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10-26-2009, 04:08 PM   #1
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Pentax-F 50/1.7 grinding noises while focusing

So I got a F 50/1.7 today in great optic and cosmetic condition and tried it on a friend's body as my K-x isn't here yet. When I focus, particularly when pointed up or down, I hear grinding noises. When I take it off and focus with my fingers, it actually got stuck a couple times.

Is there anything I can do to fix this?

Also, I have 2 other Pentax-F (28-80 and 70-200)'s that focus a lot faster (is the F 50 known to focus slowish? How about the FA?). Of course they don't have the buzzing noise or get stuck

10-26-2009, 05:02 PM   #2
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QuoteOriginally posted by Eruditass Quote
So I got a F 50/1.7 today in great optic and cosmetic condition and tried it on a friend's body as my K-x isn't here yet. When I focus, particularly when pointed up or down, I hear grinding noises. When I take it off and focus with my fingers, it actually got stuck a couple times.

Is there anything I can do to fix this?

Also, I have 2 other Pentax-F (28-80 and 70-200)'s that focus a lot faster (is the F 50 known to focus slowish? How about the FA?). Of course they don't have the buzzing noise or get stuck
I don't find the F 50 to be slow focussing at all (that's comparing it to an F28, a couple of DAs and an FA. Sorry no idea about how to help with the grinding noise but it sounds like something (dirt, sand etc) is stuck inside where it shouldn't be.
10-26-2009, 05:17 PM   #3
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My F 50 1.7 is definitely faster at focusing than my Takumar-F 28-80.
10-26-2009, 06:34 PM   #4
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Can anyone take a video of their F focusing? Is there an easy way to open up the part that could be causing it?

10-26-2009, 07:38 PM   #5
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hi. it's possible that the focusing mechanism is misaligned? does it vibrate/shudder and mis-focus? if it does, then it really is misaligned. but before you do that, try to do a lot more tests with other bodies and lenses for comparisons. I got a lens before that shudders when the focusing ring retracts back in during AF. I thought the screwdrive AF mechanism of the body would break, thank goodness it didn't.
10-26-2009, 08:40 PM   #6
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Unfortunately I am body-less at the moment, but I can try to meet up with a friend soon, so I haven't tested if it mis-focuses. It seems like it focuses fine through the viewfinder and locks on, but vibrates and shudders only when point up or down some.
10-26-2009, 08:53 PM   #7
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does it shudder violently? I'm beginning to think that it's really mis-aligned. I'll try and test my copy now and see how it behaves !
10-26-2009, 09:02 PM   #8
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Nah, it didn't shutter violently, just vibrates t and appeared to achieve focus, so I am thinking maybe it is dirt? Maybe I can try using the blower or some kind of lube (bad idea?)

10-26-2009, 09:07 PM   #9
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ok I'm done testing my copy. mine doesn't have any shudder nor vibration. just the usual zzztttt zzzzttt screwdrive mechanism. tried on 3 focusing mode and tilted the camera up and down. nothing unusual happened. I think that bring a big ? on the lens that you have.
10-26-2009, 09:55 PM   #10
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QuoteOriginally posted by Eruditass Quote
So I got a F 50/1.7 today in great optic and cosmetic condition and tried it on a friend's body as my K-x isn't here yet. When I focus, particularly when pointed up or down, I hear grinding noises. When I take it off and focus with my fingers, it actually got stuck a couple times.

Is there anything I can do to fix this?

Also, I have 2 other Pentax-F (28-80 and 70-200)'s that focus a lot faster (is the F 50 known to focus slowish? How about the FA?). Of course they don't have the buzzing noise or get stuck
You are not alone! My F 50 1.7 makes a grinding type noise, but only when i hold the camera in the vertical position. I don't have any focus issues at all. I assumed that there is a bit of wear in the mechanism, at one stage i had a stepring +58mm filter+hood fitted and that made it worse, so i leave them off. It's not annoying me enough to have it looked at, but it sounds like your one needs checking.
10-29-2009, 10:17 PM   #11
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Does it focus slower when tilted up or down?

Is it wear or is it dirt? Would any kind of fluid or rubbing alcohol help? probably just get inbetween the elements and mess everything up?
10-30-2009, 09:29 PM   #12
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Just checked it on a k20 and focus is fast at all angles, with only a slight vibration type noise at close focus, with no extras fitted on the lens. Mine feels like wear or maybe adjustment, man focus is smooth and free. Your lens has probably got a damaged focus gear, missing teeth etc. I wouldn't try to use any fluids or lubricants you'll end up doing more damage, best get it looked at.
02-13-2013, 10:31 PM   #13
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QuoteOriginally posted by Eruditass Quote
So I got a F 50/1.7 today in great optic and cosmetic condition and tried it on a friend's body as my K-x isn't here yet. When I focus, particularly when pointed up or down, I hear grinding noises. When I take it off and focus with my fingers, it actually got stuck a couple times.

Is there anything I can do to fix this?

Also, I have 2 other Pentax-F (28-80 and 70-200)'s that focus a lot faster (is the F 50 known to focus slowish? How about the FA?). Of course they don't have the buzzing noise or get stuck
Did you find a solution to this problem?

I noticed this on my F 1.7 lens yesterday. It didnt have have this noise before.
02-14-2013, 03:28 AM   #14
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Turn the focusing ring by hand (when the lens is not attached to the camera). Is focusing harder at certain distance settings while focusing?
02-14-2013, 06:15 AM   #15
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QuoteOriginally posted by Eruditass Quote
When I take it off and focus with my fingers, it actually got stuck a couple times.
NOT normal. There may be a simple fix, I got a DA21 with a focus problem (it was getting stuck) and it cost me 100$ to get it fixed. In the US, Erik can do it for less, but I'm in Canada.

QuoteOriginally posted by Eruditass Quote
Also, I have 2 other Pentax-F (28-80 and 70-200)'s that focus a lot faster (is the F 50 known to focus slowish?
The F50 f1,7 is probably my fastest focusing lens, or close anyway. Your lens is not in good shape
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