Miscellaneous

# What is the prime focus of a telescope?

## What is the prime focus of a telescope?

Prime Focus is where a telescope or camera lens forms an image directly on the sensor of the camera. Field Flatteners correct curved focal planes. Focal Reducers reduce the focal length of the telescope, make the focal ratio faster, and the field of view wider.

How do I know what magnification My telescope is?

The calculation is simple: divide the focal length of the scope by that of the eyepiece. So, if you have a scope with a 1,200mm focal length and a 20mm eyepiece, your magnification would be 60x. The smaller the focal length of the eyepiece, the greater the resulting magnification on any given telescope.

How does a Barlow affect focal ratio?

By increasing the focal length of a telescope, a Barlow also increases its focal ratio. For example, using a 2X Barlow with a 250mm f/5 telescope (focal length 1,250mm) effectively converts that scope to a 250mm f/10 scope (focal length 2,500mm).

### What can I see with 200x magnification telescope?

200x – Your entire FOV covers about half the surface of the moon. You start seeing smaller features you didn’t know were there, such as small peaks inside craters! 300x and above – You start feeling like you’re flying above the surface of the moon.

Is a 20mm telescope good?

A 20 mm is useful just as a 13 mm is useful in most any telescope but I’m not sure “all purpose” is a good description. My telescopes range in focal length from under 400 mm to about 2800mm, a 20mm is not a planetary or high power or even mid-power eyepiece in any of them, it’s a low to mid power deep sky eyepiece.

Does Barlow lens have double magnification?

One of the greatest advantages of a Barlow lens is that it not only will double the magnification it will effectively double your eyepiece collection!

## How do I increase the magnification of my Telescope?

It is roughly your telescope’s focal length divided by 50. You can increase the magnification by using a barlow lens, most camera-telescope adapters have a screw thread in their barrel so you can take the lens out of your barlow and put that in to double the magnification (remember, though, you trade off brightness and sharpness for it).

Is prime focus photography good for taking pictures of planets?

After doing a bit of prime-focus photography, you’ll find that it gives a surprisingly small image, not very good for thing like the planets. There is a another method which gives you a larger image scale but is very hard! Watch this space for the ‘eyepiece projection’ article coming soon!

Why is prime focus bad for photography?

This is because they are bright and therefore much easier to photograph than dim deep-sky objects. The problem with prime focus is that you can’t really do any guiding, you’ve got nothing to look through during the exposure (you can’t see through the camera viewfinder while the shutter is open).

### Should you look through the camera or through the telescope?

If you look throught the camera’s viewfinder, you should be looking through the telescope (you might need to focus it a bit, usually at prime-focus the focus point is at an extreme of the telescope’s focus). You should be ready to go! What can you photograph with this method?