Observing colour through telescopes

[PEGELLA]

Excluding planets and given normal dark skies, what minimum aperture size of a (non-refractor) telescope is required to just start getting hints of colour in deep sky objects like nebulae and galaxies? I mean in real time, unaided eye, no photography.

 

[Drakkith]

My practical experience with my own telescopes tells me that anything 10 inches (254 mm) and below yields virtually no color for deep sky objects. My largest is a 10 inch Newtonian and I can't remember seeing any color in any DSO's except perhaps M42.

 

[davenn]

^^What Drakkith said ^^

 

[glappkaeft]

I have used 38 to 60 cm telescopes under good skies and only planetary nebula with high surface brightness will show a color and it is always turquoise since the eye is the most sensitive there. Maybe a hint of turquoise in the center of the Orion nebula.

 

[PEGELLA]

Thanks for the comments. Any idea of how long an exposure time would be required to record colour from some of the larger, brighter DSO like M42? Using a 12 inch - 16 inch scope and a simple DSLR camera hook up?

 

[Drakkith]

Thanks for the comments. Any idea of how long an exposure time would be required to record colour from some of the larger, brighter DSO like M42? Using a 12 inch - 16 inch scope and a simple DSLR camera hook up?

Not long at all. Perhaps as little as a few seconds depending on the camera's sensitivity, the surface brightness of the target object, and the f-ratio of the telescope (perceived surface brightness is determined by the f-ratio, not the diameter of the scope). But you probably don't want to use a 12-16 inch telescope for astrophotography if you're just starting out. The focal lengths of these telescopes is so large that it's difficult to record exposures thanks to the high zoom. Any little error in the tracking of the mount, the alignment of the scope, or other issues like wind is magnified by high zoom levels. It is MUCH easier to use a small, short focal length telescope starting out.

Also, once you get into imaging, you can do stacking and processing, which means that even short exposures can be added together to get the equivalent of a long exposure.

 

[sophiecentaur]

I mean in real time, unaided eye, no photography.

Using a 12 inch - 16 inch scope and a simple DSLR camera hook up?

You have moved the goalposts a bit here. We are discussing two vastly different issues now.

given normal dark skies,

And what do you mean by that? Normal skies are only dark skies for some very lucky people.
If you want to do visual astronomy you will probably need to transport your kit to a suitable site. That could mean you would see things for which you would need a camera to use from your back garden.
I bought a 200mm Dobsonian Skywatcher (second hand for less than £200) which was good enough to see some definite colours (of course the Orion nebula but some others and some delightful contrasting colours of adjacent stars). Some pretty stunning views from my home (no street lights) I used a friend's 150mm Newtonian but that was noticeably worse for visual). The eyepieces supplied with most cheap kits are pretty disappointing and do not do justice to a fair quality parabolic reflector. I spent a fair bit on some 2inch eyepieces and I have never regretted that as I still have them and use them with my 120mm refractor. The stars look tiny which, to my mind, means that the resolution and flare are good.
If you start to go into AstroPhotography you will end up spending a lot of money, take a long time setting up all your kit each time and every free hour tinkering with the hundreds of images that you take. (Just letting you know - it's a brilliant hobby but very demanding.)

 

[Drakkith]

If you start to go into AstroPhotography you will end up spending a lot of money, take a long time setting up all your kit each time and every free hour tinkering with the hundreds of images that you take. (Just letting you know - it's a brilliant hobby but very demanding.)

This, a thousand times!

 

[chemisttree]

I see color in my 1974 60mm Montgomery Ward f11 scope with the 0.965” Huygenian eyepieces. Albireo is beautiful!

 

[DaveC426913]

While not a star, I was able to pick out the colour gradients of Mars in my scope well enough to illustrate it.

I drew them by hand, then (afterwards!) checked on NASA's site for what Mars looked like at the times of my observtions.

Rather pleased I was:

(If I'd partially masked the aperture to bring down the light level, I might have picked up even more detail. Maybe next time.)

 

[sophiecentaur]

Seeing colour through a telescope mis depend a lot on the individual's vision. As you get older it gets worse and worse and worse. Damned young whippersnappers can see and hear stuff that just totally passes me by.

 

[chemisttree]

Of course the original question was about DSOs like galaxies and nebulas.