# Minimum shutter and focal length for APS-C and 5DS



## AlanF (Dec 2, 2015)

There is a good article in TDP on minimum shutter speeds and focal length of lenses.

http://www.the-digital-picture.com/News/News-Post.aspx?News=17252

The author is basically right that pixel size is the key factor, and argues and experiments that 1/2*_f _is a better working rule than 1/1.6*_f_ for APS-C and 5DS/R.


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## Maximilian (Dec 2, 2015)

AlanF said:


> There is a good article in TDP on minimum shutter speeds and focal length of lenses.
> 
> http://www.the-digital-picture.com/News/News-Post.aspx?News=17252
> 
> The author is basically right that pixel size is the key factor, and argues and experiments that 1/2*_f _is a better working rule than 1/1.6*_f_ for APS-C and 5DS/R.


Thanks for sharing.

I was talking to a guy at brick and mortar store lately who also does camera workshops (studio to "wildlife" at the zoo).
He told me that for a 5Ds (R) you should use at least 1/(4*focal lengh) if you're not using a tripod and the subject is not steady. 
Even with a 5D3 he'd recommend at least 1/(2*focal lengh).

Feel free to think about this and make your own opinion.


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## zim (Dec 2, 2015)

1/(2*focal length)

Been using that for some time now. Sadly it's also an age thing for some *sigh*


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## Valvebounce (Dec 3, 2015)

Hi Zim. 
You got me thinking how to incorporate age with a sensible result, seriously, my photo buddy has problems with sway, he's approaching 65
1/(2x focal length + age) or maybe 1/(2x focal length)+ 2/(3x age) perhaps I didn't express the fraction correctly, don't like 1/(1.5x age), it doesn't look right, anyone think of a better formula. 
In case you are wondering maths formulae are not a real strong point for me. Perhaps it should be logarithmic or something so that at a young age it is a small ratio and as age increases the ratio increases? 

Cheers, Graham. 



zim said:


> 1/(2*focal length)
> 
> Been using that for some time now. Sadly it's also an age thing for some *sigh*


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## Mt Spokane Photography (Dec 3, 2015)

Maximilian said:


> AlanF said:
> 
> 
> > There is a good article in TDP on minimum shutter speeds and focal length of lenses.
> ...



I read the article earlier, but I am of the inclination to use higher shutter speeds wherever possible. With IS lenses, shutter speed is not as critical, and for moving subjects, a much higher shutter speed is needed.

I think that trying to get pixel sharp images from a 7D MK II or a 5Ds series using a non IS lens and 1/1.6*focal length will not work for a significant number of cases. Camera and lens testers have all remarked about how difficult it is to get the full resolution the cameras can yield. I used 1/2X for my old 7D.


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## rpt (Dec 3, 2015)

Valvebounce said:


> Hi Zim.
> You got me thinking how to incorporate age with a sensible result, seriously, my photo buddy has problems with sway, he's approaching 65
> 1/(2x focal length + age) or maybe 1/(2x focal length)+ 2/(3x age) perhaps I didn't express the fraction correctly, don't like 1/(1.5x age), it doesn't look right, anyone think of a better formula.
> In case you are wondering maths formulae are not a real strong point for me. Perhaps it should be logarithmic or something so that at a young age it is a small ratio and as age increases the ratio increases?
> ...


+1 for both of you. I have been using 1/(2*focal length) on my 5D3 for some time now.


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## privatebydesign (Dec 3, 2015)

The premise of the article is fundamentally flawed.

For the longest time dof (sharpness) has had a standard, an 8"x10" print at 12" viewing distance regardless of the size of the capture medium. The entire article is based on the premise that you would view a higher density image at a larger magnification ratio than the lower density image, which is daft, pixel density has nothing to do with magnification unless you view and print at 100% view (which you might do for sharpening etc but not for useful high quality images). 

It is like taking images with a ff camera and a crop camera and printing the crop camera image larger than the FF image because it has more pixel density, or to take the accepted standard, you would look at a ff image printed to 8"x10" at 12" and the crop camera image printed to 16"x20" and still viewed at 12". 

You have to have a standard to consider anything a comparison, in this instance the same sized output, either on screen or in print has to be the standard.


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