Monday, November 9, 2009
Downtown Austin Night HDR and Tips
It was a normal 5 bracketed shot with -2, -1, 0, +1, +2 exposure values. Usually, when I take my shots, I use an ISO of 100 or so. At least the lowest ISO as possible. I also like to set an aperture of somewhere around f/8 to f/11 to get everything in focus. In this case since it was a night shot, that ISO was too low for the aperture of f/8. The problem I have with my Nikon D90 is that the longest the shutter will stay open is 30 seconds unless I go full manual or bulb mode. The shutter stays open longest at +2 EV and at ISO 100, it stayed open longer than 30 seconds. That didn't make for good varying exposures at those different EVs. Most all of them exposed the same because the shutter stayed open for only 30 seconds during most of the brackets. So, I had to figure out what ISO speed would work. So what I had to do was adjust the ISO and take a few single test shots at +2 EV to find out which ISO kept the shutter close to but below 30 seconds. It turned out that ISO 640 worked. Then I could set my normal brackets and take my shots since the the rest of the EVs are less than +2, they would all be less than 30 seconds. That seemed to do the trick. The results are pretty good as you can see, but the full res shot still has a few artifacts that could stand a little more work. Overall though, I'm pleased.
I suppose I could've gone full manual and tried to experiment with different exposure times in bulb mode to get the right exposure, but I was pressed for time. So the ISO explanation above worked a little quicker for me. I was on the way to work and I didn't want to be late! ;-) Plus, the Nikon D90 has pretty good noise reduction up to about ISO 1600.
One other thing that I use to help clean things up is Imagenomic's Noiseware plugin for Photoshop. It works wonders. Here is a review of Noiseware and you can purchase it from Imagenomic here.