Train to nowhere

by Jorge Córdoba

submit your photo


Hall of Fame
View past winners from this year

Please participate in Meta
and help us grow.

Tag Info

New answers tagged

0

Just a thought: If you want to see what a given image will contain in the way of detail at 3840x2160, resize the image to fit that bounding rectangle, then display it at 1:1 on your screen, making sure that an in-focus area of interest is within the "crop" of the screen. You can then see exactly what actual detail will exist at that pixel dimension, and you ...


1

Yes, the standard viewing situation which the DOF calculation applies to, is an 8x10 inch print, viewed at 10 inches. Circle of Confusion (CoC, see Wikipedia) is an arbitrary factor in that calculation (about how well the eye sees the magnified blurriness in the enlargement). If you print it 3 or 4 times that 8x10 size, then the allowable Circle of ...


2

You are correct that the standard viewing criteria used by most DoF calculators can be inaccurate when considering large prints or high resolution displays. Your best bet is to bracket your focus/aperture or check your image at the maximum possible enlargement using the rear LCD of your camera.


3

Ideally, output sharpening is always dependent on the target medium. Optimal quality needs an image which was resized and sharpened for the intended viewing conditions. A high-res display needs a larger image than a low-res display, and a screen needs differnt sharpening than a print, all of which should, eg., be handled automatically by the Lightroom ...


-5

Let's get this straight - you're looking to double the amount of sharpening work in your workflow to provide differently (and manually tailored, because otherwise you're wasting your time) content for a small population who... are mac users possess the type of display you're targeting have that display calibrated properly were aware that they were ...


25

As mentioned in the other answers, diffraction has led to unsharpness. To put this to the test, one can attempt to sharpen the image using deconvolution by using the point spread function that corresponds to F/29. For diffraction, we have (up to an overall normalization) P(s) = {J1[ πrs/(λF) ] / [ πrs/(λF) ] }2 where J1 is the Bessel function of the ...


44

You've run over the diffraction limit. Light rays passing through a small hole will diverge and interfere with each other and a pattern emerges--a sort of banding where different frequencies/placement can cause separate rays to add up or negate each other. The smaller the opening gets, the larger this divergence/interference becomes. This pattern is called ...


14

Because of diffraction. f/29 is way too much for you to expect a sharp image. Try shooting the same thing at f/8 and you'll see the difference.


0

Performance in terms of acutance of any lens varies in a lot of ways, but throwing in the variable focal lengths a zoom lens is capable of adds to the complexity of things. Even a prime lens with a fixed focal length can vary in terms of center sharpness from one aperture setting to the next. How much that sharpness is degraded from the center to the edges ...


2

No, that's not generally true. You might look at the DxOmark website for actual measurements on different lenses. Sharpness at different points across the field is one of the things measured in great detail, and graphed using color to indicate sharpness. The sharpness varies not only with the specific lens, but varies with the zoom setting on zoom lenses, ...


5

As with any blanket statement, it's not true in every case that primes will give consistent sharpness across the field and zoom lenses won't. To take one specific example, the Canon EF 50mm f/1.8 II has much worse performance in the corners than the centre at f/2.8, whereas the Canon EF 24-70 f/2.8L II USM is pretty consistent across the frame at 50mm, ...


0

Lens sharpness is fairly complex topic as there are many variables that dictate what makes an image sharp and what does not. Here I will try and keep it as basic as possible with a just a few areas that can be considered regarding sharpness. It is generally true that Prime Lenses are sharper than Zoom Lenses. The reason for this is due to a prime Lens not ...


-3

Generally yes. A camera lens is composed of many lens elements. Each element bends light in a different way. Some elements need to be made of a different material that bends some colors more or less than others (especially at the edges). It is difficult to manufacture elements that are of unusual shapes (aspherical) or that require much finer tolerance. A ...


2

You can use a camera or lens that offers tilt capability. The zone of sharp focus doesn't get any wider, but it tilts. Example: the bottom of the frame is focused a foot away, the top of the frame is focused slightly past infinity. If that matches the way your scene is laid out it can appear you have insanely deep DoF even though the DoF at any given point ...



Top 50 recent answers are included