Last weekend I went on a photo walk with Gaensler, who lives about a half hour drive from where I live and who is also shooting a lot of HDR photos (be sure to check them out!). We decided to go on a tour of my home town which already has the christmas lights up. So we met up in the afternoon but continued shooting into the night when the lights came on and still I tried my hand at HDR. At night it is a bit more work to get good HDR shots (for one, you have to hold the camera steady longer) but also because noise can become a huge issue in post-processing.
Here is an example of this and some tips on what you should keep an eye on in processing the image. First, the source images:
As you can see, the normal exposure (middle) has the lights pretty good but the whole tree is too dark, you simply cannot really see it. The overexposed has a beautifully lit up tree but the lights are too bright and have lost all definition, so HDR is the way to go to balance these two.
When I am out shooting a bunch of HDR photos, I always use the batch function of photomatix to make a HDR of each threesome to get a first visual clue about which images have potential. I used the same preset I always used, but it is not usable for night captures, as this photo clearly shows:
As you can see, all you can see is noise. I have no idea why photomatix always tries to make the image so much lighter than the source material is (because really, even the over-exposed is not as bright). What you can see clearly here is noise and blown-out lights in the tree. Even the whole tree is too bright, imo.
With night time images you have to look at each one individually and make the processing based on the amount of light you have and the subject you captured, because that will have a lot of impact on how much light you want to have for the background and the main subject.
I decided to make two different versions, one in photomatix and one in HDR efex pro because I am still not sure which one I like better for night-time HDR pictures.
The one on the left is done in Photomatix, I made it relatively dark to make the lights stand out better in the tree and so that the illumination really comes from the tree – I especially like how the light looks in the tree. The one on the right is done in HDR Efex Pro and I decided on a bit more exposure for this one, the lights are not as distinguishable but I’m enjoying the blue sky as a backdrop for the tree.
As you can see though, both don’t have super noticeable noise (non have been de-noised yet) or have noticeable halos or color shifts in the sky, which is also a problem you can run into when you look at night-time HDR. If you get one or both, start over, it is easier that way than to get it back under control.
