to replace the 70-300 with prime lens?

Hi,
i've to change what has been my first len, the sigma 70-300. My camera is an old 350D but i'm waiting for the new 5D to pass to ff. The first choice of course would be the canon 70-200 f2.8 is II but unfortunately it is too heavy for my poor back and too heavy of course is the no IS version. I've to discard 70-200 f4 too because i use this range of focals for concerts and sports events and i need luminous lens. To solve the problem my new idea is to opt for two prime lens as 135 f2 and 200 f2.8. The advantage would be the light weight, they are luminous, black and very good. On the other side the disadvantages would be the missing of the IS and the missing of the comfort of a zoom. What do you think about that, is it a good choice or do you think there are other solutions?
Thanks

Nothing wrong with those two lenses. Another option would be to upgrade your 350d to one of the newer Rebels. You'll easily get 2-3 stops in increased high iso and more resolution. Cheaper than either one of your prime lens choices. Use it until the new 5D is released (whenever that may be),

when i sold my 70-300, i looked at the shots i took with it and found most of them were 230-300. i got the 300 f4. if the 70-200 2.8 is too heavy, take a look at the 70-200 f4. it's light

Also you will need to be closer with a 70-200/ff combo vs a crop and 70-300. To be honest to get near the same mm you would be 400-500 range on ff. just a thought, but a 7d or 50/60d and a lighter non is f4 with a tele 1.4 extender. Like others pointed out the F4 non IS is light, sharp and with the better iso handling of the newer bodies you will gain in all areas. Good luck with your shopping.

yesterday evening i was at a meeting, i tried to shot some photos with my lighter lens: 50 f1.8 and 100 f2.8 macro a i saw that i was to the limit to get good photos. Anyway i feel the need not only of light lens but of zoom too. Maybe the only solution is taking thr 70-200 f4 IS for light environment and 85 f1.8 or 125L or 200L for other cases.

other option: 70-200 f4 is and 135 f2L plus tele-converters 2x III so i'll have this focal

70-200 f4
135 f2
270 f4

what body are you upgrading to?...the ISO capabilities of a newer body in comparison to your older body may be all you need to pull off the 70-200f4...

DreDaze wrote in post #13904952
what body are you upgrading to?...the ISO capabilities of a newer body in comparison to your older body may be all you need to pull off the 70-200f4...

i think it'll be the new 5D but it depends on its features and cost. In the worst case it'll be the 5D mkII