ef-s 17-85mm IS usm

think this lense will get me by a wedding using it on my 40d? i going to attend a family wedding but want something i could get some pics of the bride and groom.

As a professional - no way. As a guest - sure.

You don;t tell us much of your knowledge of a camera... but here's some very basic tips:-
You'll definitely get some great shots with it - just keep trying and check the results in the LCD.
Stick it on AV mode and F4, press the flash (lightbulb) button to activate the popup flash.
make sure you increase the ISO if you are indoors or the shutter speed gets below about 1/80 if you're not using flash.
Bear in mind the flash will only work at full lens zoom - 85mm - less than that it will have a shadow because the lens is in the way (not sure at which point though).
try a bit or trial and error - and keep checking the LCD.

I used this lens at first when I was shooting weddings (luckily weddings here are pretty much all outdoors). It's a good lens, it's just not very fast. I love the range though, I wish they made an f2.8 version of it (like the 17-55 but 17-85).

I should add that the two copies i've used were soft and weren't good at focusing. I'll never use one again. Lloyd had a great copy he said was very sharp.

whats good for me? 50mm 1.4? my skill still ameatur so ive got lots to still learn.

My shooting partner has a copy of this lens, it took one wedding for me to convince him not to use it again, his was also soft.

Show us what you can do?
Why do you need f/1.4?
Show us a photo shot at 50mm using the 17-85mm at f/4, and explain why you want f/1.4.

dsc_1972 wrote in post #4130758
Show us what you can do?
Why do you need f/1.4?
Show us a photo shot at 50mm using the 17-85mm at f/4, and explain why you want f/1.4.

Wider aperture lenses tend to be higher quality, generally.

I have this lens, I've never had a problem with sharpness or focus. I love the range and the IS, it's a pretty good lens.

Would I use it to shoot a wedding? Not if I can help it...it's just too slow (small aperture).

dsc_1972 wrote in post #4130758
Why do you need f/1.4?

1.4 is often needed in very low-light shooting without flash but can present problems with the very narrow DOF when used at wide apertures.

Additionally the center AF point is more accurate when used with lenses having an aperture of 2.8 or wider.

The resolution & image quality of many lenses is remarkably similar by the time you get to F8, but at F4 a high quality lens will usually outperform a lesser lens.
Mike