Buying 24-70 locally - Advice on what to examine

Hi Everyone -

I'm planning to purchase a Canon 24-70 from a local camera retailer this week. Normally I'd buy online but in this particular case the lens is actually less expensive locally. This also has the advantage of being to thoroughly evaluate the lens in person before laying down the cash. Is there anything special you'd check for before purchasing? I can take pictures on my camera and evaluate them with my laptop in person. Any specific date codes that are better than others?

Thanks in advance!
-Brandon

I just traded my 24-105 for a 24-70, and here is what i did.

Before meeting up:

Ask for details, damage, etc. If the seller refuses to send pics, i usually don't waste my time.
Ask for sample pics with EXIF intact

When meeting person:

visual inspection, dings, blems, etc.
zoom ring tight? loose? smooth or does it bind?
look at the other parties gear. is it beat up? sure shows you how they take care of their gear
check for fungus, sticky blades
scratches or marks on front and rear element
take pics @ 2.8 using a focus chart both at 24mm and 70mm
does the lens mount fine?
weather seal at the mount ok? chunks missing?
shake the lens, is there anything loose?
is the rubber grip rings faded and white? (i hate that! pet peeve of mine)
view pics at 100% if you are a pixel peeper

Meet in a public place, is the seller in a hurry to leave? go with your gut instinct, if he seems shady walk away.

It's a retailer? you shouldn't have much to worry about,. Bring your camera/laptop and check it out. I'd shoot it both wide open and stopped down, look at them on your computer.

Yeah...JUST what Kwando and Rick said. Even a retailer can attempt to foist a lesser quality (or damaged) item onto a customer. Ask about a return policy. If there's no return window, it's all on you, and you MUST cover all potentials. If he won't allow you to take some shots in and out of the store and process them, or allow you to return the lens, you have to make the decision, based on your instincts.

In any case, it's a fair amount of money, so be cautious.

Regards!
Don

For this particular lens I would test it thoroughly wideopen to see if its actually sharp.

Then I would shoot wideopen and take photos of the interior of the camera shop using 24mm to 35mm. Make sure it does NOT backfocus. So look at the photo to see that you land the shot. My copy use to back focus and its not unheard of doing so with this lens. BEWARE.

Otherwise I think that lens should be good to go. Seems this lens is the harder to calibrate for canon. Test the lens at f/2.8 at all ranges.

make sure the shop has a return or swap policy.

good luck

Also make sure the barrel is solid and doesn't have any play when going wide (24mm and coming back)... if it was a workhorse 24-70 odds are that the barrel nuts that allow it to go in / out are worn and need to be replaced and then the lens has to be recalibrated.

Test it all all focal lengths. Mine was great at 70 when I got it but terrible at 24. Went away for calibration and now its probably my most used lens

Wow! Thanks to everyone for such great advice. I honestly didn't expect to receive many replies. I'll be going into the camera shop either tomorrow or Wednesday, so all of your feedback was perfect timing.

The place I'm buying from is very reputable and should let me thoroughly inspect the lens before purchase. Hopefully it's a good copy as it was one of their last in stock due to the recent rebates. If it's not a good copy, I'll just hold off for awhile until they get more. I believe their return policy is 30 days, so I should have plenty of time on my own to ensure I received a good copy.

Take care,
-Brandon