[cdubuisson]

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I just recently purchased some lenses on ebay and out of them is a Sigma 28mm f2.8. To be specific this is the title "SIGMA-Z Multi-Coated 28mm Thread Mount 1:2.8 Camera Lens W Hood Case 2 Cups Z mm". What is a thread mount and will it fit my pentax k-x? Since I bought my camera two years back I've been meaning to go lens shopping but I know nothing about lenses and this site has been EXTREMELY helpful to me. I abandoned my camera for polaroids but it was starting to get a little pricey for me.

ps. I'm new on here so HELLOOOO EVERYONE!

[Adam]

Sigma lenses will work on Pentax cameras, but they have to have the K-mount (and it doesn't sound like the one you're referring do does).

Here's the only 28mm F2.8 Sigma lens that I was able to find in our DB:
Sigma 28mm F2.8 Mini Wide II-- Manual Focus Lens Reviews - Sigma Lenses - Pentax Lens Review Database

[cdubuisson]

oh darn, is there an adapter I can get?

[Chaos_Realm]

oh darn, is there an adapter I can get?

post and image of the rear mount and it should be easy to identify.

If it is threaded it is probably what they call and M42 mount, and there are plenty of adapters for them


Edit: Is this the Item? http://www.ebay.com/itm/SIGMA-Z-Multi-coated-1-2-8-28mm-M42-thread-mount-Lens/251105754009

If yes then it is an M42 mount and you need an 'M42 to K-Mount adapter"

[cdubuisson]

ohh noo mine was wayyy cheaper. This is it: Sigma Z Multi Coated 28mm Thread Mount 1 2 8 Camera Lens w Hood Case 2 Cups Z Mm | eBay
and I bought this adapter because I bought another lens that needed an adapter Pentax M42 Screw Lens to PK K Adapter Infinity Focus for K10D KX KM K7 K5 | eBay This is what you are referring to right? I'm not sure if it is legit or not. I'm on a bit of a budget but then again I don't want something thats not going to work.

[cdubuisson]

besides the price haha yeah that is the lens that i got

[Chaos_Realm]

ohh noo mine was wayyy cheaper. This is it: Sigma Z Multi Coated 28mm Thread Mount 1 2 8 Camera Lens w Hood Case 2 Cups Z Mm | eBay
and I bought this adapter because I bought another lens that needed an adapter Pentax M42 Screw Lens to PK K Adapter Infinity Focus for K10D KX KM K7 K5 | eBay This is what you are referring to right? I'm not sure if it is legit or not. I'm on a bit of a budget but then again I don't want something thats not going to work.

OK well it is definitely not an M42 Screw mount so the adapter isn't needed. It is a Bayonet mount and more specifically it looks like the K-mount but it has an aperture coupling that I haven't seen before, yet it seems to be in the right place so it probably is but I will leave the mount ID up to someone that knows the sigmas'.

[elliott]

Looks like Pentax mount to me too, red dot, bayonet lugs and aperture lever all seem to be in the right places in relation to each other.

[cdubuisson]

OK well it is definitely not an M42 Screw mount so the adapter isn't needed. It is a Bayonet mount and more specifically it looks like the K-mount but it has an aperture coupling that I haven't seen before, yet it seems to be in the right place so it probably is but I will leave the mount ID up to someone that knows the sigmas'.

Is the aperture coupling a good thing or bad thing?

[cdubuisson]

and thank you sooo much for the help!

[elliott]

Is the aperture coupling a good thing or bad thing?

It should be fine just a different style, if it worked on the old film SLRs it should work on a DSLR. There are no A contacts though, so you'll need to use M mode with stop down metering.