Does a Digital camera need SLR?

[AprilForever]

Probably, there will be SLRs manufactured and used for the next hundred years or more. For example, the rangefinder camera is still well in use in its circle of users...

No matter how good an electric monitor may look, nothing at all beats looking at the real thing as it happens through my OVF. Long live the prism!

 

[Meh]

10 FPS cameras like the 1D series predict where the subject will be for the next frame and focus there, and do not AF each frame at 10FPS.

Sorry had to delete and edit the reply I just made if anyone started reading that: Yes, in "one shot" mode the AF locks and then the camera will fire away without refocusing between frames.

You're referring to predictive AF and that is what my comments are relative to. With predictive AF, the camera will fire away at whatever the frame rate is and will take an AF reading between every frame and adjust focus between frames. And you're right, it also measures the speed of the subject and predicts where the subject will be in about 60 milliseconds (or whatever the shutter lag for the camera is) in the future when the exposure will be taken and focus there rather than focus where the subject is at that moment. Between each frame AF measurements are made, a focus position is predicted, and the focus element is moved to that position. It's essentially the same process whether in one-shot or predictive mode the difference being whether it focuses where the subject is now or where it will be 60 ms later. And in predictive AF mode, if it can do that between frames then it is doing it in less than 0.1s (for a 10fps camera).

Mirrorless cameras do something similar. The new Nikon may improve on this with much faster focusing. The previous mirrorless cameras are hampered by a lack of computing power, but the new Nikon seems to have plenty of it. Sony also has upped the stakes with their latest mirrorless cameras, but there are still lots of problems to solve before they get to professional levels, and the viewfinder is one of the biggest.

Depends which mirrorless cameras you are referring to. My comments were referring to the differences between contrast AF and phase-detect AF. The new Nikons V1 and J1 (if that's what you're referring to) claim to have a hybrid AF that uses contrast and phase-detect and I'm not sure how they implemented it. The Fuji camera I mentioned has phase-detect built into the image sensor but it is slower (0.158s) and masks off some photosites so technically that affects the image and has some other issues I believe.

The Sony SLT (if that's what you're referring to) are not true mirrorless... they just use a translucent prism in place of the mirror that doesn't flip. It stays in place and splits the light up so that 70% goes to the image sensor and 30% to the EVF and AF sensors. The downside to this system is of course that you lose 30% of the light (about a half stop) from the image and also that the image may be slightly degraded (not much though) because the light used for the image must pass through that translucent mirror. In a flipping mirror camera, when the mirror flips up 100% of the light is used for the image and does not pass through an additional optical elements.

Feel free to correct anything I'm not getting quite right.

 

[49616E]

Some photographers may not like having to use the lcd all the time with the power that it consumes. Especially the wilderness sort that do not have a convenient way to charge batteries or want to carry around a bunch of them.