Sigma 120-300 f/2.8 EX OS

Maximono wrote in post #13463611
Got out in a bit better light today and got some nice Shots. All taken with the 1.4x Canon mk2 TC attached. I was really pleased with the quality and got a nice sharp image at 420mm wide open at f/4, these were both at F5.6 though.

IMAGE LINK: http://www.flickr.com/​photos/acwildlife/6420​331435/
Redshank - Off To The BTO by iBirder Formally Wales Birder, on Flickr

IMAGE LINK: http://www.flickr.com/​photos/acwildlife/6419​476657/
Snow Bunting - Golden Hour for a Golden bird by iBirder Formally Wales Birder, on Flickr

Ashley, how is your AF speed? Does the Canon 2x TC slow down your AF considerably? I know it does that with Canon lenses, I'm just not sure if that's how it works with Sigma lenses as well.

Got my new Vanguard ball head and put it to the test. Finally, no sloppyness, no wobble.
Just a quick indoor shot with the MC7 2x TC, 600mm, f/6.3:

gabebalazs wrote in post #13463944
Ashley, how is your AF speed? Does the Canon 2x TC slow down your AF considerably? I know it does that with Canon lenses, I'm just not sure if that's how it works with Sigma lenses as well.

Hi, Im only using the canon 1.4x TC at the moment, I've just ordered a Sigma 2x DG tonight as I tried the kenko 2x DGX in a shop today and wasn't impressed by there price compared to what I could get a new sigma 2x for. I'd imagine the canon extender wouldn't improve AF speed over the sigma or kenko extenders as it's really down to how fast the lens is to begin with. the new Canon mk3 extenders and mk3 lenses will focus well together and possibly faster if not more accurately due to canon putting better focusing chips into both bits of kit so they work well together.

Maximono wrote in post #13464723
Hi, Im only using the canon 1.4x TC at the moment, I've just ordered a Sigma 2x DG tonight as I tried the kenko 2x DGX in a shop today and wasn't impressed by there price compared to what I could get a new sigma 2x for. I'd imagine the canon extender wouldn't improve AF speed over the sigma or kenko extenders as it's really down to how fast the lens is to begin with. the new Canon mk3 extenders and mk3 lenses will focus well together and possibly faster if not more accurately due to canon putting better focusing chips into both bits of kit so they work well together.

I see. What I was referring to is that the older (I and II) Canon TCs slowed down AF speed of Canon lenses as much as 50%, supposedly to achieve better accuracy. I presume that was intentional and caused by the electronics in the TC + Lens combo and not just merely having less light due to the TC.
Just like you mentioned, the new III TCs and new II series superteles would not slow down as much. I think there is still some AF speed reduction though.

I've read somewhere that there is no such intentionally controlled electronic speed reduction in third party TCs, so I assume any potentional reduction in AF speed with a Sigma (or Kenko, or Tamron) TC is only due to physics, having less light for the AF system to work with and not due to some chip inside the TC.

Just ignore me, I'm just thinking loud...

Looks like I have too much time on my hands, here are some more indoor shots at 600mm. These look great to me for 600mm but obviously these are controlled indoor shots, manually focused...

600mm f8:

Content warning: NOT AN IMAGE

Awesome shots guys, love the birds (which is what I'd use this lens for) and the closeup of the cat is very nice!

This lens and corresponding TCs will definately be joing my collection once I save up the coin!

Wow, Gabe. This lens takes a 2x like a champ!

gabebalazs wrote in post #13464745
I see. What I was referring to is that the older (I and II) Canon TCs slowed down AF speed of Canon lenses as much as 50%, supposedly to achieve better accuracy. I presume that was intentional and caused by the electronics in the TC + Lens combo and not just merely having less light due to the TC.
Just like you mentioned, the new III TCs and new II series superteles would not slow down as much. I think there is still some AF speed reduction though.

I've read somewhere that there is no such intentionally controlled electronic speed reduction in third party TCs, so I assume any potentional reduction in AF speed with a Sigma (or Kenko, or Tamron) TC is only due to physics, having less light for the AF system to work with and not due to some chip inside the TC.

Just ignore me, I'm just thinking loud...

That's interesting actually. I know that from reading on canons site that the 1.4x tc slows af by up to 50% and the 2x is infact up to 75%. I didn't realise it was slowed down for accuracy but I guess that makes sense. I'm wondering now if my canon 1.4 is now slower than if I got a sigma but then also If I'm gaining on accuracy. Hmm. Can anyone who has both the canon 1.4x and the sigma or kenko confirm any difference?

All with the 2x III at 600mm

Great egret is almost full frame
Kingfisher heavy crop
Stonechat is cropped

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OK, now we're talking! Keep those bird images (especially BIF) coming! I love that kingfisher.

love the Egret in flight and with a 2x thats awesome

Taken in really low winter light at 420mm wide open at F/4, fully processed. Im really pleased with the sharpness.

IMAGE LINK: http://www.flickr.com/​photos/acwildlife/6427​033005/

^^These last few rounds of sample shots have me wondering if I need to buy one of these...

can

kenko 1.4 420mm 4.5

both at 600mm 6.3

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