Noise? sensor?

WanderingMind · 29 Feb 2008

I notice this on a lot of my photos, especially when there is a colour gradient. What is it? noise? the sensor on the 350d?

Untouched raw, 100% crop

It gets worse when sharpening is applied
1.0px 100% unsharp mask

Do the better models have smoother looking gradient colours?

yourapocalypse · 29 Feb 2008

I'm just going to assume you shot those on ISO 100?

Helium_Junkie · 29 Feb 2008

More expensive cameras have more sensitive sensors that produce less noise, at entry level you cant avoid a little noise in a dark scene. You can do things about it though, for example: Neat image, Noise ninja. Go have a look at them

Shoot with the lowest ISO you can.

WanderingMind · 29 Feb 2008

lol yes iso100, 1/20 sec @ f/16

Jonnyreb · 29 Feb 2008

Theres a little but of noise on there, and when you sharpen noise you do indeed make it more obvious. Its by no means noisy though and what you would propbably expect to see in a block of colour.

The key point is the size of the pixel pitch - how many pixels are thrown onto the sensor. This affects the signal to noise ratio.

One of the best performers is the EOS 5D which has a full frame sensor, but only 12MP - lots of room so bigger pixels to greater signal / less noise.

Newer processors counteract this basic physics, but only by 'cleaning' the image in-camera. This then results in the output needing a higher level of sharpening to restore detail.

Somthign to bear in mind is the bit depth of output. Until recently this was 12bit in digital cameras, but has been increased to 14bit in the most recent generation. the positive impact of this is greater number of colours and smoother gradient to images.

WanderingMind · 29 Feb 2008

^^ Thanks Jonny for the great explanation, makes sense

Another reason to get a 5D lol

pxl8 · 29 Feb 2008

Did you process in Adobe Camera Raw? In the past similar questions have popped up and the answer was actually down to processing in ACR and it's default mode of auto-correcting and the shot was actually under-exposed so when ACR corrects it noise is introduced.

WanderingMind · 29 Feb 2008

Yes, iv'e tried canon dpp for converting aswell and there is no difference in quality, so I just use cs3. It does seem to be in all my shots if I look close.

gman · 29 Feb 2008

If it helps here's a shot with the 5D: http://www.flickr.com/photos/blakeseely/418392155/sizes/o/

And one from the 350D: http://www.flickr.com/photos/eawortman/393413301/sizes/o/

I can see noise in both of them although less obvious with the 5D. I suppose it could depend on what post work has been done.

Check out http://www.pixel-peeper.com to see other photos by people with 350D's and also other cameras.

laser_jock99 · 29 Feb 2008

If you can easily select the affected areas (e.g. if it's just a sky background) then a quick application of the Gaussian Blur filter will deal with it.

Chappers · 29 Feb 2008

If you're using CS3 use ACR to process the images. You can make use of the improved sharpening tools in ACR to help reduce the noise you are introducing with unsharp mask. ACR and Lightroom, sharpen in the luminance channel not the colour one, thereby reducing colour noise. Also the blue channel is usually the noisiest anyway so that's why noise is worse in the sky areas.

If you shoot RAW that will help as well, as the in camera jpeg has already been sharpened. You are therefor sharpening on top of sharpening making matters worse. Shooting RAW you apply camera sharpening, only once at the RAW conversion stage