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 ...


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 ...


47

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 ...


42

Shooting blurred photos can be considered opposite of black and white photography - while black and white is about hiding colors to bring out shapes and shadows, blurring helps to reveal colors by hiding shapes and shadows. An interesting subcategory is a combination of the opposites - black and white blurs - where distractions by both details and colors are ...


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 ...


25

While using shallow depth of field is the most common technique to get blurred background, there are some other ways: using plain background so it would not need any blurring set up your own background - you'll have full control over color and pattern shoot against sky or some other plain surface (longer lens will help you by having smaller segment of ...


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

There is NO difference at ALL because the physical aperture has not changed. The Fuji Finepix S4000 simulates a small aperture using an ND filter. When you stop-down the ND filter slides into the optical path. The Aperture written in the EXIF data is adjusted to reflect the transmittance of the ND filter, but note that since the size of the opening has not ...


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 ...


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

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

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 ...


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.


14

Firstly I notice your aperture is set at 1.8. This will make DOF very narrow, making focusing very difficult. Also your camera is very good at higher iso, so try using 1600 / 3200 initially. Try setting the following. Use auto focus to focus on something with a defined edge (the tops of the trees?), then switch to manual to keep the focus. Use a higher iso, ...


14

You're confusing the blur in the background that's due to having a shallow depth of field with motion blur from a long exposure. The exposure length has pretty much nothing to do with it here. It's all about the aperture. (And if you want to change your composition, the distance to the subject.) Depth of field has been covered in great length on the ...


14

It is indeed a rule that comes from film cameras. On point 4 the answer is simple: Multiply the focal length with the crop factor of your sensor. Because the sensor is smaller than a full frame sensor, it will not cover the full image circle, cropping out a smaller image. This has the effect of looking like a longer focal length. E.g. on Canon, a 50mm ...


13

One more suggestion: if the picture is meant to be a background for something else (like a computer desktop, a printed page or a work of art), then the "something else" forms the foreground of the resulting work, and the picture in the background should not excessively distract the viewer from it. Thus, a completely blurred or defocused picture may be ...


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

Well if you're just talking about motion blur from your handheld shakiness - pretty much all the modern IS/VR/OS designs handle 1-stop differences pretty well. 1/30th at 105mm might be pushing it, but most current IS designs handle a two stop difference well, especially if you're a somewhat steady person. At the claims of 3-4 stops is really where things ...


12

I did some quick Google Books searches, and while I can't pinpoint the origin, there are a number of references to it as a rule of thumb or general guideline in the early 1970s, and none that I can find before that. There are plenty of earlier references to the idea that a longer focal length requires a faster shutter but they're all general advice. The ...


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