The Reality of the "Crop Factor"

First let me say that there is no advantage in having a "Crop Factor". It is one of those phrases that is thrown around as if you magically get more reach. In reality it is a smaller sensor that wastes or throws away the outside edges of a Full Frame sensor. It just crops your full frame picture down to a smaller size.

However, there is an advantage in having a sensor with a denser pixel count. While I wouldn't have agreed with this back in the 7D days, I would have to say now there is an advantage of having the 7D II body and its increased resolution.

On Jan 1st I was bored and I had a test I wanted to perform to confirm some of the things I was seeing with the 7D II. I set up a test with the 500mm, shooting in manual live view focus mode, shooting at F/4 I took a make shift ISO 12233 chart I had printed off line. I started at 15 feet and took a base shot with the 5D II. Then at 18" intervals I took shots to give comparisons at x1.1, x1.2...etc. I did this with the 1D IV and the 7D II. Then I cropped the center of the pic and resized all samples to the exact same size. My thought process is that this is what we would have done with a real life pic. We would have cropped to get the exact picture we wanted. The end picture would have been either printed or displayed in the exact same size.

What I found is that the 7D II x1.2 was just a hair better than the 5D II x1.0. At the 7D II x 1.3 the 5D II x1.0 clearly beats the 7D II x1.3x. So what I find is that the x1.2 + just a little bit is probably the benefit we see in a crop body where resolution counts.

With the 1D IV the 5D II the 5D x1.0 is much better than the 1D IV x1.1. There is minimal if no additional resolution value using the 1D IV.

The 7D II held an x1.2 advantage both over the 1D IV and 5D II.

Here is an example in real life. The Blue Jay is the same area and about the same distance as the Female Cardinal. The Blue Jay is with the 1D IV and the Cardinal with the 7D II. Shot at 500mm same time of day. Close to the same settings. You can pick the shots apart and say maybe this or that was done wrong, but I am seeing similar shots over and over again.

Notice the Blue Jays eyes compared to the Cardinals. The Cardinals have just a bit better resolution.

https://farm8.staticflickr.com/7512/...56ee8a45_c.jpgBB1H5832 by hdnitehawk01, on Flickr


https://farm8.staticflickr.com/7521/...ac7d005c_c.jpgCQ2A2128 by hdnitehawk01, on Flickr


Now the negative of using the 7D II.

The 7D II is not as precise as the 1D IV. The 1D IV seldom misses. Usually if it misses it is because of me putting it in a bad condition.
The 7D II is random. It will have the bird in focus within the DOF but it will miss the critical point that puts the eye in sharp focus. The 7D II takes a +4 to +6 with the new 500mm. I am thinking about shipping it to Canon to check the AF system. I cannot trust it for a critical shot.

The 7D II is slower than the 1D IV. It also seems like it hunts for focus more.

I haven't given up on the 7D II yet. I have seen the benefit of its increased resolution on small critters and birds in focal length limited conditions. But its AF system has to perform better.

Hi Rick...

I very much appreciate the analysis...and phenomenal pics.

I just want to make sure I understand your methodology. You started at 15 ft, and moved back in 3 ft increments. So is:

• x1.0 = 15 ft
• x1.1 = 18 ft
• x1.2 = 21 ft
• x1.3 = 24 ft?

If this is the case, and the 7D II was barely better than the 5DII at x1.2 vs x1.0, then that would be 21'/15' = 1.4x (+)

So, if that is correct, the 7D II's advantage is roughly equivalent to an optically perfect 1.4x TC without the 1 stop loss of light (but DoF differences)

If that interpretation is correct, not bad at all.

Quote:

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Originally Posted by Kayaker72

Hi Rick...

I very much appreciate the analysis...and phenomenal pics.

I just want to make sure I understand your methodology. You started at 15 ft, and moved back in 3 ft increments. So is:

• x1.0 = 15 ft
• x1.1 = 18 ft
• x1.2 = 21 ft
• x1.3 = 24 ft?

