Double lens systems

[novawildcat]

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Say you have a system with two converging lenses, how does it affect the image observed at the end of the system? I'm using the EK shortcuts for determining whether an image is real, inverted, etc. Say you place an object in front of lens #1. I know the image will be real and inverted after it goes through lens 1. Now what happens to the real and inverted image as it goes through lens 2? Does it switch to virtual and upright?

 

[lixxx669]

Say you have a system with two converging lenses, how does it affect the image observed at the end of the system? I'm using the EK shortcuts for determining whether an image is real, inverted, etc. Say you place an object in front of lens #1. I know the image will be real and inverted after it goes through lens 1. Now what happens to the real and inverted image as it goes through lens 2? Does it switch to virtual and upright?

First of all, even a converging lense can produce a virtual image. So if you place your object in front of lens #1, but the distance of the object to the lens is less than f, then the image will be virtual.

For double lenses system, all you need to do is to write some equations:
1/o + 1/i = 1/f
1/(d-i) + 1/i' = 1/f'
where o is object, i is the image of lens #1, f is the focal length of lens #1, d is the distance between lens #1 to lens #2, i' is the image of lens #2, f' is the focal length of lens #2

Thus whether the final image is real of virtual depends on whether i' is possitive or negative, and it depends on the value of o, d, f and f'

 

[Econ2MD]

First of all, even a converging lense can produce a virtual image. So if you place your object in front of lens #1, but the distance of the object to the lens is less than f, then the image will be virtual.

For double lenses system, all you need to do is to write some equations:
1/o + 1/i = 1/f
1/(d-i) + 1/i' = 1/f'
where o is object, i is the image of lens #1, f is the focal length of lens #1, d is the distance between lens #1 to lens #2, i' is the image of lens #2, f' is the focal length of lens #2

Thus whether the final image is real of virtual depends on whether i' is possitive or negative, and it depends on the value of o, d, f and f'

Great explanation. The image from the first lens becomes the object for the second lens.