K20 Display cuts out with Sigma Lens
Could it be the chip in the sigma lens?
How to tell? what to do about it?
Contact Sigma, they might be able to tell by series number what chip is in it and if it needs an upgrade/replacement for it to be compatible with the newer Pentax cameras.
I don't know who pays the bill.
Instead of Pentax making sure the lenses fit, Sigma makes sure the Lenses fits the camera that's why older lenses sometimes does not work correctly.
here is something on flickr about it http://www.flickr.com/groups/sigma_lenses/discuss/72157606282211513/
here is the contact information for Sigma.
http://www.sigma-photo.co.jp/english/network/index.htm
The thing is your lens seems to work okay so I think something else is going on, you could check you exif data if the lens focal length and that sort of thing show up properly.
If so, you may be inadvertently touching the shutter button on the grip with the palm of your hand when you're holding the camera to look at the screen. It might only happen with the Sigma because it's a heavier lens that needs more support, and you're holding the camera slightly differently. Just a thought. See this thread for something (a bit) similar, and this one for something more similar.
Cayman, as you use a grip too, does this sound familiar? I know you've only experienced it with one lens, but could it be coincidence? Do you always get the malfunction, or has it happened once or twice with this lens only?
Dan
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1432 posts
15 years
Chester,
U.K.
When trying to make changes to the settings using menu or Fn button the rear screen goes blank , usually after a few seconds, but the actual time to blankness varies between 2 and 10 seconds. The lens functions perfectly, AF and aperture changes with no problem.
Have cleaned the contacts, but still no difference. I have never seen this happen with any other Pentax or 3rd part lens.
Any ideas?
Davex.
Please feel free to play with any images I post.
My flickr: link