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Thread: Crop factor

  1. #1

    Default Crop factor

    http://www.kenrockwell.com/tech/crop-factor.htm
    http://digital-photography-school.co...tor-explained/

    After reading the two above articles I got a better understanding of crop factor

    But still got some doubts:

    1) If a 50mm lens is fitted on a D60, it has the equivalent of a 75mm lens right? So that means the zooming capabilities has become more "powerful" since the 75mm can zoom better?

    2) After the auto enlargement, will the printed picture look like:

    the full or the coloured ones?

  2. #2

    Default Re: Crop factor

    If I'm not wrong, the Red box is for Nikon, the Blue for Canon. No idea about Green.

  3. #3

    Default Re: Crop factor

    Quote Originally Posted by PyeeL View Post
    If I'm not wrong, the Red box is for Nikon, the Blue for Canon. No idea about Green.
    So for:

    1) The zoom will be equivalent of that of a 75mm
    2) But after printing out it will look like the red box

    ?

  4. #4

    Default Re: Crop factor

    If you're on Nikon, and if I remember correctly, the crop factor is 1.5x
    If your lens' focal length is 50mm, yes, 50mm x 1.5 = 75mm equivalent on a full frame sensor. It's not a zoom, but a focal length.

    If you're on Nikon, your image taken right out of the DSLR will be just like the red box, as compared to the whole frame that full frame sensors can capture.

  5. #5

    Default Re: Crop factor

    Blue - 1.6x
    Red - 1.5x
    Green - 1.3x
    Full - FF

    So your would be the Red.
    Last edited by fitzy; 24th November 2008 at 08:29 PM.

  6. #6

    Default Re: Crop factor

    Quote Originally Posted by gameboyz View Post
    http://www.kenrockwell.com/tech/crop-factor.htm
    http://digital-photography-school.co...tor-explained/

    After reading the two above articles I got a better understanding of crop factor

    But still got some doubts:

    1) If a 50mm lens is fitted on a D60, it has the equivalent of a 75mm lens right? So that means the zooming capabilities has become more "powerful" since the 75mm can zoom better?

    2) After the auto enlargement, will the printed picture look like:
    you get it out of cam

    theoretically speaking, there is no such thing as zooming capabilities. read up on "field of view" and "perspective" and you'll understand what i mean. yes, when 50mm lens fitted on 1.5x crop factor camera, will become 75mm lens.

    basically, you have different types of sensors

    1. full frame (no crop factor) cameras like canon 5d give you what is seen on teh film strip

    2. 1.3x crop cameras like one of the canon mark series gives you what should be seen in the green box

    3. 1.5x crop gives you red, like most nikon/pentax cameras, some other brands too like sony

    4. 1.6x crops like in canon entry level dslr gives you blue box.

    what you see through your respective camera viewfinder with the same lens mounted will be based on the box. what you get out of the camera after snapping too.

  7. #7

    Default Re: Crop factor

    Quote Originally Posted by fitzy View Post
    Blue - 1.6x
    Red - 1.5x
    Green - FF

    So your would be the Red.
    wrong.

    green is 1.3x

    full frame will give you film equivalent

    that is what the film border is there for..

  8. #8

    Default Re: Crop factor

    Was about to edit, too quick to post. Thanks for the correction.
    Last edited by fitzy; 24th November 2008 at 08:30 PM.

  9. #9

    Default Re: Crop factor

    Crop factor is not equivalent to zoom, becoz effects like DOF are still observed based on the lens aperture and focal length. E.g., a 50mm @ f/2 will deliver the same DOF regardless of which body it is mounted on (be it 1.6x, 1.3x or FF). However, since the FOV for a 50mm on a 1.6x body is 80mm, it is not going to deliver the same DOF as a real 80mm @ f/2 (if such a lens exist in reality) mounted on a FF body.

  10. #10

    Default Re: Crop factor

    Quote Originally Posted by gameboyz View Post

    1) If a 50mm lens is fitted on a D60, it has the equivalent of a 75mm lens right? So that means the zooming capabilities has become more "powerful" since the 75mm can zoom better?

    2) After the auto enlargement, will the printed picture look like:

    the full or the coloured ones?
    theres no "zoom" involve in crop sensor when using 35mm lenses, the Field-Of-View will just become narrower because the sensor/view finder CAN'T see the full image circle! think watching widescreen movies in a 4:3 display/CRT, instead of seeing the full picture, only a portion of it is display on the TV. this is a handicap not a feature.

    the confusion here is the field of view, a 35mm full frame's 50mm lens when use on the crop sensor--take canon 40D for example--due to its inability to see the whole image circle, the 50mm lens will appear to have the same FOV as 80mm on 35mm full frame. every thing except the FOV remain the same as 50mm lens, including DOF.

    Canon Focal Length Compare
    Last edited by kurtlim; 24th November 2008 at 09:43 PM.

  11. #11

    Default Re: Crop factor

    Because in layman terms focal length means zoom right? Telephoto lens with super zooming has high focal lengths ..

  12. #12

    Default Re: Crop factor

    Quote Originally Posted by gameboyz View Post
    Because in layman terms focal length means zoom right? Telephoto lens with super zooming has high focal lengths ..
    no zooming means that you can change the focal length.... a super-zoom means that the change in focal length is large, a 18-200mm zoom lens is a super zoom, a 200-400 would not be called super-zoom even though the focal length is longer it is only a 2x zoom while the former is 3.5x zoom
    please dont mix up terms
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  13. #13

    Default Re: Crop factor

    Hi guys I think I understand it:

    Quote Originally Posted by http://www.photoxels.com/tutorial_focal_length.html
    So, for a dSLR using an APS-sized image sensor, the focal length of a 55mm lens becomes approx. (55 x 1.6 = ) 88mm lens. This is both good news and bad news. The good news is that you can now achieve super telephoto coverage without buying costly and unwieldly lenses. For example, a 100-300mm zoom lens, with a focal length multiplier of 1.6, now acts like it was approx. 160-480mm. The bad news is, of course, that your 18mm super wide-angle lens is now acting as though it were approx. 28mm, making it almost impossible to obtain the kind of super wide-angle coverage that most professionals desire.

