How can I determine the properties of a thin lens using basic formulas?

In summary, the conversation discussed finding the effective focal length, power, surface curvature, radius of curvature, format size, and Airy disk diameter for a lens with a known focal length and shape. The formula for finding the focal length was used to solve for the other values, except for the format size which was not clearly defined. The formula for surface curvature was mentioned and recommended to be found in a textbook or notes.
  • #1
AaronBurr
5
0

Homework Statement


I've tried to attached the image of the diagram. If that isn't working please let me know.Height of incident marginal ray now 25. Assume a thin lens.
Find:
a. the effective focal length
b. the power of the lens
c. surface curvature for front and back surfaces (assume equiconvex shape)
d. radius of curvature for each surface
e. format size (assume square)
f. Airy disk diameter

Homework Equations


a. the effective focal length
1/f=1/u+1/v
F=1/2*r

b. the power of the lens
p=1/f

c. surface curvature for front and back surfaces (assume equiconvex shape)
C=1/R

d. radius of curvature for each surface
F=1/2*r

e. format size(assume square)

f. Airy disk diameter
=2.44*λ*f ⁄#

The Attempt at a Solution


With the known formulas I don't think I have enough information to solve anything besides f. and the solution to part f doesn't help solve the other parts. If I can just find the focal length I think the rest will fall into place.Can you point me towards whatever bit of information I'm missing?

Thanks so much.
 

Attachments

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  • #2
The f-number is the ration of the focal length to the diameter of the entrance pupil.
 
  • #3
Thank you so much! I knew I was just missing something obvious! I think I've got parts a, b, c, d, and f correct. But I'm still a bit unsure of what is being asked in part e? I don't know what they mean by format size. Any ideas? Again thank you for your help.

a. the effective focal length

F-number=f/d
1/10=f/25mm
F=5/2

b. the power of the lens

p=1/f
p=1/(5/2)
p=2/5c. surface curvature for front and back surfaces (assume equiconvex shape) (Both lens have same radius of curvature)

C1=1/R
C1=1/5

d. radius of curvature for each surface

f=1/2*r
R1=2*f
R=2*(5/2)
R=5

e. format size(assume square)

??

f. Airy disk diameter

=2.44*λ*f⁄#
=2.44*587nm*1/10
=143.228
 
  • #4
F = f / D
10 = f / 50 mm ...
The optical power of the lens, P, is in diopters, D, if f is in meters.
The surface curvature of a lens, C, also in diopters, is much more complicated than that of a mirror.
It is the inverse of the radius of curvature, r, in meters, of the lens.
Have a look in your textbook or notes for the formula.
 

1. How do I find the lens information on my camera?

To find the lens information on your camera, look for a label or sticker on the lens itself. It should have the brand, model, and other specifications such as focal length and aperture. If you are unable to find this information on the lens, you can also check the camera's manual or the manufacturer's website for more details.

2. What is the importance of knowing the lens information?

Knowing the lens information is important because it helps you understand the capabilities and limitations of your camera's lens. This information can also help you make informed decisions when purchasing new lenses or accessories for your camera.

3. How do I identify the type of lens on my camera?

The type of lens on your camera can usually be identified by its focal length, which is measured in millimeters. Wide angle lenses typically have a focal length of 35mm or less, standard lenses have a focal length of 50mm, and telephoto lenses have a focal length of 70mm or more.

4. Can I change the lens on my camera?

In most cases, yes, you can change the lens on your camera. However, this depends on the type of camera you have. Mirrorless and DSLR cameras allow for interchangeable lenses, while point-and-shoot cameras typically have a fixed lens.

5. How do I find the lens information on a vintage or secondhand camera?

Finding the lens information on a vintage or secondhand camera may be more challenging, as the label or sticker on the lens may have worn off over time. In this case, you can try researching the camera's model or serial number online to find more information about the lens. You can also consult with a professional camera technician for assistance.

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