Megapixels?

[Taallyn]

Yeah, stores and manufacturers have been pushing the megapixil numbers because it is an easy number for people to understand ... or easy to confuse consumers with depending how you look at it. It is was is generally called the "Megapixil Race". It is always good to ask questions to an independent source like DPS as we aren't trying to sell the camera to you.

[chrisbassett]

Physically smaller sensors are cheaper to make.
Lower quality materials are cheaper to use.

Point & shoot cameras tend to have very small sensors
Consumer DSLRs and some of the lower end pro-sumer DSLRs have sensors slightly smaller than 35mm film
More expensive pro DSLRs have sensors the same size as 35mm film
"Proper" pro digital cameras have larger, very expensive sensors.

Other aspects of the sensor that contribute towards image quality
1. Pixel sensitivity - the smaller the pixel, the more it is susceptible to noise...think of the effect of getting grainy images when you shoot in low light. For a given sensor size, a higher megapixel count = smaller pixel size.

2. Pixel interference - sensors are electronic devices, and there is always some level of interference between electronic devices. The more closely packed the pixels are, the more they will interfere with each other, affecting the image quality. Again, same sensor size with higher megapixel count = high pixel density.

3. Pixel count - the more pixels used to capture an image, the more detail is captured. This means the image should be sharper, and can be printed at larger sizes.

The optimum number of megapixels for your camera is your personal choice of a balance of the above.

Most consumers who buy a DSLR will end up with a sensor that is slightly smaller than a 35mm film, with between 7 and 12 megapixels. The sensor size will not change, so that means that as the megapixels go up, the pixel density will go up, and the pixel size will go down. This will increase interference and noise, but the big question is will you ever notice this?

If you spend all you time shooting in good light or daylight, then probably not. If you shoot at night or indoors with no extra lighting, then you may notice a difference or feel a general "could be better"-ness about photos from a sensor with a higher pixel count.

If you are only ever going to display the images on screen, 7 to 8mp is way more than adequate, and will even give you a good leeway for cropping.

If you want to print your photos at up to A4 (or, say 12"x8"), 7 to 8 megapixels is more than adequate. In fact you could probably print up to twice this size and not worry about it too much unless you start getting very close to the print.

Another factor is file size. The larger the number of pixels, the larger the file-size for each photo. This is getting less important as memory cards, hard-disks, internet storage and bandwidth are all becoming larger and cheaper.

In the end, it's down to personal choice. If you're worried about it, take a memory card to your local shop, decide on a few test scenarios and get comparison shots with a few different cameras. Try a moving target, some daylight shots and maybe something less well lit. Do the same with a few different pixel counts and cameras within your price range, take the photos home and check out the differences, if any.

If you notice the difference in noise between a 7mp camera and a 10mp camera, then you may want to stick to the 7-8mp range. Otherwise, it's a question of money and brand...which is a whole other subject.

Phew.

[crunch]

Surely the image processor also plays a part? Two different camera brands with the exact same sensor (size & no. of megapixels) will produce different results based on how that data is processed.

Although I'm sure the best of Canon (digicIII) and Nikon (expeed?) are on par anyway. The other dSLR manufacturers can't be too far off either.

[alpha1john]

I'm new but I think I have a good grasp of some of the concepts that may help clear some of this up.

Megapixels allow you to capture an incredible level of detail in one click. In the past it we critical that you compose your picture in the viewfinder before you took the picture. Now you have the ability to grab a huge amount of image and the ability to cut/crop/sharpen/shade... etc. all after the fact.

But just as in the days of VHS dubbing - it matters which tape you are using for the initial copy and which you use for the dubbing. Branding matters. Trusting in a brand's quality matters. Sure you can get more megapixels for less money somewhere but if the resulting 'Master' image is crap... you can't make it into art no matter what you do.

It's never just one thing. Great optics on a poor body or used with bad electronics or data capture - will just lead to frustration.

My first digital camera was a used Sony One-shot with a ~1.5 megapixel (or so) level of detail. The colors and optics and software were all top notch. They still are. By today's standards the level of detail is wanting. At such low resolution I learned I had to make sure to compose all my close ups as I took them. For standard printing it looked great. Trying to blow up the kids standing next to the back of the house on Easter where the original includes the whole back of the house (don't ask, I don't know why) left such pixilation of the picture that it was unusable.

If there was only one thing that matters it would be the person taking the picture and what exactly they want from that 'click'. No matter how good the tools are if you don't know how to use them, you will never see what 'could' happen with everything working together to create a real masterpiece.

I'm no authority believe me on the art of photography but I'd like to think that I understand the concept well enough to add intelligently to this thread.

[rediguana]

Originally Posted by crunch

Surely the image processor also plays a part?

I was thinking that late last night myself!

