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02-22-2009, 02:05 PM   #1
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Megapixels vs. Noise

I have a K100D Super(6.1 MP)
Recently I did some low light shooting and had to use ISO 1600 or 3200.
The noise was very noticeable.
Would it have been less noticeable if I had more Megapix?

02-22-2009, 02:12 PM   #2
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Traditionally a higher pixel count on a given sized sensor meant more noise at all ISO settings.
Lately that has not been the case. Generational improvements in sensor design seem to be keeping pace or improving the noise performance at all ISO settings, even as pixel counts get higher.
Under exposure excacerbates the noise problem, so low light work at high ISO settings is quite difficult for a digitlal sensor.

Best current cameras for low light and high ISO work would be the Nikon D700 and Canon 5D Mk II, both provide excellent results under difficult conditions. Both are significantly more expensive than the Pentax offerings.
02-22-2009, 03:28 PM   #3
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QuoteOriginally posted by stgmgr Quote
I have a K100D Super(6.1 MP)
Recently I did some low light shooting and had to use ISO 1600 or 3200.
The noise was very noticeable.
Would it have been less noticeable if I had more Megapix?
Basically there are 2 main sources of noise in electronics: free electrons (caused by temperature) and cross talk.
The first is noticeable as random (white) noise, the latter often as banding.

There are some ground rules here; if you amplify an analogue signal, you also amplify the containing noise.
Increasing your ISO is like turning up the volume of your amplifier.
Try that once without any signal, you'll hear some noise coming from the speakers. That's why we call the spickels in your picture "noise" although you can see it, not hear it...
Hence, in low light, you increase your camera's ISO setting = increasing signal amplification -> you are also increasing noise.

If you compare two sensors build using the same semi conductor processing, the one with the less pixels is the one with the (presumably) largest pixels.
The larger a pixel, the more surface to there is to capture incoming photons. The more photons captured, the more signal, the less amplification (ISO) needed, the less noise.

A common approach with vendors is noise reduction.
That is in camera software detecting noise patterns and blending / smearing them with the surrounding pixels. So you get less noise, at the cost of losing resolution caused by the smearing.

Newer CMOS sensors generate less noise making more pixels per sqaure inch possible without too much noise. However, with the same technology used to make a 6Mp sensor, it will always generate less noise than a 10Mp sensor with that technology.
Your K100 has a somewhat older generation CCD sensor, a more modern CMOS senor can hold more pixels and still generate less noise.

Have fun.

- Bert
02-22-2009, 06:30 PM   #4
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One thing you may want to do is work in black and white if you're shooting such low light/high ISO pics. The noise ends up looking much more like traditional film grain when converted to black and white, rather than the ugly multicolored blobs you get when you leave an ISO3200 shot in color.

02-22-2009, 10:23 PM   #5
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I do not think enough people recognize or give credit to the K20d for its excellent handling of noise. When you consider the camera is producing images @ 14.6 MP and ISO 3200 is still usable for smaller prints, I think you have to acknowledge the excellent noise hadling properties of the K20.

As has been said here already, perhaps in different words, it takes a lot more ingenuity to get a 14.6 MP camera to produce usable, high ISO pics, than it does to get a 6MP camera to do the same--when they are using similarly sized sensors. Here is a new thread of K20 high ISO (3200) images from a fellow forum member:

https://www.pentaxforums.com/forums/post-your-photos/51861-iso3200-dog-agilit...00-ex-hsm.html
02-22-2009, 11:18 PM   #6
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QuoteOriginally posted by stgmgr Quote
I have a K100D Super(6.1 MP)
Recently I did some low light shooting and had to use ISO 1600 or 3200.
The noise was very noticeable.
Would it have been less noticeable if I had more Megapix?
As others have said, basically, no, it's the other way around. The K20D might be slightly better, but that's not because it has more pixels - it's because it is CMOS rather than CCD technology. And it's not *that* much better from what I've seen.

On the other hand, if you shoot RAW and have decent PP software to do noise reduction, you can get some pretty amazing results for ISO 1600 or 3200 on the K100D Super.

It also helps to get the exposure as bright as you can in camera. In low light, you are always struggling to get a fast enough shutter speed. So your best friend is gong to be a lens with a large maximum aperture (f/2.8 or lower). If you were shooting with a "slower" zoom like the 18-55, 50-200, 18-250, etc, where the maximum aperture is f/4 or f5.6, you'll be struggling. The best upgrade would be a "faster" lens (larger maximum aperture - meaning lower f-number).

Could you post some samples you weren't happy with and say what lens you were using, and what the aperture and shutter speed were?
02-22-2009, 11:22 PM   #7
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Looking forward, what do you guys see as happening in terms of noise in anything that might be announced at PMA? I've been holding out on getting the k20 in hopes that the possible 30 will have closer noise performance to the new-ish models from the other manufacturers. Thoughts?
02-24-2009, 12:37 AM   #8
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QuoteQuote:
dantekgeek Looking forward, what do you guys see as happening in terms of noise in anything that might be announced at PMA? I've been holding out on getting the k20 in hopes that the possible 30 will have closer noise performance to the new-ish models from the other manufacturers. Thoughts?
The K20's difference in noise is more related to its "hands-off" philosophy than it is to the competition's better performance. The K20 shows more noise in its images ( as well as more detail) at default because the K20 provides the user with the freedom to strike the delicate balance between noise and detail for him/herself. It is that simple! The K20 is performing on a par with the competition in terms of noise, particulalry when you consider the sensor size to MP ratio. If you want a K20's pics at higher ISO to resemble the competition, then crank up the noise reduction to Strong and there you have it, though even @ Strong the K20 will not give you the smearing which is so telling of the competition.

Pentax should be applauded for taking such a daring approach to the issue of noise because it demands a more educated and autonomous user. Educated and autonomous users are not the majority of buyers--one need consider this for a moment, me thinks. Even DPreview, not known as Pentax fanboys by the stretch of anyone's imagination, boldly acknowledges this fact in its K20 review which can be accessed here: Pentax K20D Review: 18. Photographic tests (Noise): Digital Photography Review I purposively picked up in the review where the discussion of noise begins: this is a direct comparison to Pentax competition. Also, below is an excerpt from the review which I find appropriate to your post Dantekgeek:


QuoteQuote:
Although we would expect many K20D owners to be willing to indulge in some degree of post-processing, it's still important that the JPEG output be optimized (or, at least, optimizable for each user's tastes). Noise reduction is always a fine balance between reducing noise and retaining detail and there are different attitudes towards where that balance should be struck. The K20D gives the user a degree of choice about their preferred output - light nr, luminance nr only, luminance and chroma nr, stronger luminance and chroma nr. However, even this heaviest setting is only comparable to the default noise reduction settings of its peers (in terms of detail, as well as noise). The K20D doesn't give the option to produce the smeared but essentially noise-free images that others offer.
In summary, you have, in the handling of noise, Pentax' bold and unique approach which sets it apart from its competition, not in terms of quality of performance; rather, Pentax is set apart from its competition in terms of the autonomy it affords its user. This is, in a nutshell, why many people come to Pentax--THEY DO NOT COME TO PENTAX TO RESEMBLE THE COMPETITION---THEY GREW OUT OF DOING THAT IN HIGH SCHOOL--THEY COME TO PENTAX TO DISTINGUISH THEMSELVES FROM THE COMPETITION.

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