Teleconverter pros/cons

[DanCanon]

I am considering purchasing a teleconverter and would like to get anyone's opinion who has one or has used one. I have heard good and not so good things about them. Is it worth the money or am I better of buying a telephoto lens?

 

[epp_b]

Pros:
- More reach for cheap

Cons:
- They degrade quality more than some would deem acceptable, especially 2x TCs
- They only work well on fast primes, and OK on fast zooms
- They can limit or cripple AF and metering systems with some lenses

 

[gsgary]

It's all down to the lenses you have, top quality primes they work great i have the Canon 1.4X and 2x Kenko pro300DG and it is wicked on my 300F2.8L but i wouldn't use it on a zoom

 

[Overread]

There are 2 types of TC on offer for canon users:

1.4TC - probably the best sort of TC on the market - it offers you a gain in focal length with minimal loss of image quality (on top end lenses image quality loss in the field is almost impossible to notice) and only reduces your max aperture of the lens by one stop. This does mean that an f4 lens is the smallest aperture (remember smaller aperture bigger f number) lens that you can use on on and still retain your auto focus

2*TC - this is different beast altogether - image quality takes a noticable hit with this TC (Even pro grade lenses have image degradation - however they are able to suffer this and still deliver very good results); and you also lose 2 stops of light - so f2.8 lenses or wider only - unless you intend to work only with manual focusing.

ITs also important to note that teleconverters will only work with specific lenses - canon TCs will only work with L grade lenses and even then they do not work with the entire range of L lenses. Sigma make a good 1.4TC which is comparable (image quality wise) to the canon - though it lacks the weather sealing of the canon. The sigma 2*TC is slightly softer than the canon and also not a full 2times increase in focal length (about 1.95 in actuality) so it a tiny bit shorter. Chances are most times this difference is not going to be that noticable were you working in the field.

Also as TCs degrade image quality they do only work on the better lenses - lower grade lenses will suffer image degradation and chances are will not make up for the increase in focal length