46mp sensor useless for landscape?

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TonyY

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In most landscape situations, aperture needs to be set less than f/8 for large DOF. But according to the article below, 19mp is the max a 35mm full frame sensor can capture for red light (wav length of 0.0007mm) at f/8, doesn't matter if your camera has 36 or 46mp sensor...

http://www.luminous-landscape.com/tutorials/resolution.shtml

TABLA3.jpg


So, what happens when a landscape picture is captured by 46 mp 35mm sensor at f/11? Do we see more blue than green and red? turquoise color shifted?
 

dtaylor

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TonyY said:
In most landscape situations, aperture needs to be set less than f/8 for large DOF. But according to the article below, 19mp is the max a 35mm full frame sensor can capture for red light (wav length of 0.0007mm) at f/8, doesn't matter if your camera has 36 or 46mp sensor...

If you photograph scenes which contain nothing but varying brightness levels of pure red, then yeah, I suppose you're limited to 19 MP.

For the rest of us, there is definitely a resolution gain moving to a 46 MP sensor.
 
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Oct 16, 2010
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I won't try to say that I fully understand the article. However, real world results suggest that there is no such problem. The 5Dii has more than 19mp and has been considered an excellent landscape camera - I don't recall anyone noticing odd colour shifts when stopped down below f/8. And those with a working D800 seem delighted with their cameras too.
 
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Not an expert in optics but I thought even though the system overall may not render an individual pixel accurately more is still better because it's a form of oversampling, so when downsizing the more information still gives a higher probability of reconstructing the image accurately.

One thing I must say though is that some of the tables look like cut and paste jobs which make it hard to follow. Some are in fractions of a mm, others in um instead of the more conventional nm you'd normally use to describe visible light wavelengths, although maybe a regional thing.
 
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Not at all. When light is passed through a small aperture it can interfere with other light near it. That's a real simple explanation of the physics of it. What that means to a photographer is that if you stop down your lens too much you will start to lose resolution instead of gaining it.
You normally gain resolution when you stop down a lens because there is less tendency for aberrations in the glass to show up. You have to remember that you are bending light in order for a lens to work and different wavelengths get bent different amounts when they pass through glass (think of a prism) and lens coatings try to correct for this but there are practical limits to how perfect you can make a glass surface and how well these coatings can work in the relatively cheap lenses photographers work with. These are consumer lenses and they have price constraints.
When you take smaller samples of the light by using a smaller aperture you tend to have less problems therefore increasing your resolution when you stop down the lens. However, at some point you will start getting destructive and constructive interference when all the light hitting the sensor is coming through a smaller and smaller holes. If it was simply destructive interference then you would start losing your reds starting at deep red and going through the spectrum until you hit deep purple. Light waves can combine to make brighter, constructive interference or darker, destructive interference so instead you just start to get fuzzy reds then oranges then yellows etc... as you stop down a lens. As you decrease the aperture, higher megapixel cameras will start to pick up on this fuzziness and lose resolution.
You are never going to get better resolution with less megapixels in theory (of course there's a lot more problems in real life with high megapixels e.g. increased sensor noise and other stuff I'm not going to discuss right now). What all this technical crap means is that if your goal is to get as much information into your landscape photo as humanly possible, really small apertures are not necessarily a good way to do it. You may gain DOF but you may lose detail. Ultimately there is a sweet spot in each lens that will give you the most possible resolution where you get rid of enough lens aberration that decrease sharpness without losing too much to diffraction. Higher megapixels cameras on really nice glass tend have a smaller sweet spot because it will pick up the diffraction problems sooner.
In practice you want lots of megapixels as long as the pixels are of a good quality for landscape photography so you can pick up fine detail. There is a tipping point however where you are just not going to get better resolution with more megapixels and we've hit that point with the D800 and even some of the really nice glass. However you have to make a decision as to what aperture to use based on the DOF you need and how your lens performs as far as aberrations are concerned and also depending on how much resolution your sensor can get. You will only figure it out by taking lots of pictures and paying close attention to your results (have fun pixel peeping). Basically this article is saying that you don't want to just set your camera to iso 100, F22 or F32 and sit there for half an hour for the exposure. You will lose a lot of detail from diffraction. Just test out different apertures, ISOs and Fstops til you figure out what gives you the best picture for you combination of camera, glass and subject. Don't worry about the math or this article, just don't be dumb and close down your aperture as much as humanly possible and think you will get a better picture.
If parts of this don't make sense please realize that it 4am and I have insomnia and this is my way I'm getting to sleep tonight. I'd love to hear well intentioned corrections if I have something wrong but take my writing with a grain of salt. I think I understand the basics of this topic but I may not have done a great job explaining it.
On a related note, I have cheap glass and I'm not huge into landscape photography but what do you experienced landscape photographers think about focus stacking for landscapes as a way around the diffraction and DOF issues you can run into in landscape photography? I know that it requires a specific subject (not catching clouds in the perfect formation or sunset pictures) but I've been screwing around with doing HDR focus stacking landscapes mostly as an experiment (lots of fun spending hours in photoshop stitching together thirty photos to make one). Is anyone actually doing that stuff? If so, have you got anything good with it? I've done it a couple times just to see if I can do it and the results are kind of interesting. Anyone else try it and what do you think?
 
