for the contact pin and the tiny sphere for the aperture clicks.
The problem is the build quality of the SMC-A F1.7 is abismal compared to the F1.4. A small piece of metal that acts like a spring is attached to the lens body by a bit of melted plastic, this tends to brake easily... I've seen people use plastic as well as super glue to fix it. Its quick and easy

I have just re-read your post and you say your K20 doesn't recognise the A position. Mine does, so I suspect it may be a little more serious.

I wouldn't think it to be a viable option to get it repaired, probably cost more than its worth.

I would have a go at it myself if you are mechanically minded.

Heres an exploded view of the lens. If you want the full sized version, PM me your e-mail address and I will send it to you.

[IMG]http://i184.photobucket.com/albums/x261/ClarkyinAus/50mmlensillustration.jpg[/IMG]

You can see the pin here which locks it into the A position.
[IMG]http://i184.photobucket.com/albums/x261/ClarkyinAus/50mmA17.jpg[/IMG]

I am pretty mechanically minded, but I must admit that I find that diagram a bit daunting!

So I would basically open up the back of the lens as far as the aperture ring, find part X510 which is probably floating around loose in there, and superglue it back onto the ring?

Edumad -- is your caution to be careful about losing the small parts? Or that they're difficult to get into place because of the size?

Thanks!

That diagram scares the bejesus out of me!

Both!

I always work over a large cake tin so if anything drops out it'll get caught (if a 1mm ball bearing meets carpet you'll never see it again).

And you'll certainly need nimble fingers (and good tweezers) to get everything back into place. Tricky sometimes but certainly not impossible.

Tigerita - give Harrow Technical a call - they give a guide price of £35.50 for repairs to small primes (and an indication of a discount for PU members ).

I've just sent 2 recent acquisitions with fungus to them for cleaning and have used them for repairs to an LX (major rebuild - new shutter blind - didn't tell SWLTBO what it cost and it's still my most expensive camera in my (expanding) collection) and an *ist (sticky shutter).

Robin's very helpful - well worth a call


Steve

For someone as talented as Hefty, he would have that lens back together before morning tea.

Of course you wouldn't have to disassemble it down to the last screw, but the diagram will give you an idea of what you will need to do.

I reckon it will be a fun project to take on good for those cold rainy days when you are stuck in the house.

Hi Clarky, thanks for posting that illustration. I also have a copy of that lens. Does part X510 have anything fitted in the tiny hole on the inside of it? At the moment I use the lens as an "M" with F ratio limited to range of 1.7 to 9.5 which is OK. Optics are excellent.
cheers
bb2

i would also use magnets if you have them, they are very handy to keep every bit and piece where you can see them. If you have a magnetic screwdriver that very usefull as well.
I'd say I enjoy this dismantling of things, ever since in childhood I opened up almost all my motorized toys. But I too jittery (is that correct), so even with tweezers its hard for me to handle those small parts.

I've gone so far as to do some work inside a light box, so that any parts flying of (there is a ~ 1x4mm spring in there) are trapped. I've been burnt before...

My A1.7 has the same problem - though not quite as bad in that I can get the "A" button to lock if I persist

Try this:http://homepage.mac.com/jpelling/index.html