The Mega Pixel myth

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Could someone please explain the myth.

I was told that one should not trust the MP rating due to the fact that it has become a marketing gimmick. Cheap point and shoot cameras are boasting meg pixel ratings of more than 10.

Would this mean for example a Fujitsi point and shoot camera that has 12mp will take more detailed pics than a Canon point and shoot that has 6mp.

Its my understanding that one wouldnt be able to see the difference in detail, only if it is blown up real big.
 
Let me give you example. There are P&S cameras that have 12MP but the Canon 5D is sharper and better in every way. It has more to do with the size of the chip and how the chip works than the MP.

Resolution is one small part of what makes a great pic. It has a lot more to do with dynamic range (colour range) than MP.
 
I think the OP is referring more to what picture will have more detail, not which picture looks better (eg better lighting etc).
 
SuPaStA said:
I think the OP is referring more to what picture will have more detail, not which picture looks better (eg better lighting etc).
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:confused: This makes no sense whatsoever.
If a picture has more detail then obviously it will look better.
Lighting on any camera is dependent on how well the camera performs in low-light conditions and it has nothing to do with MP.
 
SuPaStA said:
I think the OP is referring more to what picture will have more detail, not which picture looks better (eg better lighting etc).
Click to expand...

They're all interlinked. Can't talk about the one without talking about the other.
 
Higher MegaPixel means one thing and one thing ONLY: there are more pixels in the resulting picture. I does not mean you will get higher detail, especially not in Point&Shoot world. A big factor is the camera's ability to convert the sensor information to a high quality JPEG image. Most point&shoot cameras don't have the processing power that even entry-level DSLRs have, and the resulting images are almost always use faster (i.e. more lossy, poorer compression) compression algorithms.

One day I'll go back to some of the places I took pictures of with a 6 MP DSLR, and take those same pictures with my fairly expensive 8MP P&S and post them here for comparison.
 
OK, I went back and shot one of my shots again with my fairly expensive P&S. I tried to get the images as close to one another as I could with respect to the field of view, but unfortunately it seems the P&S's live view lies a little. Anyway, I set it in program mode, and ISO200 (because that what the DSLR shot was on), metering to center, focusing to center, NR on, face detect, red-eye reduction and all other gimmicks which might confuse the camera in this situation are switch off.

Here's a 100% crop from the P&S, Noise reduction on, ISO200, f/3.5, 1/1.5 second shutter, 12mm:
8MP_PS.jpg


Now here's more or less the same 100% crop from the 6MP DSLR, Noise Reduction on, ISO200, f/8, 4s shutter, 55mm:
6MP_DSLR.jpg


BTW, this particular P&S cost more new than the DSLR did. Both were end-of-line at the time.

I rest my case...
 
As your pixel counts increase the lens starts to become a problem. In expensive cameras the lens matches the CCD sensor, but in cheaper ones this is not the case.
In very high resolutions the lens presents the resolution barrier, the glass of the lens in fact.

In other words, you get what you pay for.

A camera with a Leica, Zeiss, Nikon, Canon or Fujinon glass > than cheaper (yet branded) cameras with standard lenses.

I'm taking this from discussions about HD camcorders like the Panasonic HVX200 and the Sony PMW-EX1.
 
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Agreed, but the blotches you see in my 8MP P&S shot are not due to the lens (it's a Zeiss lens, by the way), but a combination of noise, poor image processing and too lossy jpeg compression.

Incidentally, when I played with the Canon G9, the jpegs wasn't much better, but RAW was much sharper and in Aperture I was able to produce results much closer to what I expect from a DSLR.

One more piece of the puzzle, aside from the lens, and the size of the sensor, is the image processor. It never ceases to amaze me that my Canon 40D can spit out a very high quality jpeg image much much faster than my dual core 2GHz MacBook can.

I agree that you get what you pay for, but I'll add to that that what you get doesn't necessarily justify the money you spent. High end point&shoots are disproportionally expensive. Many of them are more expensive than entry level DSLRs, yet the results they produce are not as good. OK, for shots taken in good light, the differences may be harder to tell, but in anything other than perfect conditions, it's very apparent.
 
When I get my G9, I'll do some more comparative tests - I'll have a high end P&S of higher MP than my DSLR, from the same manufacturer, using the same image processor (Digic III). Should be interesting...
 
Thanks HavocXphere. I should add that the DSLR's colour is only correct because I set the white-balance manually. There are too many light sources - I don't think any camera will get it right there. But even so, the P&S shot, despite the camera liberally boosting contrast, looks washed out by comparison.
 
http://photo.net/digital-camera-shopping-forum/00HmSY

There's a discussion also on this subject, a little old, but still valid.

Some of the points:

Looking at the specs of the A640, I start by noting that the sensor crams 3648 pixels into 7.2mm (the long dimension of a 1/1.8" sensor) - a pixel pitch of 2 microns. Frankly, such tiny pixels are just pointless. The small pixel area means that each pixel is collecting very few photons especially when using the camera at higher ISO settings. This will give rise to noisy images - and some of the noise will be due to the effect known as photon shot noise, which is an unavoidable consequence of the physics of light. The small pixel volume limits the maximum dynamic range that the camera can capture as well, and also reduce the accuracy with which colours are captured. Moreover, at anything other than the f/2.8 wide aperture at widest zoom, the image will be diffraction limited - so even if you were using the finest Zeiss lens ever made, you won't get the benefit of the sensor resolution. Someof the issues are nicely explained with some excellent examples and calculator tools here (the other tutorials are worth a read too):

http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

http://www.cambridgeincolour.com/tutorials/noise.htm

In short, the 10MP specification has been chosen for marketing reasons, and not for reasons of image quality. Dollars to donuts you'll be getting MUCH better image quality from your D70, despite only having 6.1MP.

Incidentally, I think that the "good glass" idea is not entirely correct. A very fine grain film such as Tech Pan far exceeds the resolution capabilities of even the Nikon D2X (the current DSLR pixel density champion), so flaws caused by the lens would be as noticeable or more so to film shooters testing lenses for technical performance. Often overlooked is the influence of the optics that sit immediately in front of the sensor silicon - the anti-alias and IR filters and the microlenses. These can cause light to bounce around in ways that reduce image quality, meaning that some lenses perform noticeably less well with some digital sensors than they do with film. Re-designing lenses and adding additional anti-reflective coatings to rear elements (not needed when shooting film) can reduce these artifacts
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