Teleconverter for 600D with Sigma 70-200mm f2.8 EX DG OS HSM?

[CgRay]

I've been reading that 2x teleconverters aren't that great. That they can cause a lot of image quality loss as well as slowing down or even stopping auto focus from working altogether. What do I need to know about teleconverters to make an educated purchase?

Thanks,
Cg.

[cicopo]

This is the best info I know of.

http://photography-on-the.net/forum/showthread.php?t=41922

Adding a 2X to an f2.8 lens will still allow Af on most bodies because you're now an f5.6 lens. It may degrade the image a bit depending on the specific TC so do your homework before shopping.

[ebiggs1]

Anytime you add anything into the light path of any lens, you are going to degrade the image quality. Now, that may be a slight or it can be a significant loss.

I have always subscribed to using the original manufacturers accessories and in this case I still think so.

Sigma makes two tele converters that will work with your lens. Both are designed for your lens and retain all features including AF.

The Sigma 70-200mm f2.8 EX DG OS HSM is of such high quality it has room to give up a small amount of IQ, introduced by the tele converter, and still be better that some 70-200mm without one.

Another consideration is how big do you intend to make the prints? Do you use a tripod?

So you must weigh all the factors of IQ and cost plus slower AF, etc, and decide if it is for you.

I recommend the 1.4x over the 2x, though.

[CgRay]

@ cicopo. Thank you. That's a hell of a lot of information.

@ ebiggs1. Thank you also for your insight. From the information I have researched so far, I was leaning towards the sigma 1.4.

I'm not buying for a while, so I have plenty of time to learn more.