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Author Topic: 46mp sensor useless for landscape?  (Read 22282 times)

TonyY

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46mp sensor useless for landscape?
« on: October 07, 2012, 01:22:28 AM »
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



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?

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46mp sensor useless for landscape?
« on: October 07, 2012, 01:22:28 AM »

TonyY

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Re: 46mp sensor useless for landscape?
« Reply #1 on: October 07, 2012, 01:31:16 AM »
Plus optica resolution from the center to edge of the image degrades and low pass filter.

TonyY

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Re: 46mp sensor useless for landscape?
« Reply #2 on: October 07, 2012, 01:42:07 AM »


corresponding to article above, maybe that's why Sigma Foveon X3 was designed this way: thinner blue and thicker red layer.

Canon should buy Sigma Foveon X3 technology and make a 35mm full frame sensor. http://en.wikipedia.org/wiki/Foveon_X3_sensor

dtaylor

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Re: 46mp sensor useless for landscape?
« Reply #3 on: October 07, 2012, 02:37:44 AM »
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.

Hillsilly

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Re: 46mp sensor useless for landscape?
« Reply #4 on: October 07, 2012, 02:45:40 AM »
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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dhofmann

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Re: 46mp sensor useless for landscape?
« Reply #5 on: October 07, 2012, 03:03:15 AM »
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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Re: 46mp sensor useless for landscape?
« Reply #6 on: October 07, 2012, 03:09:14 AM »
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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Re: 46mp sensor useless for landscape?
« Reply #6 on: October 07, 2012, 03:09:14 AM »

natureshots

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Re: 46mp sensor useless for landscape?
« Reply #7 on: October 07, 2012, 04:07:04 AM »
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?

natureshots

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Re: 46mp sensor useless for landscape?
« Reply #8 on: October 07, 2012, 04:12:31 AM »
If you really want to do some good landscape photos, screw digital. Get a medium/large format film camera and a bathtub.  Its definitely cheaper too, just don't drink the silver nitrate if you're doing B+W.  ;)

TonyY

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Re: 46mp sensor useless for landscape?
« Reply #9 on: October 07, 2012, 09:26:27 AM »
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

neuroanatomist

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Re: 46mp sensor useless for landscape?
« Reply #10 on: October 07, 2012, 10:34:02 AM »
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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Re: 46mp sensor useless for landscape?
« Reply #11 on: October 07, 2012, 11:08:31 AM »
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.

neuroanatomist

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Re: 46mp sensor useless for landscape?
« Reply #12 on: October 07, 2012, 11:52:30 AM »
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:

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Re: 46mp sensor useless for landscape?
« Reply #12 on: October 07, 2012, 11:52:30 AM »

TonyY

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Re: 46mp sensor useless for landscape?
« Reply #13 on: October 07, 2012, 12:25:12 PM »
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:



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

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Re: 46mp sensor useless for landscape?
« Reply #14 on: October 07, 2012, 12:45:13 PM »
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.

+5
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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Re: 46mp sensor useless for landscape?
« Reply #14 on: October 07, 2012, 12:45:13 PM »