Brandon Dube
  • Member for 6 years, 6 months
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Are there any secrets in lens design?
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29 votes

In general there are no secrets to lens design. Everything important, all breakthroughs, etc., are shared publicly or semi-privately with modification through patents, conferences, papers, etc. ...

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What swirly bokeh technique is this and how can I achieve it?
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26 votes

This photo is taken with a petzval lens which corrects all aberrations decently except for, well, petzval aka field curvature. Because the edges are in focus at a further distance, the blur is ...

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What is this rainbow-effect when photographing through curved (cylindrical) glass called?
11 votes

Does your camera have a polarizing filter on it? This looks like stress induced birefringence.

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What's the opposite of a fisheye lens?
10 votes

A fisheye lens isn't designed to have extreme barrel distortion -- the distortion is the result of trying to map a sphere onto a plane. A regular lens follows the equation image height = focal length ...

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Why do mirrors give less sharpness, gamut, and contrast than lenses?
10 votes

Mirrors are better than lenses in that they are inherently free of chromatic aberrations, and are reflective over very wide spectral bandwidths. For these reasons, they are very attractive design ...

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Are there lenses that exhibit absolutely no focus breathing?
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9 votes

If you are looking for a macro lens that does not noticeably breathe, the best one that I know of is the $1800 Zeiss 100mm f/2 Makro-Planar. The Canon 100L and non-L are both quite bad for this, and ...

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Determining the size of the smallest resolvable detail for a given camera
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8 votes

If you want tens to hundreds of pixels per 50 micron area, you need a microscope. Based on your object size, with that resolution, you want at least 10px/50um * 3000um/50um a 600px wide view of your ...

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What are the production cost breakdowns for lenses?
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6 votes

Price of materials Optical glass and glass-like materials is priced according to a fairly unique model. The most ubiquitous glass, Borosilicate Crown glass is used as a base price and other ...

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How can I experimentally determine the size of my lens’s aperture?
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6 votes

One method is to use the camera to make the measurement. This is actually surprisingly accurate, and is how most T stop measurements are done with a single reference measurement using a ...

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Does the same focal length on the same camera always result in the same FOV?
5 votes

If two lenses have exactly the same focal length and exactly the same amount of distortion, then on a camera they have the exact same field of view. The exception is when you get to very wide angle ...

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How does sensor size affect the brightness of an image given the same field of view and aperture?
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5 votes

The image brightness will be the same. The entrance pupil size does not matter for image brightness - what matters is only the F number (or more accurately, T number which is equal to the true f ...

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How is focus-breathing controlled in lens design?
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5 votes

A lens that is truly telecentric in image space necessarily has no focus breathing. That is to say, the chief ray is parallel to the optical axis between the rear element and the image plane. Here ...

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How many times is the image inverted inside a DSLR camera?
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4 votes

The image forming lens flips the image once. For the imaging sensor, there is one flip. The viewfinder is made up of a fold mirror, the one in the mirrorbox of the camera, a focusing screen, and ...

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What would happen if a camera used entirely different primary colors?
4 votes

The intensities recorded by each specialized pixel can be mapped to the hue spectrum below. The Bayer matrix does not map to any color. The image is interpolated to yield a full-color-per-pixel ...

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What is the cause of this non-uniform bokeh effect?
4 votes

To build on the other answers, this is indeed caused by a lens with undercorrected petzval. It is also vignetted, but more in one plane than the other. Here you can see a ray intercept plot for a ...

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Why does the autofocus capability depend on the aperture rather than the amount of light available?
3 votes

Here's a diagram of phase detect autofocus When the image is in focus, (2), the two pencils of light go to the same place. When it's out of focus, they go to different places (1, 3, or 4). The two ...

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How would apodization impact landscape photography?
3 votes

First, consider what apodization is. It is the intentional gradual vignetting of a lens, with the intention, typically, of producing better bokeh. Think of it like a radial graduated ND filter being ...

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How can I increase the flange focal distance (back focal length) of DSLR lens?
3 votes

You cannot alter the back focal length of a lens without changing its optics. Specialized adapters exist to do this, but there is usually a large loss of image quality. Your best bet is to not use ...

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How do I connect Leica Summicron-M 1:2/50 E39 lens to Canon EOS 5D body?
3 votes

This is not possible. The flange distance of M mount is 27.8mm while EF mount is 44mm. The lens would function as an extreme macro lens only on EF mount, so no one makes Leica M to Canon EF adapters....

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What lens design limits derive from the width of the lens mount?
3 votes

The mount's throat diameter limits the exit pupil diameter. It also has strong control over vignetting, so it restricts the pursuit of ultra-large aperture lenses with acceptable light falloff.

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What Kelvin-range of "white balance" does the human vision compensate?
3 votes

This one is complicated. The natural response of your eye in well-lit conditions is known as the photopic response. When the light goes down a bit, your eye switches to Mesopic vision, essentially ...

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Is it possible to commission a custom lens that would significantly outperform stock lenses?
2 votes

Your question boils down to "is the 25/2 Batis the pinnacle of optical design; is it not possible to do any better." The answer is no; it is a local optimum of performance size and price. Some ...

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change HUE in photoshop with true RGB?
2 votes

RGB is a color space, but with dimensions of a red primary, green primary, and blue primary, it is not one which has any inherent notion of lightness, saturation, or hue. To make adjustments to ...

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Can deconvolution help improve the apparent sharpness of mirror lenses?
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2 votes

for a mirror lens, we [or Samyang] know the geometry of the lens pretty exactly, and hence its point spread function. The first part of this sentence does not naturally give rise to the second. ...

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Can the antialiasing filter be removed to get sharper images?
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2 votes

No, it would not make sense to do this. The first reason is because the optical low pass filter (OLPF) and sensor are often glued together to help with flare issues, making this operation impossible ...

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What is this Angenieux lens?
2 votes

This is one of the earlier long range zooms for TV / motion picture. Many generations later, your lens is now this beast weighing in 13kg and costing $100,000.

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Image Stacking for noise reduction using MATLAB
2 votes

Your noise may not be zero mean, but the larger issue is that you are adding to a uint8 array. These values go up to 255, and will overflow likely by the second image. You should do your ...

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Why is the area in focus in front of the focus distance narrower than behind it?
2 votes

Depth of field is all about angles and being able to tell a difference between them. As things get further away, the angles change less and less. If you move forward 1m at a distance of 2m, you may ...

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What is the T Stop of a Human Eye?
2 votes

Your eye can be treated exactly like a camera lens, and its maximum f/# really is around f/2.2 or so. The cornea has an index of refraction of around 1.33, so the fresnel reflections are around 2% or ...

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How do zoom lenses restrict their widest aperture at the telephoto end?
2 votes

Whether a zoom lens is constant aperture or variable aperture has first to do with the design, a secondly to do with mechanical factors like opening or closing a diaphragm. A zoom lens works by ...

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