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DPChallenge Forums >> Hardware and Software >> How many megapixels do we really need?
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03/04/2012 03:51:25 PM · #1
Most of you will have noticed the dramatic increase in megapixel counts for the amazing new cameras hitting the market already this year - Nikon D800, Canon 5D MK III, Sony A&& and NEX7 for example. It seems not so long ago that we crossed the 10 Mp resolution standard; now we begin a new era with more than 20 Mp as the typical new minimum. Even last week, we saw the new Nokia cellular telephone introduced with a 41 Mp count. Where does it end? What do we really need? Do we sacrifice anything to gain these enormous pixel counts? Are all chips the same? Are all CMOS photosites the same? What differences are there due to FX versus APS versus 4:3, etc.? Is it just a ploy to get us all to buy new equipment or are we actually gaining benefits from these innovations?

When is enough megapixels enough?
03/04/2012 04:14:56 PM · #2
5DmkIII increased to 22 from 21. Not dramatic, but still plenty of pixels.
03/04/2012 04:23:15 PM · #3
My trusty old Olympus E1 from 2003 only has 5Mp but they are such beautiful pixels. And the old Kodak sensor produces such lovely colors.
03/04/2012 04:27:39 PM · #4
you can get hasselblad backs upto 60mp or there are large format 8x10 at 110mp its horse for courses i guess

computing and storage will have to catch up, my 5d at 12mp takes beautiful pics but the mk2 takes even better pics, but i think i'll be happy at 21mp
03/04/2012 05:09:10 PM · #5
Megapixels are not the most important thing but are useful when you want to print a large size photo. IMHO photography still involves printing and it's not only a matter of viewing on screen.
03/04/2012 09:00:01 PM · #6
Much as the D800's 36 mp sounds amazing, I can't help but wonder what kind of file sizes you'll end up with. Not to mention noise. I'm thinking in the mid-20s or so would suit me fine.
03/04/2012 09:28:50 PM · #7
The numbers sound outrageous, for sure. Heck, my first DSLR was 6.3Mpx, and it held its own against popular 35mm color slide films in the resolution department... not so much in other areas. My second DSLR has 12.7Mpx, exactly double my first, and the difference is big, but as techies we know that to double the resolution (in line pairs per picture height) we need to have 4 times as many pixels. So I'd need 24Mpx to double the resolution of my trusty ol' Canon 10D.
As storage becomes ever cheaper and computers capable of processing the gigantic files (or so they seem today) without breaking a sweat, the answer to "how many do we need?" is inevitably "however many we can pack in." Of course, we give up in noise, but we can always downsample and get it right back. Oversampling and binning has other advantages as well, such as sampling all colors for each (binned) pixel. To me, the only real disadvantage of the high pixel density is lower full-well capacity, which limits dynamic range. As long as they pay attention to moving forward with areas of image quality *other* than resolution, I'm fine with the higher pixel counts. They just give me more flexibility in processing.
03/04/2012 09:44:39 PM · #8
Hmm my first p&s was 2.01mp, the Canon Powershot A700 was 6.1mp...then my first DSLR, the D40, was 6.1mp and now the D90 is 12.3 mp. I know the D7000 shoots in the 21mp range and have been considering it, but wondering if I should just wait for its replacement.

Meanwhile, back to Nikon for the D90...again...so while I'm at Vistek I'll get my grubby little paws on a D800 and take it for a spin.
03/04/2012 09:51:45 PM · #9
I am very shy at taking street photos of people. I dont have the confidence to point my camera to a total stranger and take photos. One technique i learned is to use a wide angle and point my camera to an object other than my subject while keeping my subject in frame. Then i crop out the image to digitally center and zoom in to my subject. But the cropping and zooming are limited to a point where it starts to pixelate. So yeah i think im gonna need 24 megapixels or more.
03/05/2012 05:25:10 AM · #10
Originally posted by LandzEnca:

I am very shy at taking street photos of people. I dont have the confidence to point my camera to a total stranger and take photos. One technique i learned is to use a wide angle and point my camera to an object other than my subject while keeping my subject in frame. Then i crop out the image to digitally center and zoom in to my subject. But the cropping and zooming are limited to a point where it starts to pixelate. So yeah i think im gonna need 24 megapixels or more.


