What affects noise at higher ISOs

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Bruce120

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Bruce
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I have a D50 and D200 and have tried to experiment with shooting at higher ISOs when doing portaits etc. I always seem to end up with noise on peoples faces.

I had a look at Puddleducks thread here http://www.talkphotography.co.uk/forums/showthread.php?t=142343

The images in this have very little noise visible, not sure if they have been cleaned I doubt it though.

Can you tell me what would cause noise at higher ISOs is it skin tones, colours within the shot or they way the shot is lit?

Hope this makes sense
 
Well one of the main reasons why Puddleducks images are much cleaner is that he is using a D700, which is a full frame sensor. Because it has a larger sensor and the same amount of pixels as say a D300, each individual photosite is much larger. this in turn means it collects more photons relative to the amount of random noise caused by the sensor.

Having said that, there are ways you can reduce noise; Using noise removal software. Programs such as noiseware, neat image, noise ninja etc can do a very good job of removing noise while keeping detail in a shot. Another way of reducing noise is to overexpose the shot (without blowing the highlights) then correct the exposure in post processing. if you exose to the third quadrant rather than the middle of the histogram, you can end up with cleaner images.

But esentially; get a new full frame camera, or use flash to reduce the need for high ISO.

Hope that helps. :)
 
Oh, sorry I see what you mean. Yeah, the lighting probably helps a fair bit there, and the fact that the images have been reduced to 720px wide probably help mask some of the noise.
 
not sure if I understand the question quite correctly but I'll throw something in here

please note, I could be talking utter pants here...
At higher ISO's the sensor has a greater current pushed across the pixels. What this does is increase the signal to noise ratio as lots of pixels close together with high currents can cause cross talk on the sensor elements. Noise and unknowns are higher.
Therefore you get a messy picture.
As I said, not sure how true this is. the larger the pixels, the less interference that occurs so a full frame sensor running at 12MP would be able to handle higher currents, and thus higher ISO's without the associated degeneration of the SNR

therefore for 'cleaner' images, you need more light, and a lower ISO or at least an ISO the camera can manage with very little noise, like ISO400..??
your variables are light, aperture, shutter speed and film sensitivity. Each has it's trade off and you need to balance all four for any exposure.

the exif from those images reads as a D50 with ISO1600 and sharpened in camera

F number: 4.5
Shutter speed: 3.90689
Flash: 0
Gain control: 1
Contrast: 0
Saturation: 2
Sharpness: 2
 
Basically noise is "data" not associated with the image. The level of this data increases as the ISO is raised. This is why noise is less noticable at lower ISO.

Noise levels where very noticable over ISO400 with some of the earlier Nikon range including yours. For some time Canon very much had the edge on low noise levels but some of the later Nikon models are just as good and some would say better.
 
Some interesting info in here. Thank you.

Not meaning to hi-jack, but how different is the noise handling from say a D40 to something like a D90? It's something I've noticed recently when messing around in manual mode especially with the darker tones in pictures.

TIA
 
I think in Andys pictures the light is helping. I have shot flash portraits [accidently] at ISO 1600 on a D200 and been shocked by how little noise there is compared to what I would normally get on that camera. Noise also tends to be more obvious on darker skin tones [darker areas in general but you mentioned portraits] and its a problem I have doing the karate shots using high ISO's even on a D300, the noise is more obvious on the kids with darker skins than for instance, my daughter who is very pale. Lastly, when you shrink the images for web use, the impact of the noise is reduced anyway and it's also the case when printing, what looks horrible on screen can become perfectly acceptable as a print.
 
Bruce120 said:
That is all very useful thank you but I think those images were shot with a D50
Click to expand...

There is very little noise at full image.

Drop me a line and you can have the NEF :)

I've always found the D50 sensor very good at high ISO.
 
I trust that the image is true :)

I will just have to practise and see what situations yield different results. I was looking for more specifics like daylight will produce less noise than lamps etc?
 
its the blacks in the image, they create the noise.
 
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