[othar]

OK, I feel dumb. Where would I find the autofocus sensor on a K-5IIs and a KP?

I think they are at the bottom of the mirror box, right under the mirror.

[UncleVanya]

OK, I feel dumb. Where would I find the autofocus sensor on a K-5IIs and a KP?

I’m not the expert. My understanding is limited to what I’ve read. It’s under the main mirror. I’d google for some video and hope you strike gold.

[Ishpuini]

Apart form my two DA* zooms (16-50 and 50-135) requiring a hack to return them to screw drive AF after my having mistreated them for years, only the Sigma EX70-200/2.8 comes to mind.

The optically very nice Sigma EX70-200/2.8 (pre DG version) just couldn't focus accurately on my Pentax *istDS. At f/2.8 it would have back focus at 70mm and front focus at 200mm or the other way around. Impossible to correct with lens specific focus adjustments, and in those days liveview wasn't up to the task for precise manual focus. I sold it when the DA*50-135/2.8 was released, but I heard more recent Pentax APS-C bodies no longer had that issue with the lens? Regardless, the DA*50-135 was a more practical range to me, so I never looked back.

Wim

[MarkJerling]

My Sigma 70-300 DG-macro lens would often cause my K5 to freeze - no buttons would work. It seemed to happen if one was focussing and zooming at the same time and always more toward the 300mm end. The only fix was to remove the battery from the K5 after which it would be fine. Interestingly, it's never happened with the K-1II and that same lens. Granted, I use that lens much less on the K-1II but still, it's never done it.

[Denver]

Vivitar K mount 135, worked on the film camera fine but the mount would not even connect to a K S2. There was the projecting lip that you never see on a Pentax lens that prevented it from being used on a digital Pentax camera.

[UncleVanya]

Vivitar K mount 135, worked on the film camera fine but the mount would not even connect to a K S2. There was the projecting lip that you never see on a Pentax lens that prevented it from being used on a digital Pentax camera.

Typically you can remove those flanges with some lens surgery. What a pain that is however if the piece can only be hacked off another part.

[ZombieArmy]

Yah had a sigma zoom lens that just wouldn't focus on my K-01. Would just spazz out and go back to closest focusing distance.

[tranq78]

Oh I've got one. But in reverse.

Local camera shop had a gorgeous used FA*80-200/f2.8 + hood. They couldn't get it to work on autofocus. They sold it to me for 1/2 the used listed price as a manual focus only lens, no refund no warranty.

I took home and it works fine in AF on my film MZ-S. AF is working fine on my K-50 as well.

Camera store happy and I was happy.

[UncleVanya]

Oh I've got one. But in reverse.

Local camera shop had a gorgeous used FA*80-200/f2.8 + hood. They couldn't get it to work on autofocus. They sold it to me for 1/2 the used listed price as a manual focus only lens, no refund no warranty.

I took home and it works fine in AF on my film MZ-S. AF is working fine on my K-50 as well.

Camera store happy and I was happy.

I wonder if they had the focus ring in the wrong position when they tested it. Pushing it forward and backward is how you switch between auto and manual focus.
Great buy!

[5ks]

My K-5 with the FA 35mm/2, somehow it would never achieve perfect focus. It made me scratch my head about the FA 35, which has quite a good reputation between pentaxians. Once I got the K-1 it really did shine, and I realized the problem was with the K-5

I got my FA35/2 some two years before I got K-1, having K-5 those days. I did not use FA35 much with K-5 and actually did not need it much, as I had also DA 35 Ltd. But with K-1 I also like to use my FA35/2 as it's quite sharp and renders the image nicely (some film-era nostalgia ) despite the occasional CA.

By the way, I've also tested the DA 35 Ltd with K-1 and found (like some others in the forum) that it's quite usable specially in close ups and macro. Less vignetting in macro that if the target is farther away. Seems like the FOV actually gets narrower when focusing very close.

[luftfluss]

K-70 + DA 20-40 Ltd. The lens AF'd fine on my K-3 II but wouldn't focus to infinity on my K-70. All my other lenses work fine on both bodies.

[Lord Lucan]

Vivitar K mount 135, worked on the film camera fine but the mount would not even connect to a K S2. There was the projecting lip that you never see on a Pentax lens that prevented it from being used on a digital Pentax camera.

I don't have a Vivitar lens, so don't know what that lip is, but Pentax lenses do have a black-painted shield alongside the aperture stop-down lever. I have an old Sigma 70-250mm F3.5-4.5 which has the shield but a bit larger and in a slightly different position from a Pentax one. It fits OK on my Pentax film cameras but not to a K10-D I once had - the shield came up against something as you tried to twist it on. I was thinking of filing it down to reduce its size, but when I changed from the K10-D to my K-1, I found it did fit the K-1 after all.

I don't know why Sigma could not have made the shield the same shape as a Pentax shield, unless they were trying to use some common components across different lens mounts, and got away with it during the film era.

[tranq78]

I wonder if they had the focus ring in the wrong position when they tested it. Pushing it forward and backward is how you switch between auto and manual focus.
Great buy!

I suspect that's what happened but I don't know for sure. The camera shop said they didn't have a body for me to test the lens out on, a previous buyer had tried it on his camera and returned it due to it being non-functioning in AF. I simply bought the lens and took it home to try.

So now I have 2 of these superb lenses. Question: what's better than one FA*80-200? Answer: two FA*80-200 lenses.

[UncleVanya]

I suspect that's what happened but I don't know for sure. The camera shop said they didn't have a body for me to test the lens out on, a previous buyer had tried it on his camera and returned it due to it being non-functioning in AF. I simply bought the lens and took it home to try.

So now I have 2 of these superb lenses. Question: what's better than one FA*80-200? Answer: two FA*80-200 lenses.

LOL - Now I have this vision of a photographer with a K-1II and a K3iii and two FA* 80-200's and he's shooting in both directions and spinning around saying - GOT THE SHOT BABY!

[luftfluss]

LOL - Now I have this vision of a photographer with a K-1II and a K3iii and two FA* 80-200's and he's shooting in both directions and spinning around saying - GOT THE SHOT BABY!