5D C.Fn-20. What is it exactly ?

[kribee]

Hi,

 

Could you please explain to me what is this mysterious (to me)

function 20 ?

 

Also, I've read somewhere that by setting it off makes you gain

some writing speed. So can I set it off without loosing anything essential ?

 

Thank you

[rainer_t]

Hava a look here ...

 

http://photonotes.org/reviews/eos-5d/appendix.html

 

... look for "Data verification kits"

[colinsouthern]

Essentially it adds an additional piece of data that can subsequently be used to veryify that the original data hasn't been altered - I imagine it's probably only of use in legal/forensics/evidence type situations - it's used in conjunction with an optional data verification kit that Canon sell.

 

Cheers,

 

Colin

[micah_marty1]

Don't know whether it's helpful, but TrustImage has a little bit more on data verification here:

 

http://trustimage.org/more/onVerification.html

 

...and there's a little bit on the verification process's effect on write speed in #6 on this page:

 

http://trustimage.org/dvo.html

 

(Links to Canon's and Nikon's press releases re: their verification kits are just above the "Postscript" near the bottom of that second linked page.)

 

As far as whether the usefulness of data verification is limited largely to "legal/forensics/evidence type situations," data-verifiable originals could be useful in proving to skeptics what was and wasn't done to ANY remarkable photo, of any subject, for example this one here:

 

http://www.madmariner.com/seamanship/piloting/story/FALLING_BOAT_PHOTOS_F_081007_SP

 

(How the data-verifiable original of an impressive photograph could be made available for scrutiny by skeptics is discussed in #5 on that http://trustimage.org/dvo.html page.)

[beauh44]

What Colin said. If you're not concerned about proving a photograph has been un-altered in court, chances are you'll never need it. I believe the Data Verification Kit requires a special card reader and CF card as well. Good luck!