lens repair

[j_r6]

Hi everyone,

I am a brand new SLR photographer and have just purchased a k1000 off of ebay with the 50mm smc pentax-a lens.

 

Unfortunately the lens can only focus at about 10 feet, and turning the focus ring has no effect (though it now slips freely). Originally it slipped from infinity to about 4 ft freely, but after applying some muscle I loosened it up. I don`t think I damaged it.

 

Deciding that the repair would cost more than a replacement lens (estimates are 35$ alone), I thought I`d make a go of it myself. I was able to disassemble it, but not able to get at the focus ring. I was able to unscrew the lens housing from its case, and separate the aperature mechanisms, but that`s it. Sorry I don`t have a better terminology. So my question is how do I do it (expose the focusing mechanism to get at the ring)? I`m hoping I can crazy glue or solder it together or something.

 

Also in the process I managed to lose a bearing (extremely small ~a few mm) which I believed lay under the button that unlocks(?) the aperature ring. Can I estimate a replacement or is that just asking for it? Is it important that I replace it at all? For the time being I`ve got a completely analog f-stop setting due to this, which is kind of neat but doesn`t necessarily give me the f-stop I want.

 

I also want to know what kinds of lube I can use in the housing.

 

I have searched the net for this lens` schematics with no luck. I have called pentax who were rude, and ultimately of no use in getting replacement lens, parts, diagrams, or anything.

 

Finally -it seems like a got a problem camera!- at shutter speeds of 30, 15, 4, 2, 1 but not 8, after the shutter is depressed, and the curtain opens and closes, there is a slight bouncing noise like someone rattling the strap hinges on the front. I can`t see any problems with the lens off.

 

If anyone has any suggestions please mail me directly if you want at: nospam_jd.r@iname.com (remove the nospam_) before you send it.

 

I was also wondering if it is possible to change a lens mid-roll? Everyone tells me it is, as the film is behind the curtain, but I saw many mid-roll lens change bags advertised.

 

-Thanks.

[edsel_adams]

What gave you the idea to rip apart your lens?This isnt usually something a photographer would normally do!If you look on Ebay or elsewhere you can buy a used 50mm lens for pretty cheap!

[hkbmac]

Wow!First of all, 50mm lenses are dirt cheap. My guess is that your home fix destroyed the lens. The Pentax K1000, and most manmual Pentax bodies are noisey around 1/15th and 1/8th. the sound you are hearing is normal. There is no problem switching lenses mid roll, unless you decide to do a home overhaul of your shutter.

 

Brian

[j_r6]

Thanks for the info so far.

 

Just for the record, the lens I bought from ebay was ALREADY unable to focus, even before I touched it. That is it only focused at 10 feet.

 

So playing around with it hoping to fix seemed better than having to move around myself to focus my camera (though I might get some interesting framing I wouldn`t have otherwise thought of). Actually the lens is pretty well built and though not quite fool proof to reassemble, if you pay close attention to the markings, you`ll see there`s only one way the pieces fit back together and mesh nicely. Just take care when finally unscrewing the lens case from it`s housing, that you mark where the threads align.

 

So anyway, I really just want to know how to get at the focus ring. I`m a bit afraid to pry it apart, but then again at this point...

[bernhard]

Did you try to remove the rubber from the focussing ring, there should be some screws underneath.

[douglas_green1]

Well, I would cut you some slack. The Pentax SMC-A lens is mechanically junk. They cut costs dramatically between the SMC-M series and the SMC-A series. And you got a piece of junk because of it. Your best bet is to buy another K-mount 50mm lens 2nd hand. Ideally, find an SMC-M Pentax lens. But you might also find a decent K-mount 50mm lens from Ricoh, Sears, Vivitar, or Chinon for $10-15 on ebay or at some camera show.

 

And yes, it's fine to change lenses in mid-roll. Just don't point your camera into DIRECT sunlight while you're doing it, or you might lose 1 shot. Shutters are MOSTLY, but not 100% COMPLETELY, light tight.

[wbowman]

I recently sold a Pentax K1000 with that same "bouncing" noise you described. I can assure you that it had zero effect on the functionality of the camera.