If this is the case, and the 7D II was barely better than the 5DII at x1.2 vs x1.0, then that would be 21'/15' = 1.4x (+)

So, if that is correct, the 7D II's advantage is roughly equivalent to an optically perfect 1.4x TC without the 1 stop loss of light (but DoF differences)

If that interpretation is correct, not bad at all.

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Woops my bad. 18" is correct not 3' however since I did this on New Years morning and there is a possibility of New Years Eve coming in to play let me go home and make sure the markings on the floor were not 3' instead of 18".

Still if I did make the mistake it makes the benefit appear even greater.

Brant, it was indeed 18", the 3' was my mistake typing today. I corrected the OP.

I reset the test up tonight and this time took a little more care than I did the first time. I had almost identical results. This time the 5D II crop was just a shade better than the 7D II x1.2 crop. From what I see x1.2 is the number.

There is about a 20% resolution benefit over the 5D II. I wonder how much this benefit would disappear with the 5D III's additional 5% pixel density.

Rick...thanks for the clarification and additional testing.

There is a lot to that conclusion. On one hand, if you want all the reach you can get, 1.2x is something. On the other, it is pretty impressive how far away from the "ideal" 1.6x it really is. And this is just "resolution" and not considering tone, color, noise, etc.

Again, thanks for the comparison.

Doesn't it really boil down to pixel pitch and how many pixels you can get on your subject?

The 7DII has a lot of pixels on a smaller sensor (20.2 megapixels on a 22.4 X 15 mm sensor ) so each pixel is very small compared to say the 1DX (18.1 megapixels on 36 X 24mm sensor)

When you take an image like the birds you took, the 7DII will have a lot more pixels on the bird itself than a full frame camera would.

With more pixels on the subject the IQ holds up much better when cropping...thus the "illusion" of more reach.

Is this thinking correct?

7DII : sensor is 22.4 x 15 = 336 square mm's
20.2 million/336 = 60,119 pixels/sq mm

1DX : sensor is 24 x 36 = 864 square mm's
18.1 million/864 = 20,949 pixels/sq mm

Hi Joel.

That is the argument for the "crop reach" benefit, but it essentially assumes ideal scale up between crop and FF sensors. If ideal conditions existed, two 18 MP sensors with the same framing and same lens would give the same resolution. But they do not.

What ideal scale up neglects is the quality of the pixel on target, different sensitivity to imperfections in the lens (crop uses lens center more), and I am sure other factors.

I think a few people were entertained by this, but AlanF did an analysis of different online crop vs FF resolution test results. What he came up with was that the true benefit of crop vs FF in terms of resolving power was ~1.16x-~1.19x (numbers are fun... :o). Very similar to what Rick just observed in his side by side tests, granted they are testing using different methodologies. Actually, Rick's test very much interested me as he was not holding framing to be consistent, yet made similar conclusions.

Joel:

I agree with Brant - not all pixels are created equal. I had read AlanF's bit on CR a while back and it seemed to agree with what I had found with the 1DX vs 7D. That is, although I was loosing reach (so to speak), I could heavily crop the 1DX and still come out with a better image. The 7D was not very friendly to cropping at all. Not to mention, I could raise the 1DX ISO up past the 7D's capability and still crop to get a better image. I would say the 7D-II has better pixels than the original 7D, so it is getting to be a tighter comparison. However, I would not discount that you are effectively magnifying the noise artifacts, and a better set of pixels with less noise is going to hold up to cropping better. If you want that sharp glassy look in the eye of the bird, it is much more difficult to achieve if it is speckled with noise. Good noise reduction procedures like you use are helpful, but they would be even more effective if you start with cleaner set of pixel data.

The rub is, the FF has to loose a lot of pixels to get to the same framing, but with the 1DX vs. 7D, I still found the 1DX's better file to create something more pleasing. I still have the 7D and pick it up occasionally to give my 400mm more "reach", but it does not take long to put it back down and put the lens on the 1DX.

