What is the dynamic range in photography ?
The digital camera cannot capture the scene as we see. There are highlights on the scene, shadows and mid-tones. If you used a digital camera probably noticed that in bright sunlight the sky can be white colored, without any detail. This is when the camera “burn out” the highlight because cannot capture the too bright scene.
On the other part of the spectrum in dark areas often it is very hard to capture any detail, the image will be simple black instead.
If we don’t need to capture the bright and the dark details on the same picture, it is not very hard, because if we want to see details in the shadows we can overexpose the image to be brighter or in other case if we don’t want the sky to be burned out we can underexpose the picture to be darker.
Many cases we choose to burn out the sky if the detail in the darker areas is more important, for example if we make a portrait.
The range of this black-white difference of light levels of the camera we call dynamic range. If the camera can capture more range between in the bright or dark areas that camera is better.
Dynamic range is measured in EV (exposure value). 1 EV is a double or half stops of light, or one diaphragm changes on the lens (for example from f/4 to f/5.6 is half quantity of light or 1 stops).
If the scene has for example 10 EV dynamic range this means that between the darkest and brightest part of the frame the difference is 1024 times of light (between the darkest shadows and the brightest sunlight). I hope it is not to scientific.
If the scene dynamic range is 2 EV this means the difference between the lightest and darkest part is 4 times of light,
When is Dynamic range most important ?
Dynamic range is most important when there are very bright and dark details on the same image, mostly landscapes. Usually the sky is very bright and if there is a tree on the picture there are some shadows as well.
How the dynamic range changes when we increase ISO ?
The above chart is a DXOMark comparison of three Aps-C cameras. What we can see that dynamic range is decreases as we increase ISO sensitivity. This is why for landscapes the lower ISO values preferred to maintain the dynamic range of the image. If the range is decreases this means we blow out even darker parts of the image or we get simple black instead of even light shadow areas.
HDR stands for High Dynamic Range. The idea is here to make multiple images and blend into one image afterwards in order to get all the detail on the same picture. Newer cameras makes HDR images in camera, other way we need to blend the pictures with some kind of photo editor software.
Graduated filters or grads
Other way to cope with dynamic range problems is to use Graduated density filters. What is it ? It is a half transparent half grey filter. Usually the graduated filter has a rectangular shape. Other question what is it good for ?
In case of a high dynamic range scene the grad filter is used to make the sky darker in order to not burn out and looks more saturated. The graduated filters are selected by stops, there are 1,2,3 stops of graduated filters. Obviously the three stops filter is stronger. The bad news is that good quality grad filters are not cheap, the price is around the price of a cheap lens. Lee filters makes high quality grad filters for example.
The cheaper but not as high quality is the Cokin plastic grad filters. To try out it is definitely more cheap, the price is around 20 Eur, without the filter holder.
How different cameras compare in dynamic range ?
Most digital cameras has a dynamic range of 10-12 EV. Few cameras goes above 13 EV and very few camera goes above 14 EV. The Nikon d7200 has a dynamic range of 14.6 EV and the Nikon d810 also around that. Other good camera is the Fuji S5. The Panasonic GH4 has a dynamic range of 13.4 EV, which is very good.