Will grainy images be improved with more megapixels?

[Minface]

Hi DPS friends,
I generally enjoy my Nikon D70 but have never been very pleased with it in low light. I find some images grainy and unsharp.

I would love to upgrade my camera but I am wondering if I will notice significant improvements in graininess? The place I most often notice the problem is in family shots where the family is about six to eight feet away, in natural light.

I have heard from some people that increasing the number of megapixels is not necessarily a cure for this problem.

Any thoughts?

[dcclark]

Graininess almost always results from your camera choosing a high ISO in low-light situations. There are a few solutions:

- Improve lighting. Not always possible, but you can get an external flash, for example.

- Get faster lenses (such as lenses which go to f/1.8 or f/1.4), which can collect more light. Then your camera won't have to push up to such high ISOs.

- Get a camera which has better high ISO performance. In general, more megapixels means worse high ISO performance, as manufacturers cram more and more sensors into the same space. However, some newer cameras with larger sensors (note: not the same as more megapixels!) have better high ISO performance -- see the D700 for example.

So the summary is: no, getting more megapixels is not the answer. The best answer is really to get faster lenses, or find other ways to avoid high ISO.

[OsmosisStudios]

Not really. The noise in images is more caused by the ISO setting youve chosen. Having more megapixels increases the resolution, but doesn't really help with noise.

[Doug Pardee]

Originally Posted by Minface

Hi DPS friends,
I generally enjoy my Nikon D70 but have never been very pleased with it in low light. I find some images grainy and unsharp.

I would love to upgrade my camera but I am wondering if I will notice significant improvements in graininess?

The megapixel difference won't help the "graininess", but DSLR sensors keep getting better and better with noise. The D90 has considerably less noise than your D70: according to DPReview, the D90 has less noise at ISO 6400 than the D80 does at ISO 3200, and for the specific case of luminance noise in dark shadows, the D90 has about the same noise at ISO 3200 that the D80 does at ISO 400.

The extra megapixels will give more resolution, which should help sharpness. If your photos are noticeably unsharp, though, it's probably not the sensor resolution but something else. It could just be camera shake from having a slow shutter speed. Or if you're shooting JPEGs at ISO 800 and up, apparently the D80 applies some heavy noise reduction and your D70 might be the same.

DxOMark rates the D90 sensor at 72.6, compared with the D70 sensor at 50.2, with the D90 getting a "low light ISO" rating of 977 vs. 529 for the D70. They even rate the D90's sensor above the D300's on just about every measure.

[jmart]

Originally Posted by Doug Pardee

The megapixel difference won't help the "graininess", but DSLR sensors keep getting better and better with noise. The D90 has considerably less noise than your D70: according to DPReview, the D90 has less noise at ISO 6400 than the D80 does at ISO 3200, and for the specific case of luminance noise in dark shadows, the D90 has about the same noise at ISO 3200 that the D80 does at ISO 400.

The extra megapixels will give more resolution, which should help sharpness. If your photos are noticeably unsharp, though, it's probably not the sensor resolution but something else. It could just be camera shake from having a slow shutter speed. Or if you're shooting JPEGs at ISO 800 and up, apparently the D80 applies some heavy noise reduction and your D70 might be the same.

DxOMark rates the D90 sensor at 72.6, compared with the D70 sensor at 50.2, with the D90 getting a "low light ISO" rating of 977 vs. 529 for the D70. They even rate the D90's sensor above the D300's on just about every measure.

Wow, thanks for that reference Doug, I had never been to this site beofre, but it looks like a great resource for determining which camera to buy. I have been on the fence for shelling out the money for a new D90 (upgrade from my D40) for a while, and this provides more quantifiable proof to do so!

[inkista]

Actually, more megapixels might help, by making the noise smaller over the picture overall, but it can be offset by how the noise performance is affected by the pixel density, so the short answer is "maybe, maybe not."

However, aside from simply the high iso setting, the other big culprit of noise is underexposure. So, one technique to try to reduce noise is digital pull-processing. Checking that you don't run off the end of your histogram with blown highlights, expose slightly more than you normally would while shooting RAW. Then, in post, adjust the exposure back down. You should have less noise in the shadows that way. Another digital technique that's similar to HDR for accomplishing this is Guillermo Luijk's Zero Noise.

More traditionally, you can also just use noise reduction software, like Neat Image or Noise Ninja.