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Camera depending notes: 

- ixus850_sd800 uses Propset 1 of Properties (see http://tinyurl.com/6zbv9b)
- ixus850_sd800 does NOT have a real IRIS Diaphragm, it only has an ND Filter! 
Mind this.
- CHDK for firmware 1.00d is the SAME for 1.00e


Subject distance override
 - always works in movie mode
 - needs activated AF lock in still image mode