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Old Nov 8, 2003, 11:04 AM   #1
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Default Digital zoom to mm?

I'm in the market to purchase a digital camera. Right now I have a Pentax IQZoom 115-S which has a 38mm-115mm zoom. What would be an equivilent digital zoom to what this camera offers? 4x? 10x? 20x? I cannot find a conversation chart anywhere!

Thanks to everyone for their assistance.

Serion
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Old Nov 8, 2003, 11:25 AM   #2
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Actually, the best information to have is the focal length range that you cited... 38mm - 115mm tells you much more information than the zoom factor.

The 4x, 10x, etc only tells you the multiple between the widest setting (38mm) and the maximum zoom (115mm). 38 times 3 is 114... so the zoom factor for your camera is approximately 3x.

But, that only tells you the proportions between the widest and narrowest view, as I said before. Another camera might also have a 3x zoom, but if it starts at a 30mm wide setting, the maximum zoom will only be 90mm. So your camera would have a narrower field of view at max zoom (ie, objects are bigger assuming the # of megapixels is the same), but the other camera would do better at wide angle shots.

The canon A70 and A80 both have a 3x zoom, but the 70's range is 35mm-105mm and the 80's range is 38-114mm, just like yours. So, the 70 has a 'wider' wide angle, but the 80 has more magnification at full zoom.

Another thing to keep in mind is that the focal length ranges that they give are usually not the 'actual' focal length of the camera's lens, they're given in numbers that represent the focal length of a 35mm film camera with the same characteristics. This is because different digitals have different sensor sizes, and if they gave the 'actual' focal lengths for these different cameras, there would be no basis for comparison. If this paragraph doesn't make sense, just ignore it and use the numbers . I'm probably not familiar enough with all of this to give a really clear explanation .


Kevin
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Old Nov 8, 2003, 1:27 PM   #3
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Default Re: Digital zoom to mm?

Quote:
Originally Posted by Serion
I'm in the market to purchase a digital camera. Right now I have a Pentax IQZoom 115-S which has a 38mm-115mm zoom. What would be an equivilent digital zoom to what this camera offers? 4x? 10x? 20x? I cannot find a conversation chart anywhere!

Just want to clear something up...on digital cameras there are two types of zoom...first comes your optical zoom just like a film camera with moving lenses. A digital camera might have the same optical range as your camera, 38-115mm which is 3x zoom (2.3x zoom in from the equivalent of the human eye).

After fully zoomed in optically, digital zoom kicks in (unless you have it disabled due to its poorer quality). Digital zoom is the equivalent of cropping the picture and enlarging, adding information to the picture that wasn't there before. If you have a 3x digital zoom, that number is multiplied by the full optical zoom number to give the final millimeter number...if you are 2.6x zoomed in digitally, 115mmx2.6=299mm but just remember that it's an illusion...it's not as good as true optical zoom.

For instance, my own camera is a 38-380mm optical zoom camera or 10x...after that the 2.7x digital zoom can kick in to provide a total of 1026mm or 27x total.
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Old Nov 8, 2003, 5:35 PM   #4
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Thanks to everyone for their responses ... you guys rock!
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