I also noticed you go back and forth with your 1DX and 1D IV. Unfortunately for the IV, on a cloudy day with limited light, for the extra "reach" of 1.3X you need to increase the ISO(compared to the 1DX) to get a higher shutter speed to counter the shake issues with the higher effective Focal length. Now you have more noise compared to the 1DX which can shoot at a lower ISO because the effecting focal length has less shake issues. So now I have a cleaner file that I crop and compare to a noisier file - I would be curious to see which one produces a better picture... I would thing the 1DX, but it may be close.

Pat

I certainly agree all pixels and all sensors are not equal and neither are the down stream electronics so ...... when you bring in all these other factors there is a lot to consider BUT solely for the purpose of resolution (all else being equal) I would think more pixels on the subject would be superior. With so many other variables entering into the comparison it is almost impossible to control for all of them and making comparisons is dicey. Also, most of the images that we are using to compare are very small files for web presentation. The differences may be much more apparent when you go to make a very large print.

With good light and a good photographer the 7DII, 5DIII, 1D4 and the 1DX all seem to make beautiful images to me .... no matter the numbers:)

Pat, I agree with you on the 7D. I did the same type of comparisons with the same results against the 1D IV. The 1D IV could crop more and had a more pleasing image.

From what I am seeing now the 7D II has just as good of an image in respect to color and pixels when compared to the 1D IV. There has been improvement.

Of course you can not crop it as much as a FF body, but your crop is limited by resolution. Looking back at Joel's numbers the 7D II sensor is 336mm. Maybe my math and formula isn't right but the jest of it will be, if the 7D II has 20% resolution wouldn't an equal resolution FF image be 336 sq mm x1.2= 403.2 sq mm. With the FF having 854 sq mm you would be cropping 450 sq mm away.

Joel, the illusion of more reach is that your picture is already cropped by the camera. But you and I both know that if you are shooting wild birds we are cropping for framing whether it be full frame or a 7D II. Then the question is how much can we crop. The Blue Jay image is typical, I was at a distance that it was hard to get good eye detail with the 1D IV. What I look for in eye detail are the little lines around the eye ball. The 7D II could still resolve it. So for extra reach if my maximum is 20' before distance takes away resolution I can still go out another 4' and get the detail at 24'.

This resolution benefit is only realized if you are cropping, and only if you are cropping the FF close to or less than the Crop Body's sensor size.. What I see is the resolution fall off from going to a properly framed FF pictures is greater than the gain of crops resolution.

So shooting small subjects like wild birds that you almost always have to crop it could be beneficial.
It is only beneficial if you have good lighting, dawn and dusk FF bodies are going to rule.
For me the 7D II would be a good accessory to go with the 500mm to give me a x1.2 advantage when shooting small birds during mid day.
The AF system performance of the 7D II has to improve or all of this is null and void.

Ok, so now I am completely lost. So Canon is coming out w/ a high(er) megapixel camera. I had read somewhere that the current lens inventory can generally run up to 50ish megapixel before running out of resolving power to the photosite.

Does this have bearing or did you guys just explode my grey matter for kicks and giggles. :)

Of course it has bearing. A FF 50 mp camera will have about the same resolving power as the 7D II.

The 7D II advantage isn't the crop it's the pixel density.

If we are getting a 20% gain with the 7D II, you would get the same with a FF. The difference is you get it across the FF pic and the FF benefit. I bet the high ISO performance will be lacking though.

As far as resolving ability, my makeshift tests were using arguably Canons sharpest lens, the 500mm II.
I wonder if 50mp will be well above any lenses ability.

50 MP will require the very best of lenses. It'll be worth it for the super user who has the best of the best lenses, but not so much for the typical user IMHO.

Dave

Quote:

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Originally Posted by HDNitehawk

First let me say that there is no advantage in having a "Crop Factor".

