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For a given scene, if I take 2 similar shots:

  • short exposure time (maybe using higher aperture, higher ISO...)
  • long exposure time (lower aperture or ISO)

The goal is to have the shots with the same exposition, but with different settings.

Is the dynamic range the same between the 2 shots?

i.e. if I want to try to capture a scene that has a large dynamic range (like a sunset for example), should I try to use a long exposure time (with ND filters and tripod) or not?

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  • \$\begingroup\$ The dynamic range of the camera is always the same for each ISO setting, and it drops by approximately a stop for each stop of ISO increase. However the contrast range of each photo you take IS dependent on exposure time. You may not necessarily use the full dynamic range offered by your camera in each and every shot. If you are not saturating your photos, which means exposing to the point of nearly over-exposing, then you can probably expose longer to utilize more of the dynamic range offered by the camera. \$\endgroup\$
    – jrista
    Commented Sep 9, 2012 at 17:39

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The most significant factor that affects dynamic-range captured by the sensor is ISO. The higher the ISO, the lower the dynamic range. So to maximize dynamic-range you have to shoot at the native ISO of your camera. Longer exposures can add very slightly more noise as the sensor heats up but if you compare this to the loss of dynamic-range from using a higher ISO, it is completely insignificant.

Take a look at DXO Mark's measurements for the K-5 for example. It's a pretty dramatic drop from 14 EVs at ISO 80 to less than 6 at ISO 51200.

enter image description here

Camera settings affect the dynamic-range of JPEG images. Most modern cameras have a highlight priority option which lets them store more dynamic range when producing a JPEG. Color modes or picture styles also affect this. The modes with the least contrast such as Natural or Faithful, show the most scene dynamic range.

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    \$\begingroup\$ Amazing! You've just blown my mind, I've been taking dark+hdr scenes with high ISO (to minimize the noise, as you said, cf photo.stackexchange.com/questions/6615/…), but I should have gone with low ISO! \$\endgroup\$
    – Matthieu Napoli
    Commented Sep 9, 2012 at 20:18
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Dynamic range is independent of exposure time and settings. Regardless of whether you take a shot at f/16 for 1/60th or f/8 for 1/125th (for example), if the dynamic range is too large for your sensor to cope with, some part of your shot will be exposed incorrectly.

A scene with large dynamic range essentially requires two different exposures in the same shot: a longer exposure for the darker part and a shorter exposure for the lighter part.

ND filters and the Black Card Technique are examples of methods where this is achieved in-camera. Nowadays, it is also extremely easy to blend two separate shots together in post-processing.

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