Mp v Sensor v Processor

[dorsetdruid]

Hi guys, this is my first post and I'm wondering if anyone can answer a question for me.
I'm in the market to upgrade my Pentax K200d and obviously would like to get something that will give me a good technical start as far as picture quality is concerned.

It used to be a megapixel war but now all kinds of other factors come into play, notably sensor size and processor capability.
Does anyone know if there is a list of cameras that would give me a ranking as to which combination would be more favourable?

Is it better to get a larger sensor but less pixels, for instance.
I'm confused as to why some of the top end cameras have for example 12 or so megapixels but command a premium price tag.

At the moment I'm looking at the Canon 550D as it almost seems too good to be true since nothing else appears to come even close to its spec for the price.

Any help would be greatly appreciated.
Have a great day.

Dave

[chris-p]

Hi Dave, welcome to the forums

To be honest, there is no right or wrong answer.

You're right, there was a megazpixel war, and there still is in some respects. However, the conventional wisdom (until recently) was that packing more pixels onto a sensor of a fixed size means you have to have smaller pixels. These smaller pixels capture less light each which means you have to amplify the signal more and, therefore, you get more noise.
You can see this thinking reflected in the range of Nikon cameras which, until very recently, all stopped at the 12-12.3MP mark and were considered the top of the tree for high ISO/low noise performance.

Of course, this sort of technology never stands still for long and when Canon released the EOS 7D they pretty much blew everyone else away.
You're talking about an APS-C sized sensor with 18 million photosites on it, which means they are pretty tiny (compare the fact that the Nikon D300s has 3.3 million pixels per square centimetre to the 5.4 million of the 7D). The Nikons pixels are 5.49 micrometres across while the Canon's are 4.3 microns.
This makes it sound very one sided (as well as dull) but the thing is, the EOS 7D completely re-wrote the "small pixel pitch = lots of noise" rule book.
I've used this purely as an illustration that, as you've already said, it's not all just about the number of pixels.

The only technical aspect I would add is that processing capacity/ability is not something that is always as important - it depends on what format you shoot. If you're shooting in RAW you won't get any noise reduction applied to the photos so processing performance is negligable. It's obviously far more important if you shoot in JPEG.

The thing with the top end cameras is that they're now specialised tools for different jobs. I'll take the Nikon range simply because I know it better...

The D3s and D3x have the same sized sensor but completely different numbers of pixels. The D3s has 12.1MP on a honking great full frame sensor. This means the pixels are huge. So they capture a lot of light and you can shoot in very low light situations without having to crank up the ISO and get more noise. It also means that the files are smaller and so it can shoot more frames, more quickly and write them to a card quicker.
Basically, it's lean, fast and good in low light.

The D3x on the other hand, has 24.5MP on the same sized sensor. These pixels are much smaller and so the signal they generate needs more amplification. However, this isn't all bad news. While the files are larger and take longer to write and can't be shot as fast, they are much much higher resolution. They can be printed larger and they contain much more detail.
If the D3s is a responsive, low light tool, the D3x is a high resolution, high detail studio and landscape camera.

The only thing I would add with regards the prices is that you're paying for a lot more than just the pixels on the sensor. You're paying for professional grade build quality (magnesium alloy chassis, better plastics etc), more advanced ergonomics, better features and far greater durability just to name a few.

Finally though, to try to answer your question "what's best for you?". Unfortunately the answer is another question. What do you shoot?
Upgrades are a tricky business and it really depends on what sort of photography you do and how much you have to spend. Changing systems will necessitate a change in lenses as well which will add to the initial outlay, while upgrading within the Pentax range means you get more camera for the same money as you don't have to replace the lenses.

The 550D is an excellent all rounder, and many people have questioned why you would spend more on cameras like the 50D, 60D and 7D but hopefully I've explained some of that above with regards to more advanced features, ergonomics, build and robustness.
I would also consider the Nikon D5000 as it's the the major competitor to the 550D, but I would also suggest you look at cameras further up the Pentax line such as the K-7 and new K-5 (if they're not too expensive).

[chris-p]

OMG, I've written an essay.

Sorry!!

[dorsetdruid]

Many many thanks Chris-p, an essay is just what I needed.

Looking at the info you've given I would guess that, since my photography is based around landscapes and still life sometimes needing to be enlarged a fair degree, that a higher pixel count would suit me better. I don't need a high burst rate or write speed.

With processors now being able to compensate for a lot of the noise generated by smaller pixels I'm kind of favouring the 550D as it looks pretty much future proof for me.

The only stumbling block for me, and this may sound a little picky, is that it's not a Nikon.
Years ago (way before digital was even dreamt about) my kit consisted of a Nikon setup exclusively and I guess there's still quite a reservoir of brand loyalty floating around inside me despite having bought the Pentax.

If someone could convince me that a Nikon of roughly the same price would suit me just as well I'd be all over it.

Thanks again for your help. Invaluable.

[PaulMontgomery]

How much would you want to enlarge? Not so long ago, magazines were running centre-spreads from 4 MP I've got an A4 print on the wall from a 2MP camera - its fine unless you look at it from less than 6 inches...

[GeoffWessex]

If you wanted to stay with Pentax - and why not, if you've got some Pentax fit lenses to use - you may like to take a look at their K-7 - 14.6Mp with 4Mp/cm2 density - or, a little more expensive, the K-5 - 16.3Mp with 4.4Mp/cm2 density (but quite a few other improvements as well). If money were no object and I really wanted to stick with Pentax, I'd go for the K-5. (I'd really like a Pentax Full-Frame camera but I wouldn't recommend anybody holding their breath while they wait for one).

[chris-p]

I'd suggest the K-5 if you stay with Pentax. It's brand new out and full of excellent technology.

Nikon-wise, they've been sticking to the lower resolution/lower noise theory until very very recently. The D7000 is the only real Nikon upgrade to add a significant degree of resolution, but it's over £1,000 so it's a HUGE step in price as well. The D90 is excellent (I use one for landscapes and it's great - there are a few here) but it's only 12.3MP.

For your money, the K-5 is the best option unless you really really want to shell out for a D7000.