Field of View of lenses A , C2 , D

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I just learned about the D lens last week and ordered one to use as a rear camera since the A lens unit I have regularly fails to save the last video. The field of view is much less than I expected so I measured the horizontal field of view of the D as well as a C2 lens.

D full sensor 1080p: 100 degrees horizontal
D crop sensor 1080p: 80 degrees horizontal

C2 full sensor 1080p: 130 degrees horizontal
C2 crop sensor 1080p: 110 degrees horizontal

A full sensor 1080p: 80 degrees horizontal
A crop sensor 1080p: Haven't tested yet but probably under 70 degrees horizontal
 

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How do you come up with these measurements?

According to Eletoponline365 (the Mobius manufacturer's eBay outlet) The D lens has a horizontal FOV of 130º and the C2 lens has a horizontal FOV of 135º

https://vi.vipr.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=162595466790&t=1508318843000&tid=10&category=3323&seller=eletoponline365&excSoj=1&excTrk=1&lsite=0&ittenable=false&domain=ebay.com&descgauge=1&cspheader=1&oneClk=1&secureDesc=1
C2lens.png

http://www.ebay.com/itm/152353033475
Dlens.png


While we're on the subject, the new A2 lens is approximately 90º horizontal FOV (very similar to the original A lens but with less barrel distortion.)

http://www.ebay.com/itm/162585601608
alens.jpg
 
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I printed a protractor and placed the camera with the lens at the center
 
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Such a method is way too crude to accurately determine lens coverage.
How is it crude? It's literally measuring the field of view of the lens. I also held a pencil vertically and moved to each 10 degree increment and called out the measure, but that's not necessary
 

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How is it crude? It's literally measuring the field of view of the lens. I also held a pencil vertically and moved to each 10 degree increment and called out the measure, but that's not necessary
Well, as for crudeness, your results for one thing, especially the D lens measurement. The accuracy of your method would fall off exponentially the farther you get from lens. I've actually tried your method quite some time ago and it never matches the real world actual FOV at a distance. FOV, as seen by a lens projecting into a sensor is an optical phenomenon that is only vaguely related to the angle you can measure with a protractor. It's just not that literal.

Your approach to this is reminiscent of your claim that you can hold an M12 lens up to the light and determine the aperture by observing the size of the hole you see inside the lens.
 
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Well, as for crudeness, your results for one thing, especially the D lens measurement. The accuracy of your method would fall off exponentially the farther you get from lens. I've actually tried your method quite some time ago and it never matches the real world actual FOV at a distance. FOV, as seen by a lens projecting into a sensor is an optical phenomenon that is only vaguely related to the angle you can measure with a protractor. It's just not that literal.

Your approach to this is reminiscent of your claim that you can hold an M12 lens up to the light and determine the aperture by observing the size of the hole you see inside the lens.
You have no idea what you're talking about just like you had no idea what pixel binning is. Accuracy doesn't "fall off with distance". If anything it's MORE ACCURATE with distance because the convergence point of the lens becomes less relevant. The horizontal field of view is literally the angle that the lens sees horizontally. I really don't understand what your motive is here. Do you have some interest in claiming that field of view is "not that literal"?
 
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You're talking about calculating field of view based on lens and sensor specifications. I'm talking about physically MEASURING actual field of view of the actual lens and camera system.
 

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You have no idea what you're talking about just like you had no idea what pixel binning is. Accuracy doesn't "fall off with distance". If anything it's MORE ACCURATE with distance because the convergence point of the lens becomes less relevant. The horizontal field of view is literally the angle that the lens sees horizontally. I really don't understand what your motive is here. Do you have some interest in claiming that field of view is "not that literal"?
It's trigonometry, friend. Notice that the calculation includes distance.
 
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It's trigonometry, friend.
No trigonometry is required if you're measuring the angle directly with a compass. Do you believe that measuring angles is impossible? If so, I'd like you to go and do some research into surveying or land navigation, both of which depend heavily on measuring angles.
 
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Trigonometry is required to CALCULATE angle FROM distances. You can also measure an angle directly.
 

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You seem to enjoy indulging in a lot of magical thinking when it comes to all things phtographic, even after posting grossly inaccurate results. I guess that's your privilege but don't expect others to go along.
 

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https://www.edmundoptics.com/resources/application-notes/imaging/understanding-focal-length-and-field-of-view/

Perhaps the key sentence is this whole article as far as you method is concerned is the following:

"In practice, the vertex of this triangle is rarely located at the mechanical front of the lens, from which working distance is measured, and should only be used as an approximation unless the entrance pupil location is known."

Your method of placing the camera on a piece of paper with a protractor printed on it ignores the optical plane deep inside the lens.
fov2.jpg

Land surveying and navigation is different than lens optics.
 
