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Does smartphone angle of view depend only on focal length?
As I understand it, on a 35mm camera if 2 different lenses have the same
focal length then the angle of view would be the same in each case. Is it the same on a smartphone (only focal length determines angle of view) or does sensor size also affect the angle of view? |
Does smartphone angle of view depend only on focal length?
In article , Sam Brown
wrote: As I understand it, on a 35mm camera if 2 different lenses have the same focal length then the angle of view would be the same in each case. only if the sensor size is the same. a '35mm camera' can have at least five different sensor sizes. Is it the same on a smartphone (only focal length determines angle of view) or does sensor size also affect the angle of view? it does, the same as with any camera. |
Does smartphone angle of view depend only on focal length?
On 24/12/2018 10:40, Sam Brown wrote:
As I understand it, on a 35mm camera if 2 different lenses have the same focal length then the angle of view would be the same in each case. Is it the same on a smartphone (only focal length determines angle of view) or does sensor size also affect the angle of view? Both determine the FoV. See: https://www.edmundoptics.eu/resource...field-of-view/ Ffor example. -- Cheers, David Web: http://www.satsignal.eu |
Does smartphone angle of view depend only on focal length?
"Ken Hart" wrote in message
... On 12/24/18 6:10 AM, nospam wrote: In article , Sam Brown wrote: As I understand it, on a 35mm camera if 2 different lenses have the same focal length then the angle of view would be the same in each case. only if the sensor size is the same. a '35mm camera' can have at least five different sensor sizes. A '35mm' _style_ _digital_ camera can have different sensor sizes. An actual 35mm film camera has one sensor size, 24x36mm. (Unless, of course, it is a half-frame 35mm camera, or one of the early 35mm cameras made before the 24x36 standard, but that's a different animal.) Is it the same on a smartphone (only focal length determines angle of view) or does sensor size also affect the angle of view? it does, the same as with any camera. In theory, if the film/sensor size is increased, the angle of view from a given focal length lens will increase, and the magnification of the image will be less. An 80mm lens on a medium format camera (60mm film size) is a 'normal' lens. An 80mm lens on a large format camera (4"X5" film) is a wide angle lens. An 80mm lens on a 35mm film camera (24mm X 36mm) is a long or telephoto lens. (In the real world, a lens is designed to cover a specific film/sensor size. Putting a 35mm camera lens on a 4"x5" camera will most likely give you a small image in the middle of the film.) Very useful. I used an online calculator for field of view but it calculated a narrower horizontal field of view using my smartphone camera's specs (69 degrees) than the smartphone could see (just over 80 degrees). To check this, I printed a protractor and marked on the printed protractor the two limits of the horizontal angle of view I could see on the screen. I drew lines back from these points to the center of the protractor. However when looking through the smartphone with the protractor center was held against the lens, the lines did NOT converge to a point. I could only get the point of convergence (the protractor centre) in the viewfinder if I held the protrector center about 6mm in front of the lens. Presumably this is what is called the "front principal plane" in the page David Taylor linked (figure 2). https://www.edmundoptics.eu/resource...field-of-view/ Is it usual to have the front principal plane of a smartphone quite so far in front of the outer lens element? |
Does smartphone angle of view depend only on focal length?
In article , Sam Brown
wrote: Is it usual to have the front principal plane of a smartphone quite so far in front of the outer lens element? you're way overthinking this. generally, camera makers give a 35mm equivalent because that's what people are familiar with. use that as a guide to compare. |
Does smartphone angle of view depend only on focal length?
