Sigma mount conversions to Sony - No long lenses?

Hi,
I don't know if the answer to this is known, but I find it curious that you can convert the mount on Sigma lenses to Sony but only with a select series of lenses. For example, the long sport zooms(150-600/60-600) it is not available. 
Is this a licensing issue or is it expected to be available at some point in the future?
I guess a canon mount plus the MC11 is the only option?
thanks
Scott

I also think it's strange that no long Sigma zoom lenses are available in E mount. No idea whether its a licensing issue. What I can say is that after trying several Sigma 150-600S lenses with several MC11 adapters.. I would stay away from that combination. Afc simply doesn't work from just under 500mm upto 600mm anywhere between close focus and 10 meters. My camera store sent me the new 60-600Sport lens, Canon mount. to test and that works brilliantly with the MC11.
Rene

The reason they are not available is because it would require a redesign with linear stepper motors to get the same level of performance, something that's not needed in the ART series as they aren't action oriented lenses.  It would be a massive investment by Sigma to do that for a very small market at the moment.  Now that Nikon and Canon are in the mirrorless game, as those systems become a larger piece of the overall volume, the market will increase enough that linear stepper motor design versions of these lenses would start to make sense.

E.J. Peiker wrote:The reason they are not available is because it would require a redesign with linear stepper motors to get the same level of performance, something that's not needed in the ART series as they aren't action oriented lenses.  It would be a massive investment by Sigma to do that for a very small market at the moment.  Now that Nikon and Canon are in the mirrorless game, as those systems become a larger piece of the overall volume, the market will increase enough that linear stepper motor design versions of these lenses would start to make sense.

Thanks, EJ, that makes a lot of sense. Is that the reason why adapted lenses(i.e. Canon to Sony) don't work as well as they do on native bodies? Or is it a small miracle they work at all? 

Scott Fairbairn wrote:

E.J. Peiker wrote:The reason they are not available is because it would require a redesign with linear stepper motors to get the same level of performance, something that's not needed in the ART series as they aren't action oriented lenses.  It would be a massive investment by Sigma to do that for a very small market at the moment.  Now that Nikon and Canon are in the mirrorless game, as those systems become a larger piece of the overall volume, the market will increase enough that linear stepper motor design versions of these lenses would start to make sense.

Thanks, EJ, that makes a lot of sense. Is that the reason why adapted lenses(i.e. Canon to Sony) don't work as well as they do on native bodies? Or is it a small miracle they work at all? 

Yes that is a major reason why DSLR lenses typically give up focus speed and tracking when adapted to a mirrorless camera.  It is of course way more noticeable on telephoto lenses it is since much more likely for a telephoto to be used for any kink of continuous AF due to subject motion.