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Thread: Conversion of zoom power in compact cameras to SLR/DSLR

  1. #1
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    Default Conversion of zoom power in compact cameras to SLR/DSLR

    Hi clubsnappers,

    Does any of you have any idea if there's any conversion chart for cross reference between the zooming power of compact cameras (e.g. 4x, 8x, 12x ... etc) to those of SLR/DSLR lens (e.g. 35mm, 50mm, 100mm ... etc)?

  2. #2
    vince123123
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    Default Re: Conversion of zoom power in compact cameras to SLR/DSLR

    The 4x 8x etc just means the largest mm value divided by the smallest mm value, ie a 50-100mm lens is a 2x zoom. There is no way to convert an x value to a mm value as it is a proportionate value and not an absolute value.

    Most compact cameras also come with specifications showing their zoom range in 35mm equivalent. Which model camera are you looking for?

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    Default Re: Conversion of zoom power in compact cameras to SLR/DSLR

    Hi vince123123,

    When most compact cameras mentioned about their zooming factor, like 8x, I just wonder that "8x" thingy is equivalent to how much mm of those lens we are using on SLR and DSLR.

  4. #4
    vince123123
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    Default Re: Conversion of zoom power in compact cameras to SLR/DSLR

    As stated above, the 8x cannot be converted to 35mm format - it is an expression of ratio between the largest mm divided by the smallest mm.

    Why don't you tell us what camera model you are looking at and I'll see if a mm equivalent is available for that model.

    Quote Originally Posted by Qazwer
    Hi vince123123,

    When most compact cameras mentioned about their zooming factor, like 8x, I just wonder that "8x" thingy is equivalent to how much mm of those lens we are using on SLR and DSLR.

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    Default Re: Conversion of zoom power in compact cameras to SLR/DSLR

    most compact cameras start at 35-38mm. some [wide zoom] cameras start at 28mm. this should make a good reference.

    8x means widest focal length multiplied by 8, so normally it'll be 280mm.

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    Default Re: Conversion of zoom power in compact cameras to SLR/DSLR

    Quote Originally Posted by roti_prata
    most compact cameras start at 35-38mm. some [wide zoom] cameras start at 28mm. this should make a good reference.

    8x means widest focal length multiplied by 8, so normally it'll be 280mm.
    Hi roti_prata, Thanks for your expanation. I think I get it liao ...

    Hi vince123123,

    I dun have a camera to compare with ... Don't get me wrong, I'm just curious to find out. That's all ...


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    Default Re: Conversion of zoom power in compact cameras to SLR/DSLR

    Recalled back there is once if didn't read wrongly is depends on the equiv of digital camera stated by the manufacturer. If it says "35mm equiv" then the 1X shall at 35mm, 8X is around 280mm and 12X will be approximately 420mm.

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    Default Re: Conversion of zoom power in compact cameras to SLR/DSLR

    Quote Originally Posted by blurrblurr
    Recalled back there is once if didn't read wrongly is depends on the equiv of digital camera stated by the manufacturer. If it says "35mm equiv" then the 1X shall at 35mm, 8X is around 280mm and 12X will be approximately 420mm.
    okay ... understood liao! Thanks bro.

  9. #9
    vince123123
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    Default Re: Conversion of zoom power in compact cameras to SLR/DSLR

    35mm equivalent refers to the film format, not the focal length of the lens...so I'm not sure if your information is still correct.

    Quote Originally Posted by blurrblurr
    Recalled back there is once if didn't read wrongly is depends on the equiv of digital camera stated by the manufacturer. If it says "35mm equiv" then the 1X shall at 35mm, 8X is around 280mm and 12X will be approximately 420mm.

  10. #10

    Default Re: Conversion of zoom power in compact cameras to SLR/DSLR

    Not necessarily is x35 when it says 35mm equivalent. This is because "35mm" refers to the format and not the focal length equivalent.

    The 35mm equivalent of 1x optical zoom of a camera depends on the camera in question and it ranges mostly from 35-38mm. So for a camera such as my Nikon Coolpix 5700, the 1x optical is 35mm and so my maximum 8x optical zoom is 8x35 = 280mm equivalent on the 35mm format. For the Fuji F10, the 1x is 36mm and so its 3x optical is 3x36 = 108mm equivalent on the 35mm format. For the Sony F717, its 1x is 38mm and its 5x optical zoom is 5x38 = 190mm.

    I suppose the above is what the threadstarter wants to know.

    To complicate matters, such long 35mm equivalent zoom is achieved only because sensors of these camers are much smaller than the full 35mm format frame size. The zoom is only apparent and not actual. The actual focal length of my Nikon Coolpix 5700 at 8x optical is 8x8.9 = 71.2mm only even though it's 280mm equivalent on the 35mm format. So it appears to have the same magnification as a 280mm lens on a 35mm full frame size camera but the image formed in side the camera is actually similar in size to using only a 72mm lens on a 35mm full frame size camera. The image appears to be zoomed by a 280mm lens only because the CCD sensor is much smaller in the Coolpix 5700 than a full frame 35mm format camera. So the details that can be captured by my Coolpix 5700 is far lesser than what a DSLR can. Most DSLRs use APS-sized sensor and have a crop factor of 1.4-1.6x. So a 200mm lens used on such DSLR has a focal length of 280-320mm on a 35mm equivalent format although its actual focal length doesn't change and is still at 200mm.

    In sum, comparing the focal lengths between consumer compact cameras and DSLRs is a little more complicated than what appears on the surface.
    Last edited by Clockunder; 13th January 2006 at 06:35 PM.

  11. #11
    vince123123
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    Default Re: Conversion of zoom power in compact cameras to SLR/DSLR

    Clockunder's explanation is correct - didn't want to go into the essence of the third para for fear of confusing, but well done all the same!
    Last edited by vince123123; 14th January 2006 at 07:09 AM.

  12. #12

    Default Re: Conversion of zoom power in compact cameras to SLR/DSLR

    Great explanation Clockunder. Learnt something new again. Thanks for the great effort.

  13. #13
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    Default Re: Conversion of zoom power in compact cameras to SLR/DSLR

    Quote Originally Posted by vince123123
    35mm equivalent refers to the film format, not the focal length of the lens...so I'm not sure if your information is still correct.
    Maybe i read wrongly but somehow my calculation tally so I assume is calculated that way
    Last edited by blurrblurr; 15th January 2006 at 10:35 PM.

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