"nospam" wrote in message
... On 22:20 24 Dec 2018, "Sam Brown" wrote in : "Ken Hart" wrote in message ... On 12/24/18 6:10 AM, nospam wrote: In article , Sam Brown wrote: As I understand it, on a 35mm camera if 2 different lenses have the same focal length then the angle of view would be the same in each case. only if the sensor size is the same. a '35mm camera' can have at least five different sensor sizes. A '35mm' _style_ _digital_ camera can have different sensor sizes. An actual 35mm film camera has one sensor size, 24x36mm. (Unless, of course, it is a half-frame 35mm camera, or one of the early 35mm cameras made before the 24x36 standard, but that's a different animal.) Is it the same on a smartphone (only focal length determines angle of view) or does sensor size also affect the angle of view? it does, the same as with any camera. In theory, if the film/sensor size is increased, the angle of view from a given focal length lens will increase, and the magnification of the image will be less. An 80mm lens on a medium format camera (60mm film size) is a 'normal' lens. An 80mm lens on a large format camera (4"X5" film) is a wide angle lens. An 80mm lens on a 35mm film camera (24mm X 36mm) is a long or telephoto lens. (In the real world, a lens is designed to cover a specific film/sensor size. Putting a 35mm camera lens on a 4"x5" camera will most likely give you a small image in the middle of the film.) Very useful. I used an online calculator for field of view but it calculated a narrower horizontal field of view using my smartphone camera's specs (69 degrees) than the smartphone could see (just over 80 degrees). To check this, I printed a protractor and marked on the printed protractor the two limits of the horizontal angle of view I could see on the screen. I drew lines back from these points to the center of the protractor. However when looking through the smartphone with the protractor center was held against the lens, the lines did NOT converge to a point. I could only get the point of convergence (the protractor centre) in the viewfinder if I held the protrector center about 6mm in front of the lens. Presumably this is what is called the "front principal plane" in the page David Taylor linked (figure 2). https://www.edmundoptics.eu/resource...notes/imaging/ understanding-focal-length-and-field-of-view/ Is it usual to have the front principal plane of a smartphone quite so far in front of the outer lens element? In my case this made a significant difference. By pulling the camera back 6mm from the point at which the lines seems to converge, it increased the angle of view (horizontally) by 10 degrees. It's almost pointless having a 35mm equivalent is it is so wrong. I was asking if anyone knew the the explanation. |
Does smartphone angle of view depend only on focal length?
On Mon, 24 Dec 2018 06:10:09 -0500, nospam wrote:
In article , Sam Brown wrote: As I understand it, on a 35mm camera if 2 different lenses have the same focal length then the angle of view would be the same in each case. only if the sensor size is the same. a '35mm camera' can have at least five different sensor sizes. Can you please clarify this? I thought that "35mm camera" meant a camera with a 36x24mm sensor. Ciao, Alberto -- http://www.phototeleport.com - Open source, multi platform photo uploader Blog personale: http://blog.mardy.it |
Does smartphone angle of view depend only on focal length?
In article , Alberto Mardegan
wrote: As I understand it, on a 35mm camera if 2 different lenses have the same focal length then the angle of view would be the same in each case. only if the sensor size is the same. a '35mm camera' can have at least five different sensor sizes. Can you please clarify this? I thought that "35mm camera" meant a camera with a 36x24mm sensor. you thought wrong. a '35mm camera', aka an slr, can have sensors in various sizes, including full frame, 1.3x, 1.5x, 1.6x, 1.7x, 2x and 2.6x. full frame is 24x36mm, with the rest progressively smaller. that's seven different sizes, not counting video modes, although two of those are obsolete and can be ignored. in some cases, the same camera supports more than one size. for example, nikon full frame cameras will automatically switch to 1.5x dx mode when a dx lens is attached because that's what dx lenses are designed for. that can also be overridden because some dx lenses cover a wider image circle at some focal lengths, or the photographer wants the vignette effect. https://www.oreilly.com/library/view...18530818/image s/ch002-f002.jpg there is also a 1.3x crop mode on some nikon dx slrs (already 1.5x), which is roughly 2x. https://imaging.nikon.com/lineup/dslr/d7100/features01.htm#a10 The D7100 features two image areas for still images ‹ DX format (23.5 x 15.6 mm) and 1.3x crop of DX (18.8 x 12.5 mm). tl;dr - the field of view of a given lens can vary, depending on which camera it's attached to and the settings on the camera. |
Does smartphone angle of view depend only on focal length?
On Thu, 27 Dec 2018 07:11:38 +0000 (UTC), Alberto Mardegan
wrote: On Mon, 24 Dec 2018 06:10:09 -0500, nospam wrote: In article , Sam Brown wrote: As I understand it, on a 35mm camera if 2 different lenses have the same focal length then the angle of view would be the same in each case. only if the sensor size is the same. a '35mm camera' can have at least five different sensor sizes. Can you please clarify this? I thought that "35mm camera" meant a camera with a 36x24mm sensor. A 35mm camera is a camera which uses 35mm movie film. These come is sveral different frame sizes using one or two movie frames. i.e. 3/4" x 1" or 1.5" x 1". Some cameras metricated the dimensions with the result that there are also frame sizes of 19mm x 25mm and 36mm x 25mm. The double-frame cameras predominated and their physical form factor set the pattern for the earlier digital cameras. Although digital cameras do not use film some people still refer to them as '35mm cameras', but they are not. The image sensor size of first commercialy viable digital cameras were not derived from the frame size of 35mm film. -- Regards, Eric Stevens |
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