---

I must respectfully disagree. The crop factor has significant advantage for many people – lower cost (or in the specific case of the most expensive crop 7DII vs the cheapest FF 6D, far more features and better performance of everything except the image sensor).

Quote:

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Originally Posted by neuroanatomist

I must respectfully disagree. The crop factor has significant advantage for many people – lower cost (or in the specific case of the most expensive crop 7DII vs the cheapest FF 6D, far more features and better performance of everything except the image sensor).

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I will agree with the lower cost with some bodies as an advantage, of course the value of the 7D II compared to the 1Dx makes it look very attractive. Really I wasn't comparing dollar value. If I were I would say the 7D II is the best value in a camera that I have seen from Canon since I went digital.

I will agree that the 7D II has far more features than the 6D, so far I wouldn't say it's "performance of everything except..." has been better than my 5D II. The 7D II has AF issues that in the two months since I recieved it I have been unable to resolve. It may go to Canon shortly for a check up. Some of the things I see it doing I am seeing others making the same complaints on other forums.

Quote:

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Originally Posted by Dave Throgmartin

50 MP will require the very best of lenses. It'll be worth it for the super user who has the best of the best lenses, but not so much for the typical user IMHO.

Dave

---

Whatever a typical user is you are probably right.
The same is true of taking advantage of any resolution advantage the 7D II has. Camera shake, bad lenses, poor lighting and other things take the advantage away.

Quote:

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Originally Posted by Dave Throgmartin

50 MP will require the very best of lenses. It'll be worth it for the super user who has the best of the best lenses, but not so much for the typical user IMHO.

Dave

---

True...to get absolute optimum performance or for those cropping heavily. I am not one of those that wants a high MP sensor camera. Mostly, I am would not look forward to the file size and would absolutely be reaching the point of diminishing returns, IMO. But even for most photographers, compressing a 50+ MP image to useable ranges (web pages, 8x10, 16x20 prints, etc) would have benefits such as helping reduce noise, give better resolution, etc. Also, there are a number of affordable lenses that are among the best performers Canon offers especially when stopped down a bit.

I think the popularity of this camera, if it becomes true, will be a function of perceived need, cost, and image file size (of course, assuming features/performance are there). On the perceived need, I ran a poll about a year ago; 17 of 22 of those voted those the ideal number of MPs was in the 20-30 MP range.

Of course, that could all change if Canon blows us out of the water with IQ at a reasonable price.

Quote:

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Originally Posted by Kayaker72

On the perceived need, I ran a poll about a year ago; 17 of 22 of those voted those the ideal number of MPs was in the 20-30 MP range.

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One of the rumors floating around is that the 50mp sensor will be the same as the 7D II, just larger. I think the key word for your poll was perceived. If the rumor is correct the resolution we are seeing with the 7D II might be close to what we can expect for a FF. A new question would be do I need that additional resolution benefit for the type of shooting I do. As well would I be able to take advantage of the increased resolution with the technique I use to shoot.

I personally can see a benefit for maximum resolution with wildlife, landscape, macro and architectural photography. Beyond that the current full frame offerings have enough resolution for any other types of photography I do.

Rick...your post got me thinking about what the actual benefit would be. First off, IMO, IQ in general will increase with more MP. I think specific types of photographers and photography, as you mention, will benefit more from the extra resolution. If pixels were ideal, it would be a linear relationship. But they are not ideal.

If pixels were ideal, then a crop sensor would truly given 1.6x resolution bump. You came up with 1.2x. 1.2/1.6 = 0.75. If the rumored 51.1 MP sensor camera is truly based on the 7DII sensor, then the 51.1 MP sensor would be somewhat equivalent to 38.3 MP if we applied the 0.75 ratio compared to your 1.0x (5DII). So, a benefit, no doubt.

But, as I mentioned above, the reasons crop resolution isn't ideal are both sensor related and lens related. As the lens related issues would no longer be a factor, 0.75 would likely be the low end.

