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Thread: shutter speed = 1/focal length?

  1. #1
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    Default shutter speed = 1/focal length?

    You know as a general rule of thumb, we're advised to set our shutter speed something around 1/focal length of the lens to avoid camera shake. For example, using a 50mm lens, it's advisable to use something around 1/50 second. The question is, that when you have the 1.6x focal multiplier of digital, would you use the actual focal length (written on the lens) or 1.6x that in order to estimate the shutter speed to use?

    I believe you would use the 1/focal length/1.6. But what do others think?

  2. #2

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    For safety sake, use 1/(1.6xfocal length) ......

    Anyway, 1/xxx is just a guide, the main thing is whether your hand is steady enough or not

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    I don't think you need to multiply by the 1.5 or 1.6 factor. Reason is simple as the magnification is due to the smaller size of the CCD and not the actual focal length.

  4. #4

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    The purpose of avoiding camera shake is to ensure sharp images.

    There are at least two considerations as far as image sharpness is concern.

    1 The enlargement factor
    2 Your personal tolerance.

    On this note it is probably correct to say that for the average photography a shutter speed approximately one focal length can only produce a "reasonable" sharpness for a reasonable enlargemene. I know that I am vague. There are some who think that they can hand hold a 35 mm rangefinder and produce "sharp" pictures. But I think their tolerance level is probably low and the enlargement factor small.

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    student: I meant, all other things being equal. Assume equal tolerance of sharpness and hand shaking etc... Would you use the 1/focal length or 1/focal length/1.6? (I use 1.6 instead of 1.5 not only cuz I'm using a 10D, but because the effect is more pronounced the larger the focal multiplier).

    nemesis: suppose you had a 10x focal multiplier (just suppose!) instead of a 1.6x focal multiplier, you still think you'd shoot with your 50mm lens (becoming a 500mm lens) at 1/50? It's true, the focal length of the lens hasn't changed, but it's sensitivity to movement has, because you've zoomed in (or cropped out a tiny part of the view). A 1mm movement of your hand translates into quite a large movement when you only look at the center 1/10 of the field of view.

    Anyway, this is kind of just tech talk, actually like some have pointed out (or alluded to), the final result could depend on other factors like your own tolerance of sharpness, and whether you happen to press the shutter at a moment when your hand is in motion or still... but just for interest's sake, I thought I'd ask this question. (as opposed to having a real concern over the matter).

  6. #6

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    Quote Originally Posted by nemesis32
    I don't think you need to multiply by the 1.5 or 1.6 factor. Reason is simple as the magnification is due to the smaller size of the CCD and not the actual focal length.
    You need, although it may not be 1/(1.6xfocal length) ..... for the fact you are getting greater magnification for the same amount of space, and thus more sensitive to handshake, if you do not believe, try to handheld a macro 1:1 picture (that is absolute magnification on 50mm lens) at 1/100, you might still have handshake .

    Just treat it this way, you get a full picture taken with a full frame 35mm picture taken at 1/60 on a 50mm lens, blow it to 8R, chances are you will not see any handshake, but crop a portion out you might see some. "Sharpness" is achieve not by virtual of you are not having handshake, but by the virtual more information are cluttered into same amount of space and thus some information (such as minor handshake) is not easily seen. For the same picture, you ask your printer to crop it (from the centre) to 70% (25mm) of itself size and blow it to the same 8R as you would with 100% of the 35mm film you might see some handshaking.

    Anyway 1/FL is just a guide, it is not accurate. One has to know their own limit.
    Last edited by blurblock; 14th October 2004 at 03:11 PM.

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    Quote Originally Posted by toasty
    student: I meant, all other things being equal. Assume equal tolerance of sharpness and hand shaking etc... Would you use the 1/focal length or 1/focal length/1.6? (I use 1.6 instead of 1.5 not only cuz I'm using a 10D, but because the effect is more pronounced the larger the focal multiplier).

    nemesis: suppose you had a 10x focal multiplier (just suppose!) instead of a 1.6x focal multiplier, you still think you'd shoot with your 50mm lens (becoming a 500mm lens) at 1/50? It's true, the focal length of the lens hasn't changed, but it's sensitivity to movement has, because you've zoomed in (or cropped out a tiny part of the view). A 1mm movement of your hand translates into quite a large movement when you only look at the center 1/10 of the field of view.

