At what aperture can you see some colour

Spiney (Steve) · #1 07-04-2006, 05:27 PM

I'm saving for a 12" premium Dob (I'm 2/3rds of the way there) but would be interested as to what size aperture can you expect to see colour in DSO's, Nebulae etc? Can you see any in a 12" or do you have to go much larger say 16" or larger?
Opinions anyone.

cjmarsh81 · #2 07-04-2006, 05:43 PM

I don't know. But I can tell you I have a 10" and cannot see colour.

MattyD · #3 07-04-2006, 05:59 PM

I was under the impression that it's our eyes that are the problem, and not necessarily the optics? You need a really long exposure regardless of the size of the telescope to get colour. Well that was my impression I could be wrong.

RAJAH235 · #4 07-04-2006, 06:48 PM

Spiney. I can see green shading in the Orion Nebula in my 10" Meade dob, depending on conditions. I have also picked up a little pink on occasions. You should have no probs with seeing colour in M42 with a 12" dob providing you have reasonable eyesight.
The reason we do not see all the colours like the photo's is because our brain/retina, processes the photons immediately. Unlike a film or CCD chip which accumulates them...
That is why the No.1 rule is "Aperture Wins".
More photons = more resolution/definition & colour.
HTH.

L.

janoskiss (Steve H) · #5 07-04-2006, 06:51 PM

See this thread:
http://www.iceinspace.com.au/forum/s...ead.php?t=7322

mickoking · #6 07-04-2006, 07:53 PM

Quote:

Originally Posted by Spiney

I'm saving for a 12" premium Dob (I'm 2/3rds of the way there) but would be interested as to what size aperture can you expect to see colour in DSO's, Nebulae etc? Can you see any in a 12" or do you have to go much larger say 16" or larger?
Opinions anyone.

I have a 300mm premium Dob and you can make out colour on some deep sky objects (orion neb, some planeteries etc).

anthony2302749 · #7 07-04-2006, 08:09 PM

Quote:

Originally Posted by MattyD

I was under the impression that it's our eyes that are the problem, and not necessarily the optics? You need a really long exposure regardless of the size of the telescope to get colour. Well that was my impression I could be wrong.

What you are saying is correct the problem is with our eyes. We have two main types of photoreceptors called rods and cones. These cells are located in a layer at the back of the eye. Rods are used to see in very dim light and only show the world to us in black and white. The other type of photoreceptors, the cones, allow us to see colors. They are not as sensitive as the rods so they only work in bright light eg day time.

So to see colour you need to collect enough light from a celestal object to make it bright enough to tickle your colour receptors, so an aperture of about 20 to 30" may do it?

As to why celestial object look green in colour when using telescopes up to 12" plus some more, is because our Rods (night vision) operate at a wavelenght of +/-540nm this equates to the green part of the spectrum.

For further infromation follow the link http://askabiologist.asu.edu/research/seecolor/

ving (David) · #8 08-04-2006, 07:39 AM

I see stacks of green in alot of nebulars, galaxies are grey, some planetaries show greens and blues too.... this is in a 8" newt

Spiney (Steve) · #9 08-04-2006, 09:41 AM

Thanks for the thread steve, looks like this will answer many of my questions.
I'm not expecting to see nebulas like the photos in magazines etc, but it would be nice to discern some colour on occasions. Its amazing how ving can see colour in an 8" and others can't see any in a 10". Ving you got eyes like an owl or something? Lucky bugger.
So if aperture rules how much better is a 12" over a 10", can this be quantified at all?
What do you all reckon?

RAJAH235 · #10 08-04-2006, 10:11 AM

Only improve by ~ 1 magnitude,(eg; down to 15.5 visual). Should get more colour/res/def etc..

L.
http://www.go.ednet.ns.ca/~larry/astro/maglimit.html

Striker (Tony) · #11 08-04-2006, 11:11 AM

Just dont get your hopes up to high...I have seen colour through Andrews 12.5 Dob out at a dark site at Leyburn but it does not jump out at you.

Starkler (Geoff) · #12 08-04-2006, 11:49 AM

I see colour in brighter planetary nebs, the homunculus and sometimes in M42. I havent seen colour in anything else other than stars.