[duane_kucheran]

AFAIK lenses were designed and built by people so I've gone on the premise that they can also be repaired by people. It takes a bit of knowledge & thought and at most you're out the cost of replacement.

 

The focussing helicoid should be driven from the external ring thru some setscrews which are probably now loose. These are accessible from under the rubber grip on the focussing ring. This link has a general description of the problem & how to fix it: http://www.kyphoto.com/classics/variouslenses.html

 

There are other useful bits of info on the site.

 

Good luck & cheers,

 

Duane

[richard_oleson]

i think the pentax lenses couple the focus ring to the barrel with 3 screws that go in from the front, under the ID ring and filter thread part.

 

that wouldn't have been too hard to fix. your main problem now is that you've disassembled some stuff that's a lot harder. if you can get the stuff you took out back in the way it was, you'll be able to tighten up the focus screws without any trouble. if not, you can replace the lens for probably about the same $35 you would have spent on a repair.

 

rick :)=

 

http://rick_oleson.tripod.com

[roger c]

Forget it - buy another s/h lens. A 35mm lens is much more versatile, if not as fast.

[stemked]

I'm not certain about the 50mm f2 lenses, but I disagree with Mr. Green about the 50mm 1.7 A and 50mm f1.4 A lenses. These lenses are far superior to the 50mm 1.4 M lenses, optically and equal mechanically. I have personally shot with all the following over the years; 50mm 1.4 SMC Super Takumar (ST) (screw mount)=50mm f1.4 K lens; 50mm f1.4 M lens; 50mm f2 A; 50mm f1.7 A; and 50mm f1.4 A and 50mm F 2.8 macro. My evaluation is not that different from what others have said and I'll pass along that web site if I can find it. The ST, 50mm f1.4 and 1.7 A and 50mm f2.8 F macro lenses are fantastic optics, the 1.7 and the macro top every other manufacture's lenses in this focal length. The M lens is the only poor performer of the lot, optically anyway. The 50mm f2 lens (which had been my first K-mount prime) isn't a bad lens either, but it isn't up to the standards of the other lenses noted. You can get the 50mm f2 for a song (I sold mine in ex++ for just $35) and the 1.7 and 1.4 A lenses typically run $50-75 and $85-120 respectively (sometimes though you can get these lenses for a 'steal' at pawn shops as nobody buys them).

[j_r6]

Hi everyone,

 

let me first just thank all of you for your input, I apologize for not giving individual responses. It`s great to find such an active group, and I look forward to asking you many more questions!

 

It seems you guys are bang on. I was a bit confused looking for the rubber ring, but finally discovered there was none! And that`s the problem. There appear to be a few shreds of one (or it might be the surrounding plastic). So what was happening is that the focus ring slid freely over nothing, that is, no grip on the helicoid via the screws -I think. So it seems someone got there first. I guess I will look for a gasket or similar ring.

 

As for the bearing problem, I guess if I can`t find a replacement I will live with it. As far as I know, this shouldn`t affect the light meter at all and only slightly throws off the dof scale on the lens which is supposedly not that accurate anyway?

 

On the matter of money, I am just a poor student and my weak Canadian dollar means a 35$ lens is really 55$ or about half the cost of the camera! I think any lens is worth saving as long as you don`t make it worse. I have now assembled and disassembled the lens quite a few times and feel pretty confident about it, and I have learned a lot in the process. If any of you have junk lenses I would suggest the same -it`s better than tossing it.

 

-Cheers!

[doug_stemke1]

Hi.

 

If you are REALLY looking for bargins then look no further than screw mount lenses. You can get a $15 (US) adaptor and then pick up dirt cheap screw mount lenses. The SMC Super Takumar are certainly the cream of the crop and I've seen them as cheap as $10, especially the 50mm bunch. I used one regularly for about a year on a P30T until I got my first K mount 50mm. True, shooting stopped down (if you shoot anything other than wide open) is a bit of work, but it quickly becomes second nature. If you go this route you can also pick up often for change (less than $10) 35mm f2.8 and 135mm f2.8 lenses. I still occasionally use a Spirltone 135mm f2.8 that I got for just $3! It's a lovely lens too, absolutely first rate for portraits. I don't think most people would even use it for a door-stop today.