    Anyway, this is kind of just tech talk, actually like some have pointed out (or alluded to), the final result could depend on other factors like your own tolerance of sharpness, and whether you happen to press the shutter at a moment when your hand is in motion or still... but just for interest's sake, I thought I'd ask this question. (as opposed to having a real concern over the matter).
    Like i have said, as long as you follow 1/focal length, reasonable sharpness shd be ensured. As you do not actually zoom in but rather is more like cropped from the same pic, it shd still be sharp.

  8. #8

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    I think it's more like 1.6 crop factor rather than 1.6x multiplier factor

  9. #9

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    Quote Originally Posted by nemesis32
    Like i have said, as long as you follow 1/focal length, reasonable sharpness shd be ensured. As you do not actually zoom in but rather is more like cropped from the same pic, it shd still be sharp.
    Nah lar bro, you need it, zoom or crop whatever. Just think about it for a while and you will get it. Just like a teleconverter, it's still a crop from the main lens but your vibrations get magnified. This is also why a pic may look ok at resized 300x200 but not at 100% view at 3000x2000.

    It's a loose rule though.

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    Quote Originally Posted by 2100
    Nah lar bro, you need it, zoom or crop whatever. Just think about it for a while and you will get it. Just like a teleconverter, it's still a crop from the main lens but your vibrations get magnified. This is also why a pic may look ok at resized 300x200 but not at 100% view at 3000x2000.

    It's a loose rule though.
    Is that so... hmmmm must find out more.

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    Yeah, the 1/focal length is a guideline. It its not affected by crop factors. Its still the same lens. The vibrations does not increase or decrease as you crop nor does it increase/decrease when you increase sensor density. Meaning 8 megapixels > 6 megapixels, your image gets bigger does not mean now your lens shake magnifies more.

    Also need to consider how fast the subject is moving.

    Just for fun... I ever handheld bigma at >200mm and shot a triathlete at 1/(<20sec) with no handshake... only one CSer saw that I think.... must've felt strong that day.

  12. #12

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    Quote Originally Posted by toasty
    student: I meant, all other things being equal. Assume equal tolerance of sharpness and hand shaking etc... Would you use the 1/focal length or 1/focal length/1.6? (I use 1.6 instead of 1.5 not only cuz I'm using a 10D, but because the effect is more pronounced the larger the focal multiplier).
    You have heard the other opinions. I don't shoot digital, but I think it is dependent more on the focal length than the "chip size"

    Personally, because of the type of photography I do (portraits, stills, and landscape) I almost always use a tripod, with mirror locked-up if possible on my SLR. I do not trust my hand holding abilities. If I need to hand hold, I will at least try to shoot at 2x focal length for "insurance" purpose. I have photographs shot at 1/15 sec and appeared "quite sharp" at 8x10 inches but that was taken with me leaning against the wall, etc etc etc.

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    Lets look at it this way: for the same lens, the same shutter speed, and the same amount of hand shake, but on 2 formats: full frame and 1.6X cropped.

    Both systems will generate the same amount of absolute "blurr" on the recording media.

    If the final result is the same size, say a 8R print, then the "blurr" on the 1.6x cropped sensor will be magnified more, and thus more noticeable, and thus requires a higher shuttle speed to better cope with hand shake.

    I vote for using 1/1.6X focal length. Having said that, it is still just a guide. Your mileage may vary. The shooting situation also affects the choice of shuttle speed. For example:

    - you would probably need a higher shutter speed at the end of a long day of shooting compared to when you first started off in the morning.
    - you would probably need a higher shutter speed if you are shooting outdoors with strong winds.
    - you would probably need a higher shutter speed if you are shooting from a boat sailing on Singapore River
    - you would probably need a higher shutter speed when you are excited and breathing more quickly and your heart is pounding harder than usual.
    - you would probably need a higher shutter speed than 1/500 sec if you are shooting with a 500mm f/2.8 bazooka lens hand held...(not sure if such a lens exisits, but if it does it is going to be huge)
    - you would probably need a higher shutter speed if you have only slept for 2 hours the night before, or if you are shooting under intoxication..a.k.a. drunk shooting

    So, don't take this guide too seriously. It is more important to known your own capability in holding the camera steadily.
    As complexity rises, precise statements lose meaning and meaningful statements lose precision.

