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Old Oct 1, 2003, 10:56 PM   #1
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Default Wondering about zoom...

Hi everyone,

As a novice to photography, I thought that the purpose of zoom was to bring things CLOSER. I recently bought my first digicam with a 3x optical zoom. Now, it did seem to me that on max zoom, things weren't really very close. I just figured that 3x zoom is just not very much. HOWEVER...! Today I was taking a picture of one of my kids at max zoom, and while looking throught the optical viewfinder, I happened to open my second eye as well, looking at my kid with both eyes, one through the optical viewfinder at max zoom, the other regular, and the picture was the EXACT SAME. Meaning that the max zoom was just what I see in real life. Is this normal? Or was I, unbeknowst to me, born with a 3x zoom eyesight :shock: ?

On a different note, the cam I just bought is the relatively new Kodak dx 4530. It doesn't have many manual controls, but I'm a beginner anyway, and I also wanted to go for 5mp. Staples are having a sale and are selling it for $349 now, so I snapped one up. I am ECSTATIC about the pictures! Sharp, clear, and beautiful...!

TIA,

Shraga
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Old Oct 1, 2003, 11:12 PM   #2
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The 'X' in zoom is ONLY a ratio between the widest angle and the closest telephoto, so it's 3x closer than wide angle, NOT 3x closer than the eye! The eye focal length is ~50mm...as you didn't mention which camera you or your child has, I can't say exactly how much 'X' factor your camera has compared to the human eye!

My own camera has 10x optical zoom, but when compared to the human eye it only brings you 7.6x closer...the rest of the 10x is the wide angle (making you see more of the scene, further away).
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Old Oct 2, 2003, 10:22 AM   #3
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To give a clear example:

A camera that has a 25-75mm lens is a "3x" zoom.
A camera that has a 100-300mm lens is a "3x" zoom.

But clearly they are very different lenses that would be used for very different purposes.

The human eye sees with the equivalent of 50mm (I believe) so something smaller than 50mm is wider angle (sees a wider field of view) and something larger is a telephoto.

Eric
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Old Oct 2, 2003, 1:54 PM   #4
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If the human eye is 50 mm, then I've really got a problem. The camera (Kodak dx4530) supposedly has 3x zoom, with a 38-114 lens. So at max zoom, the object should look a LOT bigger/closer than what I see with my eye. However, as mentioned, it's the exact same size. If I keep both eyes open with one looking through the viewfinder, I see totally normal, the same with both eyes...Very, very weird...
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Old Oct 2, 2003, 2:43 PM   #5
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The human eye sees things in a similar manner to a 50mm lens on a camera that uses 35mm film.

Other size film cameras use a different lens as the 'normal" lens. For a digital camera with a smaller "film" size, that same 50mm lens is more like a mild telephoto.

I think that a 35mm lens would be more of a "normal" lens for most digital cameras.
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Old Oct 2, 2003, 2:43 PM   #6
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The viewfinder on most consumer cameras is very small, and is mostly a framing tool.

Also, the viewfinder on a non SLR camera is not TTL (through the lens), but even the image seen through an SLR viewfinder (which is TTL), does not always appear to be the same size at 50mm.

I just checked two cameras (one digital, one film). With the smaller digital camera, I had to zoom to 117mm before the image looked the same size as with my eyes.

With the film SLR, I only had to zoom to 70mm before the image appeared to be the same size.

If my SLR had a larger viewfinder, then the difference would be probably be closer to 50mm.

So, the size of the viewfinder appears to be the main reason why you see these types of differences.
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Old Oct 2, 2003, 2:52 PM   #7
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If I remember properly, a lens that provides a 45 degree field of view in the horizontal plane, is what is considered to be a "normal" lens.

Even here, it all depends on how large the print that you're looking at is, and how far away from the print your eye is. If you made an 8 x 10" print from a 35mm film frame using a 50mm lens, the objects in the photo would be quite similar to the way they appear to your eye.

For a telephoto image to look "real" (proper perspective, etc.,) you've got to hold the print much further away from your eye. For wide-angle shots, you've got to hold the print right up in front of you. The important thing for things to look "normal" is that the angle of your eye, looking at the object on the print/viewfinder/screen/whatever be the same as the angle your eye saw the object at, when it was photographed.
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Old Oct 2, 2003, 3:35 PM   #8
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Jim, I'm happy it's not only my cam. So the question I have now is,would a picture taken with the digicam at 117 be the same as a picture taken with the film camera at 117? According to what you're saying, I'm guessing it should.

What I still don't understand is, if the viewfinder is smaller, wouldn't that make objects look BIGGER, as there is less room in it to see everything around the center object?
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Old Oct 2, 2003, 4:53 PM   #9
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Digital cameras have two sets of focal length numbers...one is the 35mm equivalent; the focal length varies depending on the size of the CCD...because of that digital cameras also have a 35mm camera equivalent focal length so you can compare them.

For instance the Olympus C-700 has a 5.9-59mm (actual) focal length and the C-750 has a 6.3-63mm (actual) focal length...both are 10x cameras but because of the different size CCDs the focal lengths can't be compared; so the equivalent focal length from a 35mm camera is used so they can be compared on an equal plane...the 35mm camera equivalent of those two cameras are actually the same at 38-380mm.

Regarding the viewfinder, as others said, you can't compare what you see in the viewfinder with what you see with your eye...the viewfinder is only a framing tool to see what your camera is framing. If you want to compare properly you'll have to take a picture, mark the spot where you're standing, print the picture to the same scale you took the picture at, and then stand in the same spot comparing the picture to the actual scene.
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Old Oct 2, 2003, 11:12 PM   #10
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Did you happen to notice that the image in the viewfinder is smaller than the view from your other eye? I don't own a digital camera with an optical viewfinder, but as I recall the image in my point and shoot film camera was considerably smaller than the view of an object with the naked eye. Just speculation, but food for thought nonetheless.
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