Best DSLR or ILC for Night Sky Imaging?

Started Nov 8, 2017 | Questions thread
Trollmannx Senior Member • Posts: 5,471
Re: If you want the best, a dedicated cooled CCD cameras are far better than all the DSLRs and ILCs

kiwi2 wrote:

1llusive wrote:

As aperture increases on telescopes, we see more detail.


Yes larger apertures on telescopes usually also come with longer focal lengths so you get more magnification and more resolution. Less diffraction due to a greater area of light relative to the edge.

Not quite so - aperture determines light grasp and resolution.

Faster telescopes (lower f/ratios) collect the same amount of light as similarly sized slower telescopes (higher f/ratios). Aperture is the key.

Resolution is diffraction limited. The aperture of the telescope determines resolution, not the focal ratio (f/number).

For visual observing, it still also comes back down to f-ratio to how bright a telescope is for diffuse objects like nebulas and galaxies. A bigger telescope just gives you more magnification for the same brightness relative to its f-ratio. Which is why you get to see more detail in small dim galaxies with the bigger telescope you have.

For visual use f/ratio is irrellevant.

For photographic use take a look at plate scale, extended objects, etendue and point sources of light...

Visual use:

Use different eyepieces with telescopes having similar aperture (we are talking telescopes here so aperture is the diameter of the objective lens or mirror) but different f/ratios to get the same magnification. What happens then?

But visual observers of such deep space objects wouldn't want to use a large f/16 refractor that was built for planetary observation. Deep space subjects would appear too dim in it.


They would rather use big newtonians between f/4 to f/5 like these...

This is more about price and portability than anything else...

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