telephoto extender? worth it?

[rweakins]

I have been looking at some longer telephoto lenses. I have a canon 70-200 f4L. just curious to see what the reviews on an item like the canon telephoto 2x extender i could get and make sure it's compatible with a rebel xt as well as a 40D

 

[rweakins]

I have been looking at some longer telephoto lenses. I have a canon 70-200 f4L. just curious to see what the reviews on an item like the canon telephoto 2x extender i could get and make sure it's compatible with a rebel xt as well as a 40D

meaning is the extender a good enough product to "substitute" for a longer telephoto lens

 

[R.Youden]

I am in a similar situation.

I have the 40D with the 70-200mm f4

From what I can understand the 1.4x and 2x are good devices. The downside with the 2x is you loose a bit of picture quality and you get no autofocus which is a shame. But it is a damn sight cheap than buying a new 400mm lens. There is a very good review here:

Digital Picture Review

Let me know how you get on, I am very interested in the extender too.

 

[Kebabselector]

I have the 1.4ex for use with my 70-200 f/4 and my 300mm f/4. It's nice to be able to have slightly longer lenses but I personally don't think it's a substitute for a the real thing (though, the reality is money. The £200 I spent on the 1.4ex got me a 420mm f/5.6 IS lens - which I guess isn't too bad).

I found performance not too bad, but the images are a little softer with the 1.4x (and apparantly worse with the 2x).

 

[rweakins]

darn being a broke college student who can't afford, or even come close to affording, the glass he wants

 

[compuwar]

In general, I find 2x teleconverters to be not able to produce images up to my standards when mated with a prime lens designed to go with the converter. However, you may have different standards of acceptable for your images- so if you have a place where you can try one out, you may find you can accept the trade-off.

I'm generally ok with 1.4x TCs, though on some zooms they just don't seem to work well at all. Nikon offers a 1.7x that matches the long superteles well enough to be just inside acceptable for me, but that's with a very stable shooting platform and reasonable shutter speeds- but a 2x TC is just too much of an image quality trade off for me. Others seem to get good images with them, but I'm very picky and haven't been able to reproduce their results despiite a lot of experience with long lenses.

 

[ChrisA]

I have been looking at some longer telephoto lenses. I have a canon 70-200 f4L. just curious to see what the reviews on an item like the canon telephoto 2x extender i could get and make sure it's compatible with a rebel xt as well as a 40D

Most people find that the 1.4X extender is the best one to get.

The 2X extender causes your lens to loose two stops. Making an f/4 lens and f/8 lens. But read the specs on your camera body. I think you need at least f/5.6 to make the auto focus work. If you use a 1.4X extender then you loose only one stop so your f/4 lens becomes an f/5.6 lens and will still auto focus

The math is not complex. f-number is simply the focal length over the lens diameter. A 2X extender makes the lens twice as long but the diameter remains the same, so the f-number doubles which means two stops. ("stops" are set up so that each doubles the effective square area of the lens' front element, hence the progression 2, 2.8, 4, 5.6, 8,...)

The 2X extender is only really usable on a fast f/2.8 lens. It will turn one of those nice fast lenses into an f/5.6 lens which is still usable.

 

[pinktank]

1.4 one is very useful for bird photographers and the like