[ZEPsikopat]

Hi all

I recently acquired an used F 135mm f/2.8. After a few shots, I'm definitely seduced by the lens sharpness, contrast, and so.
But the autofocus is damn noisy. It makes an horrible gear noise, as if all the mechanism was out of lube or something like this, It doesn't occur during the whole barrel move, but mostly at the close end, between 80cm and 1.30m focus distance. Odd thing, is that it does more noise going from close focus to infinity than coming back.

Anyone encountered the same issue ?

[bwDraco]

I don't have this lens, but this could be an issue with the internal focus helicoid or gear train. The lens may need to be serviced.

Do you have any similar problems with other lenses?

--DragonLord

[kaipa]

Look at lens reviews here. Some reviewers comment about noise, so this is could be a general issue with this lens, I think. It should not affect the operation, though.

I have FA 135/2.8, and it is not noisy.

Btw, congrats! This is an awesome lens, one of my favorites.

[axl]

I used to have FA135 and don't recall it being noisy, not more so than other Pentax lenses but F50/1.7 was probably the noisiest lens I've owned

[Nick Siebers]

ZEPsikopat, mine is like that too. I posted about it a while back, with a video, and others said they thought it was normal. Maybe a video of yours?

Nick

[Pentaxor]

Hi all

I recently acquired an used F 135mm f/2.8. After a few shots, I'm definitely seduced by the lens sharpness, contrast, and so.
But the autofocus is damn noisy. It makes an horrible gear noise, as if all the mechanism was out of lube or something like this, It doesn't occur during the whole barrel move, but mostly at the close end, between 80cm and 1.30m focus distance. Odd thing, is that it does more noise going from close focus to infinity than coming back.

Anyone encountered the same issue ?

what camera are you using?

[ZEPsikopat]

Sorry, forgot to specify, I'm using a K-5.
I have other lenses which are reasonably noisy (FA43, F50 1.7, F100 macro, bigma...), but this one was not making an homogeneous noise during the whole course.
Moving the focus ring by hand doesn't make some special noise, you feel that the course is wide, but I can't feel any grip in the helicoid. Maybe the gears needed to lube themselves, as it wasn't used for a while. I'll ask the vendor if he had a similar feeling when he was using it.

Anyway, I'm testing in daylight now, and I can't make it be noisy anymore. It was occurring when the AF was hunting in the dark or partially reflective areas, going from infinity to close focus and backward.

Does anyone knows how to "fool" the AF to make it hunt on the whole range ?

Edit: Nick, I just looked at your video, and imho you have the normal noise of the lens (gear noise during course, and thump on the edges of the helicoid. I have almost the same noise, but a slight rattle noise on top of this at 90-120cm.

---

Last edited by ZEPsikopat; 01-15-2011 at 01:38 AM.

[axl]

How to fool AF to hunt? Just put lens cap on.. Good luck

[ZEPsikopat]

Did some more tests (btw to fool AF with cap on K-5 you have to deactivate AF assist).
The noise occurs when the camera is pointing down (tripod shows 10 degrees tilt). Maybe the weight of the focus block is making it accelerate and do more noise ?

Can anyone with the same lens try to see if the focus is noisier when pointing down ?

[Pentaxor]

I'm not sure if such horrible gear noise produce a significant wobble or judder, but if it does, I think it might be misaligned in a way. if yours runs like Nick's, then it should be pretty much ok.

[ZEPsikopat]

Well, even if it is noisy, this lens is still sharp at wide open (on the full resolution you can distinguish me in the reflect in the eye):
( sorry for the picture subject, was the only one not complaining about having his picture on the Internet )


K-5
100 iso
F 135mm f/2.8 @2.8
1/180
Flash reflected on the ceiling.

Big drawback however, is the amount of CA at these apertures, but it remains usable in post processing.
I think I will keep it, not worth trying to silence it, the optical quality is still here.

[Pentaxor]

Well, even if it is noisy, this lens is still sharp at wide open (on the full resolution you can distinguish me in the reflect in the eye):
( sorry for the picture subject, was the only one not complaining about having his picture on the Internet )


K-5
100 iso
F 135mm f/2.8 @2.8
1/180
Flash reflected on the ceiling.

Big drawback however, is the amount of CA at these apertures, but it remains usable in post processing.
I think I will keep it, not worth trying to silence it, the optical quality is still here.

I'm sure a minor problem wouldn't deter you to immediately return the lens and in most cases, probably just live with it or had it repaired especially you got impressed by it's resolution. the added rarity of the lens makes it much more a keeper.

there are only two faults that I noticed about the lens. first is the CA at wide open which is not as bad nor the worst among lenses as people might think and easily correctable during pp. the second would be the MF ring which I find inconvenient and deemed unusable due to it's looseness. I would say the lens is made for AF functionality rather than MF. if Pentax only corrected this problem, it would had been one of Pentax's perfect lenses and would cost more than what it is going for, especially it's rarity. personally, I like this better than the DA*50-135 at 135.

[blende8]

the MF ring which I find inconvenient and deemed unusable due to it's looseness. I would say the lens is made for AF functionality rather than MF. if Pentax only corrected this problem, it would had been one of Pentax's perfect lenses and would cost more than what it is going for, especially it's rarity. personally, I like this better than the DA*50-135 at 135.

I agree 100% with this. The same is true for the FA version.