If you want to use a dslr without flicker, what is the best way to go about it?
I'm planning on buying my first DSLR (probably CANON or NIKON) but am worried about the\
flicker stories. So for a not technical guy, what is the easiest way to prevent flicker?
Use specifiec lenses, camera's or ... ?
What you need to do is disconnect the camera from the lenses, so they can't communicate electronically. When they do, the camera constantly re-adjusts the focus and exposure, meaning it changes each time you put your hands in front of the camera, and then changes back when you withdraw them - but not always to exactly the same setting.
The most common method is to use a Canon EOS camera and Nikon lenses that can be used with adapters. The adapter doesn't let the camera and lens communicate electronically - which means you need to get lenses that have a manual (physical) focus ring and aperture ring - and unfortunately Canon lenses don't have an aperture ring - exposure is handled electronically by the camera. For this reason the best method is to use a Canon body with Nikon lenses. But be sure you're getting lenses that do allow manual focus and exposure - so stick with AI and AIS lenses.
There's more info on this subject on this thread. The relevant info on using Nikon lenses with a Canon camera starts where I linked to, but there's probably more relevant info found throughout the thread.
As already said -
First step, don't use the Canon lenses, or any kit lens, but get some second hand manual lenses from another maker. I use Nikon and Olympus OM mount lenses with adapters on my Canon 40d, and a film I worked on recently was using Pentax lenses with an adapter on a Canon 7d.
With a Nikon camera body and lenses, you partly unscrew the lens, so all electronic connections are disabled, also the lever that opens the iris between shots to give you a nice bright image in the viewfinder can't reach the tab on the back of the lens, so it stays stopped down all the time like a professional cine camera lens. The opening and closing results in the lens sometimes not stopping down all the way in time, which gives you flicker. With a Nikon lens on a Canon body, it stays stopped down. It makes the view darker but it's worth it.
Next, check all the settings in the camera menus to remove any auto adjustments for white balance, exposure, focus, anything.
I am one of those who had to use a power conditioner to smooth out the voltage from my local electricity supply. It was varying by one or two volts, and that was enough to make the lights get brighter and darker. Another way around it would be to get lights that don't respond to small changes in voltage, like Fluorescent lights. I wanted to use my collection of halogens so I opted for a double-conversion UPS from Eaton Powerware - it converts ac to dc, stores it in a battery, outputs it as DC and converts back to AC. A couple of volts are lost but it is consistent and that fixed my flicker. To test the mains voltage, I connected a multimeter to the power and put it in front of my camera and took single frames of it over a 10 minute period. Sure enough, when the needle showed higher voltage, the shots were brighter.
But if you don't already have much lighting, look at compact fluoro lights. Also, I recently had some LED downlights put in place of the halogen downlights in my ceiling, and the electrician said they couldn't be used with the type of dimmer I had - so possibly some LEDs are also unaffected by small changes in voltage? Not sure about that.