  14. #14
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    Hi roy

    I think it's very impt to find out the fact as it will determine whether to increase the iso etc.

  15. #15

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    As to what Roygoh has already pointed out, its better to understand your own limits with the particular set of equipment you work with. Why limit yourself by following a rule?

  16. #16

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    The guideline would be 1/(focal length * 1.6).

    For example, the CCD of a compact digital camera is much much smaller than a 35mm. Say Olympus C-770. The lens is 6.3 - 63mm. At 63mm, do you shoot at 1/63 sec or 1/380 sec to minimize handshake?

    Same for a DSLR. Crop factor do magnify handshake if you print the same size and compare.

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    Quote Originally Posted by Zplus
    Yeah, the 1/focal length is a guideline. It its not affected by crop factors. Its still the same lens. The vibrations does not increase or decrease as you crop nor does it increase/decrease when you increase sensor density. Meaning 8 megapixels > 6 megapixels, your image gets bigger does not mean now your lens shake magnifies more.

    Also need to consider how fast the subject is moving.

    Just for fun... I ever handheld bigma at >200mm and shot a triathlete at 1/(<20sec) with no handshake... only one CSer saw that I think.... must've felt strong that day.
    Although the absolute vibrations do not increase the picture area decreases, so the relative vibration increases (vibration relative to the elements in the picture). A 1mm vibration on a 35mm frame is 2.8% of the frame. a 1mm vibration on a 22mm frame is 4.5% of frame. Relative to the size of everything in the picture, a 1mm vibration is more severe as you shrink the area of view. Look at it another way: if you have take a picture and blow it up 100x and crop out a part of that, any handshake will become amplified. If you shrink it down to the size of a passport photo, the vibrations become insignificant, relative to the picture. That is why I think that even though the focal length of the lens itself remains unchanged, the 1.6x focal multiplier (or focal cropping) affects the shutter speed you should use.

    About hand-holding at slow speeds, sure it's possible. It really depends on the exact moment you press the shutter and what your hand is doing at that instant. If you're lucky, you'll press the shutter and it will open and close at a moment when your hand is not in motion (or relatively still). It's possible to take a sharp picture at 1/20s, and then proceed to take a blur picture at 1/50s using the same lens and same conditions. (not likely, but possible).

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    Quote Originally Posted by nemesis32
    Hi roy

    I think it's very impt to find out the fact as it will determine whether to increase the iso etc.
    The important fact to find out is not whether 1/focal length or 1/(focal length * crop factor) is the correct guideline to use. No guidelines are absolutely correct for everyone.

    The important fact to find out is your own capability.

    If you are shooting digital what's stopping you from trying a few shots to find out your own limits?

    There is a chance that you might be one of those with very unstable hands (no offence...just for discussion sake) whom 1/(focal length * crop factor) might not work for you even...so let's say you actually need to use 1/(focal * 2) because of unsteady hands, but decided to use 1/(focal length) or 1/(focal length * crop factor) based on the theoretical discussion here, and end up getting blurred pictures, who can you blame?
    As complexity rises, precise statements lose meaning and meaningful statements lose precision.

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    Quote Originally Posted by roygoh
    The important fact to find out is not whether 1/focal length or 1/(focal length * crop factor) is the correct guideline to use. No guidelines are absolutely correct for everyone.

    The important fact to find out is your own capability.

    If you are shooting digital what's stopping you from trying a few shots to find out your own limits?

    There is a chance that you might be one of those with very unstable hands (no offence...just for discussion sake) whom 1/(focal length * crop factor) might not work for you even...so let's say you actually need to use 1/(focal * 2) because of unsteady hands, but decided to use 1/(focal length) or 1/(focal length * crop factor) based on the theoretical discussion here, and end up getting blurred pictures, who can you blame?
    Hi Roy

    I know what you mean. Ultimately is down to individual's capabilities. Will try it out one of these days.

  20. #20

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    Quote Originally Posted by Bean
    For example, the CCD of a compact digital camera is much much smaller than a 35mm. Say Olympus C-770. The lens is 6.3 - 63mm. At 63mm, do you shoot at 1/63 sec or 1/380 sec to minimize handshake?
    This is the best example yet.

    Another example of variable crops is with a telescope with different power eyepieces (ie different crops). Obviously the higher powered eyepieces will be very susceptible to vibrations.

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