If, like me, you're considering upgrading to a better digital camera, you're probably thinking that image quality is determined by the number of megapixels. However, there's an interesting article here (http://www.kenrockwell.com/tech/mpmyth.htm) that states the number of megapixels is largely irrelevant once you get past 3 million and that the whole obsession with megapixels is largely hyped by camera manufacturers.

Whilst I accept much of the article, I've also found that, when blown up to A4 size, much of the landscape photos I've taken on my ageing Kodak 3.2million MP camera do tend to lose definition. So if one accepts the article and wish to print digital photos up to A4 size, how many megapixels do you actually need?

isn't it the lens' that are important rather than the amount of megapixels? can't answer your question sorry:(

You need a better lens really. Get a Digital SLR if you want better image quality when enlarged, they are all 6mp or more anyway.

There are a number of factors that come into play with your question:

1. Number of pixels
2. Lens quality
3. Density of pixels on the sensor (more pixels on smaller sensor *may* cause issues with artifacts in the image aka. noise)

I'd generally suggest for a decent compact by a respected brand, go for ~5-6MP mark.

I'm sure someone will be kind enough to provide more detail with calculations to give you a more reasoned number ;)

cameras are the same a severything else you get what you pay for.
we have 2 cameras at 7mp one is good ones not.

I would suggest reading this thread...

http://www.sheffieldforum.co.uk/showthread.php?t=286180

at post #5, it goes into more detail of what really matters...

Basically nobody needs a 10 Mpx camera unless they are going to blow their pictures up to poster size. If you want better pics, get a digital SLR (TTL) camera which you can buy different lenses for and get a big fat lens which takes in lots of light. Most of my photography is destined for web pages and so I have to crop and reduce the size of the picture anyhow. Unless you print everything out or you always use a tripod before zooming right in to a small section, then more and more megapixels is utterly pointless and a complete waste of money.

Especially when you consider that the best size for a big photo on line is just 800 pixels wide.

I have an Olympus digital I've owned ever since digitals first came into being. I also own an Olympus film SLR. I was convinced the digital would take good pictures based on the excellent lens on the SLR. I was not disappointed. Though the camera has only 2 pixels I have no problem printing up to 8 x 10. The only problem is its a little slow firing first shot and slower still reloading. So if I want to shoot sports I take the film camera.

Though the camera has only 2 pixels I have no problem printing up to 8 x 10.

Crikey - that's one amazing camera ;)

Crikey - that's one amazing camera ;)
I thought about it after I wrote it, and thought what the hell.

Theres another interesting article here; http://6mpixel.org/en/? about the same subject.

As a general rule of thumb most images print at 300dpi (dots per inch). So, divide the width and height of your image to get an approximate 'optimum' print size - eg a 6MP will probably be 3000x2000 pixels which is 10x7 or there abouts.

There are a whole bunch of factors though - distance from the printed image when viewing (ie. lower resolution yet large images look ok if you stand further away) and sensor quality. That's why the really expensive DSLRs (eg. Nikon D3 and Canon EOS 1D 16v DOHC) have 'full frame' sensors - the sensor itself is the same size as a normal 35mm negative. Typical DSLRs have APS-C sensors (same as the short-lived APS film cameras), whilst your typical pocket point and shoot may cram all 12 megapixels onto a chip the size of gnats thingy... With a larger sensor each pixel gets more room to breath and the gubbins that sit between the sensor and the lens (themselves micro-lenses to focus the light into each individual pixel) can be larger thus providing a higher quality image.