That made me wonder how much of the divergence from ideal is lens and how much is sensor. Which got me playing with numbers. When people report the "pixel size" the calcs I have seen are simply taking the sensor area and dividing it by the number of pixels. So, for the 5DIII, FF sensor area is 36 mm x 24 mm = 864 mm2 / 23 MP = 6.1.

But, that is another "idealized" calc. It assumes that there is no edge to the pixel. Or, using the pixel=bucket analogy, no edge to the bucket. And a bucket without edges doesn't hold water.

I suspect one of the reasons that higher pixel densities are not as efficient as lessor densities is that with higher densities more of the sensor area is lost to the "bucket edge." This may be around the actual pixel on the sensor or maybe the Bayer filter.

So, the reason for my post, I am wondering if others know, is that correct?

Newer cameras all have sensor micro-lenses. In the bucket analogy, these are funnels sitting over the buckets that help gather the light that would have hit the edge of the bucket. I doubt they're 100% efficient, but they are an effort to minimize bucket-edge issues, which include lost light and disappearing fine details.

Quote:

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Originally Posted by DavidEccleston

I doubt they're 100% efficient,

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Yep...I forgot about the micro-lenses as I was writing my caffeine infused post....but, still, even though they are referred to as "gapless"....even the micro-lenses may have some sort of structure (i.e. not "gapless"), and you have to wonder about the % efficiency, as you mention.

But, the point being, how does something like this scale with pixel size? The bucket analogy makes it easy for me to see how the bucket edge would scale unfavorably with decreasing pixel size---that higher pixel density sensors (i.e. crop sensors) have a higher bucket edge/deadspace to active pixel ratio compared to lower pixel density sensors.

This could be off, and the micro-lenses could really be "gapless" as the 7DII has a higher QE than the other FF sensors. But that may be measuring something slightly different. Anyway, I may spend some time looking into this when I have more free time.

Thanks......

Attachment 2360

Attachment 2361

So, in addition to enjoying photography, I also enjoy the science behind photography.

I didn't find what I considered to be a "smoking gun" reference for the ratio of "bucket edge"/photosite being one of the reasons smaller pixels are not observed to have the same efficiency as larger (or higher pixel density sensors vs lower pixel density sensors).

Most references regarding pixel density talked about what you would expect:

• Diffraction
• Noise or, signal to noise ratios
• Specifically, various noise due to the electronics tends to limit IQ from smaller pixels
• Inherent issues with dynamic range

Then, I found some talk about the "adsorption length" of the different wavelengths of light. The IQ with smaller pixels from red wavelengths may be limited before blue. Most of this is summarized in the "clarkvision" link below.

I did find a reference that the actual photosite is only about half of the sensor area with the other half being the structure and electronics. There is also a lot of talk about inefficiencies with the microlenses, especially as you move away from the center of the sensor. Basically light hitting the above pictures straight on would be focused straight below. But light hitting it at an angle would be less so. Sony, for the Ar7, was offsetting the location of the microlenses as they moved away from the center of the sensor to try to account for this effect. But efficiency with microlenses is an issue.

Two good references:

http://www.clarkvision.com/articles/...ter/index.html
http://www.cambridgeincolour.com/tut...ensor-size.htm


By the way, Roger Clark ran a model (first link) assuming a Quantum Efficiency of 45% and estimated that the optimum IQ on a FF sensor would be 33 MP. Interesting, as the 7DII's QE is rated at 59%, so perhaps the "optimum IQ" would now be obtained with more MPs.

BTW, if anyone knows of a good link on this topic, I'd be interested. Granted, I am still making my way through Roger Clark's work.

Brant, some quick cave man calculations. I know the configuration isn't exactly as the premise but it gives an idea.
I am going to use Joel's numbers to build on rather than research this myself.

The 7D II with 336 sq mm and 60119 pixels per sq mm.
Square root of 60119 gives us 245.19 lines per mm.
Multiply that by 2 gives the linear distance between pixels over the sq mm, 490.38 mm.

