What to look out for? Buying a used lens (No warranty) DA 12-24

[Pentaxtic]

I am looking to buy this lens from a local person. He is offering a good price for it and I was wondering what I should look out for when I get to handle the lens:
So far I have these items to watch out for:

1. Oil on the aperture.
2. FUNGUS- Watch out for spiderly looking lines.
3. Focus- Front/Back focus- Should I bring a laptop? or just use the LCD screen on camera?
4. Decentering. Laptop or can I use the LCD screen.
5. Scratches on the lens (front and back)
6. ????

It's about 200 US cheaper roughly about 600US dollars. It includes a Marumi UV filter. He used it 5 times.


Thanks in advance,

[fearview]

focus at infinity?

sharp at every object you shot?

--

[hll]

i recommend you to use a laptop, especially for BF and FF.

[Peter Zack]

You list is fine and if you are going to do some shot tests make sure you use a tripod. too many of these complaints are most likely user error or body movement after the AF is locked.

Generally this lens is very well regarded and there have been few if any complaints.

[hll]

hey, don't forget to lock the mirror even you use a remote control, it is a must.

[Pentaxtic]

Thanks for the replies.

Now I just need to borrow a laptop and buy a tripod!

ps Does focus at infinity mean that everything is at focus at the highest f stop? ie f22?