I'm sure it plays a part, but probably lesser so than the actual physics (sensor size, density etc). The processor is really there to correct and tidy up what falls on the sensor, so in some regards it is a bit like Lightroom or Photoshop - yes it can and does improve the quality, but only so much. There is only so much you can do with post-processing which is effectively what the image processor is doing.

[Kamuel]

whoa there are counts for shutter life?!

anyway, I think there needs to be a medium in a good number of megapixels without being too low or too high. This is how I understand it:

Too low: you can think of this extreme as the very basic, early camera phones that came out very small pictures with hardly any detail at all.

Too high (in a particular sensor size): your camera can take in so much information but trying to cram it in such a little space you get more noise/grain in your picture. (I've been told this is why you shouldn't necessary go for the tiny pocket size cameras with like 12MP they come out with these days)

Just right: You get pictures that are sufficiently big enough for you to work with and provide the detail you want without excessive noise.

My Canon S3IS only has 6MP. I bought it when the S5IS was already out (has 8MP) but i figure the extra 2MP for almost $200 wasn't cost efficient at all for the casual photography I was begining with. It produces some splendid shots! I only plan to make 4x6 prints for now (personal records, scrapbooking?) and even my old 4MP camera was enough for that.

[neilwood]

There are no easy rules with regards to this subject.

Larger sensor should equal better image quality (IQ) - all other things being equal. Very important to understand the bold type.

Take one manufacturer, Canon for example:

Current range goes 400d 450xsi, 40D, 5D, 1Ds, 1D (ignoring the Mk numbers on the 1 series.

The 400D and 40D share the same image sensor but the 40D will produce higher quality images. How so i hear you ask. 2 reasons for this - 1) upgraded microlenses on the sensor which allow better light capture on the 40D 2) upgraded image processor Digic III on 40D as opposed to Digic II on 400D.

The 5D has a larger sensor than the 40D but has an older processor and older sensor. Therefore the IQ increase is not as substantial as you might expect.

The only thing to do to work out the best for you is to 1) read all the reviews you can lay your hands on and 2) Try some different bodies.

[Darryl]

I have taken a lot of very nice photos with my 4 mp casio camera. Without cropping an image, I can have one printed at 8x10 and it looks surprisingly good. This camera does produce a good deal of noise though, and that's the main reason I went shopping for another camera. When it comes to carrying one on a mountainous hike, if it's not for the specific purpose of picture taking, I'll carry the P+S. If I had wanted to upgrade, yet still have a P+S, I'd probably be looking for a 6 or 7 mp camera with the largest sensor that was offered in these- that would have satisfied my need for a cleaner picture, yet still being very easy to carry. One of the things I wanted in my upgrade was a better zoom range- so far three more important things than mp are lower image noise, greater zoom range, and compact ruggedness.

As it happened, I got an 8 mp dslr, the rebel xt. This camera is way bulkier, and though it can be used as a P+S, it has so much more flexibility that it will be a plaything for me for a good while. It's much more difficult to fit it in with my hiking package, so for a couple reasons, other than mp, it may not have been the best choice. I do like it and it does take very nice pictures, and I'm not upset that I bought it, but it has its place. The full res image (8mp) is much larger in file size than the 4mp images from the P+S, so there could be an impact for you depending on your computer. Two things in particular, how much memory you can devote to storing images, and how long it takes the computer to manipulate then as you view them, and modify them. In that vein, I feel that the 8 mp images are about as large as I would want to be using. I'm actually happy that I didn't get the 10 mp camera, since much of my enjoyment of the hobby is viewing and manipulating my photos on the computer. I would be annoyed if that became too time consuming to do- so there now is a valid reason to not choose a too high mp rated camera.

I have to say also though that most any camera will let you take pictures in smaller sizes than its maximum resolution, but sometimes it's annoying to have to set that, then reset it back, for the occasion when a scene warrants the highest pixel count the camera can deliver. It may be kind of pointless to have say a 10 mp camera when you almost always set it for a smaller image size.

A lot boils down to your enjoyment of the hobby. If you are not pleased with your pictures because the camera can't deliver enough detail, maybe more mp will be a good thing. You do have to be a good enough photographer to enable your camera to deliver the best it can- if your technique is not good, more mp won't do you any good.

I researched extensively before I bought, but I didn't fully understand the relationship between sensor size, mp rating, internal picture processing quality, and image noise. Knowing what I know now, I may not have made the jump to the dslr as soon as I did- I might have been happier with a much improved P+S for the next couple years, then going for the dslr later.

Well, hopefully I've presented another way to look at the issue of mpixels. For me personally, almost every other issue is more important, with low image noise being right up there. After that it's ruggedness, speed of operation, zoom range- . If I was going to be printing in large format, if detail was not adequate, or if I was going to be heavily cropping, mp rating would figure higher.

[i_luv_ph0tos]

most people say DSLR's are good...