Extra Megapixels Useless?

[EchoingWhisper]

According to DxOMark, the best lenses for DSLRs have a resolution of 66-67 lp/mm - which equals to about a maximum circle of confusion of about 15 µm. Using the Diffraction Limit Calculator of http://www.cambridgeincolour.com. The maximum pixels a full frame sensor should have is 24 megapixels and crop sensor should have about 10 megapixels, why do lots of crop sensors have 16-18 megapixels?

 

[mangtarn]

cameras with higher megapixels produce images that produce better results when cropped.

also marketing. 'bigger is better'

 

[shootermcgavin]

I'm interested in this too, I was told by one camera guy at the store that over 10 is basically useless also and that an old 10mp full frame camera would be a great way to save money.

 

[EchoingWhisper]

cameras with higher megapixels produce images that produce better results when cropped.

also marketing. 'bigger is better'

IMO, no. Once passed the lens diffraction/circle of confusion limit, extra megapixels looks the same as the one without the extra megapixels bicubic enlarged.

 

[12sndsgood]

if a camera has 10 megapixel a new one with 12 has to be better no matter what. look at any store camera ad. about the only thing they tell you is the name of the camera and how many megapixels it is. people come up to you and ask you how many megapixels your camera has.

 

[Big Mike]

why do lots of crop sensors have 16-18 megapixels?

Because numbers sell cameras. As mentioned, when you see a typical electronics store advertisement...they tell you the name of the camera and how many megapixels it has. Thus we had the 'megapixel race', where camera makers pushed to new limits with every new model.

Photographers who have a good understanding of the issue, were grumbling that they didn't want more megapixels, they wanted lower noise at higher ISO, they wanted better dynamic range etc. I once heard a rumor that engineers at Canon even admitted that they could have produced cameras with better image quality, but the marketing dept. forced the issue of higher MP, so that's what they made.

The race has slowed down in recent months/years...and it may be coming to an end. Canon's new flagship camera, the 1Dx (due out next year) has a lower MP count than it's previous flagship camera, the 1Ds mkIII.

Another issue, as mentioned, is the resolving power of the lenses.

he best lenses for DSLRs have a resolution of 66-67 lp/mm

OK...but what about lesser quality lenses? They will just compound the problem.

That why, when people are considering buying a high MP APS-C camera, like Canon's 60D or 7D etc., they should also consider that they will need very high quality lenses to take advantage of their camera's sensor. This is also the reason why the camera companies are re-enginneering their lenses. Canon's 70-200mm F2.8 IS is a good example. They recently released a new 'II' version, which is supposed to have better resolving power than the older version. It's also $800 more than the older version.

 

[c.cloudwalker]

I'm interested in this too, I was told by one camera guy at the store that over 10 is basically useless also and that an old 10mp full frame camera would be a great way to save money.

That, or something close to it, is also what I was told. A while back. Has newer technology made this different? Maybe. But tbh I'm not enough of a geek to be able to answer that.

All I know, is that my Hasselblad which has a sensor 3 times as big as a FF camera (or is it 4 times?) does not have 3 times as much mpixels as the newest FFs. So it sure doesn't have 4 times as much. Let's leave the snob factor aside here and look at this rationally. If Hasselblad (or any other medium format maker) could do so much better than they can today by just adding to the mp number, why don't they?

Maybe because they are dealing mostly with people who actually pay close attention to the IQ and will not pay more $ for no more IQ.

As I was reminded not too long ago when asking about digital backs for 4x5s and 8x10s, there are physical limitations to the sensors available today. There are none in the formats I was asking about. Does that mean someone could not claim to make one? Yes, sure, except people willing to carry around a view camera are few and far between today and they are probably more discerning and better informed than the average DSLR buyer.

Let's not forget that the average DSLR buyer is probably first and foremost buying a name. Just look at the number of threads about Nikon vs. Canon as if those were the only cameras out there...

Second, they are buying mpixels and the brands are giving them what they want whether or not it makes any difference :er:

 

[KmH]

There is a reason Nikon offers 2 versions of the D3 - the D3s and the D3x. The D3s is designed (optimized) for shooting action sports, and the D3x is designed (optimized) for studio work.

The $5200 D3s has 12.1 MP, can shoot 9 fps, and has a max base ISO of 12,800. The $8000 D3x has 24.5 MP, can shoot 5 fps, and has a max base ISO of 1600.

DxOMark - Compare cameras side by side

 

[unpopular]

While the math might be sound here, actual evidence does differ.

Canon EOS 1000D / Rebel XS Review: 33. Compared to (Resolution): Digital Photography Review
Canon EOS 550D / Rebel T2i Review: 18. Resolution: Digital Photography Review

While the two images were processed differently, I don't think this can account for a 1000 line/inch difference. I suspect that what you're looking at is that while the absolute resolution limit might be a 10um circle, the extinction point - where no measurable detail can be recovered, is much higher resolution. So while a lens won't perform as nearly well as the sensor, detail still can be recovered from a higher resolution sensor than compared to a lower resolution sensor.

I also have other suspicions concerning enlargement and print resolution as well, though I need to research these ideas bore I can comment.

