Hot answers tagged

51

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 ...


50

Bokeh is specifically the out-of-focus areas of an image. Gaussian blur is an algorithm to fog selected image areas, to hide details or make them look out of focus. The main differences: bokeh is created optically, gaussian blur in post-production; in bokeh, the amount of how wide an out-of-focus point will be smeared is determined by its relative distance ...


48

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 ...


39

It depends. In many cases, it may actually be possible without any further visual aids in the picture. Many lenses, if not most, will show different longitudinal chromatic aberration in front of and behind the focus plane. If you scroll down just a little bit on the linked page, you will see this demonstrated with a picture of a focus test chart. With this ...


37

What you are looking for is large depth of field. This is an optical property, not something applied as a special effect, so it's not something you can turn on or off. The raw image captures the light focused by the lens, and inevitably there will be parts of the scene which are either too far or too close — out of the range where the rays are tightly ...


35

Actually, this is intentionally done and can be duplicated with any camera and flash combo (ish). To me, the second and third image seem indicative of a technique known as second curtain / rear curtain sync. The first appears to be good ol' flash during a long exposure...(more below)... In all of the examples, a decently long exposure (for the event) was ...


24

shutter speed 0.5 seconds This is likely to be a bit of your problem. The shutter causes vibration of the camera. So, too, does your hand pushing the release button. At faster speeds, this vibration does not affect the shot. Likewise, at very slow speeds (a few seconds +). But there’s a sweet spot somewhere between a second or two and ~1/30 where that ...


20

The blur is caused by the shutter being open for much longer than the duration of your flash. The orange color of the blur is due to the ambient lighting being much warmer in color than the light from your flash. Since the camera has almost certainly set white balance automatically to match your flash, the much dimmer and warmer ambient light has a very ...


20

When the aperture is positioned to minimize vignetting, the bokeh shapes for objects that are too far is rotated by 180° compared with objects that are too near. (The aperture image is reflected through its center point.) If the arrangement of your aperture blades is not symmetric around the center point, you can try finding "reference bokeh" that are ...


19

You've hit the diffraction limit. That link has some amazing answers with a lot of detail, so I won't be redundant, but in short, once the aperture gets to be below certain physical size, diffraction causes inevitable blur. For your camera (and any other camera with an APS-C-sized sensor), the limit is a little beyond f/11. The amount of light let in doesn'...


18

This looks like the effect of noise reduction at high ISOs. Heavy NR is common in compact cameras with small sensors. Fujifilm cameras of that generation did it very well compared to others of the time, but there's only so much blood you can get from a stone. On most modern high-megapixel point and shoot cameras, you'll see this even at low-ISOs if you ...


18

Use more light. Open windows, turn on more room lights, bring in extra portable lights. Use a flash. You say there is "no chance" to use a flash, but since you gave no justification for that it remains valid advice. Added: I just looked at the manual you linked to, and right on the front page it clearly shows a popup flash. A spot light from almost ...


17

The Japanese word Boke (ボケ) or the American spelling Bokeh, refers to the out of focus areas of a photograph. It does not necessarily mean only the background blur, it refers to foreground blur as well. Bokeh is often used to refer to the quality of out of focus blur more so than its presence. In Japanese, Boke Aji (ボケ味) is used to specifically refer to the ...


17

Have you tried the High Pass Filter in Photoshop? Make a selection around the area of the image you need better focus on, press ctrl-J to jump this to a new layer. Then, in the Filter menu, scroll down to Other, and choose High Pass. Depending on how large your photo is, you might want to choose from 1-6 pixels. You will probably have to ...


17

I don't have Photoshop, but there's an ancient open source project called refocus-it (for iterative refocus), which uses some of the same techniques as Photoshop's new-in-CS6 deblur feature. This should give better results than sharpening with unsharp mask or a high-pass filter. Below, I chose (after some experimentation) a radius of 3.1 and (since the image ...


16

You appear to be using your lens (100-400/5-6.3) with the aperture wide open. I would expect the glow in your photos to be significantly reduced or absent stopped down to about F8. Many lenses "glow" when used wide open, especially in bright light with high contrast. It is likely associated with spherical aberration and is typically reduced or completely ...


15

The simple recipe is to convolve with a Laplacian of Gaussian kernel (3x3, with 8 in the middle surrounded by -1 and take the abs(result)) . After this you get some artifacts if it is a jpeg image, and out of focus borders that have a high intensity difference will also "ping". The result you can threshold to detect the strongest edges and remove teh ...


15

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.


13

If you remember the exact radius of the Gaussian blur, and you processed and saved the images in a 16 bit or greater format then you can remove the blur by inverse filtering in Matlab. If you don't remember the radius, or you truncated the pixel values by working or saving the image as 8 bit (and then used lossy JPEG compression for good measure destroying ...


13

There is definitely something very wrong here. That's not a focus or DOF issue, but looks like the lens suffers from extremely strong field curvature. It's normal for a lens to be sharper in the center than around the edges, and this effect gets stronger with wide open aperture and at the extreme ends of the zoom range (your last sentence indicates that you ...


13

First, I'll talk about what cameras do normally, then about how motion affects this operation. In order for an image to be sharp and in focus, all light coming from a single point on the object being photographed must fall on a single point on the film or sensor. If you take a picture of a face, you want all of the light reflecting off the left eye fall on ...


12

No, a higher resolution sensor does not increase the difficulty of handheld shooting. It does mean that is is more difficult to realize the full potential of the higher resolution sensor, but that doesn't mean the results are worse than they would be with a lower resolution sensor.


12

From the comments, it seems like this is your problem — you're probably focusing past infinity. See Why do some lenses focus past infinity? Or, if you're not turning the ring all the way and instead relying on the marking, it may just be that the marking isn't precise enough. Try the suggestions at Where to focus when shooting landscapes? instead.


11

This is achieved by what is known as panning. To explain it simply, you basically follow your subject with your camera (in a panning motion.) It takes quite a bit of practice to get it right, but patience and practice will pay off with great looking shots. More information on capturing moving subjects can be found HERE.


11

First of all you need to use a good resize algorithm for that case. Lanczos, or Photoshop's Bicucbic optimized for reduction. And then to make for better contrast around the letters you can use some output sharpening. Secondly, there is a minimum resolution you can use to render the fine letters. The book is a perfect example because of the different fonts ...


11

The fact you're seeing this with two very different bodies suggests to me it's in the lens. Long zooms tend to have a bunch of elements (anywhere from a dozen to twenty, in my experience). No lens coating is perfect, and no lens surface is perfect. Every time light passes through an air-glass or glass-glass interface at an element surface, there's a small ...


10

When filming a landscape as a whole, I do not want to have the focus on that single tree, but on the whole skyline. mattdm's answer about depth of field is spot-on, so I'll just add a few practical points: Depth of field depends in part on focal distance. That is, for any given aperture setting, depth of field will increase as the distance to the subject ...


10

A sufficiently fast shutter would do it, but that also may very well not be a satalite photo. Google maps also uses arial photos and the detail of the plane in the photo seems too high and the plane too large in comparison to the ground for it to be taken from space. My guess is that the photo was taken from another plane, probably moving in a similar ...


10

Do the math. Let's say the plane is moving at 200 MPH, which is a plausible value right after takeoff or right before landing. Note that the flaps are extended, so one of these is the case. 200 MPH is 89 m/s. There is some blur. I'd say about 250 mm or less motion of the plane during the picture is about the limit that picture is showing us. That would ...


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