Colour?

[smeech]

This may seem like a rediculous question for some but when observing DSO's and planets do you see colour? I am still yet to decide on a scope so don't know the answer.

I'm swaying between a 127 mak and a 80 mm frac. They are both good both do different things. If the missus says yes I might just get both!

[barkis]

Your scopes won't show colour. DSO's are devoid of colour observationally, but the cameras Film, or sensor will record the colour present during processing.

The Orion Nebula may look a greeny grey colour in the eyepiece, but that is simple the colour of Hydrogen, which most of the nebula consists of.In fact, most of the Universe is populated with Hydrogen.

You can't see the colour, because the eye isn't sensitive enough, and the vast distances involved, means the energy put out by these distant objects is vastly depleted.

The major gas planets, namely Jupiter and Saturn can emit colour. Not strongly, but detectable.

Hope that helps a bit.

Ron.

[smeech]

Thanks Ron. Clears it up nicely.

Steve

[Ben Ritchie]

Your scopes won't show colour. DSO's are devoid of colour observationally

DSOs include star clusters though, and red giants show clear colour - i've always liked how they stand out from the rest of the stars. M103's a nice example, or the red giants in the double cluster.

The green in M42 is a mixture of ionized Oxygen and the Hydrogen beta line, there's more Hydrogen emission in the red but the eye isn't very sensitive to it (a CCD is, though).

[John]

Deep sky objects are almost invariably seen in shades of grey but you will see colour tints in the planets but not as striking as the images of course.

[smeech]

DSOs include star clusters though, and red giants show clear colour - i've always liked how they stand out from the rest of the stars. M103's a nice example, or the red giants in the double cluster.

The green in M42 is a mixture of ionized Oxygen and the Hydrogen beta line, there's more Hydrogen emission in the red but the eye isn't very sensitive to it (a CCD is, though).

Of course. I took a photo whilst I was in Greece and saw one (I think). Certainly looked red in the photo. I would have not idea which one it was, if it was one though.

Thought I would with the planets just wasn't sure about the DSO's.

[barkis]

Of course you are correct Ben. I omitted star temperatures and their relative colours, and of course the Globular and Open Clusters are classed as Deep Sky Objects, with discernible coloured stars within them.

Ron.

[assasincz]

As for the aparture you have mentioned, as with planets, there are colours to be seen, but do not expect them to be rainbow-sharp colours - they are rather pale, "-ish" like in my mind. But distinctive nevertheless - Mars seems orange-ish, Jupiter pink-orange-yellow-ish with ocassional hints of brown, Saturn looks yellow-ish, Neptune blue-green-ish, etc.

With DSOs, things are not always so jolly. As was mentioned, there are some bright stars giving beautiful colours (my personal favorite is the Garnet Star μ Cephei - very nice red)

The only DSO I ever saw with a hint of colour with my 4.5" scope was the NGC 6572 planetary nebula - it was blue-ish, due to its brigthess combined with its small angular size. Other than that, it just shades of grey we are talking about I am afraid.

Some people suggest that with large enough aperture, there is colour to be seen in DSOs like M57 and such, but with 6" aperture and below, it is just B&W guessing game. Unless of course you have blacker than black skies and fit enough eyes

[smeech]

Thanks all. Very helpful indeed. This was the only question I couldn't answer by trawling previous posts - or my search skills aren't up to much!

Hasn't helped my decision any though - still want both.

[JimStan]

I seriously doubt that you will ever see any color in any nebulas, even the brightest ones such as M42, with anything less than around a 12 inch scope. Using such a tool, I have been able to make out a slight greenish cast in the brightest area surrounding the trapezium area, but all those beautiful shades of red and purple that radiate outward from there in photographs, are totally lost to the eye.

Pick out a scope based on your desire of what you want to view the most. Get a long FL scope for planetary viewing and a faster scope for DSOs which require more extended angles of view.

Keep in mind that if you have to carry one to a remote viewing spot, portability is also a prime consideration. You are NOT going to want to cart a 15 inch Dob to a remote site, and otoh, you would not be serving yourself justice to limit a scope's size to something quite small if you had the opportunity to wheel it out from a shed to a viewing spot only a few feet away! ( or even better, had it set up in a permanent observatory ! )

Just a few thoughts running around in my mind.

Jim S.

[Scosmico]

You can get colour on planets an doubles for sure with a 5".

This may seem like a rediculous question for some but when observing DSO's and planets do you see colour? I am still yet to decide on a scope so don't know the answer.

I'm swaying between a 127 mak and a 80 mm frac. They are both good both do different things. If the missus says yes I might just get both!

[swamp thing]

Keep in mind You are NOT going to want to cart a 15 inch Dob to a remote site,

Sorry, but the whole point of a large Dob is that you DO want to to cart it to remote sites.

That is why most of us buy them.

If you have to travel, make it worthwhile.

Regards Steve

[acey]

Depending on scope, eyepiece, eye and viewing conditions:

Planets: (potentially) strong colour, all hues.

Stars: (potentially) many colours, often dependent on contrast with neighbouring stars, but people tend to see red most strongly, also blue and yellow. Double-stars can show striking colour contrast effects.

Galaxies: no colour. In 19th century they were known as "white nebulae".

Nebulae: some show blue/green, a very few may show red with sufficiently large aperture and dark skies (though this is very rare and basically covers two examples: M42 and IC418).

A lot depends on the observer's own colour perception. Star colour can be seen with the naked eye or binoculars, planet colour with very small aperture (e.g. 80mm, if the optical quality is good enough). DSO viewing depends more on sky darkness than anything else; any colour you happen to see is a bonus.

[smudgeball]

Hi

On a really clear night I've managed a really faint hint of green from M42, but I'd been out a long time with my eyes well adjusted to the dark and my scope cooled down.

My scope is F10 and I'm more into lunar / planetary.

If the missus says yes I might just get both!

Oh and good luck !!

Neil

[smeech]

Hi

On a really clear night I've managed a really faint hint of green from M42, but I'd been out a long time with my eyes well adjusted to the dark and my scope cooled down.

My scope is F10 and I'm more into lunar / planetary.

Oh and good luck !!

Neil

Yes well that was a short conversation. One it is!

Thanks all. Thought this was a simple question, but appears it's a little more complex than I thought.

[faulksy]

the ring nebula shows colour

[JimStan]

Sorry, but the whole point of a large Dob is that you DO want to to cart it to remote sites.

That is why most of us buy them.

If you have to travel, make it worthwhile.

Regards Steve

As they say here in the states, "to each his un ! ! ! " ( old TV commercial ! )

You are correct, it is easier to lug a large Dobsonian around than it would be to carry the same size in a GEM mounted OTA ! But larger scopes are essentially for the younger set, and the older one gets, the more apt he is to pick a smaller scope for portable viewing .

Clear skies, and thanks for the thoughts!

Jim S.