Why SLR camera doesnt display the image on LCD screen before taking the picture ?

Question

why SLR camera doesnt display the image on LCD screen before taking the picture ?

while normal digital camera displays the image on the LCD screen ? I thought SLR camera was better. then why doesnt it display the image ?

Answer 1

SLR camera IS better. It has an excellent optical viewfinder, that allows you to see the exact image that is about to be captured live, with no delay or distortions bright or dark. The image you see is actual image projected by the lens, not a off-center separate viewfinder window. It allows you to see exactly how camera focused or manually adjust focus (can't do that effectively on LCD), it doesn't get tricked by tricky light situations, etc....

Why would you trade that for a very low resolution (despite your sensor being 6-10-12 megapixels, the best LCD displays are only 0.5mp or so, so they don't show anything even close to being accurate representation of what you're photographing)

So why not LCD anyway? Well, to see the actual image in a viewfinder the camera has a mirror between the lens and the matrix, that reflects it up there. So it blocks lights way into the viewfinder. When you're taking a shot mirror flips up momentarily opening the light path to the sensor, and after picture is taken it goes back into position. Also, if LCD is used, it has to do the metering and auto focus based on images it sees. These are both a lot slower and less effective than dedicated auto focus / metering units on the optical path of an SLR. Which is why SLR's are so fast to focus and have negligible shutter lag as compared to point and shoot models.

All that said - there are some high end SLR's that do allow live view. There's even one in the prosumer level that does that - Canon Rebel xsi, that uses a tricky optics and I think an additional low-resolution ccd for that. But trust me, I'm talking from experience of using an older SLR which had that function - after you've used SLR for a while, you will only want to use the LCD for times you need to shoot from a tricky angle, where you can't stick your head to the camera! It's that convenient to use optical viewfinder on SLR!

LEM.

Answer 2

P&S cameras use the LCD screen as the viewfinder in most cases.

DSLR cameras use a standard viewfinder just like their cousins the 35 mm SLR.  The data in the viewfinder  and the focusing tools are much more critical than using a LCD, especially when controlling depth of field.

Those few DSLR's that do have Live View on their LCD's are there for specific uses, such as when the camera is mounted on a microscope, telescope or being used similar to a view camera when shooting tabletop product shots.

Holding a over two pound camera at arm's length, especially with a long lens just begs for camera movement

The over 40 year method of holding a SLR that is not mounted on a tripod is to hold the camera to the face of the photographer using the left hand to hold and control the lens and with right hand on the camera with the index finger on the shutter release .. this steadies the camera so hand held shots cam be taken with the minimum amount of camera movement.

And the DSLR cameras are much better for a host of reasons

* A sensor that is over 15 times larger than P&S cameras

* Superior analog to digital converters and image processing electronics

* Higher quality lenses and lens interchangeability

* Operating features needed and used by professional photographers

* Complete control of all the cameras functions.