Zoom in is equivalent to move forward?

[zli034]

For the digital cameras, is the zoom-in is equivalent to move forward the camera? My simple camera gives me 5 level zoom in, it has 3X optical zoom, but it takes me to press the button 5 times to reach the highest limit.

Can I determine the forward distance of each zoom-in button pressed? Therefore, instead of using the zoom, next I can just move forward my camera.

 

[yungman]

No. Zoom in not only pull the image closer, it also compress everything also. I am a photographer. Look at picture taken with a telephoto lens of a person with a far away scenic background. The background look much closer than it really is. This is the compression I am talking about.

For same reason a wide angle lens make the background look farther away. This is the trick of taking picture of people with nice scenic background. I stand close by to the person, use wide angle lens so I can get a lot more of the background to make the picture look very exciting.

The other extreme is if I want to emphasis the person in the picture, then I use a telephoto to take the picture. Because the background get pull in, you don't see a whole lot to keep the attention to the subject. Also with tele zoom, the background usually out of focus so you put more attention to the subject in focus.

You can do a lot of tricks with zooming in and out than just moving closer. I speak as a photographer, look up angle of view, depth of field for scientific explanation. I'm absolutely not an optical engineer.

 

[DaveC426913]

For the digital cameras, is the zoom-in is equivalent to move forward the camera? My simple camera gives me 5 level zoom in, it has 3X optical zoom, but it takes me to press the button 5 times to reach the highest limit.

Can I determine the forward distance of each zoom-in button pressed? Therefore, instead of using the zoom, next I can just move forward my camera.

All digital cameras have an optical zoom spec and a digital zoom spec. 3x optical and 5x digital is typical.

Optical zoom uses the geometry of the camera lens to do a "real" zoom - i.e. optical zoom provides more detail in that smaller area than un-zoomed. eg. If you couldn't read a license plate at standard setting, you might actually be able to read it when optically zoomed.

Digital zoom simply crops down the existing pic and expands (interpolates) it to fill the frame - i.e. digital zoom does not provide any more detail than when unzoomed. eg. If you couldn't read a license plate at standard setting, you will not be able to read it any better when digitally zoomed.

Digital zoom does nothing that PhotoShopping the picture after-the-fact can't do. You can crop your 4000x3000 pic down to the tiniest detail that only fills 400x300 pixels, then you can increase that little 400x300 image back up to 4000x3000, but there is no more detail in the final 4000x3000 pic than in the 400x300. That's digital zoom.

In conclusion:
Optical zoom: very desirable.
Digital zoom: virtually useless.

 

[russ_watters]

No. Zoom in not only pull the image closer, it also compress everything also. I am a photographer. Look at picture taken with a telephoto lens of a person with a far away scenic background. The background look much closer than it really is. This is the compression I am talking about.

Just to throw some simple math into this, if you take a picture of two objects, standing 10 feet from one, with the other 10 feet behind, one is 10 feet away and the other is 20 feet away. So if the objects are the same actual size, the further one looks half the size on film.

If you back up 10 feet and zoom in 2x, the near object will appear roughly the same size in the picture, but now the far object appears to be (20+10)/2=15 feet away instead of 20 feet away and is larger in the frame. You can use this effect to screw with the size of objects in a picture, ie to make to vastly different sized objects appear the same size. Google gives some awesome examples, including a woman kissing the Sphinx:

http://www.google.com/search?source...T4ADBF_enUS311US311&q=perspective+photography

 

[Andy Resnick]

Just to add to the good answers, optical zoom changes the *angular* magnification. and thus the field of view. The term 'magnification', especially when written as (for example) 5X, is sometimes confused with microscopy, where the term refers to the ratio of the actual sizes of image to the object.