I discovered a very simple and safe hack for the Canon 350D DSLR. It increases the maximum ISO from 1600 to 3200 with virtually no increase in noise. It also enables spot metering. The only modification to the camera firmware is to set a single bit from off to on which allows the camera to boot from the Compact Flash card. The rest of the software that enables these functions lives on the card and is loaded when the card is installed in the camera. To remove the software you remove the card and replace it with a card that isn't bootable.
I am making the software available from my server because I have tested it and checked it for viruses. It's clean and it works. None of this makes any changes to your computer other than downloading the files themselves.
First download these files:
Change the extension on the CardTricks file from .xyz to .exe once you have downloaded it. There is no install required. It makes no changes to your computer.
The scanled file is the firmware upgrade and doesn't need to be unzipped.
The last is the software that lives on the CF card. It must be extracted to the directory of your choice on your computer.
Following are the instructions to perfrom the upgrade:
Make sure battery is FULLY CHARGED. Camera must be firmware ver 1.0.3
1. Format your CF card. Copy scanled.fir to the card.
2. Insert CF to camera and run firmware update from the bottom choice of the 5th Menu setup screen. Screen will show "CF card containing firmware is required to update". Wait for blue LED to light steady. Wait another 30 seconds.
3. Turn off camera and take battery out and back in. Leave it off.
4. Insert CF card in card reader. Run Cardtricks and select the CF card by clicking on the picture of a memory card. Format the card in Cardtricks using the format button.
5. Using Cardtricks make the CF bootable. Check "CF boot sector" at the bottom right of the Cardtricks screen and then click "make bootable."
6. Copy the files in 350d_iso3200_spot directory to the CF card.
7. Insert CF in the camera. If the camera is booting from the card the Blue LED will flash.
To use the ISO 3200 function press INFO and you can change ISO levels from there by pressing the ISO arrow key. For spot metering press Menu and the DP button with the blue LED.
Blue led will blink and there will be a sound. Spot metering will be enabled.
FYI, the Canon DSLRS run ROMDOS and treat the CF Card as a floppy drive. Because the camera operating system is in ROM you cannot mess up the camera to the point that the firmware can't be reloaded.