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Thread: is it correct to compare zoom this way ?

  1. #1

    Default is it correct to compare zoom this way ?

    hi,

    i'm a newbie to dslr.

    for a PnS camera, 3x zoom means 35-105mm

    say for a standard kit kens for Canon 450D, 18-55mm lens means this zoom is "less" than my PnS camera, but macro is much better than the PnS

    is this correct, with my ignorance ? thanks.


    Last edited by ranger; 27th July 2008 at 04:19 PM.

  2. #2

    Default Re: is it correct to compare zoom this way ?

    Quote Originally Posted by ranger View Post
    hi,

    i'm a newbie to dslr.

    for a PnS camera, 3x zoom means 35-105mm

    say for a standard kit kens for Canon 450D, 18-55mm lens means this zoom is "less" than my PnS camera, but macro is much better than the PnS

    is this correct, with my ignorance ? thanks.


    Not very correct.. But Sorta.

    18-55 means.. 18 to 55. Which means you can't reach as far much as a 35-105.

    Macro photography is close-up photography; the classical definition is that the image projected on the "film plane" (i.e., film or a digital sensor) is close to the same size as the subject. On 35 mm film (for example), the lens is typically optimized to focus sharply on a small area approaching the size of the film frame. Most 35mm format macro lenses achieve at least 1:2, that is to say, the image on the film is 1/2 the size of the object being photographed. Many 35mm macro lenses are 1:1, meaning the image on the film is the same size as the object being photographed. Another important distinction is that lenses designed for macro are usually at their sharpest at macro focus distances and are not quite as sharp at other focus distances. (wikipedia)
    Meow!

  3. #3

    Default Re: is it correct to compare zoom this way ?

    Quote Originally Posted by GavinTing View Post
    Not very correct.. But Sorta.

    18-55 means.. 18 to 55. Which means you can't reach as far much as a 35-105.

    Macro photography is close-up photography; the classical definition is that the image projected on the "film plane" (i.e., film or a digital sensor) is close to the same size as the subject. On 35 mm film (for example), the lens is typically optimized to focus sharply on a small area approaching the size of the film frame. Most 35mm format macro lenses achieve at least 1:2, that is to say, the image on the film is 1/2 the size of the object being photographed. Many 35mm macro lenses are 1:1, meaning the image on the film is the same size as the object being photographed. Another important distinction is that lenses designed for macro are usually at their sharpest at macro focus distances and are not quite as sharp at other focus distances. (wikipedia)
    hi,
    ok, if the macro part is wrong.
    is the zoom part correct, cos more concerned on the zoom part.
    thanks.

  4. #4

    Default Re: is it correct to compare zoom this way ?

    zoom is a ratio of focal lengths.. 55/18=3.05x so your 18-55 actually has more "zoom" so to speak.. don't confuse focal lengths with zoom..

  5. #5

    Default Re: is it correct to compare zoom this way ?

    Quote Originally Posted by J-Chan View Post
    zoom is a ratio of focal lengths.. 55/18=3.05x so your 18-55 actually has more "zoom" so to speak.. don't confuse focal lengths with zoom..
    Yeah. Read this: http://en.wikipedia.org/wiki/Zoom_lens

  6. #6

    Default Re: is it correct to compare zoom this way ?

    http://www.photography101.org/images/focallength.jpg

    Try taking a look at this. Taken at same distance. Different focal lengths. 18-55 lens can produce the 18, 35, and 55 images, and of course, in between.

    35-105 can produce the 35, 55, 100 images, and in between. Get wht I mean?
    Meow!

  7. #7

    Default Re: is it correct to compare zoom this way ?

    Thanks, GavinTing, racoon31e, J-Chan.

    so to speak, would it be correct that Canon G9 will be having more "zoom" than 450D since G9 is 44.4/7.4 = 6x while the 450D is only 55/18 = 3.05x.

    sorry for my ignorance.

    if i place a G9 & 450D kit together at same point, G9 will able to zoom further away than 450D kit.


