Magnification factor?

How does the maginification factor in binoculars compare to the focal lengths in lenses? For instance, a 8X32 binocular will make the object you are looking at look 8 times closer to you than it really is. How does that compare to looking at the same object thru, say, a 300mm lens?

Any ideas?

MALI

It's hard to guage without knowing what "normal" is in "binocularese"... whoich I don't off hand,. but if normal is like 35mm film.. then it's 50mm.. so a pair of 8X binocs should be like a 400mm lens. whoich actually sounds about right.

And.... the "normal" lens focal length for the APS-C sensor cameras (20D and its sisters) is about 31mm, making an "8X" lens about 248mm for that (the APS-C) format.

The nearest thing on a camera to the magnification of a pair of binoculars is the viewfinder magnification. This tells you how large things appear when looking through the viewfinder, compared to the naked eye. Note that it tells you nothing about what is captured in the image.
On a 350D, for example, the viewfinder magnification is 0.8x with a 50mm lens. So, for 1x magnification you need a 62.5mm lens, and pro-rata thereafter. To get the same degree of magnification (through the viewfinder) as a pair of 8x binoculars you would need a 500mm lens.
Also note that the sensor size doesn't come into this - a 20D (1.6 format sensor, same as 350D) has a viewfinder magnification of 0.9x at 50mm and a 5D (full frame sensor) has 0.71x at 50mm.

Of course, most people don't worry much about viewfinder magnification on a digital camera as it doesn't tell you what the picture will contain. The apparent size of objects in the photo will obviously depend on how large you print/view the photo and from what distance you look at it. That cannot be related to the binocular magnification unless you specify a viewing size/distance.
The concept of the 'normal' lens (50mm on full frame, 31mm on a 1.6 factor sensor) says that you will get '1x magnification' (i.e. objects will appear same size as with the naked eye) with something like a 10x8 print at arms length. If those print viewing conditions are what you are interested in, then you can regard the 'normal' lens as giving 1x magnification for the print. Of course, in this case, things will look a lot smaller than 1x when you look through the camera viewfinder.

Wow, guys. You are something. Thanks a bunch. That's why I love this forum.

I started to think about this question when I got interested in taking a picture of the moon, which by the way for some reason I cannot understand I have not been able to do properly so far even with my 70-200 on a 20D but that's another story.

I first started reading about binoculars and scopes and how to attach a digital camera to them to take pictures.

This scope for instance can be used for that purpose:

http://www.bushnell.co​m …_scopes/specs/7​8-2065.cfm

I have not bought this yet but I started to think about how much magnification I would get if for instance I get a 2X extender for my 70-200. I was trying to understand if I can in fact get a similar magnification of the moon with the extender-lens combo as the scope in question.

But what I understand from your explanations, it looks like my lens+extender combo cannot get near this scopes' zooming capability, right?

Thanks again. And if anybody can pitch in any ideas, I would love to read and learn more about this.

MALI

You have to underexpose when you are taking picture of the moon. Remember that the moon is reflecting the light of.... the sun. And the sun is quite a big source of light. I tried yesterday, I was two stop below what my camera was telling me to use and I was still getting an overexposed moon. So I decided to go in full manual mode and I used these settings: f/8.0 and a shutter speed of 1/125s at 100 ISO

If you're comparing to using that scope, then I guess it depends on how it's attached to the camera. If you simply remove the eyepiece and connect it direct to the camera via an adapter then you just need to know the focal length of the objective lens in the scope - this could be directly compared to a lens focal length. If the adapter uses some other optics, then you'll need to ask whoever makes the kit...