another lens question

Hi guys. i'm about to go buy a lense to go with my kit 18-55 for the 350d. I'm looking at the tamron range for their affordability and reasonable quality for the newbie. The specific question i have is about the name of the lens. for example, one i am looking at is the 28-80mm F3.5-5.6 ASL EOS. I thought the part of the name that says F3.5-5.6 is aperture (now my head hurts!), but in the description for the item, it says min aperture is F22.

I've also no idea what the ASL bit is, and i guess the EOS bit means it is compatible with the 350d. help, as always appreciated.

Karf

the f/3.5-5.6 means that at 28 mm its maximum aperture is f/3.5;at 80mm it's f/5.6. It stops down to f/22 in either case. Your 18-55 has similar markings. ASL is Tamron's abbreviation for Aspherical, meaning some of the lens elements aren't spherical sections. This is sometimes done to control lens aberrations, but aspherical elements cost more to make than regular spherical ones. And EOS should mean it's for the Canon EOS, but that particular reference may be the store's listing.

nice simple explanation. thanks Jon. One other thing, if the max aperture at 28mm is 3.5, does the camera stop you from going higher, what i mean is, do the numbers on the readout keep going along its whole range regardless of what the lens can do?

No - the aperture readout is controlled by the lens. If you set up in APerture Priority (Av) mode at 18 mm on your "kit" lens and zoom out to 55 mm, you'll see the aperture that's displayed shift as you go.

Thanks mate. I just tried on my 18-55 and the readout shifts in TV mode rather than AV (i would have expected it in AV mode as you said).

musn't grumble.

cheers