Can I use an old flash on a new camera?
Well…yes, no, maybe. It depends on the flash and the camera.
Most point and shoot cameras don’t allow for any kind of additional flash to be connected directly to the camera. Not to say you can’t still use additional flash equipment. More on this further down.
If you have a hot shoe mount on your camera, and you are trying to connect a hot shoe style flash, then you can probably use it. You may have to use the automatic settings on the flash itself or use it in manual mode, but most will work to a limited degree. If you want all the automatic features of the flash to work with the camera, you will generally have to match the camera and flash. For example, most Nikon flashes will work with most newer Nikon cameras, but you may not have all the automatic features such as TTL (through the lens) exposure or auto zoom. Some independent flashes may well work also, with similar restrictions.
However, I wouldn’t expect a brand name flash to work with any automatic features on anything other than the same brand camera however (You wouldn’t expect to use a Canon lens on a Pentax camera either, would you?)
You may have an old flash that connects by a cord (commonly called a PC cord – PC standing for Prontor/Compur) – this is not the same thing as PC computer. To connect this cord, which has a male end, your camera will need to have a little (female) PC hole in it to plug in the cord. Unfortunately, most new cameras today are manufactured without such connection. The demand for more and more modern features on equipment has relegated the PC connection to the same bucket as your cassette tapes. The lowly PC connection only provides an electrical connection between your camera and flash to allow you to set off the flash when you push the shutter release button. Any automatic features that are built into the flash may still be usable however, just not controlled by the camera.
Now, if you have a PC cord flash and a hot shoe camera, you can buy a little adapter that fits on your hot shoe that has the female PC connection. It should be available online or in camera stores for about $10-15. Quick fix to allow you to use that flash!
Back to the point-and-shoot cameras and old flashes. To use an additional flash with a point and shoot camera, buy a remote trigger called a “slave trigger”. This is a little gizmo that triggers your external flash to go off when it senses your on-camera flash going off. The beauty of this little guy is that you can move the flash around anywhere you want (as long as it can ‘see’ the other flash going off). I’ve seen these for under $10 online.
Here’s a professional hint for you. If you want to practice your portrait photography skills, but don’t want to spend a ton of money on equipment, buy an old studio light or large ‘handle flash’ such as Metz (just search Ebay, Craig’s List or Kijiji…there’s lots of used equipment out there), and a cheap slave trigger (maybe even an umbrella to soften the light). Use a low power flash on your camera (such as the little pop-up built in flash many cameras have now). But, make the slave flash your main light off to the side. Your pop-up flash then becomes ‘fill-in’ flash, softening shadows. Esthetically, it’s best to have your main light off camera anyway, and this will allow you to do it cost effectively!