Report K-1 bugs/issues here

yes all correct. The Sigma 10-20 3.5 works, but the 50-150 just crashes the camera firmware. It may be that my firmware is older than the other users lens here in the forum. Does it mean I should send the lens to Sigma (if I really want to use it on the k1)?

Well presumed Mike! Tried the lens on older Pentax's?
If so, perhaps Mike could suggest why it would work on some bodies but not the K-1. The only issue close to that I'm aware of is a failure where the mount contacts open circuit so doesn't communicate with the main part of the lens. I've got one that's intermittently like that, but it doesn't turn the camera off. Something like this: https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/239946-sigm...

No idea why it doesn't work on the K-1 as I'm not an electronics engineer but the very first post on this thread mentions the 70-200mm doing the same thing and so do a few more throughout.

Edit: There is mention on the other forum of the 120-400mm also doing it.

I would as you also need the mount changing for use on the K-1 (which will work but is prone to putting a tiny scratch on the body so Sigma are doing that for free).

My only issue with Pentax was sorted with the introduction of the K-1 in providing a FF digital SLR to allow full use of my Pentax FF lenses. I've seen the test's showing Pentax's accuracy with AF that Algi mentions. It goes past that. For birder's, particularly BIF, we won't get the results we want from our Pentax kit. By that, I mean quantity and quality of shots in focus.

I've used the K-1 now on several occasions at shows and am struggling to get the flash sorted properly. I've read up on different ways to approach "fettling" the settings. So what am I seeing? I'm seeing huge contrast range in the lighting of subject matter, especially if it's reflective (motorcycles with high chrome).

If a shoot with another system camera at the same settings, focal length, ISO and aperture priority, the flash results are spot on with balanced, even illumination.

I really am struggling to do that with the K-1 at the moment (also same issues with my K3 and K5-IIs, as far as flash goes). So it may be me. If it is, why do I get great results from another system using the same settings?

It does not mater at the end of the day, for me it's a minor disappointment. I'm a Pentax user that uses other kit that performs better in area's where my Pentax kit struggles. The only thing that matters is getting good results with minimal input by using suitable equipment designed specifically for the task.

As far as third party lenses and flash guns not working with Pentax bodies, there's no issue with Pentax, all of their glass and current flash guns works just fine. I do use Sigma lenses with Pentax. My other systems are all proprietary glass to ensure full compatibility and AF speed.

You would not use a narrow flat bladed screwdriver to tighten a pozi or Philips head screw, you use the right tool for the job.

mount changing? I wasn't aware of that, what is it?

LINK to Sigma page

I notice it will also need doing on the K-70 LINK

I have a 85mm 1.4, 70-200mm 2.8 and 24-70mm 2.8 to send off, I haven't bothered up to now as I don't intend buying a K-1 but if the K-70 needs it then it may be that future bodies (a K-3II successor) will also.

oh yeah, read that. I did several tests, I cannot see how the mount can scratch the body, I must miss something

I think some of the lens mounts were of different thickness so you may be lucky but you might as well get it done anyway, would be useful if you ever decided to sell it.

I e-mailed the customer support, let's see what they say. Thank you for the help!

The sigma K-mount flange is much wider than that on the camera body, try putting a Pentax rear lens cap on to see how much is left exposed. The replacement mount is chamfered around the rim to reduce this difference, and it would be interesting to see if this is now the standard fitting on all new compatible lenses.

where is supposed to leave the scratch? Can you show me a photo?

daaaamn that's micro I'll check