View Poll Results: Which one is correct?

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  • 1/ (focal length)

    58 46.77%
  • 1/ (focal length x crop factor)

    66 53.23%
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Thread: POLL: 1/focal length rule

  1. #61

    Default Re: POLL: 1/focal length rule

    Personally for me, I read from a few resources (forget where liao) that should use 1/(focal length * 1.6).

    Since my lens has IS which will give it around 2 stops. This 2 stops just nice will cancel out the crop factor.
    1/(focal length *1.6) *2 is about equal to 1/focal length.

    So in the end, I still use 1/focal length. My 2 cents.
    EOS 550D EFS 18-200 IS + Sigma 50mm F1.4 HSM + 430EXII

  2. #62

    Default Re: POLL: 1/focal length rule

    Well, it's just a rule of thumb...meaning everybody's mileage varies, but as it is, the 1/(FL * CF) makes more sense.

    Simply:
    Do you hand hold a PowerShot S5 at it's long end (72mm, 432mm eqv.) at 1/80s ?
    Last edited by grantyale; 10th December 2008 at 05:09 PM.

  3. #63

    Default Re: POLL: 1/focal length rule

    I prefer (as some poster here did) to call this a guide instead of a rule. Yes, crop factor have to be taken into consideration. The guide is to let the shooter know that when he is reaching the threshold, he/she should be more careful with the handholding techniques - breathing, stance, grip etc.

    Another way to look at it is a statistical probablity. As you use a slower shutter speed, your chances of a blurred shot due to camera movement will increase. I think there was an article in Rob Galbraith or Luminous Landscape that compared the performance of an IS and non-IS using statistics - ie. % of good shots at a particular shutter speed.

    You will be surprise that you can get sharp pictures at low shutter speed. I shot a sharp picture at 1/25 at 200mm on a 40D (no image stabiliser). But then again, there were also a lot of my shots taken at higher shutter speed that came out blurred.

  4. #64

    Default Re: POLL: 1/focal length rule

    I beg to differ on the crop factor to be taken into account at all. Crop factor as the name implied means cropping behaviour is involved, as some articles outside clearly indicated cropping has NOTHING to do with focal length of the lens. You don't get a 300mm focal length just because you have a 1.5 cropping factor on the sensor using a 200m lens. Cropping only means less usage of the optical glass, it doesn't lengthen the optical zoom of the lens. If the theory of minimum shutter speed to be revolving around the optical focal length of the lens, then cropping factor should be out of the formula.

    Imagine, this, using DX sensor, my hand shake is top and down in total of 1cm in movement, so every pixel in it move by 1cm. Then I crop further, resulting only with 1 pixel by 1 pixel as actual image. so now the cropping factor is extreme. Does it means the 1 pixel this time move more ? or should it still be 1 cm in movement ?

    So my observation here is cropping does not gives more optical focal length, so it doesn't result in larger magnitude of movement due to hand shake. If you are comparing between D300 and D700, almost same number of pixels, you definitely know that the pixel pitch of D300 is smaller than D700. It merely means more resolving power on the sensor itself, provided the resolving power of the optical glass is not exceeded.

    But I suspect another attribute should be in the formula instead of the cropping factor. It should be the pixel pitch, but I must say given the magnitude of the movement, the pixel pitch is negligible and therefore can be ignored.

    Thanks
    Last edited by David Kwok; 12th December 2008 at 12:36 PM.
    D3S|N70-200|N24-70|N24-85|N50f1.4|N35f2|SB800|SB900|Yashica GS|S95
    www.flickr.com/photos/davidktw

  5. #65
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    Default Re: POLL: 1/focal length rule

    In the film days. Leica guideline is 1/ (focal length x 2). With all the crop camera and P&S, it should be 1/ (focal length x 2 x crop factor) without IS, VR or VC to get sharp picture without tripod.
    With IS, VR or VC, best play around with 1/ (focal length ) without tripod.
    The best is tripod. No 1/(whatever) rule

  6. #66

    Default Re: POLL: 1/focal length rule

    Quote Originally Posted by David Kwok View Post
    I beg to differ on the crop factor to be taken into account at all. Crop factor as the name implied means cropping behaviour is involved, as some articles outside clearly indicated cropping has NOTHING to do with focal length of the lens. You don't get a 300mm focal length just because you have a 1.5 cropping factor on the sensor using a 200m lens. Cropping only means less usage of the optical glass, it doesn't lengthen the optical zoom of the lens. If the theory of minimum shutter speed to be revolving around the optical focal length of the lens, then cropping factor should be out of the formula.