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TonyY

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Hillsilly said:
I won't try to say that I fully understand the article. However, real world results suggest that there is no such problem. The 5Dii has more than 19mp and has been considered an excellent landscape camera - I don't recall anyone noticing odd colour shifts when stopped down below f/8. And those with a working D800 seem delighted with their cameras too.

The 5DII sensor is a bayer filter image sensor, 19mp is actually 6 mp, 3 pixels represent 1, see
350px-Bayer_pattern_on_sensor.svg.png
 
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Jul 21, 2010
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TonyY said:
The 5DII sensor is a bayer filter image sensor, 19mp is actually 6 mp, 3 pixels represent 1

False, 19 MP is actually 19 MP. The Bayer mask provides color sensitivity (and requires interpolation) but the spatial resolution is unaffected. Note, though, that when Foveon counts the three 'stacked' pixels separately, that's a misrepresentation - a '14 MP' Foveon has only 4.7 MP of real spatial resolution.
 
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TonyY

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neuroanatomist said:
TonyY said:
The 5DII sensor is a bayer filter image sensor, 19mp is actually 6 mp, 3 pixels represent 1

False, 19 MP is actually 19 MP. The Bayer mask provides color sensitivity (and requires interpolation) but the spatial resolution is unaffected. Note, though, that when Foveon counts the three 'stacked' pixels separately, that's a misrepresentation - a '14 MP' Foveon has only 4.7 MP of real spatial resolution.

Correct, but for a specific color - red, blue or green(50% more than other 2 colors), the resolution is really less than 7mp on 5D Mark II. "14 MP" instead of "4.7 MP" is just for marketing, and the picture took by that sensor really shows fine micro details.
 
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Jul 21, 2010
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TonyY said:
neuroanatomist said:
TonyY said:
The 5DII sensor is a bayer filter image sensor, 19mp is actually 6 mp, 3 pixels represent 1
False, 19 MP is actually 19 MP. The Bayer mask provides color sensitivity (and requires interpolation) but the spatial resolution is unaffected. Note, though, that when Foveon counts the three 'stacked' pixels separately, that's a misrepresentation - a '14 MP' Foveon has only 4.7 MP of real spatial resolution.
Correct, but for a specific color - red, blue or green(50% more than other 2 colors), the resolution is really less than 7mp on 5D Mark II. "14 MP" instead of "4.7 MP" is just for marketing, and the picture took by that sensor really shows fine micro details.

Sorry, still false. You're assuming that the colors in the mask are 'pure' RGB, but they aren't - there's substantial spectral overlap, such that photons of a given wavelength, except the very ends of the visible spectrum, are detected by photosites under at least two, and sometimes all three, colors.

Here's the response of the 500D sensor:

image018.png
 
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TonyY

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neuroanatomist said:
TonyY said:
neuroanatomist said:
TonyY said:
The 5DII sensor is a bayer filter image sensor, 19mp is actually 6 mp, 3 pixels represent 1
False, 19 MP is actually 19 MP. The Bayer mask provides color sensitivity (and requires interpolation) but the spatial resolution is unaffected. Note, though, that when Foveon counts the three 'stacked' pixels separately, that's a misrepresentation - a '14 MP' Foveon has only 4.7 MP of real spatial resolution.
Correct, but for a specific color - red, blue or green(50% more than other 2 colors), the resolution is really less than 7mp on 5D Mark II. "14 MP" instead of "4.7 MP" is just for marketing, and the picture took by that sensor really shows fine micro details.

Sorry, still false. You're assuming that the colors in the mask are 'pure' RGB, but they aren't - there's substantial spectral overlap, such that photons of a given wavelength, except the very ends of the visible spectrum, are detected by photosites under at least two, and sometimes all three, colors.

Here's the response of the 500D sensor:

image018.png

Ok, I think this is too technical for me. So 46 MP is same as 36 MP for landscap?
 