Or just, you know, get more practice at composing images you don't feel comfortable with rather than buying a fancier camera!
03/05/2012 10:17:30 AM · #11
I think it depends on the photographer, and the subject matter.

Some images require more detail. Ever see a landscape from an 8X10 view camera?

At the same time the photographer has to be able to do justice to the equipment. If your problem is not resolution, but composition, lighting, focus, and post processing, then 200 megapixels are not going to make your images any better. I really can't get 100% out of my 40D, not much point in spending the money to get a 20 Meg cam that will still score a 4.9.
03/05/2012 12:08:37 PM · #12
No one has mentioned where we hit the line between lens resolution and sensor resolution. Some lenses are better than others, but the 16mp D7000 seems to get near the limit of the resolution of some of my best lenses, and has more resolution than some of the not so good ones. That is one area where physically larger sensors come into play.
03/05/2012 12:25:07 PM · #13
One interesting thing I read about the 41MP Nokia phone is that for lower resolutions, which is what most people would shoot at, it can zoom without interpolating. All it does is changes how much it oversamples the middle part.

I worded this horribly, here is where I read it.

"Meanwhile, the tremendous resolution of the 808 PureView sensor allows it to digitally zoom without the interpolation that usually gives digital zoom a bad rap. If you set the camera to oversample its 41-megapixel images down to 5-megapixels, then zoom in, it will sample fewer pixels from a specific part of the frame, to provide a zoomed effect, but never “stretch” pixels to scale up the photo the way a traditional optical zoom would."
03/05/2012 01:46:50 PM · #14
The new Nikon d800 has 76mb raw files
03/05/2012 01:51:53 PM · #15
Originally posted by adigitalromance:

One interesting thing I read about the 41MP Nokia phone is that for lower resolutions, which is what most people would shoot at, it can zoom without interpolating. All it does is changes how much it oversamples the middle part....


Yep. The easy way to get our minds around the implications of the 808's design is to imagine you have a 41 Mpx DLSR, but it has a 28mm prime permanently affixed to it. You can shoot whatever you want at 28mm and get a 41 Mpx image, but in order to get longer (apparent) focal lengths, you'll have to crop. The good news is, you can crop pretty dramatically and still have lots of pixels to work with. For example, you could crop out 90% of the frame and still have a 4 Mpx image; doing so would give you just over 3x "zoom" and about 90mm "35mm equivalent" focal length.
03/05/2012 02:51:57 PM · #16
Originally posted by Giles_uk:

The new Nikon d800 has 76mb raw files

Remember that mega-pixels and mega-bytes are not tied by a fixed relationship; bit-depth, level of detail, file format and comprssion scheme can all radically alter the size of a file. Without adding or discarding any pixels the same file will be some other size when saved in TIFF, JPEG, or .PSD format.

I'd need a lot more than a new camera before I could deal with 76MB files ... :-(
03/05/2012 02:58:27 PM · #17
Originally posted by GeneralE:

Originally posted by Giles_uk:

The new Nikon d800 has 76mb raw files

Remember that mega-pixels and mega-bytes are not tied by a fixed relationship; bit-depth, level of detail, file format and comprssion scheme can all radically alter the size of a file. Without adding or discarding any pixels the same file will be some other size when saved in TIFF, JPEG, or .PSD format.

