How Many Pixels Do You Need?

[eurasianthai]

I'm actually of the opinion that the more pixels, the better.

More pixels can't hurt, can they?

Whatever the quality of the camera, more pixels will mean more information stored in your camera.

And overall, a better end picture.

Is it?

[phetaroi]

I see it as "A" factor, but not "THE" factor.

[wrazoru]

Yup...i would agree with Phet....

Probably the big disadvantage is that they take up more space on the computer...esp. for the trigger finger happy types...

But certainly there are lots of advantages to it. It certainly does provide a sort of virtual ability to zoom more into the image.

The other thing is that most people who only send images to the web really can probably manage with 2-3 MegaPixels ...In actual fact, most computer/laptop screens are at 1024x768 (= 786432 square pixels) in resolution which is less than 1 Mega Pixel, so image an image which doesn't fit the entire screen.

1 Mega Pixel = 1,000,000 square pixels.

Where you need the MPxls the most is if you want to output to large prints.

But these, as with many things can be a continuous discussion. Really it mostly depends on the individual & how they intend to use their photos....

[hughden]

It's a marketing strategy that has got out of hand and is probably is most responsible for the degradation in image quality as technology has "progressed".

Everything else being equal, whilst accepting that they usually are not, take two cameras with a the same size sensor, and the one with fewer pixels will give you a better picture. This is because fewer pixels on the sensor means bigger pixels, means better capture of light and less noise. Sure, theoretically you can't enlarge it as much as a the higher megapixel camera, but if the other camera is producing a rubbish image to start with, there is not a lot of point in enlarging it.

What should be highlighted for consumers is something like the MP/cm² pixel density that is used on the DPreview site as part of the camera description. The lower the number of mega pixels per square centimetre, the better the image is likely to be.

But the public have been duped into thinking the more megapixels the better, and so the manufacturers keeping churning out sensors with more and more pixels stuffed on the sensors, and we keep buying them.

An example would be the 15 MP Canon 50D which replaced the 10MP Canon 40D, both with the same size sensor, and had worse image quality than the 40D. DPreview concluded:

# High ISO performance worse than 40D

# Reduced dynamic range in the shadow areas compared to EOS 40D

# Per-pixel detail not as good as on good 10 or 12 megapixel cameras

# High-end lenses required to get the most out of the camera

Look at the MP/cm² pixel density (and be shocked at how high it is on small P&S cameras), look at the other features of the camera that you might use, look at the quality of the lens and its ability (or not) to actually resolve the detail on all those pixels; and pay no attention to the megapixels. They are there to sell you the camera, not provide you with better photographs.

[VerbalKint]

Whatever the quality of the camera, more pixels will mean more information stored in your camera.

You don't need more information, you need accurate information.

As Hughden is saying cramming as much pixels on a small sensor as possible just to sell more cameras can actually damage image quality.

Here's a surpise: when you are only watching you images on a computer screen (let's take a 19 inch screen) you need little over 1 Mp (1.024) to watch it it max. quality full screen.

For printing you need more, if you print at 300 dpi (books/magazines) you can calculate it by simply dividing the maximum number of pixels by 300.

So a typical 8 mp photo would be: 3264 x 2448 pixels, so you can print at 10.88 x 8.16

Most photolabs use 200 dpi, so you can print even larger. 16.32 x 12.24

how many people wil actually print something bigger than that ?

Edited February 9, 2010 by VerbalKint

[aeon]

It's a marketing strategy that has got out of hand and is probably is most responsible for the degradation in image quality as technology has "progressed".

Everything else being equal, whilst accepting that they usually are not, take two cameras with a the same size sensor, and the one with fewer pixels will give you a better picture. This is because fewer pixels on the sensor means bigger pixels, means better capture of light and less noise. Sure, theoretically you can't enlarge it as much as a the higher megapixel camera, but if the other camera is producing a rubbish image to start with, there is not a lot of point in enlarging it.

What should be highlighted for consumers is something like the MP/cm² pixel density that is used on the DPreview site as part of the camera description. The lower the number of mega pixels per square centimetre, the better the image is likely to be.

You are partly correct and partly wrong. It is true that more pixels in the same sized sensor get more noisy images, but less pixels means also less details, so quality of image is not only about noise, but also about sharpness. If you need to print, number of pixels are important, and new interpolation algorithms give much less noisy images than before. Also new technologies are implemented, for example Canon 7d has a smaller sensor than a full frame, has more pixels than previous cropped frame cameras, but noise is not a big deal because they also reduced the size and distance between the microlenses in front of the sensor, meaning less gaps between pixels then less noise and more details.

Edited February 9, 2010 by aeon

[Sunny Valentine]

For an SLR I try to get a lot of pixels. My compacts on the other hand are chosen on moderate pixel counts. On Micro Sensors the image quality tends to decrease with the number of pixels increasing.

Still unbeaten, but the Camera was unfortunately stolen: The Fuji 30: 6 Megapixels, more than enough, and the results, especially in low light, were close to contemporary SLRs.

[astral]

I am with Hughden on this.

