DA* 300mm AF not working

Hi all

After a good few months of penny pinching I saved up enough to land a DA* 300MM at a really good price, thought it was too good to be true as the AF wont work on my K3. It simply does nothing, although switching between AF and MF on the lens mount registers on the body.

I'm currently giving the camera battery a full charge so I can flash the firmware (Current 1.1, latest 1.43) but nothing in the firmware literature to say there's noted issues with/fixes for 300mm so I'm not expecting the issue to be resolved through firmware.

The lens has in now way been abused, it's pretty much mint and boxed - although for some reason the tripod mount clamp is clearly an incorrect part which I've informed the shop about. No idea of vintage I'm afraid.

I've only got my K3 available as a Pentax body so can't try on other cameras but my 8-16 (my only other lens with SDM-type focus) works perfectly so it's not likely to be a problem with the body.

Any ideas for things to try? I've heard about manually focusing in and out but there's been no response from the AF at any point. I've heard stories about SDM issues but though these were for the most part resolved.

I'll call shop tomorrow, but any ideas on what to try beforehand appreciated.

Clean the contacts on the lens?

Steve

I wondered about this too, so had a look and they're spotless. I gave them a quick wipe just in case but no difference.

Try rotating the focus ring back and forth a few times quite fast. The lens might have been unused for a time and got a bit sticky.

Personally, I wouldn't do anything with it, bar send it back to the shop...

If you don't have an older Pentax camera body (ie pre-K DSLR) you might struggle..... On an older SLR the AF should work via the screw drive.

So, I would get the smallest screw driver you have and try to turn the focus drive on the bayonet and twiddle it... it might be stiff but turning it should slowly loosen it.

My DA*300 did go lethargic due to limited use but I was able to get it working normally again, with no further instances of lethargy.

This, presumably you got some sort of warranty with it so ask them to repair rather than refund.

Otherwise convert it to screw drive - it's easy and works perfectly well and has no disadvantages over SDM unless a very slight noise is bothersome...I have converted my 16-50, 50-135 and 300. I wish it was possible to convert my 60-250 as well - it's getting a bit slow now.

Tried the manual focus, no luck, also tried the screw drive - it certainly winds the focus in and out as I can see the focus dial move (amazed how low-geared it is!) but still no response from the AF.

Thanks for ideas in any case - I'll try again over weekend and if no joy I'll call shop next week. If the lens was one I'd had for a while and the AF died I would convert to screw drive, but it's been advertised as almost new so I'd prefer to return if it's not working.

Where are you Matt?, perhaps a nearby PUser can check the lens on their K-body.

You also say you've tried the AF/MF switch on the camera body, have you checked the switch on the lens?

Good thinking, would have been nice to meet some forum members- I'm in Edinburgh and saw some brave soul on a windswept day at North Berwick with a 645, so presumably I'm not alone!

I've sent the lens back for investigation, as it's probably a good idea to get it properly checked over. It might be a while and they might see it as uneconomical (I'd hope not, given price of lens) but I've let them know I'd be happy to hold on in case it can be resolved.

Other end of the A1 then....let's hope the dealer resolves the issue.

Sorry, never finished this off - the dealer sent the lens away for repair and all is good - sharp as a tack, I had a a fair few issues with front/back focus with my Sigma 300 APO and I've had none of this with the DA*.

Very pleased with the lens, shame about the photographer!