Does shooting at a lower MEGAPIXELS on high MEGAPIXEL DSLR improve Noise performance?

[Nikon_Josh]

Another question today guys..

I have often wondered and have never found out the answer to this one!

If for example, you shot at 12MP on a 18MP Canon 7D or 6MP on a 12 MP Nikon D3S would it improve noise perfomance? Changing the dynamic of how the sensor works?

I understand Nikon will be releasing a 24MP D400, I'm not sure how this sensor will perfom obviously! But I am intrigued to see if by shooting it at lesser pixels, would the noise/high ISO performance be effected. This is a long time question I've had that I am yet to see an answer too.

 

[analog.universe]

Downsampling in post certainly reduces apparent noise... I think it would depend on where and how the data was dropped in camera to get you the smaller capture.

(in short, I don't know, lol)

I have successfully resampled in post to reduce noise though...

 

[Sw1tchFX]

It doesn't really reduce it, it just makes it finer. and when they're REALLY downsized, like 800x600, than it gets so fine that it's hardly noticeable. It's like making smaller prints with bigger negatives. TMAX 400 has just as much grain in 35mm as it does in 120, but if we're making a 4x6ish size print, the 120 negative won't be as much of an enlargement so the grain will look much finer, and the image much clearer.

 

[Nikon_Josh]

So simply put... reducing the size of image you shoot at has no effect on the sensor itself? It just produces smaller images?

I wondered if the sensor deactivated pixels.. if you shoot at a smaller resolution. Perhaps naive... but I was intrigued.

 

[Sw1tchFX]

Nope, doesn't bin or deactivate pixels at all usually. Some point and shoots that do ISO 3200 though use pixel binning to get a usable picture at 3200 though.

 

[Garbz]

Didn't the D2h bin pixels in order to dramatically increase framerate when shooting in a smaller mode? I can't remember clearly anymore how it worked.

But basically yes you do get a noise reduction through the interpolation process. Think of this very basic example, you have 4 adjacent pixels with a brightness value of:

0, 2
2, 4

If you downsample those perfectly by 4 you end up with a pixel which has a value of 2. In practice interpolation doesn't make it a perfect average, but the principle is still the same. Noise in single pixel values will tend to be brought down through the interpolation process.

 

[Nikon_Josh]

Thanks, seems my question is resolved! So pixel binning is something that has been done before then, but it is clearly not the norm!

 

[Sw1tchFX]

It's the norm for P&S's, but not for DSLR's. The 80MP Phase One back does pixel binning to shoot at ISO 3200. The resulting image is 15MP.

@Garbz, I know the D2x had a trick crop mode where it shot at 7MP, but I don't think the D2h had any of that.

 

[KmH]

The size of the individual image sensor pixels cannot be changed after the image sensor is made.

Using only 12 MP of 18 MP just lowers the resolution.

Pixel size determines SNR - Signal-to-Noise Ratio. That's a major reason why full frame (FF) image sensors have better high ISO performance than APS-C size sensors do. The FF pixels are bigger and have a lower SNR.

 

[Nikon_Josh]

The size of the individual image sensor pixels cannot be changed after the image sensor is made.

Using only 12 MP of 18 MP just lowers the resolution.

Pixel size determines SNR - Signal-to-Noise Ratio. That's a major reason why full frame (FF) image sensors have better high ISO performance than APS-C size sensors do. The FF pixels are bigger and have a lower SNR.

Well you make a good point! But now Sony are talking about a 24 Megapixel Crop Sensor, which the D400 will most likely use! I don't really get it to be honest. I just hope we dont start seeing a billion mentions of how the camera shows noise at ISO 400. I understand technology moves on and I embrace that!

But this megapixel BS obsession just rolls on! Usually the COMPLETE idiots who bang on about how everyone needs more megapixels are the people who come out with trash like 'Oh I need megapixels, so I can do more cropping...'.

Try this as an idea, get the image right in camera perhaps??? Like a true photographer would!

I was just wondering cos if I do get a D400, whenever that may be. I know I won't be using the 24MP setting all the time.

 

[analog.universe]

It's true, for most applications we've got enough resolution already... If they're gonna dump so much money into sensor research, I wanna be able to shoot ISO 200,000 with no noise :greenpbl:

 

[KmH]

I'm very happy with my 12 MP Nikon's, both APS-C (D300) and full frame (D3).

I don't expect to need any more than 12 MP for the forseeable future.

I will be very surprised if the D400 has 24 MP. The D3x has 24.5 MP and it does not have the high ISO performance that the 12 MP D3s has, for the reasons I mentioned above.