[CXP68]

Hi,

I just bought a brand new Pentax-D FA 24-70mm lens and really like its sharpness (see the photo attached, taken wide-open under indoor lighting with K-1), but I noticed that while auto-focusing, the lens has some clearly audible consecutive knocking sounds (2 or more) before it obtains focus (which also means the focus speed is not great). This is especially obvious when I change focus point back and forth. I haven't noticed this with my other lenses. Just out of curiosity, I also tested my DFA 15-30mm (since they are both rebadged Tamron lenses), and there also seems to be similar sounds, but much more muted to be noticeable before. So far I have just tested this under low-light conditions, and am not sure if this issue will go away under normal lighting conditions.

I wonder if anyone else with this lens has had similar experience, and if this is normal. I tried to upload two audio files without success (told 'invalid format'). Many thanks!

Attached Images

View Picture EXIF

File Date

 

[jthapar]

I have both the dfa 24-70 and 70-200. My copy of 24-70 doesn't make any sound as such that you described but just an audible hiss. My first copy of 70-200 did make some grinding sounds and went into repair where they subsequently changed the motor and front filter ring!

[CXP68]

I have both the dfa 24-70 and 70-200. My copy of 24-70 doesn't make any sound as such that you described but just an audible hiss. My first copy of 70-200 did make some grinding sounds and went into repair where they subsequently changed the motor and front filter ring!

Many thanks for your quick reply. That's really helpful. My DFA 70-200mm doesn't make such sound either - only gentle hiss while focusing.

I also made comparison with screwdrive lenses (eg, DA 55-300mm), and the noises from 24-70mm are certainly quieter. I guess my concern is largely due to this rather unfamiliar type of sounds, and hope they are just normal.

[clickclick]

Just for comparison, my 15-30 on my K1 is completely silent and very fast, even in low light. I'd pursue an exchange or repair as appropriate ASAP.

[CXP68]

In Sigma and Canon land, that sound is the precursor to focus motor failure. Even worse is the dreaded squeal. If you are still under warranty, better to get it looked at before it expires.

Thank you! Yes it's still under warranty and I'll contact the company.

I haven't come across any posts about the same issue with this lens, and will be interested to hear other users' experience.

---------- Post added 08-30-17 at 04:19 PM ----------

Just for comparison, my 15-30 on my K1 is completely silent and very fast, even in low light. I'd pursue an exchange or repair as appropriate ASAP.

Thanks - will do and see how it goes.

[jthapar]

I feel pentax system is too young for a lot of these issues to be blogged or appear in forums but from my experience, there seem to be some qa issues on these new lenses. What does worry me is that the lens I got repaired wasn't even 3 months old and the warranty 'experts' here in melbourne made me feel as if I was plucking things off the air and they couldn't hear any out of the ordinary sounds. It's only when I got a bit more pushy did they send the lens to Japan to repair and Japan turned around and admitted the motor was failing.
So go with your experience and gut feeling on this one even if the warranty company pushes back. Depending on which county you're in your mileage may vary. The retailer from who I bought the 24-70 was kind enough to offer a full replacement for another unrelated issue where the lens was smearing lights in the bottom middle corners when I was attempting long exposures. The only reason the issue came forth was when I used it to photograph cityscapes using ping exposure. Again the warranty handling company didn't think there was anything wrong with it. Surprise surprise

[CXP68]

I feel pentax system is too young for a lot of these issues to be blogged or appear in forums but from my experience, there seem to be some qa issues on these new lenses. What does worry me is that the lens I got repaired wasn't even 3 months old and the warranty 'experts' here in melbourne made me feel as if I was plucking things off the air and they couldn't hear any out of the ordinary sounds. It's only when I got a bit more pushy did they send the lens to Japan to repair and Japan turned around and admitted the motor was failing.
So go with your experience and gut feeling on this one even if the warranty company pushes back. Depending on which county you're in your mileage may vary. The retailer from who I bought the 24-70 was kind enough to offer a full replacement for another unrelated issue where the lens was smearing lights in the bottom middle corners when I was attempting long exposures. The only reason the issue came forth was when I used it to photograph cityscapes using ping exposure. Again the warranty handling company didn't think there was anything wrong with it. Surprise surprise

Many thanks for your insights and advice. Actually I am not far from melbourne and so I just took the lens to their office there. Definitely can testify to what you described about the attitude. But they agreed to exchange for a new one because it is still with a week of purchase. Thanks everyone for your help.