Basics – Exposure Time.
Last Tuesday started a new series of photography tips. After we talk in the last post about the aperture, we will have a look on the exposure time today.
The exposure time is the time while the light hits the sensor. Here we have to remember: The longer the time the brighter the picture. The time is most of the time a fraction. But it’s easier to remember than the f-numbers for example: 1/2 second.
It’s also easier to remember when the light gets doubled or halved. A 1/4 second has twice as much light as a 1/8 second. We only have some exceptions to make it even more easier. So the light gets doubled after 1/8 with 1/15 and not with 1/16.
The hole time row:
30s – 15s – 8s – 4s – 2s – 1s – 1/2s – 1/4s – 1/8s – 1/15s – 1/30s – 1/60s -1/125s – 1/250s – 1/500s 1/1000s -1/2000s – 1/4000s
It is really important to get the right time for sharp pictures. If the exposure time is too long and you don’t have tripod the pictures get blurry. You can easily remember: Don’t choose a longer exposure than the reciprocal of the focal length. This sounds complicated but it is really easy! This just means: Choose at a 50mm objective a shorter time than 1/50s (for example: 1/10 is too long) and choose at an 80mm objective a shorter time as 1/80s.
Caution: This rule is for full frame cameras! If you have a camera with a smaller sensor you have to multiplane the reciprocal with the crop factor! The most SLR cameras with smaller sensor, have an APSC sensor with the crop factor of 1.6. For example, 50mm: 1/50 * 1,6 = 80mm. You can find out the factor by google (Camera xyz crop factor).
Full frame cameras are for example: Canon 5D, 6D – Nikon D750, D810, D610.
But it can be good to use motion blur, to show motion in pictures. If the exposure time is long it’s also possible that objects gets completely transparent.
Tipp: Do you want to experiment with different exposure times. So you can choose the time and your camera will find the perfect aperture for a correctly exposure. With the “aperture value mode” (Canon: TV, Nikon: S) You can just experiment with different times without have to check every time the aperture.
XX, Nico Treeman