Wrong EXIF or something is wrong with the lens?

I bought a 17-40mm and when i shoot at 17mm, CS5 and DPP both say it's 19mm? Lens seems to be perfectly normal and it's changing normally between 17mm and 40mm as far as scale is concerned. What could be wrong?

Focal lengths written on the barrel dont always correspond to exact optical focal length...morever, the focal length encoder in the lens is a discrete series of contacts that makes jumps at certain ranges...

What you're seeing is probably the actual optical focal length of the lens encoded into the EXIF which corresponds to a "17mm" setting on the barrel.

I have seen this on my old 70-200, if I zoomed to 200 it showed ~186mm but if I pushed it all the way to the stop it was 200mm. I think the barrel markings are more of a suggested FL, be sure the ring is all the way to the stop and take a picture, should say 17mm.

it's nicely going to 17mm without any problem and I cannot push it any further. I don't want to lose 2mm. I had a nice one which I sold and then I started missing 17-24mm FL and bought this one today.

All lenses have this...the written-down focal lengths are not exact optical focal lengths. Also, the 17-40 is an IF (internal focus) lens and changes FL slightly when focusing...

yes but 2mm is a lot and also I took 10-15 pics with different subjects and it's always 19mm. well I sent an e-mail to seller (it's on CL ouch..) let's see what he says. he's a nice chap though.

Twister286, I think you're confusing two different things. Yes not all focal lengths marked on the lens are exactly what they say. But when talking about EXIF info, a 50mm for example should always register as 50mm regardless of if it's slightly wider or longer than a true 50mm.

To the OP, I wish I could provide any help but I've never run into this before.

I just received an e-mail from seller saying he took just a couple of pics with 17-40mm on 5DII and of course the widest he has says 19mm! Now he has pics from 20D and they say 17mm!! How could that be? Again I trust the guy - he's a nice person.

You may be reading too much into it. Lenses aren't exactly what they say. Rather than rely on the EXIF data (which really has two errors built in: the lens inaccuracy and the encoder inaccuracy) why not set up a test where you measure what the FL really is? I don't know how, but it can't be hard. For instance the Sigma 50 is known to be around 46.

well the thing is I had 17-40mm before and more than a copy and it was never like this. I tried it on 1D Mark IIn as well and situation remains the same. Usually, I don't care for this kind of stuff but I bought this lens again just to cover 17-24mm range and now I lose 30% of that or even more and that too the most important one.

well it goes to Canon. We'll find out soon.

Lens FL is defined for focus at infinity.
If your tests involved any other distance, it's possible that the reported FL may be accurate!

Is it still under warranty?-- If it's only that one focal length in the EXIF not showing correctly and the warranty has run out, why bother sending it in?

Thats strange that the lens won't go to 17mm or won't register 17mm. I just looked up my shots with the 17-40 on a 5D2, and the EXIF definitely shows 17mm on mine. Good luck with Canon.

I looked up the EXIF on a couple of mine and it also says 17mm on the low end and 40mm on the high end so I would say return yours and get another one.

Take Care,
Cheers, Patrick