The number is pixels is not as important as the pixel density.

I would stake my Canon 40D with 10MP against any point and shoot with the same number of pixels,

expecally at the higher ISO ratings.

Cleaner imaging, and less noise.

It is actually very similar to film.

There is a limit to how small the grains can be, and to get images for high enlargement you need a larger format camera.

There were limits to film technology, and there are limits to digital.

[aeon]

I would stake my Canon 40D with 10MP against any point and shoot with the same number of pixels,

expecally at the higher ISO ratings.

Cleaner imaging, and less noise.

if you compare a smaller sensor p&s camera with 10mp and the 40d then you are right.

But if you compare 40d and 7d (I have both), same sensor size but the last one has 18mp and trust me it captures much clearer images and less noise.

[Portlandstone]

It's a subject I haven't read about in probably over a year, but from I understand is that more pixels isn't always better. If that were the case, cameras would be made at 40 or even 100 megapixels and beyond and sold today. However it's not just the pixel count, it's the ability of the sensor and other functions inside the camera to actually handle that high megapixel count. In otherwords, key elements of the camera have to keep up with the megapix count in order to produce a quality picture, or more correctly, avoid producing flawed pictures. From what I understood is that this was a big complaint when going from the Canon 40D to the 50D. The 40D was what, 10megapixels, yes? Then the 50D was 15 mp, a relatively high jump, as many were expecting it would only go from 10 up to 12. The argument was that by increasing the mp count so much it actually made the pictures worse because the rest of the technology didn't keep up in effectiveness. Tech reviews actually argued that the 50D produced images that were worse than the 40D.

edit: sorry folks, I posted my comment after only reading the first post, now realize others said very similar things.

While I'm at it I will add one more comment. For casual picture taking I kid no one, even 5MP is perfectly fine just using it on your desktop, for hobbies. I had a Panasonic FZ20 (from the 2004/2006 time range) max 5MP, never a complaint regarding loss of details (except noise was worse in those days). I also have another digicam now, FujiFinepix S2000HD, max 10MP, but I usually keep it in 5MP mode. Perfectly fine for personal use, sending pics to friends for desktop viewing. I sometimes keep my Canon 400D in "medium jpeg" mode.

Edited February 10, 2010 by Portlandstone

[harrry]

The biggest problem with large picture sizes is the transfer time to the SD card. If I am shooting brackets of fast moving objexts or sport I tend to prefer lower resolution so that more photos are taken in a given time enabling better selection.

THis of course means that I lost the benifits of the large images which can be cropped to localise the action and still retain acceptible quality.

This applies especially woth RAW as transfering 50 Meg images takes time.

[The Vulcan]

I would stake my Canon 40D with 10MP against any point and shoot with the same number of pixels,

expecally at the higher ISO ratings.

Cleaner imaging, and less noise.

Well' I'd have to challenge that statement.

Take a look at the GF1 thread Here

Small sensor p&s.

There are images there shot at 640 ISO as well as 100% crops of originals.

These stood up very well against my Canon 5D MK1 which was significantly better in IQ than a 40D

The micro 4/3rds system is certainly not one to be overlooked

[The Vulcan]

Conversely here's a few images from a Canon MK11 21megapixels

Hand held 70-200 F4 L IS with 1.4 converter (pretty heavy)

First is original

Second is 100% crop

Megapixels do count!

[aeon]

Megapixels do count!

I agree

[hammered]

I always thought low pixel density was important, so it really is about sensor size. Didnt Fuji knock out some really decent and cheap low light picture point and shoot cameras using precisely this formula?

Personally I wouldnt classify the GF-1 as a point and shoot by the way

[VerbalKint]

I agree

Very well argumented opinion

[The Vulcan]

I always thought low pixel density was important, so it really is about sensor size. Didnt Fuji knock out some really decent and cheap low light picture point and shoot cameras using precisely this formula?

Personally I wouldnt classify the GF-1 as a point and shoot by the way

Agreed but trust you see the point

[tw25rw]

Pixels matter if you plan on printing larger than a small snap shot. If you just want to view on screen, esp through a jpeg viewer, it doesn't really matter.

[aeon]

I agree

Very well argumented opinion

lazy me

[eurasianthai]

Pixels matter if you plan on printing larger than a small snap shot.

Actually, pixels matter if you need to crop.

And we're so lazy these days that we do not move anymore to get the right picture.

We do not even try.

We just crop it afterwards...

[VerbalKint]

Actually, pixels matter if you need to crop.

And we're so lazy these days that we do not move anymore to get the right picture.

We do not even try.

We just crop it afterwards...

First class studying photography my teacher told me to use my feet, not my zoom. Wise man ! Guess it's more or less the same here.

[The Vulcan]

Actually, pixels matter if you need to crop.

And we're so lazy these days that we do not move anymore to get the right picture.

We do not even try.

We just crop it afterwards...

First class studying photography my teacher told me to use my feet, not my zoom.

Try that amongst a crowd of press shooters or at a motor racing circuit etc - not a wise "move" if you value your health