[geoffw]

Don't know if this has been posted before, apologies if it has. Recently bought a K1 (shop soiled) and using the sigma 150-500mm OS on the K1. The OS works ok but I tend to use back button focus. The OS works by pressing the AF buttion, but On a K3ii or K5, using the same set up, the OS activates with a half press of the shutter button, but not on the K1. Anyone know hoe to get round this or is it the way it is? Thanks in advance. Regards.

[sergysergy]

There is an option in the custom settings.
Button Customization > AF/AE-L > Enable/Disable AF-2

[pentageek]

Well, I've got this parameter set to 'Enable AF1', and AF activates when I either press AF button, or half-press the shutter. All this with K-1 Mark I and Sigma 150-500 OS HSM.

[geoffw]

Well, I've got this parameter set to 'Enable AF1', and AF activates when I either press AF button, or half-press the shutter. All this with K-1 Mark I and Sigma 150-500 OS HSM.

Thanks but the point of enabling the back button AF is to disable the shutter button AF. This is ok but on the K3ii and 5 in this mode, a half press on the shutter switches on the OS on the lens without the focussing being enabled on said shutter button. The K1 does not behave the same way. Hope this makes sense. Regards, Geoff.

[pentageek]

Thanks but the point of enabling the back button AF is to disable the shutter button AF

... and this is 'AF2' mode - in 'AF1' both buttons trigger AF, at least in my K-1 - I've just tested it again prior before I wrote this message OS is being activated automatically together with AF (if Sigma's switch 'OS' is in position 1 or 2).

[geoffw]

... and this is 'AF2' mode - in 'AF1' both buttons trigger AF, at least in my K-1 - I've just tested it again prior before I wrote this message OS is being activated automatically together with AF (if Sigma's switch 'OS' is in position 1 or 2).

Yes. AF2 selected on the K1 as it is on the K3ii, but with the K1, the lens OS is only activated by the AF button. On the K3ii, the lens OS is activated by the shutter button, not the AF button, so you can recompose without altering the focus, which is the whole idea of the back AF button.

[photoaki]

[mention]geoffw [/mention] , aside from this one limitation, how do you like the lens with the K1?
I was itching to get on, or the 50-500mm.
Already have the DA*300mm, 1.4TC, and the DA60-250, so may be redundant, I suppose.

[geoffw]

[mention]geoffw [/mention] , aside from this one limitation, how do you like the lens with the K1?
I was itching to get on, or the 50-500mm.
Already have the DA*300mm, 1.4TC, and the DA60-250, so may be redundant, I suppose.

I've only had the camera for a week and not really had the chance to spend a lot of time with it, but like an over excited kid I had to try some of the lenses. The 150-500mm seems better on the K1 than the K3ii/5 so far in dull light. From what I've read the 300mm is better but without the versatility of the zoom. But for birds etc its usually all about longer focal length. Really kicking myself for not getting the K1 when it came out. Was building a lens base at the time and have to save to get things.

[pentageek]

but with the K1, the lens OS is only activated by the AF button.

Maybe with Mark II, or with old firmware. I believe we can make AF buttons work in your camera, if you are interested, please drop me PM.

[photoaki]

The 150-500mm seems better on the K1 than the K3ii/5 so far in dull light. From what I've read the 300mm is better but without the versatility of the zoom.

Well, that’s encouraging.
I would expect the DA* 300mm to be sharper, and it is quite a bit faster at 4.0.
Might still get the Sigma if one comes up at a good price.
Thanks for the reply!

[rogerstg]

The OS works by pressing the AF buttion, but On a K3ii or K5, using the same set up, the OS activates with a half press of the shutter button, but not on the K1

FWIW, it works the same on the KP as on the K1.