Geometrical optics and focuser
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Geometrical optics and focuser
I've been playing with geometrical optics of two lens system, and it looks like the image is always formed, either true or false - except when the object to a lens is at its focal point.
Is it because of the eye, or because of other properties not described by geometrical optics?
And why should the focal lengths of the objective and eyepiece overlap (false image)?
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Re: Geometrical optics and focuser
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Re: Geometrical optics and focuser
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Re: Geometrical optics and focuser
Also the angle that a lens "bends" the beam doesn't depend on the distance.
But I guess, it has to do with the eye: whether or not the image forms on the retina, in front of it, or behind it?
To get it, I should study 3 lens systems with true final images?
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Re: Geometrical optics and focuser
Yes.turboscrew wrote: ↑Tue Jan 12, 2021 4:56 am But I guess, it has to do with the eye: whether or not the image forms on the retina, in front of it, or behind it?
No because the shape of the human eye leads to a nearly fixed focus lens. For comfortable viewing the rays must come in parallel. They may diverge a bit but then the eye's lens must work to focus. So just assume parallel. Then there's not that much to study really.turboscrew wrote: ↑Tue Jan 12, 2021 4:56 am To get it, I should study 3 lens systems with true final images?
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Re: Geometrical optics and focuser
Re-reading it, what I meant to say is that a parallel light bundle (for instance from a star at infinity) must be processed by the optics into a parallel light bundle emerging from the eyepiece, for most comfortable viewing by the human eye. Of course the rays coming from different stars are not parallel but the rays contained in the light bundle of each individual star, are.SkyHiker wrote: ↑Tue Jan 12, 2021 9:31 amYes.turboscrew wrote: ↑Tue Jan 12, 2021 4:56 am But I guess, it has to do with the eye: whether or not the image forms on the retina, in front of it, or behind it?No because the shape of the human eye leads to a nearly fixed focus lens. For comfortable viewing the rays must come in parallel. They may diverge a bit but then the eye's lens must work to focus. So just assume parallel. Then there's not that much to study really.turboscrew wrote: ↑Tue Jan 12, 2021 4:56 am To get it, I should study 3 lens systems with true final images?
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Re: Geometrical optics and focuser
https://www.physicsforums.com/attachments/3-png.184389/
In the above image, the role of the focuser is to place the
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