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by Jakub

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0

Yes. They are commercially available. http://www.fujifilm.com/products/optical_devices/tv_cine/pdf/fujinon_catalog2015.pdf


2

It is pretty much impossible to build a lens with that wide of an aperture that is also so long. As mentioned, at 200mm the lens opening is 166mm at f1.2. This would be a physically immense lens, even more so a fi it's a zoom. If we restrict ourselves to an aperture that's realistic (say f2.8), the only issue is that such a lens will need to be very, very ...


0

The fastest zoom lens right now is the Sigma 18-35mm f/1.8 Building a 18-200mm f/1.2 might be possible but no one would buy it because it would probably weigh something like 35lbs and cost $35,000 or more.


0

The "only" is one of the problems. A 200mm f/1.2 lens needs an aperture of 166,67mm. That would be a huge, heavy lens! Look at this picture of a 200mm/2.0 prime(!): A large aperture means you need larger glass, too, and grinding large lenses precisely isn't easy. Super zoom lenses are difficult to build and are generally of inferior quality to prime ...


2

Rather than transferring mechanical motion from the camera body to the lens via a mechanical linkage (what Nikon calls a regular diaphragm), in order to control the size of the aperture diaphragm an electromagnetic diaphragm uses a small motor inside the lens to move the diaphragm based on electrical communication between the camera and lens. There are a ...


0

Of course you could always reverse engineer the lens housing completely, first place it in an X-ray machine at different angles to determine the spacing, possible movements, builtin mechanisms etc. Then take it apart physically to inspect the lenses, you can then determine the shape of each lens and its properties. You can also inspect other objects. If you ...


0

With larger mount you can have larger exit pupil diameters. Ratio of entrance pupil and exit pupil is a measure for a lens symmetry. So with larger mount I suppose you can achieve more symmetric designs. The level of asymmetry affects among else depth of field (at given focal length, distance and aperture) and depth of focus. The look of out of focus ...


3

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.


26

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. There are "temporary secrets" where something is closely guarded until it is published: For example, we have completed the final piece of the puzzle in free-form ...


1

Smaller format lenses are eased by having lower maximum image heights and smaller fields of view at the same focal length. Each aberration has explicit field dependencies which describe the rate at which they grow. For the following equations, y is the ray height at the lens and h is image height. Spherical Aberration varies by y3. Coma varies by y2h. ...


1

For Canon, the EF-S was designed to precicely scale down the geometry of EF by the crop factor. SO, the EF-S 17-55 f/2.8 gets its design kick-started by shrinking down the existing design for ... well, they don't make a EF 27-88, so not the clearest example. But I have read that some designs are scaled down. IAC, the rather large 17-55 is 1.6× smaller ...


3

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 is an image from thorlabs: To locate the chief ray, look for the ray bundle beginning from the furthest object point or angle from the optical axis. The ...


4

Cine lenses are designed to minimise focus breathing so that directors can perform large focus pulls quickly without viewers becoming disoriented by the field of view changing. However you can expect to pay five figures for a genuine cine lens (don't be fooled by Samyang/SLRmagic etc. "cine" lenses, they are just DSLR designs with stepless apertures and ...



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