The 1D x with 864 sq mm and 20949 pixels per sq mm.
Square roof of 20949 gives us 144.73 lines per mm.
Multiply that by 2 gives the linear distance between pixels over the sq mm, 289.47 mm.

490.38 / 289.47 = 1.69 more linear separation of pixels with the 7D II.

Maybe it plays a part?

Rick...that is exactly the point I have been getting at. There is more side wall with higher pixel densities. Thanks for running the numbers...there is 1.69 more mm side wall per mm for the higher density sensor (7DII) vs the FF (1Dx). I ran the numbers slightly different (5472 rows 15 mm long + 3648 rows 22.4 mm long for the 7DII) and got the exact same ratio.

Now the next part is how thick are the side walls (picture below makes them look about as wide as the pixel itself) and we could calculate the % of sensor area is photosite vs sidewall (electronics, etc). But my suspicion is that the sidewall thickness is similar (to house the electronics). If true, then is 1.69x more photosite area per mm2 for the 1Dx compared to the 7DII. So, larger sensor and a larger % of the area dedicated to photosites.

After that, the question gets to be the microlenses, are they truly gapless, how well do they work, and is there a difference in efficiency depending upon the size of the pixel/microlens? At the end, if the microlenses do their job perfectly, it offsets my original point. But, another suspicion, my guess is that the larger microlenses are better than smaller microlenses.

EDIT...by the way, some interesting photos I found in my searches:

Cross section of a sensor taken by Chipworks. You can see the electrical conduits in the posts between the pixels.

Attachment 2362


And "gapless" microlenses

Attachment 2364

I have a feeling any effect the thickness in the gap has is minimal. It would affect the accuracy of the single pixel in that it would gather a greater sample and generate a more refined reading. For instance if the edge of a line split a pixel down the middle it might have no effect at all. However if the edge of a line split close to an edge it might make the results a bit less accurate. The highest resolution you could possibly achieve would be a pixel width wide.

Another concept I have been mulling over, how many pixels are required to accurately read a line pair in any situation. In ideal situations it might be 1 pixel for the line, one for the area between the lines...etc. But that would require the line to be in the same plane as the pixel line. Turn the camera 10 degrees off horizontal from the line pair and the dynamic changes. Split the line horizontally and it changes. A lens can resolve an item at any point between vertical and horizontal, a sensor would be at optimum at horizontal or vertical.

I started thinking about this some time ago after following a few threads about lpmm vs pixel rows per mm. I alone wonder for a sensor to ever fully take advantage of a lenses resolution you would might need 4 or 5 times the number of pixel lines per mm above the lenses lpmm.

Just thoughts here, no facts. Any one have thoughts, or info on this?

Quote:

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Originally Posted by HDNitehawk

Another concept I have been mulling over, how many pixels are required to accurately read a line pair in any situation. In ideal situations it might be 1 pixel for the line, one for the area between the lines...etc. But that would require the line to be in the same plane as the pixel line. Turn the camera 10 degrees off horizontal from the line pair and the dynamic changes. Split the line horizontally and it changes. A lens can resolve an item at any point between vertical and horizontal, a sensor would be at optimum at horizontal or vertical.

I started thinking about this some time ago after following a few threads about lpmm vs pixel rows per mm. I alone wonder for a sensor to ever fully take advantage of a lenses resolution you would might need 4 or 5 times the number of pixel lines per mm above the lenses lpmm.

Just thoughts here, no facts. Any one have thoughts, or info on this?

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Would love to see links to the threads, if you still have them. I've wondered something similar. More of maximum theoretical resolution, at what point do certain fine patterns cause aliasing, etc.

My one potential contribution would be that the Bayer filter and the color of whatever you are trying to resolve would likely come into play. Granted, you could get the light intensity from each cell and maybe use that to delineate down to the pixel level. But there are out of the 4 pixel array, 2 are green, 1 blue and 1 red. Quick guess, but you may need to be working in blocks of 4 pixels at a minimum instead of 1 pixel, for theoretical optimum.

