Noob question

[drewzilla]

Hi all,

bit of a noob question. Please note i havent tried any prime focus imaging yet. Only wide field shots so be easy on me!

Can some explain how magnification works when imaging using prime focus. Are you just stuck with whatever ur scope is? Im getting a bit confused....

For example swapping a 25mm lense with a 10mm obviously gives more magnification on a given object. But when u have ur dslr attached am i correct in thinking you cannot increase magnification? So how do people get close ups of certain objects?

Do they crop the image? Or am i just thinking about this the wrong way? (probably as its late)

Cheers for any guidance

Drew

[Ags]

The image scale is determined by the focal length of the telescope. The size of the object on the chip is directly proportional to the focal length. You can influence the scale by using focal reducers (like a 0.8x reducer/flattener for a refractor).

The size of the area you are imaging can be calculated using this magic formula:

Width of chip in mm * 57.3 / focal length of scope in mm

= width of sky in degrees