How many exposures to HDR?
This an hardly discussed matter in the HDR photography world. How many exposures do you need to get the best results?
It is possible answer to this question only after studying the light conditions of our subject.The number of exposures number used to create a good HDR varies from picture to picture. Usually people take 3 shots with 2 ranges of distance between each image. This is clearly the fastest way to create the final image and, in most cases, it provides excellent results. When it comes to high dynamic range, we must try to capture as much dynamic range as possible of the subject we are taking a picture of. That’s why you need to adjust the exposure depending on light conditions.
Imagine that we are in an outdoor scene, in most cases 3 exposures are enough to achieve our good results with HDR. But if instead we were indoors or in low light situations to capture the full dynamic range, for example, in the shadow detail, we may need to take more shots in order to get more exposures. This may happen, for example, if we want to capture the full dynamic range in the shadows details.
To verify the correct exposure of your picture, you always have to take a look on the histogram, a complete histogram in all its parts is a full dynamic range HDR.
In particular, in the following pictures you can see the difference between the same photo taken with 3 and 7 shows.
HDR 3 EXPOSURES
HDR 7 EXPOSURES
There are a few and slighlty noticeable differences, but the main one is that the picture made up by 3 exposures appears more noisy that one taken with 7 shots with is also more definite.The differences are not many and slight but notice able as such, the image shows a 3 appears to be noisier while the image 7 exposures is more definited.
About the question how many exposures to HDR, as i mentioned at the beginning, to make a greater number of shots in low light conditions you will not leave gaps in your dynamic range and the final result will be more attractive and clearer compared with less exposure one. But beware!Taking more than 3 shots in some cases can be a winning choice for capturing the full dynamic range, but on the other hand this same choice could penalize the image, when in fact necessary, this condition will increase the possibility of adding noise and chromatic aberrations to the end result.
© 2012, Giuseppe Sapori. All rights reserved.