  14. #14

    Default Re: Crop factor

    What about Canon EFS lenses, do I need to multiply by 1.6 to get the approx focal lenght?

  15. #15

    Default Re: Crop factor

    Quote Originally Posted by Michael View Post
    no zooming means that you can change the focal length.... a super-zoom means that the change in focal length is large, a 18-200mm zoom lens is a super zoom, a 200-400 would not be called super-zoom even though the focal length is longer it is only a 2x zoom while the former is 3.5x zoom
    please dont mix up terms
    200 / 18 != 3.5

  16. #16
    Member kenkht's Avatar
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    Default Re: Crop factor

    Crop means CROP.. doesn't mean ZOOM. Got it? It is only affecting the Field of View (FOV). Doesn't do anything to your magnification, or resolution. YOU just get less picture, got it. When people talk about eg a crop body of 1.6x, a lens of 100mm is equivalent to 160mm. Well HALF TRUTH. Your VIEW is equivalent to 160mm, yes, but you still get the same magnification and resolution of 100mm. No magic. Your lens do not suddenly become longer. Get it?

    If confuses the hell out of newbies when people talk like .. "oh you get 160mm with a 100mm, how cool is that." An actual 160mm lens will give you tons better resolution and sharpness then the 100mm could at a distant object, even though the FOV is the same. Got it?
    Just take the word as it is, crop means crop.

  17. #17

    Default Re: Crop factor

    I also have a question about crop factor.

    Let's say 105mm macro lens. With 1.5 crop factor, it's effective focal length is 157.5mm. Does it mean that APS-C sensor enlarges more (able to see more details) compared to full frame? Or still is it the same for both sensors?

  18. #18

    Default Re: Crop factor

    Quote Originally Posted by Zeddy View Post
    I also have a question about crop factor.

    Let's say 105mm macro lens. With 1.5 crop factor, it's effective focal length is 157.5mm. Does it mean that APS-C sensor enlarges more (able to see more details) compared to full frame? Or still is it the same for both sensors?
    Assuming in your example that the FF sensor has the same pixel density as your APS-C sensor, then both the sensors will see exactly the same amount of details when using the same lens. Of coz, if the FF has the same pixel density as your APS-C sensor, then it will naturally mean that it has a higher pixel count compared to your APS-C body.

  19. #19
    Member gymak90's Avatar
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    Default Re: Crop factor

    This thread has lots of posts that make the idea of crop factor, much more confusing than what it really is.

    Anyway, the green box refers to the APS-H sensor which gives 1.3x crop factor. APS-H sensor only by some Canon 1d series dslrs.

    So crop factor, is just about the sensor being smaller than full frame(which is 36X24mm). As a result, the field of view or viewing angle, is less than what it is on full frame.

    Don't believe? Go try it with your own eyes. Put your 2 palms next to your eyes. And obviously you can no longer see the stuffs at the sides.

    What people like to say is sometimes misleading. Mounting a 100mm lens on 1.6x crop factor sensor DOES NOT turn the lens into 160mm focal length. No such magic. No such trick. No such good deal.

    What happens is people often leave out is the phrase: field of view.
    Look my friends, a 100mm lens on 1.6x crop factor sensor, gives you the equivalent field of view as that of 160mm on full frame. Which is to say, your view becomes narrower. That's all. Therefore, the objects in your picture, do not magnify. They do not become bigger. They remain as normal sized.

    Using my 'palm-next-to-eye' example, you won't see things become bigger right? Do you? If yes, something's wrong

    Quote Originally Posted by Zeddy View Post
    I also have a question about crop factor.

    Let's say 105mm macro lens. With 1.5 crop factor, it's effective focal length is 157.5mm. Does it mean that APS-C sensor enlarges more (able to see more details) compared to full frame? Or still is it the same for both sensors?
    I think the above answers your question. No you don't see more details, because your subject won't become bigger in anyway. Also it depends on the number of pixels and pixel density. Number of pixels is associated with resolving power of the sensor.
    Last edited by gymak90; 24th November 2008 at 11:07 PM.
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  20. #20

    Default Re: Crop factor

    Quote Originally Posted by kenkht View Post
    Crop means CROP.. doesn't mean ZOOM. Got it? It is only affecting the Field of View (FOV). Doesn't do anything to your magnification, or resolution. YOU just get less picture, got it. When people talk about eg a crop body of 1.6x, a lens of 100mm is equivalent to 160mm. Well HALF TRUTH. Your VIEW is equivalent to 160mm, yes, but you still get the same magnification and resolution of 100mm. No magic. Your lens do not suddenly become longer. Get it?

    If confuses the hell out of newbies when people talk like .. "oh you get 160mm with a 100mm, how cool is that." An actual 160mm lens will give you tons better resolution and sharpness then the 100mm could at a distant object, even though the FOV is the same. Got it?
    Just take the word as it is, crop means crop.
    I think I understand, so you mean the website I quoted is inaccurate in saying that you get telephoto lens without paying for it?

    So basically, crop means you get a smaller picture, but quality won't be affected. The "160mm" lens has the view of a 160mm telephoto lens, but when you take the picture it results in the magnification of a 100mm telephoto lens and NOT the 160mm.

    Am I right to say this? Thanks for your help guys anyway!

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