Questions about teleconvertors

[Deleted member 11679]

Howdy do,

In my ever on-going weighing up of a zoom lens for the Motorsport season this year, I now have a few quite simple questions (probably) about teleconvertors.

Will a Canon 1.4x or 2.0x convertor work with Sigma lenses? Or are they specific to their range of gear? And is the same in the opposite direction to, will Sigma convertors work with Canon gear? If so, which are the best to get?

I understand that when you apply a 1.4x convertor you lose one stop on the f/ number, and then 2 stops on the f/ number for a 2.0x convertor. However, is the 2 stops across the zoom range on the 2.0x convertor or is it only after a certain amount of zoom is applied?

My reasons for asking this was that I first weighed up the Canon 70-200 f/4 L lens, then the Sigma 100-300 f/4, and now I am currently thinking the Sigma 70-200 f/2.8 as this would allow me to use it in darker locations i.e inside gyms or swimming pools!

I'm quite pleased I have got a couple of months to weigh these ideas up as I really want to get the right lens for me (sports shooting Motorsport, swimming and other events.)

 

[Deleted member 11679]

Interesting reads so far, thanks. After seeing quite a lot of photo's now with the 70-200 f/2.8 I am really impressed so far, my other thought with this is, that if I buy a Sigma 1.4x TC then I will effectively have a Sigma 100-300 f/4 on my hands!

 

[Deleted member 11679]

tested the lens and tc today and i was pleasantly suprised.

shooting wide open with the tc attached (f5.6) gives about the same sharpness and contrast as shooting wide open with no tc attached(f2.8).
the only concern now is af speed and hunting which shouldnt be to much of a problem in bright conditions.

Any chance of some test shots TRiP? So have you got the Sigma 2x convertor or the Canon one?

I was looking on Pbase at a lot of photo's produced by this lens, there was some great F1 shots even with what appeared to be a 2x convertor and at 400mm.

 

[Deleted member 11679]

Interesting, still hard to judge but I will watch out for photo's, thanks.

Joe, let me know how you get on with your 1.4x mate.