petrochemist

Peripheral vision is not relevant which is what your quoted angles relate to. Normal focal lengths on FF are usually considered to include 43-58mm  There are fairly examples of both extremes as ...

These values are FOCAL LENGTHS, length on it's own implies the size, while focal length indicates how much of a scene is included in the image. With simple lenses the focal length is the distance ...

If you look at the later 2/3 of my post you'll see it all relates to photography. Different red filters give very different images. Perhaps photographing glass blowing or stars aren't realms of ...

I doubt I've ever needed the speed of light more accurately than the 3x10^8 ms-1 approximation I learnt at school. 'Red' is an extremely imprecise descriptor. Both wratten #25 & #29 filters are ...

I'd be inclined to agree. There are several bits with a fibrous white bit within a more diffuse patch, which I would say look like early fungus. The more prominent white bits without the halo are ...

That is indeed how the meter USED to be defined, but it proved too inexact so the definition has been revised (1983) to the distance light travels in a vacuum in 1/299 792 458 s Fortunately knowing ...

On a compact equivalent focal length might be adequate, but on a crop camera with removable lenses the TRUE focal length can be important. An example is when adding extension tubes, or combining ...

I'd recommend a tripod if there's any need for dealing with low light. Architectural subjects don't move during long exposures & blurring any people in the shot can be a distinct advantage, so ...

i believe this is a close up auxiliary that screws onto the front of the cameras lens. Such devices are often (wrongly) called 'close up filters'. When but in front of your camera they make the ...

You need a suitable adapter ring. The series filters predate modern metric sizes. I've not seen them in series 9, but there must be a few out there (even if mot directly to 92mm). Most of my series ...

The mechanical connection to the camera varies by mount type. In the case of adaptall lenses it's a sprung loaded plate around the rear optic, which is in turn operated by levers in the mount ...

Vaseline can certainly produce the effects seen in the images. But as Isabella B is confident something clamped in front of the lens was used I think it highly likely the new lensbaby Omni system ...

In principle the same as a Newtonian telescope perhaps, even if most avoid the second reflector, instead placing the sensor at the focal point of the main mirror. Normal photographic mirror lenses ...

I have several converted cameras, including a couple that can be converted easily without any tools. My old Sigma SD14 bodies have a clip in dust filter, that also works as the internal IR block. ...

IR needs long exposures with a standard camera because the camera has a built in filter to block those IR wavelengths. If the filter is removed (the camera is IR converted) IR exposures in ...

I had a vague memory of those mapping function images, but the page has changed quite a bit since i last looked at it. I suspect one of my fisheye converters is close to orthographic It doesn't get ...

Actually a large proportion of shorter focal length CCTV lenses will not. Many of these are CS mount which requires the lens flange to be 6.7mm behind the cameras flange for infinity focus. In ...

I've found a note that the 'Yasuhara - Madoka 180 circular fisheye' is an orthogonal example. Thanks the samyang 12/2.8 is now added to my camera reference notes :)

The first shot shows a distant background & a relatively close subject both in focus. So the blur is not down to DOF of I suspect the lens at all. It certainly shows signs of long exposure, which ...

They claim coverage of non full frame sensors, but surely that depends very much on the lens. Several of the c-mounts I've tried on MFT have been a long way short of covering that format. Coverage ...