I own a Canon Powershot SX100. It's a great camera, especially with CHDK installed. It does not have the threads to mount filters, though.
I bought a cheap lens-adapter tube for 58 mm filters. It is wide enough to fit over the barrel of my camera and easy to hold in place because of its solid construction. Just pretend you are holding the lens of a SLR :)
That's all there is to it - screw the filter into the adapter and hold it in front of the lens. It works. Of course, there are always a few tweaks that will make it better. I've added some padding to the adapter so it would not scratch the lens barrel. I've also bought a couple of lens covers to protect the filters when they are not in use. Finally, I've reused a bit of the packaging the covers came in to cover the other end of the adapter and prevent dust from getting in when stored.
I now have a pair of useful and nice-looking polarizing and macro filters that I can easily carry around without fear of getting them scratched and destroyed.
Step 1: Materials and Tools
Failing to find appropriate free materials that would make a perfect adapter, I had to spend quite a bit to buy some stuff that looked perfect for the job. I got:
- a 2-piece set of 58mm adapter tubes for Canon PRO1 ($7.50) and
- a couple of 58mm lens covers ($3.50).
At the time I didn't have any filters either, so I also bought
- a 3-lens set of 58mm macro lenses ($18) and
- a 58mm circular polarizer ($9).
(A quick word of warning: "Typically ships in 4 to 7 days" usually means "Takes between 4 days and 2 months to ship", so don't order items with that tag if you are the impatient type. Items marked "Typically ships in 2 to 4 days" usually do just that. Items marked "Temporarily out of stock" are probably never coming back again.)
If you already have the filters you wish to use with your point-and-shoot, then the whole project becomes a lot less expensive, of course.
For the padding between the adapter tube and the Iens barrel I used a 5g pack of sugru. You will also need small scissors to cut up the packaging of the lens cover and a few rubber bands that will be used to hold the covers in place.
I also used some packing foam for improvised covers. I bought it for about $500 and it came with a free flat-screen TV :) To be honest, it's been lying at the bottom of the closet for a couple of years now, waiting to be useful one day. You may not be willing to dish out for a new gadget, so if you don't have any foam lying around try asking at the electronics store. It's also useful as a flash difuser, so it might really be worth it to try and find some. Or use some other thin and flexible material like a piece of cloth. Maybe an old shirt. A round object such as a small bowl and a sharp hobby knife will be useful to cut a perfect circle out of whatever cover material you choose.
Step 2: Putting It All Together
I'll let the pictures do most of the talking. I simply added a few blobs of sugru to each of the tubes until they fit nicely around the lens barrel. Do the math to find out how much you need or make a paper ring the same size as the barrel and use that for testing. Do not try to slide fresh sugru onto the barrel. Even if you cover it with some cling wrap it could get messy.
To cut a perfect piece of packaging foam for cover use an appropriately-sized bowl or plate as a guide.
Take a look at the last too pictures and read the notes to see how to put it all together. Then continue to the next step to see some pictures I've taken using these filters.
Step 3: Use It!
I hold the camera in my right hand and the filter holder in my left. This setup is very stable and if you want to change the angle of polarization you can simply turn your hand a bit instead of messing with the filter!
The macro adapters are a bit more tricky, the depth of field is very shallow and a small shift would move the focus point around a lot. I usually set the camera focusing to continuous, step quite far back and zoom in. Then I move back and forth slightly until the camera manages to get a sharp image. From there it's all about steady hands :)
NOTE: You should not hang heavy objects on the lens barrel or bump them into it. Hold the adapter in your hand and lean your hand against the bottom of the camera instead of leaning the filter against the lens. Also be careful when zooming in, the lens barrel extends and might hit the filter in front. I've never had any problems with the camera because of this, but try not to be too rough with it.
Thank you for your attention. Let me know if you have any comments, questions or suggestions.