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Transmission and efficiency

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Have you ever thought about where all photons go when they enter your telescope?

I have done a rough calculation of how they dissapear on the way through the telescope and in to the sensor, in this case it's for a rgb filtered mono camera.

The result?

You detect about 12% of the incoming photons through a refractor or 9% through a reflector!


I have the calculation on my homepage here:


For those who are curious as I'm  !


Edited by Astrofriend
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No, it's just a relative compare of a telescope with the same focallength and aperature. But the usable imagecircle area and the area of sensor matters but it's not included in the calculation, just mentioned at the end.


Ouh... my expensive telescope just a blocking device :-)


Edited by Astrofriend
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