Active D-Lighting and Noise at High ISO

Thursday, December 18, 2008 ·

On my first foray out of doors at night, "prowling" the quiet streets of Carnoustie with the 35mm f2 and 85mm f1.8 Nikkor primes in tow and revelling in the freedom, I decided to set Active D-Lighting (I'll call it ADL from now on) to "high".

This adaptive dynamic range setting helps control the extreme tones in a photograph by slightly toning down the highlights and opening up the shadows. It's quite a subtle effect but it still easily-enough seen in side-by-side shots. The biggest problem when shooting at night is managing to retain a little detail in the tones at either end of the histogram so it seemed that ADL might be a good idea in night photography where contrast can be off the scale.

The residential streets where I live are by no means well-lit but I was still able to shoot hand-held - and not always having to use my personal maximum of 6,400 ISO. When I uploaded the images - I'm shooting jpegs just now until I get the hang of using the D700 - they were slightly noisier than I'd expected. In casual shooting around the house - the kind we all do when trying to get to grips with a new camera - I'd been seeing cleaner images than these at the same ISO ratings and was praising myself for buying a full frame DSLR.

It turns out that ADL might be the culprit. I was aware that this kind of in-camera control had a tendency to increase noise but I didn't think it would be so apparent in the D700's output. In much the same way that opening up the shadows in Photoshop tends to show up noise, ADL has the same effect. There's no doubt that it was effective at squeezing more information from the brightest and darkest parts of the scene but at a cost. It's possible that having ADL set to "low" would reap some of the benefits without having to pay the noise penalty but I've yet to try that setting.

In night and low-light shooting from now on, at least until I've had a go with the lower ADL settings, I'll be leaving Active D-Lighting off on the Nikon D700. I still think it will be a real advantage when shooting into the light in landscape situations, though, where noise isn't a problem and look forward to getting out into the "field" to test it.