Is a Webcam Better than a DSLR for Astrophotography?

[russ_watters]

About the 2 image sensors, webcam vs DSLR.

The telescope generates a full image format roughly the same size of the webcam, filling the entire surface of the chip with light. The DSLR sensor cannot be filled with the image the telescope creates because its sensor is too big.

There are plenty of people who use DSLRs at prime focus for astrophotography with little or no vignetting. How a Barlow changes the light cone I'm not entirely sure, but it should widen the cone unless the internal structure of the barlow cuts part of it off.

 

[russ_watters]

I would love to have a good telescope - even if only to sit there and admire / stroke it. But it is in a queue, after a new marine diesel engine and a few other expensive bits of kit.

[shrug] Sounds like a problem of improperly conceived priorities to me.

Still, a local star party through an astronomy club or college would at least allow you to see what all the hubbub is about.

 

[Drakkith]

I have a feeling that this effectively boils down to 'f number', used all the time in photography. For a bigger sensor area, you need a bigger aperture for the same field of view and the same 'exposure' if the sensor elements have the same sensitivity / noise performance. Obviously, the purpose designed astro cams will have been optimised for sensor area, compatibility with available apertures and focal lengths and there is a huge advantage in not having colour filters there when you don't actually want them. Also, they are incredibly neat little things that fit on the telescope very comportably.

Actually the F ratio only really affects the exposure time. Big sensors are generally used equally as well on fast and slow scopes. However vignetting can become a major issue in some types of scopes when you use large sensors. Field of view is completely dependent on focal length, not aperture.