Magnification with DMK Webcam

[Higbyrichard]

This is a copy of a post I dropped on the DMK Web Cam Site with no reply to date.

I would deeply appreciate advice.

How does one calculate magnication using the DMK camera. I primarily image the Moon with a DMK 31AU through a Tak TOA 130F scope. (F /7.69 - 1000mm focal length).

The question is often asked by outsiders as to how close are we to the moon when they see the image on the laptop. I take a wild guess. There must be a way I can calculate the approximate apparent distance from the surface.

For example in this YouTube Clip I created for the local kids I guessed that we are about 1200 kilometers above the surface. In truth I have no real idea which worries me! I should be able to tell them. The focal length was 2000mm using a 2x Barlow.

http://www.youtube.com/watch?v=1_FfRpx-AxI

I am sure the answer will make me feel stupid but I would appreciate any advice.
Many thanks
Richard. Sydney
www.astro.chigby.com

[iceman]

Hi Richard

These two articles may help:

Calculating the Resolution of Solar System Images (http://www.iceinspace.com.au/63-346-0-0-1-0.html)

Calculating Focal Length from Plate Scale (http://www.iceinspace.com.au/63-386-0-0-1-0.html)

Cheers

[Higbyrichard]

Thanks Mike.

Appreciated.

Richard

[Higbyrichard]

HI Mike,

This is a bit more complex than I thought. Out of interest have you any idea what the magnification of a scope is (say 1000mm focal length) at prime focus without an ocular but using a ccd?

Richard