Pls help me fix my SMC-M 28mm f3.5

pswoods · 06-10-2008, 07:35 AM

I got this lens pretty cheap, but the diaphragm blades are too slow to use any aperture other than wide open.

I got a book from the library called camera maintenance and repair, which has a tiny bit of info about cleaning blades. I have run into two problems so far.

I don't understand how to remove the front of the lens.

The screwdrivers I got from the hardware store are softer than the screws in the back of the lens, and I am mangling both the screw heads and the screwdrivers trying to get the screws loose.

Does anyone know where I can find:

A link to pictorial info on taking the front of the lens apart
Good screwdrivers that will grab onto the screws so I can get them loose

Any other links/bibliography/advice? I want to do this myself, even if it ends up being a learning experience that hacks the lens to death but gives me enough understanding to do it right next time.

pswoods · 06-10-2008, 10:11 AM

Okay I made the repair - basically just remove glass and dump naphtha on the blades. Works great now. I have one problem remaining.

I did the repair on the same workbench where I do messy things - woodworking and guitar repairs - and I lost a ball bearing and a screw. I found a replacement ball bearing at the local hardware store, but where do you get those tiiiiny screws? It is the one that holds the thing I can only describe as a dust cover - it is the smallest of the tiny screws. I doubt it has any possible impact on IQ - just want to get back to right.

little laker · 06-10-2008, 10:53 AM

Does this screw hold the usually Black plastic ring at the back of the camera? They usually have 3 tiny little screws holding them on.

If so that piece Then I can yell you that Vivitar just glued that plastic piece in instead of screwing it on.

So that's all that I'd do, although I'd be very careful while gluing it.

I do have some of those screws around here somewhere, I just don't know where at the moment.
But if your in a bind, and living in Canada I'll just get you to mail me a self addressed, stamped envelope. And I'll mail you a couple.

I'm sure that you've learned your lesson on working on lenses in a clean area.
I often use the lid off those large rubbermaid storage containers to keep everything clean and in order, and just work on the kitchen table, or off a clean floor.

The same goes when I'm doing any servicing on my camera, including cleaning the sensor.

pswoods · 06-10-2008, 11:34 AM

Originally posted by little laker

Does this screw hold the usually Black plastic ring at the back of the camera? They usually have 3 tiny little screws holding them on.

If so that piece Then I can yell you that Vivitar just glued that plastic piece in instead of screwing it on.

That's good to know. I figured it wasn't a very important piece, as I can't see it doing anything but repelling dust/debris. I think I will just leave it as it is - I'm only missing one screw, so I'm just going to not worry about it.

Thanks so much for the offer to help.

06-10-2008, 07:35 AM	#1
pswoods New Member Join Date: Mar 2008 Photos: Gallery Posts: 12	Pls help me fix my SMC-M 28mm f3.5 I got this lens pretty cheap, but the diaphragm blades are too slow to use any aperture other than wide open. I got a book from the library called camera maintenance and repair, which has a tiny bit of info about cleaning blades. I have run into two problems so far. I don't understand how to remove the front of the lens. The screwdrivers I got from the hardware store are softer than the screws in the back of the lens, and I am mangling both the screw heads and the screwdrivers trying to get the screws loose. Does anyone know where I can find: A link to pictorial info on taking the front of the lens apart Good screwdrivers that will grab onto the screws so I can get them loose Any other links/bibliography/advice? I want to do this myself, even if it ends up being a learning experience that hacks the lens to death but gives me enough understanding to do it right next time.

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06-10-2008, 10:11 AM	#2
pswoods New Member Join Date: Mar 2008 Photos: Gallery Posts: 12 Original Poster	Okay I made the repair - basically just remove glass and dump naphtha on the blades. Works great now. I have one problem remaining. I did the repair on the same workbench where I do messy things - woodworking and guitar repairs - and I lost a ball bearing and a screw. I found a replacement ball bearing at the local hardware store, but where do you get those tiiiiny screws? It is the one that holds the thing I can only describe as a dust cover - it is the smallest of the tiny screws. I doubt it has any possible impact on IQ - just want to get back to right.

06-10-2008, 10:53 AM	#3
little laker Veteran Member Join Date: Sep 2006 Photos: Gallery Posts: 5,697	Does this screw hold the usually Black plastic ring at the back of the camera? They usually have 3 tiny little screws holding them on. If so that piece Then I can yell you that Vivitar just glued that plastic piece in instead of screwing it on. So that's all that I'd do, although I'd be very careful while gluing it. I do have some of those screws around here somewhere, I just don't know where at the moment. But if your in a bind, and living in Canada I'll just get you to mail me a self addressed, stamped envelope. And I'll mail you a couple. I'm sure that you've learned your lesson on working on lenses in a clean area. I often use the lid off those large rubbermaid storage containers to keep everything clean and in order, and just work on the kitchen table, or off a clean floor. The same goes when I'm doing any servicing on my camera, including cleaning the sensor.

06-10-2008, 11:34 AM	#4
pswoods New Member Join Date: Mar 2008 Photos: Gallery Posts: 12 Original Poster	Originally posted by little laker Does this screw hold the usually Black plastic ring at the back of the camera? They usually have 3 tiny little screws holding them on. If so that piece Then I can yell you that Vivitar just glued that plastic piece in instead of screwing it on. That's good to know. I figured it wasn't a very important piece, as I can't see it doing anything but repelling dust/debris. I think I will just leave it as it is - I'm only missing one screw, so I'm just going to not worry about it. Thanks so much for the offer to help.