Rich Ditch's Photography Blog

April 18, 2009

Low Light Moorhen

Filed under: Birds, composition, digital benefits, light, technique — richditch @ 7:25 pm
Common Moorhen - Tres Rios

Common Moorhen - Tres Rios

It wasn’t that many years ago that I would have not even bothered to try taking this image: a dark plumaged bird in a shadowed section of a small marsh. So, why try it now? Simple: I’m shooting digital now, while a few years ago I was shooting film.

I decided to do my morning birding on the other side of Phoenix yesterday morning and headed over to the Tres Rios site at 91st Avenue just north of Baseline Road. Tres Rios is a “reconstructed” wetlands consisting of two large ponds near the Gila Riverbed, adjacent to a large wastewater treatment facility. It is not a pretty place, nor is it pleasant smelling. But it gets a good variety of birds a times (at least when other people go there!).

I had about 90 minutes to walk around. I was hoping to see my Least Bittern for the year, or some Black-bellied Whistling Ducks, or even an immature Bald Eagle. I saw none of these.

But I did find this Common Moorhen sitting patiently in a dark corner of one pond where I could get a tight composition with my 300 and 2x. Only problem was the limited light was so low that even at ISO 400 the shutter speed was so slow it wasn’t worth the bother.

So, since I was shooting digital I went to ISO 800, and that gave me 1/30th second at f/5.6 (wide open with the 300/2.8 and 2x). And that was enough to pull off the shot.

A few years ago when w all shot film, ISO 50-100 was normal, with 200 available at extra cost for pushing the film in development, along with unavoidable drops in image quality.

I’m not crazy about using ISO 800 on my Nikon D200 as it produces a noisy image in most circumstances. But its only a matter of turning one dial to get it and I’ll use this advantage of digital when I need it. In the time since my D200 was state of the art other cameras have become available with much better high ISO noise performance, so ISO 800 is more than usable for many people today.

To make the noise less objectionable in this image I’ve selectively applied Noise Reduction (NR) in post processing. I use a Photoshop plugin called NoiseWare for this; others use Neat Image or Noise Ninja to do the same thing.

Since it is impossible for software to tell the difference between noise and image detail in almost all cases this is one step you want to carefully control so you don’t take out important texture from the subject while knocking down the noise. When NR is applied indiscriminately and with a heavy hand it gives the image a “melted” appearance – the important fine detail in feathers is turned completely smooth, with only the hardest edges remaining in the image. As a photographer who grew up using Kodachrome 200 for “high speed” I have a much higher tolerance for noise in an image than digital only photographers have, and I’d much rather hold on to subject detail than lose it to an overly strong dose of NR.

I begin by duplicating the base layer of my image. I name this new layer BG NR (for background noise reduction). I then use the magic wand in photoshop to select the subject, then invert the selection to get everything else (the background). With the BG selection active, I apply NoiseWare, and try various options to see how well it takes out the noise. Since I’ve done this on a separate layer I can further fine tune the result by reducing the layer’s opacity. I’ve seen to many other images treated this way where the background is creamy smooth while the subject still shows noise – this just looks too unnatural for me. By backing off on the layer opacity I can allow some of the noise to stay in the image and reduce this artificial “pasted on” look.

This is more work than i like to do in post processing, so I try to avoid the need for it. I could have spent more time with this image and allowed a bit more of the noise to remain, but it is far more usable than anything I’d have gotten with film.

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