i want to take photos using raw option and just heard about CHDK
please let me know how i do it.
thank you
As noted by others, the CHDK addition to your SX40 will add the capacity to format in RAW. It will also add other options and, as a result, alter the look of the menus in your camera's display. Look at some sample screen shots on the CHDK site.
And, as stated, RAW is not going to turn you into a better photographer. The SX 40 turns out rather nice looking Jpeg format images as is. Do you feel you are being held back by the SX 40? Just storing your data as a RAW file may not be what's limiting your progress. You will need to learn another processing system to make a RAW file an improved version of your existing Jpeg file. Are your ready to do that? Have you actually seen a demonstration of differences between a Jpeg and a RAW file as it exists in the SX system? If you have no idea what the difference is between Jpeg and RAW, then, IMO, this is not the change you should make. The newer SX50 and SX60 both capture data in RAW. You can see image samples which demonstrate the potential of each type of file by reading a few reviews of the SX50 or SX60. Also look at, say, this site to see what can be done with only Jpeg format;
Favorite Canon SX50 HS Photographs - tonybritton
Why not try a slightly different routine first? Go into your menu on the SX40 and either defeat or minimize the Jpeg effects for your file system. What you will have then will be a largely unaltered image to work with. (That's basically what Jpeg does that RAW doesn't, it makes some "corrections" in the camera rather than in post production.) Load those files into your current processing system and work with them to achieve higher image quality. If, after several weeks of using this system, you feel you really need RAW to become a better photographer, download the CDHK update. Just be aware you will be in for another learning curve to make the most of the file data.
The SX 50 has been discontinued and it is selling for some rather low prices. I just purchased one from Canon refurbished for $199. At that price, IMO, you would be better off buying the SX50 rather than hacking your SX40.