I'd need a lot more than a new camera before I could deal with 76MB files ... :-(


that was the figure i remember seeing on the dp review site not a calculation made me think though, my 4 yr old mac book pro is struggling with 200k+ 8/12mb raws from my 5d and 20d 76mb raws would need a new computer, new hds, new cards etc for 800x800 enteries on here lol
03/05/2012 03:04:10 PM · #18
Originally posted by Giles_uk:

The new Nikon d800 has 76mb raw files


I'd be surprised if they were anywhere near that big. The RAW data is pretty compressible, and normally RAW files are perhaps 1.2 to 1.3 bytes per pixel in size. So I'd expect a RAW file for a 36Mpx image would be in the range of 45MB. Still a big-arse file.
03/05/2012 03:19:54 PM · #19
//www.bradleypatten.co.nz/2012/02/d800-raw-files-around-76mb-for-fx.html

2. File sizes
With a 36.3 million pixel sensor, you can expect big file sizes, so it might be time to start stocking up on extra memory cards now. Nikon tells us that a raw file captured with the D800 will weigh in at a huge 76MB, while a 16 bit TIFF can expect to take up 212.1MB. Stock up on external hard drives now…
from //blog.1wow.com.au/most-wanted-nikon-d800/

More information about the file size and buffer memory:
//www.pixiq.com/article/the-nikon-d800-official-announcement
14-bit uncompressed RAW, 74.4MB
camera buffer memory 16 frames
12-bit lossless compressed RAW, 32.4MB
camera buffer memory 21 frames
14-bit uncompressed RAW in DX, 32.5MB
camera buffer memory 25 frames
12-bit lossless compressed RAW in DX, 14.9MB
camera buffer memory 38 frames
JPG at highest resolution, 16.3MB
camera buffer memory 56 frames
JPG at highest resoultion in DX, 8.0MB
camera buffer memory 100 frames

//www.youtube.com/watch?v=QTz0mwM48lU

03/05/2012 03:49:13 PM · #20
If a 14-bit uncompressed RAW is 76MB, that essentially means that they are using a 16-bit word per pixel, plus another 4MB of "overhead" which would include thumbnail, embedded JPEG, metadata, etcetera. Makes sense. But why no 14-bit RAW with lossless compression? I suspect that in fact the lossless-compressed 12-bit RAW contains all the information that the uncompressed 14-bit RAW contains.
03/05/2012 11:59:40 PM · #21
Re, the thread title; "How many megapixels do we really need? "

All of them.
03/06/2012 01:00:12 AM · #22
I dunno but I wish my 7D had something LESS then it has...... More is good as long as noise is under control and that is subjective.
03/06/2012 07:13:51 AM · #23
My new Sony NEX7 has 24 megapixels for the raw files but the more common 3-4 megapixels for the JPEGs. I am shooting in the "both" mode whereby it write one file of each for a combined 28 megapixels per image. Good thing I purchased a 32 GB Extreme Pro card to hold it all. Now I worry about my hard drive capacity.
03/06/2012 07:34:21 AM · #24
I like the fact that the new D800 gives you the choice to shoot 36 megapixels or 20 in Raw, if we need better low light performance we can always choose the lower setting, i'm getting the camera and will be shooting a lot of the time in the 20 mode.
03/06/2012 02:28:33 PM · #25
I forget where I read it, but I recall that 24mp will be the limit on "useable" mp's - meaning for the large majority of consumers, any detail gained by going larger than 24mp is lost via the limits of eyesight. As I age my eyesight is faltering, yet when I compare what I can see versus the majority of those I work with, I'm astounded at how bad other peoples eyes are - even with glasses. My "bad" eyesight is "x %" better than others "good" eyesight. So what are people supposed to "see" as pixels climb above 24?

It is my understanding that pixel definition is being manipulated - meaning that a sensor has a finite number of pixels that it can hold. To increase pixel count they are halved, in essence making a 6 mp into a 12 and a 12mp into a 24, etc. When comparing 12 larger pixels to 24 smaller pixels or even 48 tiny pixels, there are trade offs. The current Nikon D3x at 24mp is the standard in my view and pushes the limits of what the human eye can discern.

As a comparison, my Blackberry has a 3.x mp camera and takes simply stunning jpg photos. Go figure.

I think anyone possessing a 16-24mp camera will have a tool that exceeds detail that most can't see.

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