Bifurcator wrote:
But you're already way way WAY past the line frequency of any ink-jets I know of at 12mpx for a full 8x10 page so I don't see how this is even possible. Got any proof? Like some scans of the two? And then of course human vision is limited to about one arc minute (1/60°) at any distance - so that's like 200ppi on the high outside or about 3.5mpx at only 10 inches away from the page. (yeah, that is three point five and not thirty five megapixels.) So that assertion kinda flies in a lot of faces.
sebboh wrote:
indeed, at 8x10 the difference will be very hard to see and come mainly from smoother transitions and better/more downsizing based enhancements. i just picked the size arbitrarily, the point is that even at f/32 the higher mp image will look better at any given size.
I'm not really sure I buy that either! Just from commonly viewing lots and lots of MF-DB images of around 30 and 50mpx I see zero resolution differences at displayable sizes compared to something evan as (supposedly) weak as the D700. More megapixels sounds like a good thing to have and I suppose it might be if you do a lot of extreme cropping but in (my) reality and honest assessment it's just not - beyond a certain point of course. YMMV. And this is only the diffraction issue you're zeroing in on. There are still the issues of noise and DR. So for example while the new D800 might be great at noise and DR with all the added improvements, we can only wonder how much better than even that it would be had it a lower pixel density... etc.
there is no viewing size where diffraction hurts the higher mp sensor compared to the lower mp sensor.
OK. Diffraction blur is noticeable when comparing an image with and without it - at almost every scale from 1100 pixels across to the full 4600 of the GH2. So I would only assume that more of it would be worse than less of it.
Bifurcator wrote:
I'm not really sure I buy that either! Just from commonly viewing lots and lots of MF-DB images of around 30 and 50mpx I see zero resolution differences at displayable sizes compared to something evan as (supposedly) weak as the D700. More megapixels sounds like a good thing to have and I suppose it might be if you do a lot of extreme cropping but in (my) reality and honest assessment it's just not - beyond a certain point of course. YMMV. And this is only the diffraction issue you're zeroing in on. There are still the issues of noise and DR. So for example while the new D800 might be great at noise and DR with all the added improvements, we can only wonder how much better than even that it would be had it a lower pixel density... etc....Show more →
at drastically lower resolution there is only tiny real resolution difference. the larger megapixel image can be downsized more giving it smoother tone gradients, higher dynamic range, and less noise assuming all those things were equal a the per pixel level. as you state, assuming equal technology, larger pixels should have less noise and more dynamic range (in practice this varies), but downsizing equal technology equalizes these things making it pretty much a wash at small sizes.
sebboh wrote:
there is no viewing size where diffraction hurts the higher mp sensor compared to the lower mp sensor.
Bifurcator wrote:
OK. Diffraction blur is noticeable when comparing an image with and without it - at almost every scale from 1100 pixels across to the full 4600 of the GH2. So I would only assume that more of it would be worse than less of it.
i zeroed in on the diffraction issue because it was the part of your argument that was wrong and was rather strange given that this is a thread about sharpness where you said you needed as much as you could have. what you are missing is that there is NOT more diffraction blur with higher pixel densities. for a given aperture the diffraction blur is always the same independent of pixel density. it seems like more at 100% because you are blowing up the image to a larger size when you look at the higher pixel density image compared to the lower pixel density image. if both images are the same size the diffraction blur will be the same.
you pinpoint it yourself. It is no noise, but moiré, which is a special case of aliasing.
Moiré is a low-frequency pattern that has its origin in a high-frequency pattern in the original scene.
Thanks tooth. I probably expressed myself unusually blurry, but now I get it. I hadnt seen chroma moire like that before, and I really need to make an effort to see it. The moire I am used to see comes from high contrast and high frequency patterns. It can also show itself in a straight high contrast line, but then it's maybe better to call it jagged edges although the phenomenon shares the same optical origin.
sebboh wrote:
at drastically lower resolution there is only tiny real resolution difference. the larger megapixel image can be downsized more giving it smoother tone gradients, higher dynamic range, and less noise assuming all those things were equal a the per pixel level. as you state, assuming equal technology, larger pixels should have less noise and more dynamic range (in practice this varies), but downsizing equal technology equalizes these things making it pretty much a wash at small sizes.
