[Bela]

I have both the Pentax Rear Converter-A 1.4X-L and 2X-L that I purchased for my Pentax 300mm F2.8. Would these 2 converters be compatible with the Sigma (Pentax) APO 150-500mm F5-6.3 DG OS HSM in manual focus on my K5??

Has any one tried this combinations??

Thanks

[rvannatta]

I have both the Pentax Rear Converter-A 1.4X-L and 2X-L that I purchased for my Pentax 300mm F2.8. Would these 2 converters be compatible with the Sigma (Pentax) APO 150-500mm F5-6.3 DG OS HSM in manual focus on my K5??

Has any one tried this combinations??

Thanks

I would expect the protruding element to be an issue but don't really know. I have those converters likewise, and have made it a point to
stay with Pentax glass as I have regarded them as 'dedicated' converters. I do know they work grandly with all the classic long pentax
glass--- Both the A* 300 that you have as well as the A*400 f/2.8, 600 f/5.6 and also the FA*300 and the FA*600 and others exotics
that have the filter drawer in the back. I either have owned or do own all of the 5 lenses I specifically mention here, but with a converter like
those you would also have a question of optical compatibility as well as mechanical, and I have no clue.

[littledrawe]

I have both the Pentax Rear Converter-A 1.4X-L and 2X-L that I purchased for my Pentax 300mm F2.8. Would these 2 converters be compatible with the Sigma (Pentax) APO 150-500mm F5-6.3 DG OS HSM in manual focus on my K5??

I just posted your question in the lens sample thread for this lens, maybe the actual users of it will see it there and get back to us?

[Bela]

Good idea, Thanks!!!

[panoguy]

Ciao Bela (just had to write that), here is what I learned from a borrowed 2x-L:

Will it work?

No. The mount end of the 150-500 lens has two (integral) black plastic "blocks" cutting across the recess to the elements. Here is a photo where you can see what I mean.

See linked photo! It's very narrow at that point, and it isn't far from the lens mount. The "blocks" are thin plastic protrusions that seem to serve no functional purpose except to block access to the depth of the rear elements. My guess is that because the rear elements move forward when you zoom, Sigma wants to prevent users from sticking any longer TCs (like yours) in there and then zooming back to 150mm and knocking their TC front element with the 150-500 rear element.

[Bela]

Ciao Bela (just had to write that), here is what I learned from a borrowed 2x-L:

Will it work?


See linked photo! It's very narrow at that point, and it isn't far from the lens mount. The "blocks" are thin plastic protrusions that seem to serve no functional purpose except to block access to the depth of the rear elements. My guess is that because the rear elements move forward when you zoom, Sigma wants to prevent users from sticking any longer TCs (like yours) in there and then zooming back to 150mm and knocking their TC front element with the 150-500 rear element.

Panoguy,

Not what I wanted to hear, but thanks. Had I tried it, I could have destroy both the 150-500 & the TC. Thanks for the info!

As for the "Ciao Bella", I am not Italian (Hungarian decent) but I get the play on words . I am a 60+ years, 300 lb, grey haired old fart, Its nice to know I am still beautiful, thanks :ugh:

[Lowell Goudge]

Look on the sigma site for compatibility with their own TC. That is a starting point. If it can't work with their TC the Pentax rear converter does not have a chance.

Both TCs protrude into the lens, but the Pentax is actually deeper