 

[unpopular]

According to wikipedia:

Unfortunately, the count of pixels isn't a real measure of the resolution of digital camera images, because color image sensors are typically set up to alternate color filter types over the light sensitive individual pixel sensors. Digital images ultimately require a red, green, and blue value for each pixel to be displayed or printed, but one individual pixel in the image sensor will only supply one of those three pieces of information. The image has to be interpolated or demosaiced to produce all three colors for each output pixel.

Image resolution - Wikipedia, the free encyclopedia

So, the number of pixels contained in the interpolated output of the RAW processor is not the same as the number of effective pixels of the sensor. My processor permits what it called "Half" which takes the RGBG data from the raw file and superimposes the data, similar to color co-sampling, resulting in a file about half as large as the two other interpolation modes, "VCMDF" and "AHDMF". Uninterpolated "Half" mode does seem to produce sharper results, however, with a 14mp camera, I can only get a 7mp image using this mode. One reason I would like to get a 24mp camera is to utilize this mode.

It seems to me that digital cameras are doing all sorts of things to my images on my behalf that I would not normally approve of. Unfortunately, most processors do this completely behind out backs.

If the listed resolution is the effective pixels without interpolation, rather than the number of sensing sites on the chip then these kinds of calculations would be valid. However if the listed resolution is the total number of physical sensing sites on the chip, each pixel would be considerably larger, this because each effective pixel actually consists of four physical sensing sites occupying space. I suspect that this is the case, otherwise my camera would be listed as a 7mp camera and not a 14mp camera, according to tests using RPP's "Half" mode.

This is a result of the problem with "pixel" meaning different things depending on where you're looking.

If the "Half" mode of Raw Photo Processor is truly doing what it claims, and the image is totally interpolated, a 24mp APS-C sensor would only slightly surpass the theoretical limits of the glass we put on it, as it produces a 12mp file.

http://en.wikipedia.org/wiki/Bayer_mask
http://www.raw-photo-processor.com/RPP/Overview.html

 

[imagemaker46]

To be honest, I don't really care how many MP a camera has, I have produced great images from 4mp cameras and I have produced great images from 8mp cameras, so does any of this mean that I could produce better images with a 20mp camera, nope, not at all............it's still the brain behind the camera.

People are being suckered into upgrading all the time, better cell phones, I can still make a call and text on my 3 year old phone, yep, do I need one that tells me what the weather is like on the other side of the world as well, nope.

I'll leave all that to the population of geeks that are more interested in talking about what they have, instead of knowing how to use it.

 

[Derrel]

The extra megapixels are really handy on the freeway, when you need to pass another shooter quickly, safely, and efficiently. There's often some dufus in the left hand lane, plodding along at 8.2 megapixels, driving his beat up, piece of chit Rebel or 20D,and holding everybody behind him back. Now, if you have a 12,14,16, or 17 megapixel camera, you can just mash down on the shutter release button and watch as the CF card starts to fill up, and you blow by that plodding eight mega-pixeler, as he pretends not to see the dirty look you shoot him as you pull even, and then leave him in your buffer...these newer, higher megapixel cameras also tend to shoot faster (Canon guys tend to shoot fast), while the newer Nikon ones have buffers that tend to last longer in sequential mode (Nikon guys want to be in the game looooonger, not faster!).

Or, if there are, like, some hot women hanging around the watercooler area, and you're taking your spiffy new Canon 7D out to the front of the building to do some happy snaps on your lunch break, when the cute woman who works in payroll asks you, "So, how many megapixels are you packing?" you can proudly tell her, "Eighteen...yep, eighteen rock-hard,toned, Canon megapickles, all right 'cheer..." confident that she doesn't know that you're rounding UP...but then she catches you and giggles at you and says, "Don't you mean 17.8 mega-PIXELS?", and then, caught in a lie, you slink away and just head outside and see if the Pentax guys will have some sympathy for you getting shot down while lying to a woman about your Canon...

 

[unpopular]

Oh boy! The old "megapixels don't matter" line. I suppose if you don't mind printing everything at 4x6 that would be true.

 

[imagemaker46]

Geez, I don't know, I've seen some of my 4mp images cover the full side of a truck and look pretty good. I've seen 100asa prints look like ****, and I've seen 1600asa prints look great, starts with with a great image, correct exposure, you know the things that come with understandng how to shoot well, and not just talk.

I won't get into a bigger is better chat, I know the difference, I understand the difference. All I know is that I have produced wall size images from a 1D years ago that looked great.

 

[djacobox372]

Geez, I don't know, I've seen some of my 4mp images cover the full side of a truck and look pretty good. I've seen 100asa prints look like ****, and I've seen 1600asa prints look great, starts with with a great image, correct exposure, you know the things that come with understandng how to shoot well, and not just talk.

I won't get into a bigger is better chat, I know the difference, I understand the difference. All I know is that I have produced wall size images from a 1D years ago that looked great.

I agree if your into prints for advertising on the side of trucks mp isnt that big of deal. Super high mp only really helps if u crop heavily or print to a very high resolution, like for large gallery prints.