Question from a Reader Via Email on Night HDR Photography
I went to do a night hdr the other night and I guess that because the scene is very dark I would need more over exposures than under right? What I noticed with my camera (Canon 7D) is that there was no difference to the picture from +2 EV and +3 because they were both 30 second exposures. Now here comes my point / confusion, I set the camera to BULB mode and took some shots, one at 60 seconds, another at 120 seconds, another at 180 seconds, right up to 5 minutes which made a difference, but how do I know what EV they are because it doesn't say and Photomatix wants to know these values? I remember you stating in a previous email that you play with the settings in manual mode and bracket from that prefered exposure. The scene I had didnt have much light in it, unlike the one that you linked me to the other week, which brings me on to another question and that would be, does night HDR only work where the subject is a cityscape which has lights from the city and cars etc…. My scene was of a light house, only the lighthouse doesnt have lights because its not in use. I was at this scene around 11pm, so it was pretty dark.
My Answers about Night HDRs Using Photomatix
First of all, you are correct that there will be no difference between +2 and +3 EV when shooting in an automatic mode in most night situations. The reason is that DSLRs do not allow for longer than a 30 second exposure without a cable release. This is why I always shoot night HDRs in manual mode and use a cable release. Most of the time, 30 seconds simply won't be long enough.
As far as telling Photomatix what the EV is for the shots, I would accept the default or do a little trial and error. You can actually do the math to figure out how many stops of light are gained with the long exposure, but that is too cumbersome for me. I usually take what Photomatix gives me, look at the resulting picture, and then go back and tweak the settings if it didn't turn out right.
Night HDR definitely works on both scenes with artificial lights as well as no-light scenes. Scenes without artificial lights are MUCH easier to shoot because you don't have to worry about the transition from light to dark.
Have you considered using organic HDR on your night photos? That's actually my preference rather than using Photomatix. That's not to say I never use Photomatix for night shots. It works great, but sometimes I like the look of organic HDR a bit better for night shots.