DA* 50-135 & 16-50

Can anybody offer any explanationfor this?

Visiting the Yorkshire sculpture park today and both of these lenses refused to focus reliably. Nothing at all with the 16-50. The 50-135 worked if I prefocussed manually. I had a HD 15 limited with me and this worked fine.

So sitting down tonight and testing in my living room both of the DA* refused to focus! I tried my DA* 300 and this worked fine, also tried the DA 18-135 and this worked fine.

As a last ditch I tried both the DA* s again but used LiveView. Both worked perfectly! And now both work fine in through the viewfinder.

So does anybody know anything about this?


Thanks in advance

John

If you haven't used the lenses for a long period of time they can have focus issues. Not sure why but it's to do with the SDM motors. These lenses need to be used regularly to avoid issues.

Regards
David

Thanks David.

That could well be the problem, just seems strange that LV will get them going again??

Cheers

John

As David has mentioned. If you don't use the lenses regularly they just stop to focus and need a time(and "exercise" to wake up.
Because they are professional lenses manufacturers are expecting that they will be used every day and if they are not used on a daily basis they will just fell in sleep.
I have read somewhere that lenses with newer sdm motor don't have this problems but cant find it now.

Used to have the same problem with DA*16-50 and sold it here on this forum but the buyer knew about it and after some time he has told me that the lens is still got the same issue, still works but needs to be woke up from the "winter" sleep.

Anyway you cam make the lens to work as a standard DA lenses (screw focusing instead of SDM) if the SDM fails completely.

Here is the topic where i am selling the DA*16-50 with the SDM issue
https://www.pentaxuser.com/forum/topic/fs--da-16-50--da-50-135-44375

Thanks Marcel

I haven't been out with my camera for a few weeks because I'm busy renovating my house!

John

Than thats the problem with your lens. i know you are busy with your house renovation but try to put the lens on the camera and turn it on everyday and just focus on something, dont need to make any photo just exercise the focus and you should be fine.
If it wont focus the just refocus manually from infinite to closes distance few time and then try to focus wit AF.
Should help.

I had a similar problem with my 50-135 about a year ago. I was taking part in a photoshoot at a steam railway event. I switched the lens from my K3 to the K5 II and it worked fine. But back on the K3 it failed to operate! Other lenses worked perfectly on the K3 so I was baffled! I later cleaned the contacts on my lenses and bodies with isopropyl alcohol and have never experienced a recurrence so far! My lenses are used regularly.

I have had similar problems with my 50-135 and it appeared dead on my K5II and then I tried fitting it on my MZ 7 and the screw drive made it jump back into life again, I then put it back on the K5II and it worked perfectly, so now if I find it not working, I slip it on the film body to bring it back to life.