36 replies to this topic

[oalithgow]

Thinking of upgrading to a large Dob. I was wondering if there are some nebulae, galaxies, or planets that will start to show color to the unfiltered, natural eye while visually looking. I've read that maybe a 16 inch might start to see some good color.

 

Any DSOs with great color for a new sky hunter?

I´ve notice that coatings also take a big part on showing the color. For instance last December I´ve started using a 16” Dob I build with a set of meade Lightbridge mirrors and it was the first time I could “appreciate” color in M42 the orion nebula. I could make sense of the hot pale blue color of the center of the nebula and the dark brownish colors of the outsides. Remarkable! And that was observing from my light polluted city, but under a decent transparent winter sky.

 

Why the coating you ask? Well, previous of this telescope, I’ve also owned a 17.5” dob for several years before selling it last year. It had a Coulter optics mirror set, probably from the ´80 and the coatings were in really good conditions almost like new. Although M42 was brighter and with a bit more details than with my current 16”, I’ve didn’t appreciate the colors as well as now, and that is observing under the same conditions, same eyepieces and no filters. Also both mirrors had similar ¼ wave optics.

 

 

Another colorful object I’ve saw recently was the planetary nebula ngc6572, seen at 360X as a bright intense blue-green round object.

 

 

Clear Skies

Edited by oalithgow, 03 March 2020 - 02:44 PM.

[Starman1]

I have tried to simulate as much as possible the colors I regularly see in my 12.5" at a dark site in this heavily doctored image of M42.

I have reduced the color to approximately visible levels.  It is VERY close to what is seen on the best nights.

Note the grey-blue to the left of the Regio Centralis.

Note the "dusty-rose" color in most of the interior of the nebula

Note the "beige" color in the nebula to the right of the Regio Centralis

Note the distinct pink in M43.

Note the grey color in most of the outer edges of the nebula, especially at the bottom, which is almost a degree away from the Trapezium.

What is missing is that the Regio Centralis often appears bluish green.

 

 

Attached Thumbnails

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[Spikey131]

My 12.5 Dob must be a black and white model

 

Seriously, in my Bortle 4 skies, everything is grey.  I really need to take that scope to a dark site.

[oalithgow]

Try using your imagination then 

 

I really don´t see any pink color with my 16" dob under Bortle 5 sky, like in the photo, but instead brown for the outher clouds and gright blue in the center, reflected by the inner stars of the nebula (Is not like seing a image, is more like a perseption of the colors). Will need to try it under darker skyes.

 

One other important note is the eyepiece one is using. In my case was a 18mm Explorer Scientific 82° and a 13mm Nag T6. The colors were more aparent in the 18ES82, as it gave a bigger exit pupil. Also the type of coating of the eyepiece, as some may introduce warmer or colder false colors.

Edited by oalithgow, 04 March 2020 - 08:03 AM.

[Araguaia]

With a 12" dob and dark skies, I see it pretty much like Don sees it, including the caveat about the central region being blue-green. 

[Redbetter]

I don't see M42 like that.  I do see a more beige or rust color hue to the wings, but the bright central regions are billowing bluish white clouds.  No rose or pink at all in that region with the 20".    

[Starman1]

I don't see M42 like that.  I do see a more beige or rust color hue to the wings, but the bright central regions are billowing bluish white clouds.  No rose or pink at all in that region with the 20".    

I wish I knew why color is more apparent at times and less apparent at others.

Is it seeing?  Or transparency?  Because it doesn't correspond to the darkness of the sky.

I've see M42 in technicolor on some average nights and not on some nights a few tenths of a magnitude darker.

 

I've seen M20 as pink surrounded by blue, and, at other times, as simply various shades of grey.

Why?  I'm not sure.

 

I used to think I was unusually sensitive to the longer wavelengths, but I called a couple friends over to the scope on a night I was seeing

pink hues in M8, and all of them saw it too.  So I think it's more about the night.  I just haven't put my finger on the exact reason.

[Dave Mitsky]

I wish I knew why color is more apparent at times and less apparent at others..

I've experienced and wondered about the very same thing. 

[CrazyPanda]

I wish I knew why color is more apparent at times and less apparent at others.
Is it seeing? Or transparency? Because it doesn't correspond to the darkness of the sky.
I've see M42 in technicolor on some average nights and not on some nights a few tenths of a magnitude darker.

I've seen M20 as pink surrounded by blue, and, at other times, as simply various shades of grey.
Why? I'm not sure.

I used to think I was unusually sensitive to the longer wavelengths, but I called a couple friends over to the scope on a night I was seeing
pink hues in M8, and all of them saw it too. So I think it's more about the night. I just haven't put my finger on the exact reason.

I almost guarantee it’s physiological. Body temp, blood oxygen level, what nutrients you’ve eaten in the last 24 hours, sleep, caffeine, hydration level etc.

[Starman1]

I almost guarantee it’s physiological. Body temp, blood oxygen level, what nutrients you’ve eaten in the last 24 hours, sleep, caffeine, hydration level etc.

Then it's universal.  At the site I frequent, on the nights where I see a lot of color in DSOs, so does nearly every other observer in the lot.

And on the nights I don't, neither does anyone else.

I lean toward thinking it has something to do with the transparency of the air.

[NorthernlatAK]

I definitely think it has to do with transparency. But I do not have other observers around to compare with. On nights that I see a slight pink fringe to m57 I really wonder if others would see it.

[Araguaia]

I would say it is transparency, except for the nights when I see color in bad transparency.  Maybe it is a particular kind of transparency or skyglow - something in the atmosphere that affects the detectability of certain wavelenghts.