Sigma to PK woes

Grumpylump · 10-04-2013, 08:28 AM

Hi all. I'm an oldster looking to get back into a long-neglected hobby. I bought a Pentax K-r and a collection of AF lenses, some of which work just fine and others don't. Basically, all I want to know is, will a SIGMA SA AF FIT 100-300MM AUTOFOCUS ZOOM LENS fit on to my K-r at all and is there an adapter that will allow me to use the Sigma lens on the Pentax body.
Things have certainly advanced since I last got involved with this pastime so any help will be greatly appreciated.

scratchpaddy · 10-04-2013, 08:53 AM

Welcome to the forums! About that lens: sounds like it has Sigma's own SA mount, designed to work with their own DSLR's. The SA mount actually uses the same bayonet as Pentax, so it should fit on your camera just fine. However, the rest of the mount is a copy of Canon's EF mount, which is electronic. You won't be able to use the autofocus, and there's no way for your K-r to stop down the aperture. Also, the SA mount has a shorter registration distance, so the lens won't be able to focus as close, and it will be able to focus well past infinity.

Jean Poitiers · 10-05-2013, 03:16 AM

Welcome to PF and bonjour from France ... enjoy the forum and the K-r ... please post us an image or two soon ... Salut, J

**Kerrowdown** · 10-06-2013, 10:14 AM

Originally posted by Grumpylump

Things have certainly advanced since I last got involved with this pastime

Welcome to the forum, I thought exactly the same when I went predominately digital from years of film.

10-04-2013, 08:28 AM	#1
Grumpylump New Member Join Date: Oct 2013 Posts: 1	Sigma to PK woes Hi all. I'm an oldster looking to get back into a long-neglected hobby. I bought a Pentax K-r and a collection of AF lenses, some of which work just fine and others don't. Basically, all I want to know is, will a SIGMA SA AF FIT 100-300MM AUTOFOCUS ZOOM LENS fit on to my K-r at all and is there an adapter that will allow me to use the Sigma lens on the Pentax body. Things have certainly advanced since I last got involved with this pastime so any help will be greatly appreciated.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
For Sale - Sold: PK mount, Sears 135mm 2.8 macro soft focus	grahame	Sold Items	34	10-31-2013 07:23 PM
I think i want to cry. Tamron 300mm f2.8 woes.	gaweidert	Pentax SLR Lens Discussion	8	06-08-2013 04:04 AM
Upgrade K-r to K-5 to alleviate front focus woes?	devorama	Pentax K-5 & K-5 II	7	10-31-2011 05:46 AM
How to REMOVE a Pentax 60-300mm PK-A & R-PK Macro Zoom From my K-7	arimage	Troubleshooting and Beginner Help	17	02-24-2011 10:27 PM

10-04-2013, 08:53 AM	#2
scratchpaddy Pentaxian Join Date: Feb 2013 Location: Phoenix Posts: 3,361	Welcome to the forums! About that lens: sounds like it has Sigma's own SA mount, designed to work with their own DSLR's. The SA mount actually uses the same bayonet as Pentax, so it should fit on your camera just fine. However, the rest of the mount is a copy of Canon's EF mount, which is electronic. You won't be able to use the autofocus, and there's no way for your K-r to stop down the aperture. Also, the SA mount has a shorter registration distance, so the lens won't be able to focus as close, and it will be able to focus well past infinity.

10-05-2013, 03:16 AM	#3
Jean Poitiers Pentaxian Join Date: Apr 2011 Location: Lost in translation ... Photos: Gallery \| Albums Posts: 18,076	Welcome to PF and *bonjour* from France ... enjoy the forum and the K-r ... please post us an image or two soon ... *Salut*, J

10-06-2013, 10:14 AM	#4
Kerrowdown PEG Moderator Join Date: Aug 2008 Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake Photos: Gallery Posts: 57,819	Originally posted by Grumpylump Things have certainly advanced since I last got involved with this pastime Welcome to the forum, I thought exactly the same when I went predominately digital from years of film.