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Comparing focal lengths of nex cameras vs point and shoots

Discussion in 'Sony Alpha E-Mount Cameras' started by alaios, Aug 13, 2013.

  1. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    Hi all,
    I am just wondering what are the focal lengths the manufactures print at the point and shoot cameras.
    I have a sx220hs
    Canon SX220 HS: Digital Photography Review
    that over the lens is printed that is 5-70mm (well what is the crop factor of this type of devices?)

    on the link I gave you though it says that the focal length is from 28-392mm but then how this can be compared to my nex camera? I start to get confused with these crop factors calculations.

    I would like to thank you in advance for your help

    Regards
    Alex
     
  2. shaolin95

    shaolin95 TalkEmount Top Veteran

    942
    Jul 3, 2013
    So they show 28–392 mm as the equivalent in 35mm format. As to how it compares to your NEX depends on what lens but you need to convert using the crop factor of the Nex which is 1.5x Like 16mm will be 24mm in 35mm/full frame.
     
  3. dbmiller

    dbmiller TalkEmount Top Veteran

    777
    Mar 2, 2012
    New England
    The crop factor is how you get the 35mm (Full frame) equivalent for the lens. So the lens is a 5-70mm, and the crop factor is... (Searching net...) 5.62, so the equivalent lens on a 35mm film camera is 5*5.62-70*5.62, or approximately 28-392mm.

    Since the crop factor of a NEX is 1.5, an equivalent lens would have to be 28/1.5-392/1.5, or approximately 19-261mm
     
  4. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    Wait a sec..... this is confusing, why the manufacturer wrote over the lens 5-70mm when people going to buy can not know the crop factor?? Is like telling you that I sell my nex-f3 60 euros and then tell you that the number was not in decimal system but on hexadecimal..
     
  5. dbmiller

    dbmiller TalkEmount Top Veteran

    777
    Mar 2, 2012
    New England
    Crop factor is a function of the sensor, not the lens. The lens really has a focal length of 5-70mm. Using that lens to project onto a small sensor is what causes it to appear to be 5+ times larger than it actually is. So to achieve the same thing with a 35mm film camera, you need a lens 5+ times as big, thus the 28-392 number given as the "35mm equivalent".

    For example, take a Canon EF 50mm 1.8 lens (The nifty fifty). The lens is a 50mm lens. On a FF digital or film camera, it truly is a 50mm lens in terms of the 24mmx36mm image circle it generates over the film/sensor. But put that same lens on a APS-C camera, and that same lens is now the equivalent of an 80mm lens, since Canon's APS-C sensors have a crop factor of 1.6. The lens hasn't changed, so how could you change the markings on the lens?
     
  6. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    Yes but in a point and shoot the relation of sensor + lenses is always the same.. it does not change. Why there is no rule to write the 36mm equivalent?? That way I would be able to compare two point and shoot cameras directly. Otherwise Ican not do that and the numbers on the lens are no helpful at all..
     
  7. shaolin95

    shaolin95 TalkEmount Top Veteran

    942
    Jul 3, 2013
    I think you are making this harder than it is.
     
  8. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    Alex, if you use the affiliate link for B&H Photo and look at any digital P&S camera they list, they show the 35mm equivalent focal lengths for every single camera they sell. Not some of them. Not most of them. Every. One. Of. Them.

    Simple, no? And simple is better than complex most of the time. ;)
     
  9. dbmiller

    dbmiller TalkEmount Top Veteran

    777
    Mar 2, 2012
    New England
    The only standard is the focal length of the lens - Focal length is, and always will be, the distance in millimeters from the optical center of a lens to the imaging sensor when the lens is focused at infinity. That is the only "standard" there is. 35mm film equivalents make it easier to compare, but there is nothing that makes that a standard, so there is no requirement to put those equivalents on the camera/lens.

    35mm film isn't the only film. There are medium format and large format cameras as well that take much larger film stock. You might have a 30mm fish-eye lens on a 6x6 film camera. 50mm would be wide-angle. And 150mm might be a decent portrait lens.

    Differences in film sizes have been around forever, and all those lenses never had to have equivalent markings placed on them. The actual focal length hasn't changed. The crop factor is just a way to say how the actual field of view compares to another format. And that information is readily available on the net.

    If you want to compare two point and shoot cameras, then you need to know what the sensor size is of each camera. Then you will know whether you are comparing apple to apples, or apples to oranges, or grapefruit, or watermelons. And how to compare them.
     
  10. macro

    macro TalkEmount Regular

    152
    Feb 3, 2012
    New Zealand
    Danny Young
    I'll tell you what makes the whole problem go away altogether, there's a secret to this formula ;)

    You see what you want to take, pick up the camera, zoom in until it just looks right and then you go ...... Click !! Now if it doesn't look right, you zoom again until it does.

    I've owned super zoom cameras and started with a Sony FD-91, held 4 fine shots on a floppy disk, then 5 more super zooms and this has never been a problem ;) Every single one had the 35mm equivalent on the camera or in the instruction book, or in the advertising.

    In short, don't worry about it, but if you do........

    http://www.dpreview.com/products/canon/compacts/canon_sx220hs/specifications

    1/2.3" (6.17 x 4.55 mm) sensor with a 5-70mm zoom (on that size sensor) = 28-390mm lens in 35mm terms.

    All the best.

    Danny.
     
  11. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    And there sportsfans, we have the issue boiled down to its essence. ;)
     
  12. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    Hi thanks for this answer. Actually my "motivation" is to be able to somehow understand the focal length of a lens without having to know the crop factors. That would be very useful for comparing very fast point and shoot cameras (how close they can for example give you the distant objects).

    Regards

    A
     
  13. dbmiller

    dbmiller TalkEmount Top Veteran

    777
    Mar 2, 2012
    New England
    I think you'll find most point and shoots will describe their lens as a "4x" zoom, or "5x", or "10x", etc. On the wide end, they will most likely be in the 25-35mm range (In the 35mm equivalent), no matter what the crop factor. So if you want to know if one point and shoot has more reach than another, just compare the zoom factors.

    So a Canon G15 is a 5x zoom. The Sony RX100 is a 3x zoom. The Panasonic Lumix DMC-FZ200 is a 24x zoom.