Hi Guys..I have a Question for you about 2 lenses that I own and looking to avoid any duplication in my kit bag

I own BOTH the 70-200 mm f2.8 IS L lens and the 100-400 mm IS L lens and was wondering If I used a x1.4 teleconvertor, would that effectivley make my 100-400 mm IS L lens redundant as the focal lengths will be similar? Also , will the 70-200 mm f2.8 IS L lens suffer from very obvious IQ degradation when coupled with a X1.4 teleconvertor?

I know that you lose a stop of light so my f2.8 70-200 mm will become an F4 70-200 mm lens, but will the IS feature still work with a teleconvertor? or should I keep both lenses as i am thinking maybe I should ebay the 100-400 mm L IS lens.

For what it's worth, I will be using both lenses on a 1d mkIII or a 5d MKI.

thanks in advance

I dont think the lenses overlap that much. The 100-400L will still have an extra ~120mm reach and would probably AF faster than the 70-200L IS + 1.4X.

You 70-200 with a 1.4x added will end up as a 98-280 F4 so the 100-400 still has 120mm to go which is a noticable difference.
The 70-200 IS does not take tc's very well but the 1.4 is better. If you try it with a 2x then it degrades alot and the 100-400 will give much better quality.

You could however think about selling the 100-400 and getting the 1.4 and a 400 5.6 prime which is good value and probably the best bang for your £ in the long lenses. you will not have IS on the 400 but thats the only downside.

Also note that you keep IS on the 70-200 with a TC.

I use the 70-200/2.8 IS with a 1.4x TC to shoot dog sports outdoors. Yes the IS still works. The AF loses a bit of speed, but its not horrible. I just feels a little less "snappy".

I have noticed that with the TC strapped to it, the normally beautiful bokeh of the 70-200 is a bit more "nervous", sometimes to the point of distraction (for me, anyways) if there is a busy background (say a fence, as an example) in a shot with some length to the DoF.

I have noticed a tiny bit of halation as well, but the 70-200 takes a 1.4 TC very well.

Eventually, I would like to buy the 100-400, but still keep the 70-200. The 100-400 is what I am trying to replicate with my 70-200 + 1.4 combo due to lack of finances, but the 70-200 is such a fantastic lens which excels at so many things, I dont ever see myself giving it up for anything.

I would not call owning both "redundant".

Thanks for the feedback, Lance. I have a Kenya sfari coming up and I really should use the 100-400 mmL IS on my 1d mkIII to take advantage of the x1.3 crop instead of adding a TC to th 70-00 f2.8 IS L.

I know will be very reluctant to selt he 100-400 mm when I get back!

For safari, why not use the 100-400 + a 1.4 TC? I have never been on safari, but having read a few threads here by people who have, a 100-400 may be a little short in some instances.

Perhaps people with some safari experiences could add something?

Afaik, on a 1 series body, you will still have AF using the 1.4TC on an f/4-5.6 lens too!

I'd be reluctant to use a TC on safari with the 100-400 mm lens as it's slow enough to begin with and the losing another top of light would make it had to get a sharp shot unless i really crank up the ISO,

bluefox9er wrote:
I'd be reluctant to use a TC on safari with the 100-400 mm lens as it's slow enough to begin with and the losing another top of light would make it had to get a sharp shot unless i really crank up the ISO,

... but if shooting with a 1-series, high ISO shouldnt be too much of a concern, should it?

smiles..i had better get some practise at a zoo. my last safari i used a rebel xti and a 70-200 mm F4 without IS just over a year ago :-)