What am I missing (canon tele-zooms)

[Big Mark]

Two lenses, both by canon. have the same amount of zoom, virtually the same speed, both USM and IS. Why is the one twice the price as the other?

http://www.adorama.com/CA70300IS.html

http://www.adorama.com/CA70300ISNU.html

[JuliaGulia]

"These Diffractive Optics elements are combined to reduce size and boost image quality"

One has different glass basically, and is smaller...

If I were you and looking to buy good new lenses... I would only invest in "L" series lenses (the ones with the red stripe around the top). They are the very best glass you can get and will make a noticable difference in sharpness, contrast and overall quality of your images.

I wouldn't spend the cash on glass when, in a few years, you'll just want something better :)

[LarryD]

the difractive optics lens is newer -- it's almost two inches shorter. it's much more compact. it's a space-saver in your bag. but that's about it.

from what i've seen in pics by this lens, the optics aren't any better than the non-DO version -- some would argue that the DO's are actually inferior.

i think it's way overpriced.

[Big Mark]

ah, thanks for the help. I doubt I'll be buying either anytime soon, just couldnt figure out the difference. I eventually want something longer than the 135 I have now, but budget and indecicivness dictate that I wait at least another 6 months or so.

[JuliaGulia]

I have a 100-300 I would trade you for???

[Big Mark]

Thanks, but I think I'm set for now. For one, I've spent enough that I need to get better with what I've got before getting anything more. Secondly, I'm still not entirely sure what I want to do about longer reach. Part of me wants to look at long primes because I hear they're so much sharper, but I'm a little intimidated by their lack of flexibility and having to change out all the time.