To use colour chasing as a scope selection criteria might dissapoint you as there are not many objects out there where it is possible to see colour in dso's

Just get the biggest scope that you can transport and handle easily enough that you will actually use it.

vash (Ashley) · #13 08-04-2006, 12:05 PM

I was stumbling around lagoon and came across triffid and I could see the colours with the 10" skywatcher, it was a realy good night though.

cjmarsh81 · #14 08-04-2006, 02:25 PM

Maybe my light polluted skies are stopping me seeing colour.

Mikezoom · #15 08-04-2006, 04:20 PM

My 12" shows the "Ghost" in a beautiful blue color & I have seen the greens and slight shades of pink? of M42 too (or is that just my bloodshot eyeballs?

). Im sure there are plenty of objects that show color but its usually using averted vision. As they say its nothing like the posters but you can still see stuff that is not black, white & gray.

Mike.

dhumpie · #16 08-04-2006, 06:30 PM

I agree with what has been said about color in DSO's. I see predominantly greens and blues in high surface brightness planetary nebula's in my 6" scope. Pastle and rusty hues are doable in my 10" from less than perfect skies (mag 5.3-5.6 suburban Brissie skies). Andrew (astro_south) and me have seen the rusty hues in M42, both in my 10" and his 12.5". To see color you need to do away with averted vision and look straight at the object to allow the light to fall on your cones, which are sensitive to bright objects and colors. The rods that you use for night vision are useless for this. And aperture definately helps heaps with this....

Darren

anthony2302749 · #17 08-04-2006, 07:41 PM

Quote:

Originally Posted by dhumpie

To see color you need to do away with averted vision and look straight at the object to allow the light to fall on your cones, which are sensitive to bright objects and colors. The rods that you use for night vision are useless for this. And aperture definately helps heaps with this....

My point exactly, as outline in my earlier tread, to see colour you need to make the object bright enough to tickle the cones (colour vision) so that you can see colour. So larger the aperture the better chance to see colour.

Final for those who are interested take a look at the diagram which I have attached to this discussion it may answer why most people can detect blues, greens and grays when viewing nebulas, planetaries and galaxies.

Gargoyle_Steve (Steve) · #18 09-04-2006, 05:13 AM

I've been having discussions with myself about colour perception too ... this has been an enlightening thread .... but earlier tonight I set up my 10" dob and "examined" at M42 for a while, as opposed to having a look. I just kept looking at it, recentering it as needed. Previously I had seen it as a pretty, though basically greyscale object with some kind of greenish tinge.

After 3-4 minutes maybe I think I started to perceive stronger green colour, another minute or 2 and I THINK I had blueish tinges in the central region ....

and eventually I MAY have had the slightest pinkish tint in some of the outer reaches (before Orion slipped behind the head of a palm tree. Note to self: fuel up chainsaw tomorrow morning)

Now blue is nearly the same colour as green, and pink is the negative of (some) green shades so maybe my eyes were simply "green burned" or begging to have a rest before they wore out,

or maybe it was wishful thinking and my vivid imagination .........

But! I did also then examine Jupiter and Saturn in the same way, by keeping my eye to the eyepiece for a few minutes and the object in sight - and for the first time in this scope I have seen the Great Red Spot, and the Cassini division.

From now on if I want to have a look at something I will make it a GOOD long look, and hopefully my own personal "seeing" will improve from 6/10 to 9/10!

RAJAH235 · #19 09-04-2006, 04:00 PM

No matter how dark your site is, always take extra time at the E/Pc to let your eyes 'dark adapt' to the new view. Tis amazing how much more detail/colour you can pick out if you do.

L.

Roger Davis · #20 12-04-2006, 01:34 PM

Oh for Heavens sake above, rephrase the question to "at what aperture can I see RED?" This makes more sense, any telescope will show you greens and yellows, even a 60mm refractor!! From the ASV Dark Sky site I have used scopes from 8" to 27", real RED not "I think, therefore it's pink" finally easily occurs at around the 20" mark or more if you are red/green colour blind.