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Bruce Photography

Landscapes, 5DX,7D,60D,EOSM,D800/E,D810,D7100
Feb 15, 2011
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dhofmann said:
If you set your focus to the hyperfocal distance, or if you use a tilt/shift lens, you'll be able to use a lower f-stop and get more resolution. Also, I'd use the numbers for the green wavelength (0.55um). At f/5.6, that yields 60MP for 35mm.

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Since I live in a forest, I guess that I'm lucky to have so many green things in my landscapes. I also get alot of blue (like in ocean - but sometimes a greenish blue). I never did like the red tide. My solution for the D800 and D800E is to shoot tilt-shift most of the time and otherwise limit myself to F14 where I visually see some minimal loss of sharpness. By the way, the wider the lens, the more DOF you have. My other favorite lens is the 14-24 for Nikon and the 17mm tilt shift for Canon. Both have alot of DOF. However the 24 tilt shift Canon is another favorite. p.s. I shoot Nikon quite a bit now but will go back to Canon once they have a high MP body. Thank you for your share.
 
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The total MTF of a system is the product of the individual mtf's of the components. The final MTF will never be greater than the lowest MTF in the system.
Thus, a camera with a lens MTF of 0.9, and a body of 0.7 will be 0.63. Increase either one, and the value goes up. Suppose, we have a body with a very large number of MP, say a billion, with a impossibly high MTF of 0.99. The system MTF will then be basically that of the lens. (0.891).
What all this means is that increasing one component or the other is going to raise the mtf of a real world camera / lens system. Of course, at some point, there will be enough MTF in a camera body to cause the lens to be the limiting factor, but that is well out in the future, we are not near reaching it.
 
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Mt Spokane Photography said:
Of course, at some point, there will be enough MTF in a camera body to cause the lens to be the limiting factor, but that is well out in the future, we are not near reaching it.

I wouldn't necessarily say that. Go read about the lengths D800E users have to go to in order to get all the resolution out of their sensors. You have to use the _very_ best glass and hit the perfect f/stop with the perfect focusing (hyperfocal generally). It is already getting quite fiddly to feed 36mp... if Canon is going to do 46mp things are definitely going to get interesting.

BTW - It's a pet peeve of mine that many "landscape photographers" don't truly understand diffraction, DOF and hyperfocal focusing. If you think "all landscape shots are at f/8 or smaller" then you need to go do some reading and shooting.

Just go get a really good camera and lens, stick it on a good tripod, use manual focusing and mirror lockup and go through a series of shots from f/4 to f/22. Choose a good landscape scene with foreground interest (although your camera doesn't have to be right up against the foreground interest) and go through the aperture series while focusing at 3 different points:

1. At the foreground interest
2. Halfway to the distant object (like mountains or a far off building)
3. At the distant object

Compare your results.

The results will be pretty damn obvious. You'll get the best sharpness focusing halfway between (which is just an approximation of the hyperfocal distance that will be good enough for you to see what's going on) the near and far subjects and with an aperture that is just on the large side of the diffraction limit (generally around f/5 to f/8 for most modern sensors and good glass).

By focusing better (right at the true hyperfocal distance) you can get everything sharp with larger apertures (I'm using f/5.6 more and more often lately in my own work).

If you use a tilt-shift you can do even better than that because you tilt the focal plane so that it more closely approximates your scene (instead of just being perpendicular to your lens).

All of this is a way of saying that as we get higher MP sensors... we (the landscapers) are going to need to do more work and be more diligent to get the very best possible image.

I read an article not too long ago where a pro (really?) landscape photographer was advocating shooting everything at f/22 focused at infinity. I nearly lost my lunch. How could a "pro" never have even done the above testing? Because when you're using film or only 10mp it simply doesn't matter that much....
 
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Beyond shooting, I also definitely recommend using a "DOF Calculator" for a while (like this one http://www.dofmaster.com/dofjs.html ). You can also get really good DOF calculators for iOS and Android so you can have them in the field.

Just playing with one will give you a good idea of aperture sizes to use.

Note that according to that dofmaster website with a D800 at 24mm at f/5.6 I can focus at 11.2 ft (the hyperfocal distance) and get everything from 5.6 ft to infinity in focus.

Even at f/4 I can focus at ~16ft and get everything from 8ft to infinity in focus! If your camera is on a tripod at eye level, it's going to be rare to have something closer than 8 ft...

Once you get a feel for this you can "wing it" in the field... I generally just focus a bit beyond my foreground interest and choose an aperture around f/5 to f/8 depending on if there is something closer than that. Beyond f/8 on my 7D diffraction starts to kill any gains made in DOF...
 
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