The Bigger Reason Why Megapixels Matter for Photo Enthusiasts

Bull Elk, Rocky Mountain National Park, CO. Nikon D800e at ISO 3200.
Bull Elk, Rocky Mountain National Park, CO.
Captured with a Nikon D800e DSLR at ISO 3200. 

A few years ago, just about every Nikon DSLR captured images at around 12 megapixel resolution. The main differences between camera models, then, involved features (speed, AF) and sensor size (FX vs. DX). The biggest advantage of the FX sensor cameras at that time was sheer low-light performance. For the most part, my colleagues and I agreed, the megapixel race seemed over, or at least, diminished as an important feature.

Over the last year, Nikon has been steadily upgrading their entire camera line to 24+ megapixels. Even the low-end Nikon D3200 has a 24MP sensor. In fact, there are only three cameras in Nikon’s current line-up that don’t offer at least 24MP: the D300s (12MP), D7000 (16MP) and D4 (16MP). This had me scratching my head a little, as I certainly know from experience that a 12-16MP camera easily delivers the goods in most situations.

Why those pixels matter

A camera’s megapixel count is a measure of its resolution. However, cameras differ in terms of image quality, and lenses can also impact the ability of a camera to resolve fine details. When most of us think about reasons for why we’d need (or at least, want) more megapixels, the answer is usually:

  1. I want to print really big
  2. I want to be able to crop in on my images without losing detail

Ironically, most photographers just aren’t printing that large these days. Most enthusiasts I know are printing 12×18′ (on Super-B paper) at the largest, if they’re even printing at all. So here we are in an age where we can get a 24MP entry-level camera and yet we aren’t using it to print big! The other point, cropping, is certainly valid. However I fail to see the point of using a 24MP camera just so that I can be sloppy with my technique. Besides, the overhead of 24-36MP pixel files is such that in most circumstances, I don’t want to shoot in such a way that I’m just throwing away half the pixels each time. My personal philosophy is that if I’ve got 36MP, I want them to cover the subject as much as possible!

So that brings us back to today’s situation. 24+ megapixel cameras for photographers who generally make small(ish) prints. And here’s where those extra pixels suddenly come into play. If we examine our images at 100% magnification, you can examine fine-grain detail and also noise. The conventional wisdom is that camera sensors with larger photosites (like the Nikon D3s or D4) will have better low-light performance than their high-megapixel cousins. And at 100%, this is pretty much true, as shown in this comparison.

The 36MP D800 image (left) has larger dimensions than a 16MP D4 image (right)
The 36MP D800 image (left) has larger dimensions than a 16MP D4 image (right)
At 100%, the D800 image shows more noise (grain) at ISO 3200 than the D4 image, also shot at ISO 3200. Images were processed in Lightroom 4 with no luminance NR applied.
At 100%, the D800 image shows more noise (grain) at ISO 3200 than the D4 image, also shot at ISO 3200.
Images were processed in Lightroom 4 with no luminance NR applied (click to see full-size image).

However, things get different when you print. At a typical 240ppi print resolution, a 12×18″ image has pixel dimensions of 4320 x 2880, or about 12.4MP. That means for a 12MP camera, you’d be printing at around 100%, but for cameras with more resolution, you’re actually shrinking the image to print it. The Nikon D800 has a native resolution of 7360 x 4912 pixels. To get a 12×18″ print, you’re shrinking the image by about 42%. The end result is that the final print won’t show as much noise or grain as you’d expect. In fact, you’d be surprised to see how good even high-ISO images can be when printed at “traditional” sizes.

When scaled to a 12x18" print at 240ppi, the D800 image (left) is as good or better in terms of noise than the D4 image (right). Click image to enlarge.
When scaled to a 12×18″ print at 240ppi, the D800 image (left) is as good or better in terms of noise than the D4 image (right). Click image to enlarge.

The take-home message is that unless you crop your images severely, a 24 or 36MP image can be just as good at high ISO as images from a camera with fewer but larger photosites. Tone and color transitions can look cleaner, too. The primary reason for a camera like the Nikon D4, then, is to deliver speed when throughput is critical. At 10fps continuous shooting, the Nikon D4 is still the undisputed action camera from Nikon. So if you’ve been hesitant to upgrade to a high megapixel camera because of ISO concerns, don’t worry. Just make sure that you have plenty of memory card space and a fast computer to process those images!

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13 thoughts on “The Bigger Reason Why Megapixels Matter for Photo Enthusiasts”

  1. Thanks for a great post, Jason. The other significant plus for me of the D800 has been the 1.5x crop mode. I add 50% of reach to my 70-200 – sometimes with my 1.7x teleconverter – and still have more pixels to work with than with my D700. With good shooting technique (on a tripod, using a cable release, etc.) it’s even a low-cost substitute for a 300 or 400mm lens.