i zeroed in on the diffraction issue because it was the part of your argument that was wrong and was rather strange given that this is a thread about sharpness where you said you needed as much as you could have. what you are missing is that there is NOT more diffraction blur with higher pixel densities. for a given aperture the diffraction blur is always the same independent of pixel density. it seems like more at 100% because you are blowing up the image to a larger size when you look at the higher pixel density image compared to the lower pixel density image. if both images are the same size the diffraction blur will be the same....Show more →
Totally agreed. Diffraction has nothing to do with the pixel size and everything to do with the enlargement of the image. That is why smaller sensors have low diffraction threshold and larger sensors have a high threshold.
How much do I need sharpness?
I want it sharp right on camera and not need PP, and I found that my choosen combo of Carl Zeiss lenses and Foveon sensor(s) can reach that level 50% of the shooting times, another 50 % was my various faults.I also use Canon(s), they always need PP or the images will not be acceptable sharp.Just 2 cents of mine.
wfrank wrote:
The moire I am used to see comes from high contrast and high frequency patterns. It can also show itself in a straight high contrast line, but then it's maybe better to call it jagged edges although the phenomenon shares the same optical origin.
I think aliasing is the right word (and color aliasing if you're seeing colored artifacts) here.
Most of the statements made about lens diffraction limiting the resolution of a sensor are referring to an area defined by a single pixel, if I've read posts here correctly.
But if that area is defined by 4 pixels, or 9 pixels, recording a diffracted point of light, that information will be much better defined, and probably modeled for better contrast, noise, etc.
Aren't micro-contrast and sharpness functionally related?
I know we try to separate them as being different qualities but I can't actually recall a sharp lens that didn't also have good micro-contrast nor a lens with good micro-contrast that wasn't also sharp. I think micro-contrast is a function of sharpness and color definition (color definition being the opposite of color bleeding lest I be misunderstood).
If I examine an image from a lens with exceptional micro-contrast I can notice that the transitional areas between two different colors are very concise. And a lens that isn't sharp blurs those "borders" by the very definition of softness.
So aren't the two extremely related, even codependent perhaps?
Bifurcator wrote:
Aren't micro-contrast and sharpness functionally related?
I know we try to separate them as being different qualities but I can't actually recall a sharp lens that didn't also have good micro-contrast nor a lens with good micro-contrast that wasn't also sharp. I think micro-contrast is a function of sharpness and color definition (color definition being the opposite of color bleeding lest I be misunderstood).
If I examine an image from a lens with exceptional micro-contrast I can notice that the transitional areas between two different colors are very concise. And a lens that isn't sharp blurs those "borders" by the very definition of softness.
So aren't the two extremely related, even codependent perhaps?...Show more →
Micro-contrast and sharpness are synonymous in my opinion. When a lens has high micro contrast, it means that it is a sharp lens. Micro-contrast corresponds roughly to the 10 lpmm and 20 lpmm on Zeiss MTF tables. A high number indicates that the lens gives a very good illusion of sharpness while the 40 lpmm indicates the resolving power of very fine details.
And isn't lens resolution also a function of sharpness? We say a lens which can resolve small details has good micro-contrrast and we've already agreed that micro-contrast and sharpness are synonymous.
I slightly disagree about the definition of sharpness. To me, a lens is sharp if it has any one of a number of attributes which leaves an overall impression of high resolution. The impression doesn't have to be accurate, but as long as the photo looks sharp, it qualifies, even if it fails on closer inspection. High contrast can compensate for some missing resolution, for example.
Otherwise we just end up with all terms meaning the same thing, which is silly.
And isn't lens resolution also a function of sharpness? We say a lens which can resolve small details has good micro-contrrast and we've already agreed that micro-contrast and sharpness are synonymous.
Not necessarily. It just happens that modern Leica and Zeiss lenses combine both, but there are lenses out there with high resolution and low micro-contrast and vice versa. High micro-contrast renders a sharp image at normal printing or viewing sizes while high resolution comes into play at high magnifications. A lens which can resolve small details is high resolving, a lens which has high contrast in medium and fine structures has high micro-contrast. Not exactly the same thing.
