About teleconverters

[TiaS]

I have been looking at teleconverters for my Canon Rebel XS. It seems that most of them mount on the body and than the lens, from what I understand, mounts on the converter like it would the camera body. However some are made to screw into the threads of the lens. The differences in the 'why' of the different types are unclear to me, as well as the effectivness for the two types as far as IQ goes.

Another area of confusion is that some of my lenses focus from turning the ring at the front of the lens, but my one lens focuses from the rear of the lens. I am uncertain if all teleconverters compatible with my camera body are also compatible with all my lenses.

Some teleconverters seem to be compatible with auto focus and some with manual focus only. I have also read something about some not being compatible with zoom, but that doesn't seem right to me as that is from the lens itself.

If anyone can help clear up any of my confusion, any help would appreciated.

 

[Overread]

First lets simplify this down - what lenses do you have for your canon system that you are hoping to use the teleconverters with?

 

[TiaS]

I have a Canon 100-300 that I want to increase my zoom for the iceberg season and maybe some birds this summer too. It is a slow lens and so I have purchased a tripod. It is abit soft at 300, so I want to get a telecoverter that is 1.X5- 2X but no more as I am worried about IQ.

 

[gsgary]

I have a Canon 100-300 that I want to increase my zoom for the iceberg season and maybe some birds this summer too. It is a slow lens and so I have purchased a tripod. It is abit soft at 300, so I want to get a telecoverter that is 1.X5- 2X but no more as I am worried about IQ.

Forget it that lens is not good enough to cope with a TC, it's not that good without one

 

[icassell]

First off, the Canon TC will not work with that lens. As gsgary says, you want good glass before you start adding a TC, because the TC will only magnify the flaws of the original lens. They work best with high-end primes, but can be put into service with other lenses. If you want to try one with that lens, you might consider the Kenko Pro, the Tamron, or the Sigma (I'm not sure if any will fit it, though). On a second note, 2X converters tend to be far worse than 1.4X. Even on my Sigma 100-300 f/4, the 2X isn't very good (and it is a good lens and matched to the TC). If I were you, I would save my pennies for a better lens first (maybe a 100-400).