Cameras and magnification…

[ChrisHallett]

Very much a noob question…

I understand how the size of an eyepiece dictates the magnification of a scope but how does a camera  work in terms of magnification? Is the magnification altered within the software that you use?

[Rusted]

HI Chris,

It is directly related to the size of the camera's sensor. An everyday example would be MFT [Micro Four Thirds.]
Which doubles the image size, for a given focal length, compared with a full frame camera. It is referred to as crop factor.

Crop factor - Wikipedia

 

[Gfamily]

There isn't really a direct measure you can apply  - it more comes down to the size of the field of view. 

However, it is reasonable to say that when used for Prime Focus AP,  the image captured by a camera is roughly equivalent to that seen in an eyepiece equivalent to the diagonal size of the sensor. 

So an APS C sensor captures what you might see with a 30mm focal length eyepiece. What magnification that represents depends on the focal length of your Scope. 

A webcam with a 3x4mm sensor would be equivalent to a 5mm eyepiece - so therefore more suited to planetary imaging. 

It's a rough and ready measure, but works to explain the principle

[vlaiv]

Term magnification makes no sense when used in imaging context.

Magnification means that you magnify something - with eyepiece and telescope - it is angles. Moon is half a degree when viewed with naked eye and if you use x100 magnification - it will look 50° wide (0.5° * 100).

Take image of that same moon - how magnified is it? Well that depends on what sort of screen you are viewing that image and how far away you stand.

Imaging is projection rather than magnification. You project image and turn angular size in physical size on sensor - and that in turn changes physical size of image on sensor into number of pixels.

There are two measures of this projection - one is FOV - how much of the sky in angular units will fit onto sensor. Second is how many pixels covers wanted angular patch of the sky - arc seconds per pixel.

 

[AstroMuni]

Take a look at https://astronomy.tools/calculators/field_of_view/

You can compare the effect of various eyepieces vs cameras using the Visual mode & Imaging tabs. As an example I have a 130mm x 650mm fl scope and a ASI224mc camera. The equivalent eyepiece would be around 6mm fl for viewing.