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Old Sep 17, 2006, 4:23 AM   #1
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I've never owned a DSLR before.. only point and shoots like a S2-IS... I'm such a noob, I don't even know how to understand what 18-55mm means! I get f stops and ISO... but how can I translate a 12x zoom like on my S2 to a new DSLR lens? They don't seem to say, unless none of them have a zoom, unless you buy a special telephoto lens.. What are the typical zooms that you would have with the lens' that come with the package deal on a Rebel XT, or a K110D or a D50?



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Old Sep 17, 2006, 5:42 AM   #2
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well 12x or 3x is pretty irelevent consediring focal length. It means that the end of the zoom range is Xx bigger than the shortest. The main kits for entry level dslr's are usually a 18-55mm (or equivalent) which is a winde angle to what the human eye see's. and a 50-200mm (or eqivalent) whcih is a normal lenght to a moderate telephoto. Hope i helpd. Oh and your s2 is focal lengths are 36-432mm (i think).
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P.S. if i was wrong anywhere someone please correct me.
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Old Sep 17, 2006, 6:11 AM   #3
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As mentioned, the x factor for a zoom lens is pretty meaningless. It is used by the marketing dept to sell digicams to unknowledgeable consumers, where a bigger number is better (sort of like megapixel count).

The numbers (18mm-55mm)is the range of focal lengths the zoom covers. As a general reference, 50mm is considered 'normal'. Focal lengths below 50mm are considered wide angle and those above 50mm are considered telephoto.
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Old Sep 17, 2006, 7:58 AM   #4
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If you still really need to know, an 18-55 is approximately 3x. You divide the longest focal length by the shortest to obtain the "x" factor. The reason "x" is meaningless is simple. A 10-30mm, 18-55, and 100-300 are all 3x zooms, but as you can see, these lenses would be vastly different and used for different situations. My lens with the longest reach (zoom) is a 200-400mm, thus it is a 2x zoom!!
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Old Sep 17, 2006, 1:27 PM   #5
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They have pretty well covered this subject but I am going to add my .02 worth.

I have a Nikon 8800 that is a 10X zoom camera. That actually translates to a 35mm - 350mm equivalent on a 35 mm camera.

Your 12x zoom would be similar. However, I don't know the starting point for that camera but lets assume it is like 30mm then your lens would be the equivalent of a 30mm to 360mm SLR lens.

I found all this a bit confusing at first. Now I have moved up to a DSLR and there are all kinds of things to figure out about lenses.

Cheers,
Bill
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Old Sep 17, 2006, 2:37 PM   #6
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Weeee. I am smarter than when I woke up this morning. Thanks everyone for the help!
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Old Sep 18, 2006, 2:06 PM   #7
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I think the reason that this is so confusing is because point & shoot digicams often refer to the maximum zoom in terms of "power" such as a 10X or (ten power) zoom. This term is common in other optics such as binoculars or rifle scopes. Camera lenses, however, usually go by Focal Length. When you hear a P&S super-zoom camera advertised as having a 10X zoom, it is referring to the "power" of image magnification.

The next thing that makes it confusing, is the whole "digital camera multiplier factor". The image sensor on a DSLR is smaller than 35mm film, so you take the focal length of a lens and multiply it by a factor (usually around 1.5) to get the "film equivalent" focal length. In other words, if a 200mm lens is used on a digital camera, it will have a 35mm film equiv of 300mm. A 300mm lens will have the film equiv of 450mm, and so on.

This isn't exact, but as far as I've been able to figure out, the (Power) vs. Focal Length is roughly as follows:

3X (three power) = 55mm or 82.5mm film equiv.

10X (ten power) = 200mm or 300mm film equiv.

12X (twelve power) = 300mm or 450mm film equiv.

Again, that's not exact but I think it's pretty close. I'm very new to this stuff, so if anything I've said here is wrong, please correct me. Thanks.
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Old Sep 18, 2006, 3:18 PM   #8
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Gadgetnut,

You're a little off. With digicams, it's like others have said:

10x zoom means the ratio of longest equievelant focal length to shortest equivelent.

So, one 10x digicam may be 28mm-280mm equivelent.

Another 10x digicam may be 42mm-420mm equivelent.

So, your 3x, 10x, 12x table doesn't really apply to the "X" advertised for digicams.
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Old Sep 18, 2006, 3:37 PM   #9
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JohnG wrote:
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Gadgetnut,

You're a little off. With digicams, it's like others have said:

10x zoom means the ratio of longest equievelant focal length to shortest equivelent.

So, one 10x digicam may be 28mm-280mm equivelent.

Another 10x digicam may be 42mm-420mm equivelent.

So, your 3x, 10x, 12x table doesn't really apply to the "X" advertised for digicams.
I see what you mean.But the general consumer market also knows these numbers as (power) of magnification when referring to fixed-lens digicams. I have rifle scopes that are listed as 2.8X - 10X. In those cases, it's obviously not talking about a zoom range because the (X) power designation is after each number.

From what I've seen, most digicams that list a "10X zoom" have a 300mm (35mm equiv.) focal length at the far end of the zoom. That strength of magnification in a digicam is very close to 10X (Ten Power) if I'm not mistaken.


Again, I could be totally wrong about this. I am a total noob when it comes to most of this stuff. I'm simply going by what I've been able to figure out in my reading.
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Old Sep 18, 2006, 5:34 PM   #10
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gadgetnut wrote:
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I see what you mean.But the general consumer market also knows these numbers as (power) of magnification when referring to fixed-lens digicams. I have rifle scopes that are listed as 2.8X - 10X. In those cases, it's obviously not talking about a zoom range because the (X) power designation is after each number.

From what I've seen, most digicams that list a "10X zoom" have a 300mm (35mm equiv.) focal length at the far end of the zoom. That strength of magnification in a digicam is very close to 10X (Ten Power) if I'm not mistaken.


Again, I could be totally wrong about this. I am a total noob when it comes to most of this stuff. I'm simply going by what I've been able to figure out in my reading.
Scopes and binocs are different than digicams.

According to you any 10x digicam has a 300mm equiv lens. The Olympus Sp 500 is a 10x camera and has a 38-380mm equiv. lens. There is a difference between 380mm and 300mm. Typically, most digicams start with 36-38mm at the wide end.

Follow the definition of longest divided by shortest and you'll always get a correct answer. Follow your train of thought and you're 80mm off. So it has nothing whatsoever to do with 'power of magnification'. Show me one digicam whose x-factor doesn't exactly match longest/shortest. It's close to power of magnification but not the same.
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