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I'm not ignoring it at all. I specifically mentioned it above. But the convergence point for the light rays is within millimeters of the front of the lens. It's not enough to make a difference. It would matter for a DSLR which is a much larger system

There is no magical thinking here. Did you read that term somewhere and just decide to apply it randomly? You're the one who somehow believes that measuring angle of view is impossible and that only theoretically calculating it from lens specs and sensor size is possible. You're a know-it-all who has repeatedly been wrong and seem to take joy in pretending you know more than others. Have you figured out pixel binning yet? Tired of this neckbeard nonsense.

 

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Well, of course you are "ignoring all that". It's so amusing that someone like you who posts wildly inaccurate results vehemently defends his methodology. Again, this is exactly the same as when you insisted that holding a lens up to the light and looking through it is somehow a valid methodology of determining the lens's aperture.

Let's see, if, as you say, "the convergence point for the light rays is within millimeters of the front of the lens, It's not enough to make a difference......."so how much difference in FOV might we expect from a 3mm focal length lens compared to a 6mm focal length lens? Gee, I guess a few millimeters must not be enough to make a difference. :wacky:
 
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Well, of course you are "ignoring all that". It's so amusing that someone like you who posts wildly inaccurate results vehemently defends his methodology. Again, this is exactly the same as when you insisted that holding a lens up to the light and looking through it is somehow a valid methodology of determining the lens's aperture.

Let's see, if, as you say, "the convergence point for the light rays is within millimeters of the front of the lens, It's not enough to make a difference......."so how much difference in FOV might we expect from a 3mm focal length lens compared to a 6mm focal length lens? Gee, I guess a few millimeters must not be enough to make a difference. :wacky:
First of all, yes the size of the hole viewed through the front of the lens divided into the focal length is the aperture. If you have a 35mm DSLR lens and you look through the front and it appears to be 10mm wide, that's an F3.5 lens. The F3.5 means 1/3.5 I didn't make that up, it's literally what aperture means.

A step by step guide to physically measuring aperture by looking at the apparent size of the hole is here and I didn't write this: https://apenasimagens.com/en/measuring-lens-aperture/


There is nothing wildly inaccurate here.

You're acting like a moving the camera a few mm forward and backward makes a difference when measuring an angle on a protractor the size of a sheet of paper. It's not enough to matter. This has nothing to do with focal length which is a totally different thing.
 

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First of all, yes the size of the hole viewed through the front of the lens divided into the focal length is the aperture. If you have a 35mm DSLR lens and you look through the front and it appears to be 10mm wide, that's an F3.5 lens. The F3.5 means 1/3.5 I didn't make that up, it's literally what aperture means.

A step by step guide to physically measuring aperture by looking at the apparent size of the hole is here and I didn't write this: https://apenasimagens.com/en/measuring-lens-aperture/


There is nothing wildly inaccurate here.

You're acting like a moving the camera a few mm forward and backward makes a difference when measuring an angle on a protractor the size of a sheet of paper. It's not enough to matter. This has nothing to do with focal length which is a totally different thing.
Actually measuring and calculating a lens aperture of a large vintage camera lens by evaluating the entrance pupil and focal length and applying a complex mathematical formula as discussed in your link is a quite a bit different than what you do which is to hold an M12 dash camera lens up to the light, look through it and say, "Yup, looks like it's about an ƒ/2 to me. :woot:

And on an M12 lens the focal length of a single millimeter or two such as between as between a 4 milliliter lens and a 6mm lens is significant but you apparently don't think so. If your methodology is so good then how did you manage to conclude that a 130º FOV lens is only 100º FOV?

And you continue arguing your point desite your results. I'm tired of this silliness.
 
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You are confusing two things. Focal length and sensor size are what determine the field of view.

What you're referring to with the inaccuracy in MEASURING field of view is placement of the camera on the printed protractor. Shifting the camera forward or back affects how much of the perimeter is visible. The camera SHOULD be placed so the convergence point is at that middle of the circle.

BUT a few millimeter difference in placement is not relevant.

Again, that is entirely different from focal length.
 

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[
You are confusing two things. Focal length and sensor size are what determine the field of view.

What you're referring to with the inaccuracy in MEASURING field of view is placement of the camera on the printed protractor. Shifting the camera forward or back affects how much of the perimeter is visible. The camera SHOULD be placed so the convergence point is at that middle of the circle.

BUT a few millimeter difference in placement is not relevant.

Again, that is entirely different from focal length.
Hey, if you say so! But you are still ignoring the information in post #14, so I'll say it one more time....using your method, you measured the D lens at 100º FOV, fully 30º off from the actual FOV. Have fun!
 
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