Looking for an extender that is compatible. Does an aftermarket product exist, Canon versions are not compatible?
I did a little online recon, and I think the answer is probably a no. Sigma and Tamron only say they support their line of lenses, so I am not even sure if there are dependencies on the electrical contacts for the the TeleConverter to match the lens brand. The issue I saw noted was that the rear lens element on 70-300 will come out to the back of the lens and contact the front element of the extender. You will notice different extenders from different brands have a front element that protrudes a bit forward. Many lenses have the rear element noticeably recessed. Looks like the 70-300 is the only one with that issue you have brought up however, consider it a design flaw. It may be easier to consider upgrading to the 100-400L.
if that lens has a long working distance would putting a slim extension tube inbetween the lens and extender help,? i guess it depends which end of the focal ditance you want, macro or long distance.
Good call, the extension tube in theory would work to allow mounting without physical issues. But yes it would take away infinity focus negating the advantage of adding the TC to extended the lens for long focal distance. I did read that you technically can mount it if you leave the lens at the far end as the glass will be further inside at the 250-300mm range. So you should be able to use the long end. So there may be advantages of attaching the tube for some use at the shorter end of the zoom. Still may be worth considering the upgrade to the 400mm instead.
i only have the x2 iii converters, do the ii or i have a different lens arangement, i dont know if they will fit some one here might, i ask as it was mentioned that the x2 need an extension tube to stack where the ii dont, how that would work with the lens mentioned i dont know as i not familiar with its butt end
I don't own any of them either, nor the lens, but every TC hat I see protrudes forward, and when retracted that lens has the element com right to the back of the lens, hence the issue, and assumption it is a problems with any TC.
Thanks for the intel. I’ve had the 70-300 now for a few weeks, happy with it and looking for further length vs. budget. The Canon 100-400 not an option but I see a Sigma would cost effective. Any thoughts on the Sigma 100-400?
yes i have the sigma 100-400 c, two words "get it" !! its a fantastic lens i also use the x2 iii with it and the auto focus works fine with the x2 i have even had 2 x2 and a few ext tubes to get x5 macro out of it all this on my M50 , so i get the 1.6 x also as the M50 is a crop sensor i bought my sigma new for around £600 from park cameras in london start of this year and its been a fantastic lens, has great features nice weight to it i hand hold it all the time never needed a tripod when doing wild life.