    Imagine, this, using DX sensor, my hand shake is top and down in total of 1cm in movement, so every pixel in it move by 1cm. Then I crop further, resulting only with 1 pixel by 1 pixel as actual image. so now the cropping factor is extreme. Does it means the 1 pixel this time move more ? or should it still be 1 cm in movement ?

    So my observation here is cropping does not gives more optical focal length, so it doesn't result in larger magnitude of movement due to hand shake. If you are comparing between D300 and D700, almost same number of pixels, you definitely know that the pixel pitch of D300 is smaller than D700. It merely means more resolving power on the sensor itself, provided the resolving power of the optical glass is not exceeded.

    But I suspect another attribute should be in the formula instead of the cropping factor. It should be the pixel pitch, but I must say given the magnitude of the movement, the pixel pitch is negligible and therefore can be ignored.

    Thanks
    agree. the rule has nothing to do with the camera at all. it is only the lens that comes into play. take it as if you took a picture with a FF camera, and cropped it so that whatever is left is the reciprocal of 1.3/1.5/1.6/2 times the original image size. that is basically what the cropped cameras are doing.

  7. #67
    Senior Member darrrrrrrrrr's Avatar
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    Default Re: POLL: 1/focal length rule

    Quote Originally Posted by grantyale View Post
    Simply:
    Do you hand hold a PowerShot S5 at it's long end (72mm, 432mm eqv.) at 1/80s ?
    well-illustrated.

    visible handshake is determined as much by the focal length as format size, since it's about the ratio of handshake to image size.

    anyway for me it's just a rule of thumb that i do pay some attention to. usually i'll give it some leeway but i'll have to watch out for my breathing, stability, etc.

    if i'm lazy i'll just crank up the ISO.

    or not blow my photos up to 100%.

  8. #68
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    Default Re: POLL: 1/focal length rule

    can someone add total equipment weight as a variable in this math model?

    or have the time to vary the weight while all being equal and and show some test results?
    I own Nikon D90. My primary camera comes with Whatsapp.

  9. #69

    Default Re: POLL: 1/focal length rule

    Quote Originally Posted by ch130176 View Post
    can someone add total equipment weight as a variable in this math model?

    or have the time to vary the weight while all being equal and and show some test results?
    Nice Why not you give it a trial ? Put on some dumbbells of different weights, show us at different shutter speed on the effect and we assess from your pics
    D3S|N70-200|N24-70|N24-85|N50f1.4|N35f2|SB800|SB900|Yashica GS|S95
    www.flickr.com/photos/davidktw

  10. #70

    Default Re: POLL: 1/focal length rule

    Quote Originally Posted by darrrrrrrrrr View Post
    well-illustrated.

    visible handshake is determined as much by the focal length as format size, since it's about the ratio of handshake to image size.

    anyway for me it's just a rule of thumb that i do pay some attention to. usually i'll give it some leeway but i'll have to watch out for my breathing, stability, etc.

    if i'm lazy i'll just crank up the ISO.

    or not blow my photos up to 100%.
    i refer to this forum
    http://www.velocityreviews.com/forum...eld-shots.html

    i strongly believe that the rule is based on the 'raw', unmultiplied focal length, and that the crop does not come into play.

    however, the fact is that when multiplied several times by a small sensor (say 5x and more), the camera shake is more evident. this is because the camera is actually cropping the image. for instance, if you view an image at say 25%, you may think that it is sharp. but zoom in 5x and you might on some shots detect a little blur. this is really what is affecting the results.

    due to the fact that the image is cropped and enlarged, thus the effect is amplified

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