  8. #8

    Default Re: is it correct to compare zoom this way ?

    yea, the G9 would be able to "zoom" further..

    but what if I put a 70-200 on the 450D which has only 2.86x zoom.. obviously the 70-200 would have a narrower field of vision, the term zoom is too loosely used..

  9. #9

    Default Re: is it correct to compare zoom this way ?

    Quote Originally Posted by J-Chan View Post
    yea, the G9 would be able to "zoom" further..

    but what if I put a 70-200 on the 450D which has only 2.86x zoom.. obviously the 70-200 would have a narrower field of vision, the term zoom is too loosely used..
    got what you mean.

    a qn : if i want to match the same "zoom" and "macro" of G9, what is the lens I need to get for 450D


  10. #10
    Senior Member creampuff's Avatar
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    Default Re: is it correct to compare zoom this way ?

    The zoom ratio that is bandied about is nothing more than a meaningless marketing term frequently used by camera and lens makers to impress the clueless buyer. It is a ratio derived by dividing the maximum focal length by the minimum focal length. Looking at the formula, it says nothing about what kind of lens or focal length we're talking about.

    So for example, a 10-20mm ultrawide is a mere 2X zoom, but so is a 35-70mm zoom. Yet they are very different lenses in terms of angle of view. So a superzoom like the Tamron 18-250mm gives a 13.8X zoom, but so what?

  11. #11

    Default Re: is it correct to compare zoom this way ?

    Quote Originally Posted by creampuff View Post
    The zoom ratio that is bandied about is nothing more than a meaningless marketing term frequently used by camera and lens makers to impress the clueless buyer. It is a ratio derived by dividing the maximum focal length by the minimum focal length. Looking at the formula, it says nothing about what kind of lens or focal length we're talking about.

    So for example, a 10-20mm ultrawide is a mere 2X zoom, but so is a 35-70mm zoom. Yet they are very different lenses in terms of angle of view. So a superzoom like the Tamron 18-250mm gives a 13.8X zoom, but so what?
    hi,
    i get what you mean. thanks.

    you see, i'm deciding for a G9 or a 450D. both has its goods & bads ......

    from dpreview for G9 :
    Lens 35-210mm (35mm equiv)
    F2.8-4.8
    6x optical zoom

    is it correct then the G9's zoom is "more" than a 450D kit lens 18-55mm ?


  12. #12
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    Default Re: is it correct to compare zoom this way ?

    Quote Originally Posted by ranger View Post
    hi,
    i get what you mean. thanks.

    you see, i'm deciding for a G9 or a 450D. both has its goods & bads ......

    from dpreview for G9 :
    Lens 35-210mm (35mm equiv)
    F2.8-4.8
    6x optical zoom

    is it correct then the G9's zoom is "more" than a 450D kit lens 18-55mm ?

    zoom times(x), yes more as stated it is 6 vs 2.86, zoom in terms of magnify also yes as it is 210mm vs 55mm(equiv 88mm after crop factor). but when it comes to wide, the kit lens 18mm(equiv 29mm after crop factor) will give you a much wider view.

  13. #13
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    Default Re: is it correct to compare zoom this way ?

    If zoom is the only factor you'd consider in a camera, then yes the G9 is "superior", but we cannot forget that a dSLR will give much higher image quality, and in the world of SLR, you don't look at lenses by their zoom ratio (how many times zoom), but by lens focal lengths.

  14. #14

    Default Re: is it correct to compare zoom this way ?

    Quote Originally Posted by ranger View Post
    hi,
    i get what you mean. thanks.

    you see, i'm deciding for a G9 or a 450D. both has its goods & bads ......

    from dpreview for G9 :
    Lens 35-210mm (35mm equiv)
    F2.8-4.8
    6x optical zoom

    is it correct then the G9's zoom is "more" than a 450D kit lens 18-55mm ?

    If "zoom" is all that matters to you, you're obviously not ready for a DSLR.

    You may get a better "reach" with the G9 compared to the 450D kit lens, but I bet you never even come close to the image quality that the 450D will give you.

    But, the 450D kit lens has a much further MFD than the lens on the G9, so up to you which is more important for you in macro photography. I'd get a DSLR and slap on a Tamron 90mm Macro lens anyday instead of relying on a compromise lens like what the G9 has.
    Alpha

  15. #15

    Default Re: is it correct to compare zoom this way ?

