is the focal length in a telescope better when it is larger or smaller?
snail asked:
is it possible to build your own telescope? the larger the mirror the more light it gathers what about focal length? some advertise for example 10 inch mirror with f 4.5 what does that mean?
This entry was posted
on Sunday, March 21st, 2010 at 12:00 am and is filed under Astronomy & Space.
You can follow any responses to this entry through the RSS 2.0 feed.
You can leave a response, or trackback from your own site.
is it possible to build your own telescope? the larger the mirror the more light it gathers what about focal length? some advertise for example 10 inch mirror with f 4.5 what does that mean?
March 21st, 2010 at 11:54 am
This is known as the f-number, focal number, or focal ratio. F-numbers are common throughout all imaging fields. It is a method for describing the resolution of a certain imaging tool, such as a telescope. f/4.5 is about average for a 10″ telescope. According to Wikipedia, “the f-number is the focal length divided by the “effective” aperture diameter.”
The higher the f-number, the better.
Anyone can build his or her own telescope, if he or she knows how to and has the resources. I am currently borrowing an 8-inch f/6 telescope that was home-made
Adam
March 24th, 2010 at 5:03 pm
Yes.
One question at a time, please. Viola At Neon
March 26th, 2010 at 6:40 am
Yes, you can build your own telescope and there plenty of resources for you to tap into - Nyx