what does optical zoom equate to in "mm" ?

Discussion in 'Digital Photography' started by alecmcmahon, Aug 30, 2007.

  1. alecmcmahon macrumors regular

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    Woodbridge, NJ
    #1
    i've been looking at lens online deciding on wether to upgrade to a d40,

    i have an h9 with a 15x optical zoom, i love the super zoom option, but i still seek a bit better quality.

    what would 15x,etc... equate to in mm?

    and also, does anybody know what sort of quality upgrade i would get upgrading to a stock d40 with stock lens?
     
  2. revenuee macrumors 68020

    revenuee

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    #2
    Sony rates it at 465mm

    BUT the D40 chip is bigger and yeilds a higher quality image first --- the stock glass on the D40 isn't bad -- BUT it's not stellar --- HOWEVER ... the switch to SLR is a completely different level of play
     
  3. robbieduncan Moderator emeritus

    robbieduncan

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    #3
    Basically the x times does not necessarily equate to anything in mm. It's simply the multiplication factor between the widest and longest settings. So if we assume a 10x zoom (easier to multiply) this could be wide=10mm, tele=100mm or wide=28mm, tele=280mm or any other pair of numbers where one is 10x another.
     
  4. revenuee macrumors 68020

    revenuee

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    #4
    it's a little more complex then that ... size of sensor distance of lens to sensor and the length of the lens

    ... if you were to think of normal and magnification ... in the case of 35 mm you are looking at 50mm being 1x --- and 100mm is 2x --- and 300mm being 6x
     
  5. valiar macrumors regular

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    Mar 14, 2006
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    Washington, DC
    #5
    Arghhh :)

    Arghh :) That whole "1000x zoom" thing is possibly the worst thing ever invented by the marketing departments. I hate it even more than the megapixel race, because unlike the megapixels "1000x zoom" has ABSOLUTELY no meaning.

    Let me explain...

    A zoom lens, as opposed to a "prime" lens, is simply a lens with variable focus distance (long ago these lenses were called "transfocators"). A zoom lens is, naturally, convenient because it replaces several fixed-focus lenses.

    Now, what marketdroids do when they try to peddle consumer cameras is label those zoom lenses by the ratio of the minimum and maximum focal length. Thus, a 6.5-65mm zoom lens becomes a "10X zoom!!!!!", or a 8-36mm lens becomes a "4X zoom!!!!!!!!!!".

    This does not tell you ANYTHING about the expected characteristics of the lenses. Well, except the fact that a lens with more "X" is generally a crappier lens - these are harder to design, have more elements in them, thus more imperfections and cut corners.

    In fact, that "10X" does not even mean that a the picture of an object taken at tele setting will look 10 times bigger than it will look at the wide setting. The actual dependence is a bit more complicated.

    To give you another example, I own two Olympus ZD 4/3 lenses: a 14-54mm f2.8-3.5, and a 50-200mm f2.8-3.5. In marketdroid-speak, both of these are "4X zooms!!!!!!". Yet the first lens is a standard zoom that goes from wide to mid telephoto. The second lens is a real tepehoto zoom, and is capable of taking pictures of distant objects.
     
  6. robbieduncan Moderator emeritus

    robbieduncan

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    #6
    That's assuming 1x = normal human field of view. Most compacts I've seen don't bother with that!

    Taking the H9 mentioned above as an example it's lens is described as:

    31-465mm (35mm equiv)
    15x optical zoom

    Note 31x15 = 465...

    Edit to add: valiar and I appear to agree :D
     
  7. sjl macrumors 6502

    sjl

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    #7
    The answer is an unequivocable "It depends". I have three zoom lenses for my Canon EOS 20D: the EF-S 10-22mm, the EF-S 17-85mm, and the EF 100-400mm. These are, respectively, a 2.2x optical zoom lens, a 5x optical zoom lens, and a 4x optical zoom lens. If you look at the entire range across all four lenses, I have a 40x optical zoom.

    Most typically, a compact camera has a "wide" setting equivalent to 35mm on a 35mm film camera. If that's the case, 15x optical zoom would equate to a '35-525mm' lens on a 35mm film camera. If the camera is billed as being extra wide, then the field of view at the widest setting would be equivalent to 28mm on a 35mm film camera, for a range of 28-420mm. (My money's on this particular possibility, without looking at the camera's documentation in any way.)

