Feel free to read Thom's article (overall, most of you probably are familiar with his websites, and if you're not you ought), here I will simply give you a few highlights. Thom basically says that no, there's no such thing as too many megapixels.
Those of you who have D810’s probably know where I’m going here. Try outputting an 8mp image from your 36mp NEF file with good processing techniques. The accuracy and even punch of that 8mp image is clearly better than you achieved with 8mp cameras.
OK, fair enough - although we should add that to make the comparison a fair one, we'd need contemporary sensors of the same size; comparing a 2014 FX sensor with a 2006 (Canon!) DX one is bound to reveal some differences. But yeah, the thought process is basically correct.
The thing is, who could tell and under what conditions.
Let me offer this in a different, more practical and easy-to-grasp way: Take an image shot with a Nikon D810 and one with a D3300. Assume equal skills, conditions, glass, etc. Downsize the D810 image to 24 megapixels and compare. Yes, there is a difference, if not for any other reason because we're comparing an FX sensor with a DX one. Yes, there will be a difference in acuity, as Thom says. Who could spot it, and how close to the screen (viewing at 100%) do you have to be to see it? Thom might call that photography, but I don't.
So, yes, 8mp may “be enough.” But it’s not nearly optimal. You’re going to see images taken by the guy with the “more megapixel” camera and they’re going to look better than yours, even in smallish sizes, and thus you’re going to…eventually…give in to buying more pixels.
Come on Thom, you're better than that. This is provocative and I bet you know it. Do you actually claim that this is the reason some people's photos look better than others? I am a long-term reader of your websites and I do recall this article of yours.
I've heard Itzhak Perlman play both a common production violin and his Guarneri up close and personal. Yep, the Guarneri sounded better. But the production violin sounded better than any of you reading this could have produced with it. Indeed, it sounded better with Perlman playing than it did from the professional player who handed it to him could get out of it.
On the other hand, you can't get bass notes out of a violin, and you can't make it sound like a clarnet. Sometimes you do need a different instrument to make the sound. With cameras, for instance, a D3s is a different instrument when it comes to shooting indoors in low light than a D200 is. Clear and demonstrably so (see my just posted review).
But most of the people who come to me clammoring for higher resolution haven't yet gotten all the resolution out of their current instrument. They simply haven't practiced as much and refined their craft as much as Perlman did, thus, handing them the Guarneri or Stradivarious of cameras doesn't immediately make them better photographers.
In other words - your words! - long, long, long before a photographer needs to correct any issues related to lost acuity due to megapixels, s/he will need to address far more important issues, even if we speak in strictly technical terms (I haven't even started talking about art yet). By the way, I argue that the above applies not just to beginners, or even to your average photographer but even to an experienced or even pro photographer.
As I was reading your article, Thom, I felt increasingly more unsure about the validity of your thesis. But I must say, what inspired me to offer this friendly reply to you was your last few lines.
And if you want to take great photos you want optimal data in your capture. Which means more megapixels.
This is not art, Thom. This is a clinical, cold, scientific approach to a mathematical issue. Perhaps you ought to rephrase this as thus: "If you want to see better acuity when viewed at 100%, you need to quadruple your megapixels". Then yeah, a 36MP sensor will show the difference with an 8MP one (and a current 24MP that even entry-level cameras have would need a close to 100MP sensor).
First of all, on a clearly technical level, you seem to assume that the only thing affecting acuity is the sensor size. You obviously know this is not the case. Here are only a few other parameters: lens; technique; direction and quality of light; weather/atmospheric conditions; subject motion (if any). Here's a photographic example as well:
|Taken with a 6 (six) MP Nikon D40 and a 35mm f/1.8 lens|
The amount of acuity in this image is astounding (click to view larger; this is only a downsized, casually saved jpeg, by the way). It's taken with a 6 (six) megapixels D40 and the good but consumer 35mm f/1.8 lens (stopped down to f/5.6 if I recall). I've tried to reproduce this acuity countless times, with tools as supreme as a D800 and micro-Nikkors. It just doesn't work. It might be because of light, or (more probably) because of some shortcoming of mine.
But it's not the technical aspects that matter. It's the art. I don't know, Thom, what was it about your phrasing that made me feel so strongly about it, but I think it sends the wrong message to say something like "if you want to take great pictures... you need more megapixels". No, Thom. Great pictures don't come with more megapixels (well, in some special cases they might come - if you plan to create some mural containing scenes of Yellowstone, although even then there are far more important issues needed; see your example about Pearlman above). Great images come when you have something to say and, preferably, you know how to express it in some original way.
|Acuity? Who cares...|
The image above (that won me a prize at a local competition) was taken with a 12MP D700 and a consumer 80-200 zoom. Who cares about acuity, who cares about sharpness or contrast. It's "good enough", and it becomes secondary (as it should) considering what great pictures should be about: moment, feelings, expression, emotions, thoughts. About the only thing that would have made my life a bit easier would be an autofocus lens (yeah, did I mention I was using a manual-focus Tamron Adaptall?) and that's about it.
So, Thom, although I do respect your opinion, I will have to disagree with it very strongly. It - dare I say it? - saddened me to see you talk about megapixels that way. If you want to take great photos you don't need more megapixels. You need vision, feelings and thoughts, and a way to display things in a way, ideally, nobody has done before.