Downside to Megapixels?

rmh159

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I've heard recently that high MP cameras (I believe Sony just announced a 25MP sensor) can have serious drawbacks because the actual size of the pixels on the sensor are so small. Some examples were that smaller pixels create noisier shots due to less light sensitivity and also tend to create soft images. Does anyone know about this?

Also what is a good guide for print sizes that a certain # of MP's can support? I have 2 16x20's that were shot with a 5MP P&S and I struggle to find any flaws.
 
Well I would guess that this is accurate if the sensor is the same size as the cameras that are much lower in MP's. Point and shoot cameras are a good example of this. An 8MP P&S is not of the same quality as an 8MP SLR with a larger sensor. This is my understanding anyway.
 
I've heard recently that high MP cameras (I believe Sony just announced a 25MP sensor) can have serious drawbacks because the actual size of the pixels on the sensor are so small. Some examples were that smaller pixels create noisier shots due to less light sensitivity and also tend to create soft images. Does anyone know about this?...quote]

Somewhat accurate but overly simplistic. Individual manufacturers are using proprietary methods to reduce noise despite the high pixel count. In some cases the data is filtered to take out noise before it is even recorded. In one case it is converted from analogue to digital through a noise reduction procedure. In still another case, chip design reduces noise.

The proof of what I have said is easy to find. Two cameras may use the same processing chip with the same number of megapixels but if you look at the lab data in Popular Photography you will find that one has lower noise than the other. The difference is in the proprietary methods of reducing noise by the two camera makers irrespective of mexapixels or the size of the pixels.

skieur
 
A small part of a large complex system. Yes a smaller photosensor size does increase noise as the signal needs to be amplified to catch the same amount of light, but as others have said there are other ways to improve upon it further.

One way is to look at the noise in every other part of the system (change the way the sensor is read out to the ADC ala Sony's new system, change the way the transistors are placed on the sensor, ala Nikon's system, change the way the wires are routed behind the sensor which is Olympus' approach).

Or change the sensor itself CCD to CMOS which gave a noise improvement a few years back, or put a set of micro prisms on the sensor to capture more light (again Nikon's solution).

Canon fanboys don't take this the wrong way. I simply am not familiar with their methods of improving noise, but they do have some too.
 
There is also another dynamic in that as you go up in the resolving power of the sensor (smaller phtobuckets mean smaller bits of the image which in turn means finer resolution) any defect in the lens become more apparent.

So, without the finest of glass you will get some image noise along with any sensor noise.
 

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