Magnification maths.....help please

[msinclairinork]

Hello,

I'm tired of people asking me what magnification i took a picture at..especialy when i don't know the answer.

So where better to get it? SGL!!!!

so the usual setup is a

Orion ed-80r and a cannon 300d??

Thanks,

Michael

[SteveL]

the term "magnification" only make any sense when you are visual observing, where what you see with your eye really is the magnification being used. If you setup is 200x maginification, your eye will see it 200x larger.

For imaging, you can only provide a Field of View or a resolution per pixel. The reason being that the image is display on screen or on a print out is now no longer a representation of what the eye would see. The whole scale has changed. Display the same image on a 15" screen or a 50" screen... its the same image, and the same field of view, but how you now see it has changed. So, the only valid way to describe images are with field of view size, or resolution per pixel.

For working that out, I highly recommend CCDCalc:

The New CCD Astronomy Home Page

[MartinB]

I've done some sums. Your "sampling rate" is 2.47 arc secs per pixel and your field of view is 125 x 88 arc mins or approx 2x1.6 degrees. So the width of your FOV is about a finger width held at arms length. That should convey the idea of the magnification.

[brianb]

Spot on Steve.

[msinclairinork]

Perfecto!!! Thanking you!

As you say that will keep them happy.

cheers chaps!

Michael

[themos]

Better still, find out the actual width of the photographed object in light years, divide the width of the print/image by that and tell them that it's 0.00000000000000000000000000000000000001 magnification

:-)

[msinclairinork]

Hehehe so just start saying well its zero zero zero zero for approx 10-20mins and then end it with a point one?