Lately, I have been doing very low light condition photography. In some cases, trying to get shots at night of cloud to cloud lightning and the like. When I get the pictures to Lightroom or photoshop, I have to push up the exposure in order for the shot to come out which makes the shot grainy which is noise. I am using 200 ISO, f3.4 and 4 second shots, some times longer.
I understand with the D90 that higher ISOs increase noise, but I am wondering if I can balance things by increasing the ISO to a reasonable level so I don't have to push the exposure so much after the fact?
Sounds like you are trying to do more than just catch the lightening, like also get the scene properly exposed.
The usual way to do lightening without special devices is using long exposures with small apertures. For example, f/16 for 30 seconds. This long exposure is used to get the scene close to right while giving the camera the long opportunity to catch the flash of lightening. The brief flash of lightening is bright enough to be recorded correctly at f/16 if you are lucky enough to get a flash during that 30 seconds. Or the next 30 seconds. Or the next 30 seconds....
---------+---------+---------+---------+ Joseph K Seattle, WA, USA
Mike, as with any camera to varying degrees, the noise increases when you set it to higher ISOs. However, each new era of DSLRs brings improvement in high ISO performance. While not the newest at this point, you can get very clean and acceptable images at higher ISOs with the D90, which will make your low light shooting easier with more options in terms of shutter speed. I've seen quite good images from the D90 shot at ISO 1600. The caveat, as already mentioned, is to get a good exposure. I find this is preferable to pushing the exposure in pp.
You can certainly do ISO1600 on the D90 -- I do that for photos taken at our Church during services.
However, play a bit -- I find that ISO 800 gives much cleaner results and 1250 is better than 1600. So it really depends on what you NEED.
I would try going with 800 to start, and a longer exposure. The length of the exposure you can use will depend on other things in the scene -- are clouds moving? are you shooting with trees as part of the foreground and are they moving? -- and of course on the end result you want, maybe you have trees and you want them to look like they are moving.
ISO 1600 is two stops more sensitivity than ISO 400. You will find that shooting at ISO 400 and underexposing by two stops will produce an end result that is quite a bit noisier than shooting at ISO and getting the exposure correct. In other words, it's better to turn up the ISO and get noise than to underexpose and get MORE noise. And you can also use various post processing tools and techniques to minimize noise. Finally, do some printing before you freak out about noise. For moderate sized prints - say, 16x24" or smaller - noise isn't as visible in the print as it is on the screen, especially zoomed to 100%. Viewing at 100% on a typical 75 dpi screen is like making a print about the size of a door!
_____ Brian... a bicoastal Nikonian and Team Member
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