Here's my 2 cents worth:Current lenses:
(in order of current frequency of use, most used first, least used last) - Canon EF-S 15-85mm f/3.5-5.6 IS USM
- Default lens on my 7D. Very versatile zoom range. Sharp & contrasty at all focal lengths. Above average build quality. Good bokeh. Very useful 4-stop IS. - Canon EF 70-300mm L f/4-5.6 IS USM
- very sharp, also at 300mm wide open. Quick, accurate USM AF great on my 7D for birds in flight, etc. Built like a tank. Very hand holdable esp with 4 stop IS. - Canon EF 100mm f/2.8 USM
- great macro lens, awesome detail at 1:1, great bokeh, good working length. Nice for subject isolation @ f/2.8. Hand-holdable for tele-portraits in decent light. - Sigma 10-20mm f/4-5.6 HSM EX
- great for ultrawide shots - 95% of time used @ 10mm. Good sharpness & contrast corner to corner. Bit of a focus issue at times which I overcome using manual focus. - Canon EF-S 18-55mm f/3.5-5.6
- I occasionally use it on my Canon 350D when I want a light & non-intrusive DSLR pacakge. I might give this away sometime in the future.Former lenses
(which I've now sold - loosing a bit of money on each, but I used each for some years, so I'm ok with that) - Canon EF 28-135mm f/3.5-5.6 IS USM
- my previously most used lens until I got the Canon 15-85mm. I had a decent copy (quite sharp & contrasty at most settings). - Canon EF 100-300mm f/4.5-5.6 USM
- good IQ at wide end. Low contast & not sharp from 180ish till worst at 300mm. USM focus fast & consistent. Lack of IS = hand-holding issue. - Canon EF 50mm f/1.8 mk II
- decent images possible with right settings. Unreliable, slow AF (even on 7D) is its downfall. Sharp from f/2.5, very sharp @ f/4 to f/8. Poor bokeh though.Dream lens to complete my kit
. - new Canon EF 50-70mm USM fast prime
: ideally f/1.4 - f/1.8. USM focus a priority (or STM as a possibility). IS would be a bonus, if it doesn't add too much weight & cost.
This lens must have great IQ (sharp, contrasty, low CA) & smooth bokeh wide open for me to consider it. I would use it for low light photography, subject isolation & of course portraits.
The current Canon 50mm f/1.4 doesn't have the IQ wide open I want, nor true USM.
I find the Canon 85mm f/1.8 both a bit too long focal length and it has noticably annoying CA wide open. I realise CA can be corrected in post, but I'd prefer it absent in original photos.
I've read of too many AF issues with Sigma's 50mm f/1.4 for me to consider it. Apart from that, it looks an awesome lens at a good price. While I can MF, I really want great AF in such a lens.
There you go!!!