Jerry R
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Read an optics text book and not what some layman photographers think.
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RX1R II - Cropping
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Jerry R
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Focus manually and read an optics text book.
Do the math...
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Trijicon123
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Biological_Viewfinder
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It's been my experience that while this sounds good on paper, it just doesn't translate very well in reality.
Do it right now. Grab a photograph from any camera you own and crop it to Pretend a zoomed shot. It will not look right. It loses something in the translation. And while that higher resolution and full frame can help the illusion, it's still just that, an illusion.
I tried this exact same thing with the Nikon D800e. It looks like an effect, not a photograph.
Do it right now. Grab a photograph from any camera you own and crop it to Pretend a zoomed shot. It will not look right. It loses something in the translation. And while that higher resolution and full frame can help the illusion, it's still just that, an illusion.
I tried this exact same thing with the Nikon D800e. It looks like an effect, not a photograph.
Mike Fewster
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Mike Fewster
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Mike Fewster
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Jerry R
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I do not take information posted on blogs as reliable. If you want to believe fine, but that does not make it right. This thread is a good example.
DOf is an optical property determined by the parameters used when the imaging information is recorded. How the image is reproduced and its vexing properties are a separate subject. However, they do depend on the characteristics of the recording of the original imaging information.
DOf is an optical property determined by the parameters used when the imaging information is recorded. How the image is reproduced and its vexing properties are a separate subject. However, they do depend on the characteristics of the recording of the original imaging information.
Jerry R
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I have.
Jerry R
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Mike you are right on. I know I can crop my 16 meg image down to one meg and have done this with some success. However, If I know that I'm taking an image and only really want a tighter FOV than the lens can provide I use "smart zoom" to compose and take the image to get the focus and DOF I'm looking for.
Mike Fewster
Forum Pro
Of course, information posted on blogs may or may not be reliable. It isn't a matter of "belief". It is a question of whether what is posted on that site is correct. Same with textbooks, I have seen them get things wrong over the years as well. This thread is a whole lot of opinions from people of varying experience. I'd agree that I wouldn't take just anything written here as proof.
That however is quite different to the nature of the information in the link I gave. I can only conclude that you have no idea who Ctein is. He has the standing both in science and photography to be taken as a reference point.
I agree. Whether or not a text book written for (I presume) a maths and/or physics student is the best way for a lay person to get to understand the issues is another question entirely.
Jerry R
Forum Pro
Mike,
I just read his article and I have no argument with what he says.
my concern with what is being posted by some (and I don't think the article helps) is the mixing of optical concepts when the image is created and how this is effected by print size. Its just the opposite the recorded image determines what print size and at what viewing distances it would be "acceptable".
I just read his article and I have no argument with what he says.
my concern with what is being posted by some (and I don't think the article helps) is the mixing of optical concepts when the image is created and how this is effected by print size. Its just the opposite the recorded image determines what print size and at what viewing distances it would be "acceptable".
Mike Fewster
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Ok Jerry. I am with you and I agree re that confusion.
Mike Fewster
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Jerry R
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You don't understand or don't want to understand. The DOF is an optical concept determined when the image is recorded. The printing and display parameters are a different concern.
Two images of the same scene taken with he same lens and F stop but different numbers of megapixels (same size sensor) will had the same DOF. However, the sensor with more megapixels can be printed at a larger size with the same amount of blurring as the sensor with the smaller number of pixels.
Two images of the same scene taken with he same lens and F stop but different numbers of megapixels (same size sensor) will had the same DOF. However, the sensor with more megapixels can be printed at a larger size with the same amount of blurring as the sensor with the smaller number of pixels.
As I said before, the lens only define how quickly blur comes in out of the focus plane. The DOF is a result of what is out of the focus plane but perceived as sharp, so it is dependant of the viewing condition.
I will help you redo the math, then :
DOF = Df-Dn
Df = sf²/(f²-Nc(s-f)) the far limit were things are perceived sharp
Dn = sf²/(f²+Nc(s-f)) the near limit were things are perceived sharp
with s the distance of the subject, f the focal lengh, N the apperture and c the circle of confusion
Lets do some hypothesis :
f=35mm, N=2, s=2m. Pretty common use case of RX1
Lets calculate c now, both with and without crop :
For a 10x15cm print, the standard is 300dpi, which means that if the blur is < 1"/300 = 85µm, it will be perceived as sharp.
In the first case, the uncroped picture, 10*15cm --> 24*36mm give c = 85*24/100 = 20µm on the sensor, and DOF = 26cm
In the second case, the 2*croped picture, 10*15cm --> 12*18mm give c = 85*12/100 = 10µm on the sensor, and DOF = 13cm.
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