Sigma HSM AF

After much soul searching and good advice from Penatx forum members I am about to take the plunge and buy a long Sigma lens. Before I do can anyone confirm if the Sigma 150-500mm f5-6.3 DG OS HSM lens is fully comptable with a K7. A forum search suggests that DSLR's after the K100 will work OK but I havent seen any comfirmation. I wonder what happens to the Pentax mechanical drive AF, does the Sigma AF take over or do you have to manual focus?
Regards David

Smashing and does everything else function as expected? I understand that the camera should be set to AF and then choose AF/Manual on the lens is that correct?
Dave

Tried one on a Nikon at LCE, the images look pretty good on my PC, also bearing I wasnt confident handling the lens or the camera and only a few minutes in poor light to test it. Think I will be ordering one Monday, cant wait to get it on my K7. Thanks for all the advice
Kind Regards
David

I would think the two systems would count each other out but I have heard and Olympus owner say he leaves both systems on and gets better results!!!!! Personally I doubt it as the makers and experts say dont run the two together. I may try it myself as I'm very likely to forget to switch the Pentax system off occasionaly.
Regards David

As said;
I understand the science behind lens and sensor SR, simple fact is I can see no observable difference when I leave both of them on.

My only problem with lens based SR is image shift, and this is why I often leave the lens SR off.

Davex.

Having no HSM lenses I am going to be on a steep learning curve and appreciate your valued knowledge. You seem to have had a a lot of experience with these OS systems and I will be putting all your knowledge to good use when I get my lens. I will let you know how I get on when I get it, next week I hope
Thanks for the advice as without your and other Pentax users info I would not have dared buy the lens.
Kindest regards David

Now that's an interesting observation. I'll have to take a closer look at this.

I take it you can see a difference between both on and both off?

Picked up my Sigma 150-500 lens up yesterday, Lincoln LCE most helpful and did me proud even gave me a Sigma DG UV filter in with deal. Tried it outside today at 4pm but had to have ISO at 800 so images very very grainy. However found it focused fast and IS seemed OK as long as shutter speeds above 1/60sec at 500mm (not much chance of that this afternoon) it was almost totaly dark by 4.30. Proper test soon I hope. Will update and post images when I have something I dare show.
Regards David

I have to add one thing, if you get chance to try a Bushhawk Shoulderpod on the Sigma do it, I LOVE mine, now on a Bigma.

Slightly off tack but just posted above a problem I'm having with mine. On my K-r , AF is fine for reasonably close objects (say up to about 25-30m) but after that it is very hit or miss, making a clicking noise and going back and forth either side. This seems to happen in reasonably good light and most subjects. It's unusable for distant birds in flight, helicopters etc. Do you think there is a fault. DAL 55-300 seems much snappier and to be honest I was expecting the opposite.

Having just got my 150-500 I am no expert but I have taken some birds in flight with camera set to "constant auto focus" and the focus area to "auto". In this mode the camera as normal still needs a strong contrast subject before it will lock onto it. Once locked on as long as you keep the subject in the viewfinder the camera will keep refocusing. But yes if subject is not of a strong contrast and or out of the camera's focus area it will miss the item you want, with a long lens its even harder.
Regards David

Just got my first decent photo with my new Sigma 150-500.
Very pleased with it but still need help lifting and holding to eye level. Muscles developing.
Lens, well its brilliant see for yourself this was a quick snap shot before ducks and sun went out of view.
https://www.pentaxuser.com/photo/happy-couple-37690/large
Thanks for all your guidance David