  2. Hello Jason:
    Your blog about the ‘autofocus on’ button had me hooked!
    What a pleasant surprise for having stumbled upon such a wonderful photo blog I am a regular visitor of bythom, luminous-landscape, theonlinephotographer, thatnikonguy, thefrugalphotographer,etc but never could find your site while doing a google search. May be you should put more links to your site?

    Please keep up the good work and thanks a lot!

    Sreeram

  3. some great points…maybe you’d consider a more in-depth article on Resolution-Megapixels etc illustrated for practical purposes as well as you have done this one to i.e. practical aspects of why and why-not…today we are bombarded by the MegaPix race…I am an amateur, considering the Pentax K5II 16mp…but just saw Nikon come out with entry 3300 at 24mp…makes you think a lot about thos extra 8mp i.e…thanks for article..

  4. awesome, this sheds some light on what I’ve been looking for! When you say shrinking it down do you mean exporting to a smaller size of the same type, or as a .tif? Thanks for the help I have a D800 and am planning on doing a lot of huge prints that have to be at maximum quality.

  5. Thank goodness someone FINALLY answered this issue for me. However, I am not struggling over 24mp versus 36mp. My issue is with the Nikon d7000 at 16mp and the Nikon d5200 at 24mp.

    Would the same article apply then???

  6. The general rule will still apply, albeit with a slightly less pronounced result. Historically, Nikon DSLRs maxed out around 12MP for a really long time. Now, 24MP seems to be the entry-point. You can get excellent images and even large prints from a 12-16MP camera. I regularly crop my D4 (16MP) images and print them large.

    In the case of your comparison (D7000 vs. D5200), you need to look at the bigger picture (no pun intended). The sensors on both of those DSLRs are very good. Compare the other features as to how they meet your needs:

    Autofocus
    Frame rate/buffer
    Bracketing modes

    If all you’re doing is shooting family portraits, I’d go with the D5200. But if you’re trying to shoot more action, then the D7000 (or D7100) is the better choice because it has better components to compliment the sensor.

  7. I have been a canon man for most of my life. The last good one was an A-1 (35mm). Then went digital with a rebel eos, that was in 1995. I now have a canon SX160 IS 16 megapixel and my phone is an lg g3 with 13 megapixel and HDR. I like to get my shots enlarged and would like an opinion on the Nikon D3300 set up, it has the 24.3 cmos. I mountain bike, kayak and hike in Arizona and have a lot of photo opportunities. Is it worth investing in a new DSLR or should I be satisfied using Adobe CS-6 photoshop to enlarge my shots?

  8. Not all megapixels are equal. You also have to consider sensor size. Lots of pixels on a camera phone sensor are still going to be noisy. The advantage of any DSLR is a larger sensor and interchangeable lenses. The disadvantage is usually size. I really can’t comment on any of the cameras you mention because I haven’t used them, but I do know that just about every DSLR from Nikon and Canon will deliver excellent results these days if you know what you’re doing. Megapixels are simply part of the overall equation; you can’t use that one metric in a vacuum.

  9. I use Nikon D300 and D3 both at 12 MP and my photos are used by a professional Football team for their match day programmes and Website and they request the file sizes be reduced to no bigger than 1.5mb
    There is no need for anything bigger than 12MP for most images that are shot by everyday photographers.
    But if I did landscape or Macro photography I would be desperate to buy a 36mp D810 !

  10. This may all be true, but all the same I own Canon cameras returning images of 8Mp (1-D ii N), 16Mp (1-Ds II), 18Mp (1-Dx) and 50Mp (5DsR) and up to A3+ the 8Mp images print at least as nicely as those with more pixels. The images from the 16 and 18 Mp images match the 50Mp images at A2. I am pretty sure that they would print much larger, especially with interpolation. I shoot mainly at 100 ASA so noise it not an issue, even with the cameras from the mid-2000’s. The only real advantage to me of the 5DsR is that it is lighter than the 1-series.

  11. Hey! I do portrait photography and second shoot weddings. Right now, I have an old 12mp Nikon camera, which with my 50mm lens, still gets the job done. However, I am wanting to upgrade to a full frame camera – trying to decide between the D610 and the D800. I was set on the D800 because of the higher mp, but now I’ve been seeing a lot about how images with that high of mp can actually slow things down. Thoughts?

  12. At this time, I’d highly recommend a refurbished D810 if you can find one. It’s plenty fast enough for portraits and weddings. The D800 is much slower and has significantly slower AF performance compared to the D810.

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