Zoom = mm

[JayJay65]

Been a while since I posted in here, but I never really thought about thinking this..Its hard to explain this question, but ill try my best.. Say we have a camera (we'll use mine for this example)

Kodak EasyShare Z612:
12x optical zoom, 4.2x digital zoom
420mm


Does this mean that 420mm is how far you zoom with the OPTICAL ZOOM, or BOTH (digital and optical) ZOOM?? Because at first I thought that meant only optical zoom, but now im 2nd guessing it.. Which is it??

Also, how do you figure out how much zoom is equivelant to how much "mm"..

Sorry if that sounded stupid or weird wording...

-Jess

 

[Buszaj]

Pretty sure it's optical zoom. With optical zoom the lens moves out. With digital zoom, the picture itself is digitally zoomed, thus reducing the picture quality. My recommendation is try not to use digital zoom.

 

[JayJay65]

Yeah I dont use it, trust me, just wanted to make sure.. do you know the formula for zoom = mm?

 

[Buszaj]

I don't believe that there is a formula for that. But on the forum someone told me that the higher mm number divided by the smaller one equals the "zoom." So an 18-55 mm lens would have about 3x zoom. I'm also a beginner so I had the same questions as you a month ago.

 

[Buszaj]

My bad, I'm the beginner here...lol

 

[Alex_B]

Yeah I dont use it, trust me, just wanted to make sure.. do you know the formula for zoom = mm?

there is no formula.

12x optical zoom just means than your longest focal length is 12x your shortest focal length with that lens. So without knowing at least one more number (either shortest or longest focal length), you will not be able to determine the zoom range of your lens.

 

[JayJay65]

35-420.. 420/35 = 12x optical zoom (correct)

Telephoto zoom lenses.. can they be added onto ANY digital SLR (if they are made to fit), or do you need something to put on an SLR before you add the Telephoto zoom lense..

SAL-75300 - f/4.5-5.6 Telephoto Zoom Lens

 

[JayJay65]

Same camera, different lense.. Zoom listed below (DSLR's)

Camera 1)
50-500mm (equaling 10x zoom)

Camera 2)
30-300mm (equaling 10x zoom)

Because they both have the same zoom [10x zoom], does that mean they are equal in zooming distance, or that camera 1 zooms farther because it has 200mm more zoom..?

 

[Buszaj]

Tricky question there. But I would think that camera 1 would overall "zoom in" farther. Not 100% sure though.

 

[JayJay65]

Oh I see..

 

[Milhouse]

Before you continue reading, this is a reply from a NOOB.

I think I remember someone saying that the smaller the difference between the minimum and maximum will result in a better quality lens (it specializes in a smaller range instead of generalizing in a larger one). This might mean that both lenses will have 10x zoom but the 30-300 will produce a better image than the 50-500.

I would also like a clarification on this. Not to hijack this post, I have to ask if someone could post a link that better describes lenses and how they work.

Thanks

 

[Jon, The Elder]

The Z612 features an impressive Schenider-Kreuznach Variogon all-glass, aspherical 12X optical zoom lens with a 35mm equivalent focal range of 35 - 420mm. This is a speedy lens, with a wide open aperture of f/2.8 wide and f/4.8 telephoto. The zoom coverage is further extended by a 4.2X Advanced Digital Zoom, making for a combined 50x total zoom.

Took this off of Steves Digicams site.

The "X" factor is only used by manufacturers for their P&S type of cameras. It is a VERY misleading piece of hype they use to pull in the first time buyer. That figure is arrived at by simply dividing the 420mm by 35mm.

The absolutely useless 'digital zoom' is merely in-camera processing of the largest optical zoom image.

As to quality, common sense will tell you they are not going to give you the kind of optics on a little P&S that you have with DSLRS.

The camera generally is setup to give you oversaturated and oversharpened images, which people are used to for small prints.

In operation, holding that little sucker steady at 420mm is quite a feat. It can be done, its just a lot harder to do. IS on a little unit like that is also marginal.

 

[maddermaxx]

The zoom is measured by dividing the smallest by the largest. 50-500 = 10x 50mm = 0x.

And the smaller the difference between the 2 is generally clearer.. say a 70-200 is clearer than a 50-500 just as a 500 prime is clearer than the 50-500.

 

[Unimaxium]

Same camera, different lense.. Zoom listed below (DSLR's)

Camera 1)
50-500mm (equaling 10x zoom)

Camera 2)
30-300mm (equaling 10x zoom)

Because they both have the same zoom [10x zoom], does that mean they are equal in zooming distance, or that camera 1 zooms farther because it has 200mm more zoom..?

Camera 1 definitely zooms in farther, because it goes all the way to 500mm. But Camera 2 zooms out wider, with 30mm. Like someone above me mentioned, the "10x" measurement is misleading, in that it only tells you the ratio between the widest and narrowest zoom limits on the camera/lens.

 

[neogfx]

I hate damn manufacturers that list a 'something x' zoom. Everything should just be listed in mm, then everyone knows exactly what the lens does and it would be infinitely times easier to compare different products.
For instance, I originally thought that 10x zoom meant 10x that of a standard lens, ie. what you would see with the human eye.
It should all be standardised in the interest of supplying the consumer with clear, concise, easily comparable information!