Sigma 150-600 contemporary and 1.4 extender

I’m not sure if here is the correct place to post this question, so please forgive me if it isn’t.

I’ve just purchased the above lens (Canon ef fit). When I open a photo in Photolab (ether version 4 or 5) I am given the choice of lens profiles - Sigma 150-600mm F5-F6.3 DG OS HSM C with either ef 1.4x II or ef 1.4x III.

I’ve seen that there are Canon 1.4 extenders version II and III and so I am assuming that Photolab is offering me a profile for my Sigma lens with a choice of Canon extenders.

If that is so, am I better off using the mark II or III and will DXO be bringing out a profile for the Sigma lens and the Sigma extender.

Of course, I may have misinterpreted the evidence. But any advice given would be gratefully received.

Best wishes

Hello Malcom,

for now we have done modules for Canon extender, we will look to add Sigma ones.
If you have bad resutls using existing profiles (which is possible as there is some glass in the extenders) please infrom me.


HI Marie
Thank you for your reply.

I’ve only taken a couple of photos with this combination so far - all of the moon. To be honest I cannot tell the difference between the 3 choices offered to me (no lens correction or the lens and the mark II or mark III teleconverters).
I will make a more ‘scientific’ comparison when I have some better photos to test.

Best wishes