1/Over Rule

Does anyone know what the 1/Over rule is? I did a google search and it did not return any results relating to photography.

1 over focal length (times crop factor) = minimum shutter speed to minimise camera shake when hand-holding (eg with a 200mm lens on a 60D you'd want to keep your shutterspeed above 1/320th if you don't have an IS lens).

Remember, this is just a suggested rule which seems to fit the majority of photographers. Some folks can hand-hold at a slower speed while a somewhat greater percentage seem to need a faster speed to guarantee sharp images.

As for me personally, the rule is just fine for shorter focal length lenses (under 100mm or so) but when I am shooting with longer lenses, such as: 200, 300 or 400mm, I tend to need a shutter speed a bit faster than 1/Focal Length x 1.6. That could be because the longer focal length lenses are larger with more wind resistance and a lot heavier than the shorter lenses.

However having IS compensation on my 70-200mm f/4L IS lens allows me to shoot as slow as 1/60 second with every expectation of a sharp image. I can even sometimes go down to 1/30 second and get a goodly percentage of keepers but, this is on a case by case basis. I need to have a good stance (can't be on a slope), be breathing normally (not having run to get in position to shoot the image), and have my wits about me (concentrating on my hold).

However, the older IS system on my 300mm f/4L IS lens only will allow me to go down to about 1/250 second (or perhaps a bit slower) because the IS is not as efficient and because the 300mm lens is quite a bit larger and heavier than the 70-200mm f/4L IS.

The key to needing faster shutter speeds with the longer focal lengths is the length of the lens. The longer the lens, the more exaggerated the motion to the far end of the lens. For an example of this, take a chop stick and hold it very close to the tip. Wiggle your hand just a little and watch the motion of the tip of the stick. Now, hold it by the very end and repeat the same wiggle. The far end of the stick will move a great deal farther than does your hand in the latter case.

Add to that exaggerated movement, the fact that the longer focal length lens covers a much smaller portion of the scene and the effect is magnified.

Thus, the 1/Over rule was designed for primes, rather than the compact zooms so prevalent today. It is a good starting point, though.

Pops

I should add that it's a rule for MINIMISING camera shake, not eliminating it. I've heard it said that to practically guarantee eliminating it, one has to aim for around 5 times faster again.

Probably also worth mentioning that great as IS is, it's for countering camera shake; it does ZERO in terms of freezing subject motion.

There are a couple other 1/Over rules I know of which apply to exposure. The first being termed the "Sunny 16" which defines the basic incident light exposure as:

On a sunny day set aperture to f/16 and shutter speed to 1 / ISO film speed.

Sunny 16 Rule From Wikipedia

and another version deals with exposure where you are photographing the Moon, "Moony 11":

To photograph the full Moon, set aperture to f/11 and shutter speed to 1 / ISO film speed.

Take a Picture of the Moon

Quote:

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Originally Posted by Steaphany

On a sunny day set aperture to f/16 and shutter speed to 1 / ISO film speed.

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I should just add that there is an important "part II" to that rule that's nearly always forgotten: "... for a front-lit subject, at least 2 hours after sunrise, and at least 2 hours before sunset".

I bet I'm not interested in this. :)

Rules is rules, do as your told, I'll probably watch.