    To put it in layman's term, if you want to reach real far (ie take bikini girl pics secretly at sentosa), you should get an DSLR like 450D, and get a lens with a long focal length like 300mm. Quite cheap, especially 2nd hand ones. "Zoom" is a pointless term. With a 300 mm lens and a 450D, I can take a picture of a bikini girl from my window six stories up and about 100 m away.

    But of course if you want to shoot long distance, then your image will most likely be blurred because of handshake and other factors. Anyway S5 IS has longer "zoom" than G9 what.
    Research Institute for Unicultural Visual Arts - Riuva.com

  16. #16

    Default Re: is it correct to compare zoom this way ?

    hi tjhan, Rashkae, calebk, ExplorerZ,
    thanks to all your advise.

    zoom is just one of the factors I'll consider, the others are picture quality and cost as well.

    another noob qn : why is dslr photos better than PnS like G9 ?
    say, for example i use the P mode on both G9 & 450D, will both give me different results ? and is it due to the different aperture etc capability.

    on cost wise, how much are the lens or 2 lenses that need to match the "reach" of G9 in terms of zoom distance and macro.

    from dpreview for G9 :
    Lens 35-210mm (35mm equiv)
    F2.8-4.8
    6x optical zoom



    Many thanks, I really need advise from you guys !


  17. #17

    Default Re: is it correct to compare zoom this way ?

    Quote Originally Posted by ranger View Post
    hi,

    i'm a newbie to dslr.

    for a PnS camera, 3x zoom means 35-105mm

    say for a standard kit kens for Canon 450D, 18-55mm lens means this zoom is "less" than my PnS camera, but macro is much better than the PnS

    is this correct, with my ignorance ? thanks.


    Yes, distance is the same, meaning 35~105mm on PnS vs DSLR is the same.

  18. #18

    Default Re: is it correct to compare zoom this way ?

    Quote Originally Posted by ranger View Post
    hi tjhan, Rashkae, calebk, ExplorerZ,
    thanks to all your advise.

    zoom is just one of the factors I'll consider, the others are picture quality and cost as well.

    another noob qn : why is dslr photos better than PnS like G9 ?
    say, for example i use the P mode on both G9 & 450D, will both give me different results ? and is it due to the different aperture etc capability.

    on cost wise, how much are the lens or 2 lenses that need to match the "reach" of G9 in terms of zoom distance and macro.

    from dpreview for G9 :
    Lens 35-210mm (35mm equiv)
    F2.8-4.8
    6x optical zoom



    Many thanks, I really need advise from you guys !

    Under low light conditions, proconsumers or PnS cameras will be very noisy (dots in shots). Another difference is the lens used. How good a shot is framed or composed is the photographer .

  19. #19
    Senior Member felixcat8888's Avatar
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    Default Re: is it correct to compare zoom this way ?

    DSLRs are definitely better than PnS in many ways as the bro here have mentioned. You are comparing an apple and an orange.

    But in this case, the orange can have different lenses to take whatever shots the photog wants but the apple is limited to the fixed lens.
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  20. #20

    Default Re: is it correct to compare zoom this way ?

    Quote Originally Posted by felixcat8888 View Post
    DSLRs are definitely better than PnS in many ways as the bro here have mentioned. You are comparing an apple and an orange.

    But in this case, the orange can have different lenses to take whatever shots the photog wants but the apple is limited to the fixed lens.

    hi bro, i'll also need to check my wallet before deciding to buy the apple or orange, cos orange is definitely more ex$ .... and to make the orange tastier, I may need to buy more utencils



    on cost wise, how much are the lens or 2 lenses that need to match the "reach" of G9 in terms of zoom distance and macro.

    from dpreview for G9 :
    Lens • 35-210mm (35mm equiv)
    • F2.8-4.8
    • 6x optical zoom


    I just did a forum search, if to get a 450D with kit lens + another zoom lens, will setback by $2K right ?

    Last edited by ranger; 28th July 2008 at 03:57 PM.

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