A telescope with 20cm primary mirror has f# of 5. What focal length of the eyepiece to get 100x magnification?
Sunday, April 25th, 2010 at
1:27 am
A telescope with a 20 cm primary mirror has an f# of 5. What would be the focal length of the eyepiece required to give a magnification of 100? I know there's an equation, but I don't know what it is. Thanks in advance.
Possibly related posts: (automatically generated)
- Related posts on 100x
- Scythe “ITA KAZE” Slim Hard Disk HDD Fan Cooler, 1000rpm, 14.5dBA ...
- Bulk for Life Beginner Powerlifting Program 2 | Bulk For Life
- » Pep Pills Uk Chattanooga Buy Salvia Divinorum 100x Lansing Shop ...
- Related posts on Eyepiece
- Joni Brickman » Blog Archive » 40X400x Electric Power Monocular ...
- Order zoloft 25mg generic | Depytato.msk.ru medical archive
- Amoeba gobbles algae cells in Mono Lake
 |
 125mm huygens telescope eyepiece no barrel Meade new  US $.99
|
 Unitron K125 mm Telescope Eyepiece gold letter vintage US $.99
|
 Unitron H25mm Telescope Eyepiece gold letter vintage US $.99
|
 Antique Telescope Magnifying Eyepiece US $1.25
|
 Vixen LV 5 Lanthanum Long Eye Relief Eyepiece 125 Telescope size US $1.25
|
 Meade triangle metal telescope tripod eyepiece tray NEW US $1.49
|
Assumption ; by a “20 cm primary mirror” you are talking about a mirror 20 cm in diameter.
The magnification is equal to the primary focal length divided by the eyepiece focal length.
To find the primary focal length, multiply the primary diameter by the f number.
Primary fl = 200 mm * 5 =1000mm
( 20cm = 200mm)
Mag = Primary fl / Eyepiece fl
rearranging:
Eyepiece fl = Primary fl / Mag
Eyepiece fl = 1000mm / 100 = 10mm
You have to vonvert to mm since that is what you would be working with. 200mm mirror / focal length of eyepiece = magnification or 200mm/2mm=100x
Ohhhh yeah. Skipped a step. Good show Larry.