do you have hand shake when taking pictures with PNS camera or Dslr camera?
Why not go and try out the cameras first? All 3 of them feels differently, so your hands may already narrow down your choices for you (at least this is what happened when I was chooseing my dSLR).
go the shop and try them out. consider the pricing of the cam and lenses and flash as we.. personally, i find Sony very expensive among the 3 brands.. I like the wide variety of canon lenses, wide range of focal length.. Nikon has CCD sensor that works well in low light conditions..
an article from photonotes.org - it mentions about nikon is better than nikon in low light conditions..
i also read about the specs between cmos and ccd sensor which explains ccd is better in low light condition from a link @ cs.com..
Here goes the article..
Autofocus doesnít work very well when itís dark. What can I do?
Low-light autofocus is quite a challenge for any camera that uses a passive autofocus system, like all EOS cameras. Passive autofocus means that the camera simply looks through the lens and reads whateverís there - it doesnít send out infrared or sound or light or radar beams or whatever to determine the correct focus distance. (the AF assist systems used by most Canon cameras and flash units donít change this, since the lights are optional assist systems and are not required by the autofocus system)
Generally speaking the more expensive the camera the better the autofocus. There are exceptions to this, but itís a reasonably accurate predictor of how good AF is going to be when light levels are lower. So a top of the line EOS 1V is going to have wildly better low-light autofocus than an old EOS 1000 consumer camera, for example. This doesnít quite apply with digital cameras, though - the D30 and D60 are both more expensive than roughly comparable film cameras, but have very poor low-light autofocus.
One way to get a sense of the cameraís low-light AF performance is to look at its specifications. Light levels for AF systems are measured in exposure values (EV), and autofocus systems have their light sensitivity levels expressed as a range of EV. A good camera can autofocus from 0-20 EV. A consumer camera can usually only manage 2-20EV, which means that it needs more light at the dimmer end of the scale to work properly.
Unfortunately low-light AF performance is one area where Nikon products are generally better than Canon products. Many Nikon products autofocus down to -1 EV, for example. Nonetheless there are several things you can do to help your camera with its low-light AF performance.
The majority of EOS cameras with multiple focus sensors have a cross-type sensor as the central sensor. As noted above, cross-type sensors are more accurate than linear sensors because they can detect both horizontal and vertical lines rather than just lines in one direction. So always switch manually to your cameraís centre focus point for improved accuracy.
There is one significant drawback to this approach which you should keep in mind, however. Canon E-TTL flash biases flash exposure to the selected autofocus point. So if you focus on something with the central focus point, recompose the image by moving the camera and then take a photo thereís a good chance that the flash metering will be out. In this case you should lock flash by using FEL prior to recomposing.
Passive autofocus systems try to detect changes in contrast, so help your camera out by giving it a sharp line to focus on. Look for a wall or the edge of something where one side is brighter than the other and the two areas are sharply delineated. This, more than anything else, will make a tremendous difference. Donít try to focus on a blank wall - AF systems have difficulty with featureless surfaces in bright light, let alone when itís dark.
Use an AF assist system. Many EOS cameras contain some sort of light-producing lamp which helps the autofocus system in low light conditions. The best kind of AF assist light is a bright red LED which projects a series of patterned lines. Itís relatively unobtrusive as AF assist goes, and the striped lines help the AF system lock focus. A number of cameras - notably the 10/10s, Elan/100, Elan II/50, 5/A2/A2E, Rebel S II/EOS 1000FN and others - have such red lights. Other cameras have white incandescent flashlight-type AF assist lights which work, though not as well. Others, such as the Rebel 2000/EOS 300, Elan 7/EOS 30/33/7, have no dedicated lights and simply emit stuttering pulses of light from the popup flash, which is extremely annoying. Whichever system your camera uses, however, see if it helps with autofocus. Note that some large lenses or lens hoods can block the light from body-integral AF assist lamps.
Attach an external Speedlite flash unit. All Canon Speedlite flash units contain red AF assist lamps which can help autofocus considerably, especially if your camera hasnít got one. There are a couple of limitations to keep in mind, however. First, two cameras - the 5/A2/A2E and the 10/10s - will not activate external Speedlite AF assist lights. Second, many flash units are not capable of a wide enough spread of their AF assist light beams and so cannot illuminate the outer autofocus points of multiple focus point cameras. Even those with the ability to cover all the focus points of your camera generally illuminate the centre point with lots of light and the outer points with less light. So again itís best to stick with the centre AF point.
Use a faster lens (ie: a lens with a smaller maximum aperture value). A lens with a maximum aperture of f/1.8 is going to autofocus in low light much more reliably than one with a maximum aperture of f/4.5, for the simple reason that the faster lens will let in many times more light.
Try to focus manually. This is difficult if your camera has a simple matte focus screen. But if youíre lucky enough to have a focus screen with a split circle focus assist aid (see below) then itís probably most reliable to focus manually.
although sony does make quite good electronics, they are still pretty new to the SLR market, unlike Nikon or Canon who have been making SLRs for many years. also, the lens selection, though other lens makers eg sigma, tamron are making lenses for sony mounts, is still quite limited. the last time i checked (abt 1 month ago), sony only had the 70-200 f/2.8 as a telephoto lens, and it was going for 4k!!! the nikon and canon variations are about 2k+. i would go for the d80, as its features are quite good, but the 400d also would be a nice choice. then again, if you are willing to spend lots of $$ for add-ons, you could go for the A100. it also has GPS photo memory and built-in IS.
Just my two cents worth.
Sony do have other tele lenses, and some Auto Focus Carl Zeiss lens also, not sure why you are not aware of it They will be more lenses announced soon.
There are plenty of older minolta lenses to be used on Sony Alpha mount also.
Alpha 100 do have built in sensor base anti-shake, bur GPS dongle is an external thing though.
Sony Alpha 700 hobbyist