Break the resolution rules
The old rules for shake-free photos are challenged by high-resolution cameras
Ever since I read my first book on photography there’s been one rule for sharper photos that always holds true – keep everything still. For the times you hand-hold the camera, the rule is to use the reciprocal of the focal length to avoid the chance of camera shake. So, if you use a 100mm lens, then you’ll need 1/100 sec shutter speed, and for a 500mm lens 1/500 sec.
But with the advent of hi-res digital sensors and larger screens we’ve stopped judging the sharpness of a 10x15cm print. My 24-inch monitor is 50cm wide and there’s 1920 pixels in those 50cm. Zoom in to 1:1 on a 24Mp image and it’s like looking at a print that’s 1x1.5ms. It’s no surprise that you see more faults looking at digital images at full-size on a monitor.
When the first EOS-1D was updated to the EOS-1D Mark II and the resolution jumped from 4.1Mp to 8.2Mp, many pro sports photographers found they needed to use faster shutter speeds to achieve the same level of sharpness. Fast forward to the 24Mp and 30Mp cameras commonly in use and you should realize that the old rules might have stopped being as effective.
With the current crop of cameras, solid tripods or faster shutter speeds are needed to freeze miniscule movements of subjects. I’ve been using the reciprocal of twice the focal length as my guideline for years. For portraits I do my utmost to use a minimum of 1/100 sec regardless of the lens.
If you use Program or Aperture Priority with Auto ISO, your camera will do it’s best to achieve the traditional hand-holding speeds for your lens by raising ISO. The more advanced models include custom settings to select 1, 2 or 3-stops faster shutter speeds than the rule would dictate. You can even set a fixed minimum speed too. From the
EOS 80D, EOS RP and higher models this capability is found in the ISO Speed settings, and if you use Auto ISO with Program or Aperture Priority I suggest you go and update the usage of this rule for sharper shots.