Yeah, you'll need a bit more sensor resolution to resolve actual detail correctly. Completely ignoring the RGGB four pixel block (assume we have a grey only sensor), imagine two parallel lines, one sensor pixel apart.

x.x
vvv <- These are the sensor pixel wells.
BWB <- Reads Black, white, Black
We have three pixels being shown here, from two parallel lines. They magically align perfectly with our sensor's pixels. Black, White, Black

Now, lets blow that up to 200%
XX..XX
XX..XX
\/\/\/
B W B <- Still reads Black, white, Black
Great, we're still getting our lines nice and solid in the sensor wells, but we can see more detail. Next, lets make it more realistic. The lines don't perfectly match the sensor wells. In fact, let's just move them sideways by half a pixel width.

.XX..XX.
.XX..XX.
\/\/\/\/
G G G G <- Now reads grey, grey, grey, [grey].

Oh, no! Our Black and White line pattern has become solid grey! Each line is now halfway into the pixel, and halfway into the adjacent, previously empty, pixel.

This is obviously simplified... No RGGB 4 pixel array, movement in one axis only, but it shows that our perfect high-contrast line pairs can become a grey smudge pretty easily.

edit: Changed spaced between pixels to dots so TDP doesn't remove "extra" spacing, or white space at the front of the lines.

Quote:

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Originally Posted by HDNitehawk

Another concept I have been mulling over, how many pixels are required to accurately read a line pair in any situation.

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I am off looking for some a source talking about the lack of benefit of actual light hitting a digital sensor at wider than f/2 (don't know why, I really do have better things to do). But, I stumbled upon this article. I thought you might be interested in the following quote:

"lens sharpness (rather than sensor resolution) is often the weakest link when it comes to achievable resolution. 60 line pairs per millimeter is considered an exceptionally good lens resolution. D-SLR sensors have a typical pixel pitch of 4-6 µm, corresponding to 125-90 line pairs per millimeter."

This was taken under the header of "Having too many MPixels Really doesn't help"

But, in checking his math, it is an interesting and potentially simple way to go about the problem.

If I am following him correctly, if we assume 1:1 image transfer onto the sensor, so a macro lens, then 6 um * 90 = 540 um. Double this to get "line pairs" and you are at 1.08 mm. Working backwards, dividing 1 mm (or 1,000 um) by 12 um (pixel pair) = 83 pixel pairs per mm on the sensor. Go with the 4.1 um pixel pitch for the 7D II, you would get 1,000 um / 8.2 = 122 pixel pairs per mm.

So, if we assume 1:1 image transfer, lenses aren't coming close to sensors. But most lenses are ~0.2x. If I am thinking about that correctly, at the MFD, every 5 mm is projected onto 1 mm of the sensor. So, that 122 pixel pairs on the 7DII sensor could resolve 24.4 line pairs per mm with a 0.2 to 1 projection. From here, I think we also need to consider the whole Bayer filter issue, etc.

So with macro lenses, even current sensors are overkill (at MFD), but with standard lenses, there is benefit to higher MP. This is counter to what luminous landscapes' statement, but it seems right to me.

It makes sense that many lenses are out resolved by the sensor. We see the difference in resolution from cheap kit lenses to expensive quality lenses. If the sensor couldn't out resolve a cheap kit lens would we see much difference using a quality lens? Wouldn't it be limited by the weak link.

As far as Canons top lenses I think the lenses are still ahead of the sensors. I watched the video again of the manufacturing process of the 500mm II. In the video they attach the lens up to a light that projects an image on to the wall to check out. They were not checking it on a camera body. I would guess at some point Canon checks the resolution of naked lenses against an equal image created by a sensor with the same lens. If sensors could resolve to 100% of the lenses ability wouldn't we be seeing it in the literature? Then again they want us to keep buying new camera bodies, such information could deter sales.

Rumors abound, perhaps next week we will have such a claim.