What is the effect of Optical zoom on Digital SLR Camera,which is better for results?

Optical zoom is the best for shooting subjects at a distance that you want to fill the frame. Optical zoom lens capability is true magnification of the image. It is able to utilize all the megapixels available in your camera to produce the best quality picture and enlarged prints.

Digital zoom only appears to enlarge an image by taking the pixels available, and makeing them bigger. Looking at the camera's tiny viewfinder, the image may look fine, but when you see a digitally enlarged image on your larger computer monitor, you can see the big jagged edges of the large pixels. These are even more apparent when you order large format prints, such as 8 x 10 or larger.

If you really want to best utilize a zoom lens feature, disregard the digital zoom number. Optical zoom is the only one that counts.

DSLR's by nature ARE optical ... whether using prime or zoom lenses. There is no digital zoom option on any DSLR cameras. They are sometimes found on SLR-type digitals, but they do not have interchangeable lens

In addition the sensors are MUCH larger than the ones found on point and shoot cameras.

I have posted a link so you can see the differences.

If you need more information, let us know ... someone will have an answer

The effect is to Zoom in close to distant objects. the power of the zoom is expressed as 12x (12 times) or whatever.
As said above on Digital zoom, don't use it unless the subject matter is of such importance that you can't afford to miss it.
Digital zoom is a gimmick, I don't use it for photography but leave it switched on as it's a telescope!

an optical zoom is just like the zoom on a regular slr. it uses optics to magnify an object rather than electronics. a digital zoom just expands pixels to make an image appear larger and along with it usually creates a lot digital noise.
as far as which is better is a matter of preference. most lenses will produce good results with the lower end lenses losing detail towards the edges. higher end lenses will create less noise towards the edges.

Optical zoom lets you get closer to the subject. Digital zoom just stretches the picture you have. After a while, your pictures look like Legos.

Analogy with a too-small teeshirt:

Digital zoom - stretch the shirt until it fits. (riiiiiiiiiiiiiiiiiip!)
Optical zoom - get a larger shirt.