Just bought a 17-40mm F4 L

[AAPhotog]

What are some things that I should check out to be sure that everything is working as should?
What are good ways the clean the focus and zoom dials(has like a white residue stuff maybe rain/sweat)
Seems to be good to me. Don't notice any scratches or cracks

Asking price was $550, talked him down to $460.
I don't really shoot wide so I wasn't really looking to purchase this lens(really wanted something with IS ie.24-105) but I like to see how good of a deal I can get. Sometimes, I get deals too good to pass up lol.

 

[Marsu42]

What are some things that I should check out to be sure that everything is working as should?

Print a test chart of shoot something symmetric with small details with a tripod and mirror lock up and look for decentering - every sides or corners should look more or less the same. My first (new!) 17-40L had bad decentering and the bottom was way blurrier than the top, so I had to exchange it.

Esp. on used lenses decentering can happen because of physical impacts and then lessen the sharpness even beyond the mediocre 17-40L standard wide open.

 

[sunnyVan]

What are some things that I should check out to be sure that everything is working as should?
What are good ways the clean the focus and zoom dials(has like a white residue stuff maybe rain/sweat)
Seems to be good to me. Don't notice any scratches or cracks

Asking price was $550, talked him down to $460.
I don't really shoot wide so I wasn't really looking to purchase this lens(really wanted something with IS ie.24-105) but I like to see how good of a deal I can get. Sometimes, I get deals too good to pass up lol.

You have a very good deal. I'm jealous. I got mine new for 699....

 

[J.R.]

What are some things that I should check out to be sure that everything is working as should?
What are good ways the clean the focus and zoom dials(has like a white residue stuff maybe rain/sweat)
Seems to be good to me. Don't notice any scratches or cracks

Asking price was $550, talked him down to $460.
I don't really shoot wide so I wasn't really looking to purchase this lens(really wanted something with IS ie.24-105) but I like to see how good of a deal I can get. Sometimes, I get deals too good to pass up lol.

I used to have the 17-40 but sold it in March. Wanted to "upgrade" to a 16-35 II but am still dithering :-\ and wondering whether I made the right decision.

Anyway, back to topic ... after the basic examination of the lens from the outside, the first test I usually do is check a lens for fungus (I live in an extremely humid environment for 6-8 months so used lens deals in my area break down due to fungus).

Shooting test charts as advised is probably the best thing to do but if you don't want to get into it, the only test necessary is to go out and shoot to see if you like it.

 

[Snook]

I am contemplating this lens, what do you guys think is a fair price for a used, but in perfect condition 17-40 f/4L?

 

[Menace]

I am contemplating this lens, what do you guys think is a fair price for a used, but in perfect condition 17-40 f/4L?

Rough estimate would be around 70-80% of new value.