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pixel pitch size and ISO performance


Coleslaw 15 13.4k 28 Wales
12 Feb 2012 4:48PM
Is it:
The larger pixel pitch is, the better ISO performance is?

Please explain in layman's term, as I am not a very technical minded person.....lol
JackAllTog Plus
11 6.1k 58 United Kingdom
12 Feb 2012 5:50PM
Hi Cole, Its rare i think i can share something back to you.

ISO is a measure of pixel sensitivity, that's how well it does at gathering the light signal from all the other sources of ambient electrical noise around that interfere with this measurement.
Now big pixels have larger area's to gather light in and the ambient noise is a inherently smaller percentage of that light information.
But smaller pixels can gather less light in their smaller pixels, so the ambient noise more easily swamps the light information - Poor ISO performance.

The pitch is how far till the next pixel in the row. There is 'almost' no gap between pixels, so smaller pixels are closer together - a smaller pitch.

So its the large pixels that are better at gathering available light, not the small ones as they get swamped with noise more easily as light levels drop.

How does this read?

Cheers
Stuart
cameracat 16 8.6k 61 Norfolk Island
12 Feb 2012 6:59PM
Thats about the size of it Stuart.....Smile

I'd take that a stage further, When the photosites ( Pixels ) gather the light, The resultant signal is amplified & digitised, Then it flows to the processing department....!

Smaller Pixels ( Photosites ) tend to produce a smaller signal, This then needs to be amplified, Amplification is where the noise can be made worse, The larger Pixels produce a stronger signal, That requires less amplification, Hence the noise potential from the amplification stage is greatly reduced....Smile

Thats pretty much the basics, It also explains why in general larger sensors with larger Pixels/Photosites ( ie: Full frame 35mm or Medium Format Digibacks ) Tend to have better high ISO noise performance, Technology both hard & software wise is improving things all the time, We have seen this over the last 8 to 10 years, I'd guess that one day in the not so very distant future, High ISO setting and noise will disappear to become a thing of the past, But they are not there yet, Talk of a " Black Silicon " substrate looked promising, But I have not seen anything recently.

HTH.....!
Coleslaw 15 13.4k 28 Wales
12 Feb 2012 7:10PM
hmmmm....

Canon 5d2 - With a size of 24 x 36mm, 21.03 million image pixels and a pixel pitch of 6.4Ám square

Nikon D700 - It has a pixel pitch of 8.45Ám

Nikon D4 - incorporates a 16.16 million image pixel CMOS sensor that's 36.0 x 23.9mm in size, has a pixel pitch of 7.3Ám

Nikon D800 - incorporates a 36.15 million image pixel CMOS sensor that's 35.9 x 24mm in size, has a pixel pitch of 4.88Ám

Does that mean:
D4 ISO performance is going to be worse than D700?
D800 is expected to be worst of the 4?
strawman 16 22.1k 16 United Kingdom
12 Feb 2012 7:58PM
Cole you are balancing pixel size against technology. As technology improves they are reducing some of the noise components, and it is further confused when you have different resolution as you need to consider the noise pattern as it is printed. Or to put it another way, with more pixels you can run a noise filter to produce the same level of file output detail.

What I observe is that for cameras there looks to be a point where as you pump up the gain (ISO) the noise components start to dominate. At low gain (low ISO) this noise is so low that it does not matter. And this noise tends to change with the square of the pixel area. So as you shrink the pixel size this noise rises rapidly. The point at which this matters is a mix of the ISO you are running at and the technology.

So go back to a few years ago state of art. At low ISO the A900 was able to produce just as low noise as the rest and a bit more resolution. Go past ISO400 and it started to fall behind, then pump the gain up even more and the 5D MKII is not keeping up with the D700. (You could get some performance back in the A900 and 5D by applying noise filtering and then reducing the file to a 12mp one).

So your comparison spans technologies so it is hard to answer and to be honest we would need some back to back same condition shots to draw a comparison. If it were not for the technology change I would say yes the per pixel noise of the D800 will be worst. It may be the same as the 5D2. It may be that at high ISO you can filter the results and get D700 like results. We need some cameras to test Smile.

In your shoes I would wait for the D800 to be out for 6 months and also the 5D3 to turn up. The D800 is a 30% resolution increase over your existing camera. Allowing for diffraction etc how often will you get the extra 30%? The best bit looks to be the features improvements in my eyes.
Coleslaw 15 13.4k 28 Wales
12 Feb 2012 8:05PM
I was just wondering, John, as it doesn't quite add up when looking at D4 which is supposed to be 1-2 stops better than predecessor. And people keep saying ISO on d800 would be the same or worse than D700, god knows based on what.
justin c 16 5.1k 36 England
12 Feb 2012 8:39PM
Here you go Cole, I've not read it myself, but you'll probably find your answer HERE
Coleslaw 15 13.4k 28 Wales
12 Feb 2012 8:45PM
I did say layman's term, Justin......lol Smile
justin c 16 5.1k 36 England
12 Feb 2012 8:58PM
Ooops! sorry Cole Grin That's why I said I've not read it, too tough on the old grey matter for a Sunday evening Wink Much more fun watching Whitney on the box Smile
JackAllTog Plus
11 6.1k 58 United Kingdom
13 Feb 2012 10:33AM
So in summary Bigger newer camera sensors tend to have better low light performance so long as they are not stuffed with too many pixels. And that's the question - has Nikon put too many pixels in their new D800 camera such that its low light performance is poor?

The 36 MP D800
ISO 100 - 6400
Lo-1 (ISO 50)
Hi-1 (ISO 12,800)
Hi-2 (ISO 25,600)

The 16MP D4
ISO 100 - 12,800
Lo-1 (ISO 50)
Hi-4 (ISO 204,800)
User_Removed 10 4.6k 1 Scotland
13 Feb 2012 11:10AM

Quote:So in summary Bigger newer camera sensors tend to have better low light performance so long as they are not stuffed with too many pixels. And that's the question - has Nikon put too many pixels in their new D800 camera such that its low light performance is poor?

The 36 MP D800
ISO 100 - 6400
Lo-1 (ISO 50)
Hi-1 (ISO 12,800)
Hi-2 (ISO 25,600)

The 16MP D4
ISO 100 - 12,800
Lo-1 (ISO 50)
Hi-4 (ISO 204,800)



Jack,

I think that Nikon have very cleverly introduced, almost simultaneously, two new FX sensor cameras that are sufficiently differentiated not to "interfere" with each other.

The D800 which, as Steppenwolf pointed out on a different thread, has approximately the same pixel density on the sensor as a Canon 1.6x crop sensor with 16Mp, should please landscape and studio photographers looking for loadsa pixels. The D4 should be better suited for those who indulge in action, sports or low light photography. The differentiation is probably a bit wider than currently exists between the D3s and the D700. My guess (and it can only be a guess at this stage) is that generic, non-specialist amateur photographers may opt for the D800, not least because of the "bargain" price which appears to be considerably lower than the pundits were prophesying for the D700 replacement just a few weeks ago.

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