[jk3rwood]

Hey everyone, I'm having a very strange issue with my K1 and the 28-105mm lens. Autofocus is struggling to operate in general when I'm looking through the viewfinder, typically its just in front of the focus point and will never get a crisp image like it used to. This issue JUST started this last weekend, and I've only had this body/lens for roughly a year. The weird part, is that focusing works as flawlessly as it used to, when I'm in Liveview mode. But only when I'm in Liveview! I am supposed to be shooting a wedding in a few weeks and I'm going to be one sad photog if I can't use my favorite all-around lens! Any advice would be appreciated. This issue is only with this lens, my K1 works just fine with any other lens I throw onto it. However this is my only autofocusing lens made for FF, so I'd love to get this figured out!

*Note* I have looked into calibrating this lens, but this issue is totally non-existant when in Liveview. This issue is consistent between my K1 and my K50 as well. Could the autofocus drive within the lens itself have already gone out? If so, what am I looking at for repairs, do you think?
I take very good care of my gear, and I'd find it hard to believe that Pentax makes such fragile lenses. However any advice at this point would be appreciated!!

Thanks!

[sergysergy]

Try to clean the contacts in both the lens and the camera.

[jatrax]

but this issue is totally non-existant when in Liveview.

Liveview uses a different focusing system and is not affected by AF fine tuning.

Could the autofocus drive within the lens itself have already gone out?

Not likely but the lens could have gotten bumped or damaged in some fashion that has knocked it out of alignment. (I know you take good care of your gear, we all do. But sometimes things happen we do not notice).

However any advice at this point would be appreciated!!

Suggest you try the AF fine tuning route and see if that helps. You have nothing to lose at this point and it might work.


I find the situation very odd however. You say the lens works fine in Liveview but not in the viewfinder with both cameras. Since it does work in Liveview that essentially eliminates the lens as the problem. My next thought would be some dust in the AF sensor of the viewfinder causing things to be erratic. But you say it is soft using the viewfinder on both cameras which is not what I would expect if it was dust or a hair in AF sensor

Anyway, try the AF fine tune and see if that helps. Do read up on the instructions for AF fine tuning, it must be done in a VERY precise and controlled manner or you are just guessing. Must be on a tripod, must use a focusing target, must be precisely aligned in both vertical and horizontal planes.

[ramseybuckeye]

First thing if you haven't done it, is cleaning the contacts on the lens. Could you post a couple of samples with the exif intact? There are a lot of people on the forum that may be able to figure it out.

[devouges]

Check the diopter adjustment maybe ?

[othar]

*Note* I have looked into calibrating this lens, but this issue is totally non-existant when in Liveview. This issue is consistent between my K1 and my K50 as well. Could the autofocus drive within the lens itself have already gone out? If so, what am I looking at for repairs, do you think?
I take very good care of my gear, and I'd find it hard to believe that Pentax makes such fragile lenses. However any advice at this point would be appreciated!!

Thanks!

Live view focuses via contrast detection on the sensor, the optical viewfinder uses phase detection for focusing -> two independent systems from which only the one via the OVF is influenced by AF adjustment.

[UncleVanya]

Check the diopter adjustment maybe ?

Always worth checking to see if the text and lines are sharp. If they are sharp I'd say that's not the issue but a good idea to check.

I wonder if the lens rom is damaged/scrambled/etc?

[bwgv001]

may be clean your camera; dust on the autofocus system underneath the mirror.

[veato]

Check the diopter adjustment maybe ?

I have actually done this before. Was convinced my camera was broken.

[jk3rwood]

Wow...I wish I had come here first! I will try some cleaning when I get home later today, and get a set-up for some fine tuning to see if that does the trick. Looking forward to more suggestions and hopefully figuring this all out. I've had some weird issues with my gear in the past, but this is a whole different level of "Wtf?!" in my book. Thank you so much for the advice everyone!

[UncleVanya]

may be clean your camera; dust on the autofocus system underneath the mirror.

But the problem I thought was lens specific on two different cameras. Other lenses I thought were not impacted, and the problem appears on two bodies.

[jk3rwood]

Well after numerous phone calls to camera repair shops and much research, I did a thorough cleaning of the lens contacts and it seems that could be the culprit. I do have AF functional now, but its not nearly as consistent as it used to be. I got an estimate of around $250 to get it serviced by Ricoh assuming no parts need to be replaced.... Next question; do you think its worth it?
Or should I take that $250 and throw it towards a replacement? Anyone have any recommendations for a good all-around lens with a focal range to replace a 28-105?

Thanks for all your help everyone!