Question about magnification

[Moonstruck]

Hello Robin, I will be going to a public outreach event next month and plan to use live stacking. There will probably be a lot of people there and I anticipate I will get a lot of good questions, so want to be prepared. One of the questions I think I may get is about magnification… if I have an image on my screen, someone may ask how much it is being magnified, and I am not sure what to tell them. Figuring that out while imaging involves taking the camera pixel size, scope size, and other factors into consideration, correct? I will be using a skywatcher esprit 100mm scope and zwo asi 294 camera. If I choose not to enlarge the image in sharpcap, is there a way to figure out the magnification, as seen on the screen? Just wondering if there is an easy way to answer that question without a lot of technical jargon, as there will be many people with limited knowledge of optics, etc there!

John

[admin]

Hi John,

if you go to the field of view calculator here - https://astronomy.tools/calculators/field_of_view/ - then you can work out your field of view. For your equipment, I think it will be 2 degrees by 1.3 degrees.

What does that size mean? Well, it's a patch 3.5cm by 2.25cm (not far off the size of a postage stamp) held one metre away from you.

Now, suppose that you are looking at the image filling a monitor - say a 24" monitor which is about 50cm by 30cm viewing area. If you standing a metre away from that too (comparing to our postage stamp size at 1 metre distance, then the magnification works out at roughly a factor of 13 to 14. Not actually that high, but comparable to the sort of low magnifications you would get using your telescope with long focal length (25,30,35mm) eyepieces.

Hope this helps,

Robin

[Moonstruck]

Thanks Robin, that gets me in the ballpark, so I can give a general answer in case I am asked.