    But it gets even more complicated than that. The Nikon camera you're looking at doesn't have a sensor that's the same size as a 35mm film camera. So to get an equivalent to 28-420mm lens on a 35mm film camera, you would need to get lenses covering the range from 18mm up to 280mm. Very easily done; Nikon's 18-70mm and 70-300mm lenses will do the job nicely. (although I can't comment on the image quality of these lenses, I'd expect them to at the very least be on par with a compact ultrazoom, and they'd probably be a bit better.)

    You'll probably see some improvement; the sensor in the D40 is larger than that in any compact camera, so it's less susceptible to noise (handwave, handwave.) You would see a much greater jump with a higher quality lens, but it all comes down to how much you want to spend, and what you want to do with your photography.
     
  8. raptor96 macrumors regular

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    #8
    Nothing to contribute save that I think this is a great explanation. The others too were clear but nothing so neat and succinct.

    I'd say that the D40 + stock lens will definitely give you a step up in quality. Even if you just pick up an 80-200 for ~$150 you'll still see a step IMO b/c the lens optics are better. Such a long zoom range lens on a consumer cam probably can't be great.
     
  9. seenew macrumors 68000

    seenew

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    Location:
    Brooklyn
    #9
    they might as well market them as

    Canon Powershot A750 with REALLY BIG ZOOM
    Fuji FinePix S700 with HUMONGOUSLY LONG ZOOM
    Sony Cybershot with MORE ZOOM THAN LAST TIME
     
  10. ChrisA macrumors G4

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    #10
    The DSLR offers more then just image quality. First off it handles far better and is very quick with almost zero shutter lag.

    The other thing is that if allows you to change the lens.

    THere is a higher potential for image quality but that depends on the photographer's technique. What you can expect is first you loose defects like the purple fringes around bright objects. Noise in the image. You should get better contrast and sharpness.

    The SLR allows you to add things like bounced flash

    The D40 lacks an in-body focus motor so some Nikon lenses will not work. Make sure you can live without these lenses. I couldn't. I like my 50mm and 85mm lenses. Also you do not have to buy the "kit" lens. You can buy the camera with any lens you want.

    Look at lenses pick some out then buy an SLR body. Do the shopping in that order.

    I have the Nikon 18-70mm and like it. Has several things over the 18-55. Non-rotating filter ring, "true" AF-S with instant manual focus override. About 1/2 stop faster.
     
  11. alecmcmahon thread starter macrumors regular

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    May 18, 2007
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    Woodbridge, NJ
    #11
    hey guys thanks for the info, its a difficult concept to understand , but i get the jist.

    i actually went into a retail store today and tryed the d40 with the stock lens- 18-55, the zoom wasnt great, but wasnt terrible.. the camera itself was great though, felt real good.

    so i decided imma take the plunge and sell off my sony h9 and go for the d40


    anybody have sample pictures they've taken with the stock 18-55 lens? or could anybody reccommend a good " genral purpose " lens without breaking the bank?
     
  12. raptor96 macrumors regular

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    #12
    I don't have any pics off-hand but the 18-55 kit lens will not disappoint. Colors pop and pics look very vibrant. I have it w/ my D50 and it's faaaaaaantastic.
     
  13. srf4real macrumors 68030

    srf4real

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    #13
    A more accurate and understandable standard for zooms would simply state the field of view range, but that would ruin all the marketing hype. an 8 degree fov is the same whether it's accomplished by a 10x, 18x, or prime lens... but we can't have consumers actually knowing what they're buying, now can we!:p
     
  14. miloblithe macrumors 68020

    miloblithe

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    Nov 14, 2003
    Location:
    Washington, DC
    #14
    If you want a lens that, like on a point and shoot, covers a huge range, the answer is Nikon's 18-200 VRII lens or Tamron's cheaper 18-250 lens. These will be impressive to you in terms of zoom (very wide to very distant). However, these lenses are not going to give you as high image quality as two or three or four lenses that cover parts of the same range. Nikon's $700 18-200 VRII is probably worse image quality than the combination of the cheap 18-55 kit lens and Nikon's roughly $300 55-200 VR lens. These lenses likewise can't compare image quality wise to using a 20mm prime lens (no zoom), 50mm, 85mm, and 200mm. The trade off of convenience (a do it all lens--not having to switch and carry extra lenses) is always quality (all other things being equal).

    Compare lenses here to get the general idea:

    photozone.de/8Reviews/index.html
    www.slrgear.com
     

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