Thirst For Lenses

Its been a good few months since i bought anything tasty for my camera, and i got this itchy gremlin that is telling me to buy something. maybe its an addiction!

been lookin at cheaper alternatives to the £1000 lense that i was dribbling over a few months ago, it really isnt a good idea to buy the canon 70-200 2.8L IS USM, so im thinking i can actually get two lenses for that amount of money and then maybe upgrade later, when photography isnt jsut a side hobby.

so im lookin at two lenses now the 17-55 f2.8 IS USM at £500 or EF-S 10-22mm f/3.5-4.5 at £350. the 17 ive been reading good reviews about plus it has that f2.8 ive sorta chose that one but it really is the price that gets me. still thinking.

and then the other option is at the longer end the previous 700-200 f2.8L IS USM could be replaced with the 70-200 f2.8L which is alot cheaper! or even cheaper will be the f4L version which ive read is more value for money.

i have a 28-135mm IS USM which isnt long, but it isnt wide either. it really is a good lense tho, and with a 1.6x cropped sensor on the 400D it is quite an adequate zoom.

im stuck. it would be nice to take pictures until after dusk, but would i really?
i dont think ive been taking pictures long enough to figure out my patterns. i know at least that i dont like to carry a tripod everywhere i go.

to be honest im not sure if i can tell the difference with the lenses sharpness yet. i jsut like the wide apertures. The kit lenses isnt really so bad. mind you, lense distortion is a big problem with it at the 17 end (photoshop easily fixes it)

THIS IS AN EXPENSIVE HOBBY! playing with PCs is alot cheaper. (geek)

Current Kit
Canon 400D
28-135mm IS USM
50mm 1.8 mkII
17-55mm kit
3 batteries
4GB extreme II CF
some cheap tripod

any advice would be appreciated!