Lens choice. Any advice?

[Rich_F]

I'm starting to get more serious about my motorsport photography (website is www.auto-focus.co.uk if anyone wants to have a look) and have recently invested in a 10d. Unfortunately this is currently being strangled by a 75-300 EF lens.

I want to upgrade to an L lens and a friend raves about his 100-400 IS which he has had some impressive results from. The other (more expensive) option is the 70-200 IS and a 2x converter. Does anyone have any personal experience of these lenses they could share. Would the 70-200 be worth the premium over the 100-400? I'm lured by the fact that it is f2.8 but if I need to use the converter most of the time this advantage would be negated. Is it likely to be faster or sharper than the 100-400?

Any comments would be greatly appreciated.

[gi_gav]

I'm guessing you'll be shooting trackside?

This is one of the perennial debates in terms of canon lens choice.

Personally, I went for the 70-200 2.8 IS (also with the 10D) and it is beautiful.

I haven't yet used the 100-400 but it's also a great choice.

I personally value the aperture over the range, as i can shoot at lower ISO in poor light and then crop to get better framing. The alternative is shooting with the 100-400, getting better range at a higher and grainier ISO then using something like Noise Ninja to reduce the noise.

I also prefer having the 2.8 for pit shots and portraits, and the 70-200 has the more recent IS that compensates for 3 stops as opposed to 2 for the bigger lens.

Bear in mind also that the 10D's weakness for motorsport is that the focussing isn't in the same class as the 1 series bodies, meaning that a faster lens will allow you to autofocus quicker.

As regards the teleconvertor, I've used the original (Mk 1) 2x and wasn't convinced at all. Definitely slower and seemed to confuse the autofocus. Also was visibly less sharp.

I've heard that the Mk 2 2x is better, but still a compromise.

Hope this rambling helps, but I don't think you'd be making a mistake either way!

[Rich_F]

Thanks Gav.

It will mainly be for shooting trackside. In an ideal world I'd choose the 70-200. Unfortunately cost is going to be a factor so I may have to "settle" for the 100-400. I'm sure that whichever I choose will be a vast improvement on the standard lens I'm currently using.

Another thought which has just occurred to me is to look for a 70-200 f2.8 non IS lens. Do you know if the optical quality of this lens is as high as the later IS version? I understand Canon also used to make an F4 version?