>>2989727Depends what you're shooting, they lose 1-2 stops of your aperture and don't give much in return that cropping won't give you, or having two lenses (one heavy and one light)
That F4 lens becomes a F5.6 with 50% loss of light and shutter speed to gain 40% zoom (less than the lost stop)
In general it seems the people who actually like the extender are those who have it bringing a F2.8 lens to F4.
At F4 they can still manage sports or birds during daylight, and non-action stuff in less-than-daylight.
If you start with F4 and extender changes it to F5.6, it's a pain in the ass how limited it is. It becomes too slow a lens for sports/wildlife and suffers during imperfect lighting.
Treating it like a F4 and trying to fix the shots in post will just get lower or same quality as simply digital cropping to get the exact same 40% zoom area with the no-extender wider aperture. With the added penalty that the extender doesn't allow you to choose the location of the cropping later.
They're very expensive for how limited they are (I have one lens that works with my extender, none of the rest of my collection) They don't necessarily improve quality, or save weight. I guess the one and only upside is having extra choice between close or far zoom.
Sure, a 70-200 F2.8 with extender might weigh 835g less than a 300mm F2.8, but the extender combo is only F4.
The 300mm F4/L IS is 525g lighter than the 70-200 with extender.
The weight difference between having a 70-200mm + extender versus carrying a 300mm + a 50mm prime isn't really significant. Nor a significant difference in space. Nor in swapping, you won't get wide-angle shots with the 98mm minimum on the zoom if you don't take the lens off to remove the extender, and it's just as fast to replace the 300mm with the 50mm and get much wider view. Or switch to 85mm or 40mm or whatever you want.
This is probably why gear-a-holics talk about the extender but I almost never see real pro photographers use them really.
