My Broom Pro

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mtnbowhunter
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Re: My Broom Pro

Post by mtnbowhunter » 29 Mar 2015, 00:20

is there any relationship to field of view and sensor size when using the m42 lenses??
for example - would a 2/3in sensor give a larger field of view than a 1/3in sensor???
Toni, using your zenith 10mm lens, what would your field of view be aty 100 yards?

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Torchwood
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Re: My Broom Pro

Post by Torchwood » 29 Mar 2015, 00:34

mtnbowhunter wrote:is there any relationship to field of view and sensor size when using the m42 lenses??
for example - would a 2/3in sensor give a larger field of view than a 1/3in sensor???
Toni, using your zenith 10mm lens, what would your field of view be aty 100 yards?
Most digital camera sensor measures 36x24mm which is approximately the same size as 35mm film. The sensors we use are much smaller, most of the image get lost without hiting the sensor. This can work well for us, as most lens manufacturer concentrate on the central area on the lens, so the image in the center is much sharper than the edge, that's why even cheap SLR lenses can produce a good quality. If you use a larger sensor, simply you'll see more of the image.

100mm Zenit will give see around 30yards at 100m. Just a pure guess :D

Toni
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mtnbowhunter
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Re: My Broom Pro

Post by mtnbowhunter » 29 Mar 2015, 03:34

if you can get 30yds FOV@100yds from the zenit 100mm that is really good, of course it is a big dia. lens

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MrNewbie
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Re: My Broom Pro

Post by MrNewbie » 29 Mar 2015, 03:45

I don't understand this whole FOV concept.
What does the FOV have to do with the size of to CCD pickup.
I dunno, I must be missing something here.

If you want a large FOV go to a 50mm lens, for a smaller FOV go to a 75 or larger. Simply larger lens= smaller FOV or more zoom.
Is not the size of the CCD pickup 2/3, 1/2 more related to the amount of light it can gather

Paul1961
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Re: My Broom Pro

Post by Paul1961 » 29 Mar 2015, 05:39

If you want to understand it a bit easier , grab a magnifying glass, hold if close to a wall or similar such that you can see the image formed. If the sensor is small the amount of the projected image seen by the sensor will also be small compared to a bigger sensor. So given what you see on the screen of your TV system is what the sensor sees, a smaller sensor will see less of the projected image, which makes it look more magnified on the TV screen when compared to a larger sensor.
Dunno if I've helped.

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Torchwood
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Re: My Broom Pro

Post by Torchwood » 29 Mar 2015, 09:10

mtnbowhunter wrote:if you can get 30yds FOV@100yds from the zenit 100mm that is really good, of course it is a big dia. lens
Fair enough if looking at it for magnification, I was talking about the sensor and the image.
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M42 or SLR lenses project outside the sensor, larger sensor will see more of the image, it dosent mean more magnification but more field of view. ( in fact you will have less magnification and much sharper picture)

It's like covering your 50" tv with a large board, have a cut out of 32", can you see the picture outside the cut out?

Sensors and projected image works the same.



Toni
Last edited by Torchwood on 29 Mar 2015, 09:16, edited 3 times in total.
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phoenix
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Re: My Broom Pro

Post by phoenix » 29 Mar 2015, 09:11

FOV depends both on the focal length of the lens and the size of sensor.
What confuses many people is that lenses marked 50mm or 75mm or whatever, often relate to their use with 35mm film.
These lenses project a circle of light which is large enough to cover a piece of 35mm film, which in practice is a 43mm circle.
If a smaller sensor (such as a 1/2 or 1/3 ccd) is used instead of film, then only a small portion of the circle of light produced by the lens will hit the sensor, and only the light hitting the sensor can be used to produce the image you see on your screen.
Since the sensor is much smaller, it only sees a reduced portion of the FOV of the lens.
Have a play with this link and try different size sensors with the same focal length lens and see how the FOV (or angle of view) changes
http://www.radical.org/aov/
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Torchwood
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Re: My Broom Pro

Post by Torchwood » 29 Mar 2015, 09:22

MrNewbie wrote:I don't understand this whole FOV concept.
What does the FOV have to do with the size of to CCD pickup.
I dunno, I must be missing something here.

Is not the size of the CCD pickup 2/3, 1/2 more related to the amount of light it can gather
1/2" sensor can pick up less light than a 1/4" sensor. It's all to do do with sensor reslution not the size :D

You can have a low reslution 1/2 sensor that can collect less light than a 1/4 higher reslution sensor. But 1/2 sensor will see more of the image than 1/4 sensor.


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phoenix
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Re: My Broom Pro

Post by phoenix » 29 Mar 2015, 11:01

Toni,
I'm sorry, but you're wrong about sensor resolution and size.
FOV is all to do with sensor size and focal length, sensor resolution doesn't come into it.
Use this to calcluate the FOV for any combination of focal length and sensor size - note that the sensor resolution is not required to get the correct answer. http://www.radical.org/aov/
The total amount of light collected by a sensor is directly related to it's size.
The bigger the sensor, the more light it will collect
The number of pixels in the sensor control the resolution - more pixels equals higher resolution.
The sensitivity of a sensor is controlled by the size of the individual pixels - bigger pixels are more sensitive than smaller pixels (because they have a larger surface area for the light to hit.
If you want high resolution (lots of pixels) and high sensitivity (big pixels) you need a physically large sensor so there's enough space for all the pixels.

Cheers

Bruce
LAND ROVER - THE WORLD'S WORST 4X4 BY FAR

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Torchwood
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Re: My Broom Pro

Post by Torchwood » 29 Mar 2015, 11:17

phoenix wrote: Toni,
I'm sorry, but you're wrong about sensor resolution and size.
FOV is all to do with sensor size and focal length, sensor resolution doesn't come into it.
That was sort of thing I was saying, just not articulating as good as you :D

I was saying the about relativity of sensor size to the field of view or the projected image size. Than I got cought up in pixels a bit :lol:

Toni
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