what is the magnification of a telescope without any eyepiece

Started 7 months ago | Questions thread
Tristimulus Veteran Member • Posts: 7,558
Re: what is the magnification of a telescope without any eyepiece

Just a twist to the sound answers given above.

Pixel size also matter.

When using my 24MP FF image sensor the pixels are 6 microns squares. With this camera and 530mm focal lenght each pixel covers about 2.3 arc seconds x 2.3 arc seconds at prime focus. This is the plate scale.

When using my 24MP APS-C camera with 4 micron pixels the plate scale is 1.6 arc seconds.

The image sensor with smaller pixels will resolve finer detail when using the same focal lenght. So magnification becomes a pretty useless measure in this context.

It is still meaningful to say that a 50mm lens magnifies 1x when using a full frame camera, but that is only part of the story. When using this measure my 530mm telescope magnifies 10.6x compared to a 50mm lens. But resolution also depend upon pixel size.

When I want high resolution (sun, moon and planets) my tiny industrial video and stills camera with 2.4 micron pixels comes in handy - just extend the focal lenght to f/15 (in my case a 3x barlow lens is all that is needed) and the telescope and camera combination is diffraction limited. Longer focal lenghts will only give a larger and dimmer image without any added detail.

Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow