Question about a Canon 28-70mm f2.8

GadgetRick

Ok, been looking at buying a Canon 28-70mm f2.8 L USM and have found some at very attractive prices. One mentions it's in excellent condition (pics look great of it) but has a tiny bit of dust in the elements. Now, I thought the L lenses were pretty-well sealed? btw, this lens is on Usedcameras.com and they're (supposedly) pretty reputable. I spoke with them and they told me this is normal as, no matter how well-sealed it is, it will always wind up with dust...eventually. Just checking to see if this is true of the L lenses.

My only other concern is the date code--UN--as, I believe, that indicates it was made in 1999 so it's an older lens. Good price for the older lens and it seems that shouldn't deter me. However, I've found one locally for about $50 more which is only 3 years old.

Just wanted to get opinions of you all here since you all have more experience with the equipment than I do.

Thanks.

ziggy53

For a $50 dollar difference, the ability to see and test the lens is probably well worth the minor difference in price. A 3 year old lens is easily worth more than an 11 year old lens.

Without actually viewing and testing each lens it's impossible to say if one is any better than the other.

Internal "dust" is really very common regardless of lens manufacture or lens quality. A substantial accumulation of internal "dust" may be an indication of a need for maintenance or even repairs. (Some internal "dust" is the result of internal wear.)

All lenses "breathe", even the best sealed lenses. Every time that atmospheric/barometric pressures change, the lens will breathe. It is true that lenses which change their overall length through either focus adjustment or zoom adjustment will tend to "pump" more air than fixed length and internal focus lenses, but Canon "L" lenses come in many different designs.

I use a small LED flashlight to shine through the lens in both directions to check for both dust and fungus. Fungus is the more problematic of the 2 common problems and causes potentially more image degradation.

Always understand your return privileges as many/most private sales are "as-is" and "final".

GadgetRick

Thanks. Makes sense about the dust.

I've heard about fungus but have never seen it or pics of it. Is it really that common? The pictures (of both) look clean of fungus. But I'd certainly look for it.

Gotta figure out what to do. Thanks!

ziggy53

Lens fungus is very common and will cause both reduced contrast and reduced sharpness.