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Old 27-11-2015, 11:46 AM
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mental4astro (Alexander)
kids+wife+scopes=happyman

mental4astro is offline
 
Join Date: Jun 2008
Location: sydney, australia
Posts: 5,004
Hi Tyrone,

As earlier posts have said, colour is not something that is readily seen through a telescope. All due to our human eyes not being very good under low light levels.

Ever noticed when you are in a very dimly lit room, what you see is in black and white? The colours are all still there, but the cells in our eyes responsible for colour vision are not responsive at such low levels of illumination. So, astronomical objects we just don't see in colour (except for the Moon and planets). This colour perception also has one major caveat - the individual. Some people's eyes are more sensitive to low light than others, and with a large telescope they can see some pinks and blues in some nebulae. Age is another factor, and eye health. But beyond a handful of objects, and many individual stars, we don't see colour through a telescope. Oh, and gender also is a factor!!! More than 1/3 of all males have colour blindness to some extent, from really bugger all to no colour perception at all. Colour blindness is very, very rare in women. Females tend to also have more acute colour perception than males do too - so there you go, something womenfolk can do much better than us menfolk!

Now, photography has done nothing to help newcomers to astronomy with a brand new telescope. NOTHING other than create false expectations. This is not a criticism of astrophotogrphy at all. Instead, it is an unintended consequence. People look at the pretty pictures, but are unaware of the technical situation that creates these images, so people then expect to see a gorgeous spiral galaxy with a little telescope, with magnificent stands of spiral arms and pink dots of H2 regions, or a colourful irredecent image of the Crab Nebula, or the red colouration that surrounds the Horse Head nebula.

Sorry, that just isn't the case,

Instead, things through a telescope are much more subtle and challenging to see. There are a lot of technical challenges that need to be understood, and several observational techniques that we need to teach our eyes so we can overcome some of the issues our human eyes have.

To give you an idea of how things actually appear through a scope, have a look at sketches done of objects. The sketching sticky here in IIS has a great collection of such works of many different objects and using a great variety of telescopes, including 114mm reflectors:

Sketches of deep sky objects

The Horse Head Nebula: This is one of the most challenging objects in the entire sky to see. The smallest aperture I've heard of being used to see the Horsie has been a 6", but typically no less than an 8" is needed. BUT, and a BIG BUT, aperture is not the only requirement. To see the Horsie also requires a dark sky, and atmospheric conditions to be every good. Specialized filters are also of great assistance too.

I've seen the Horsie in my 17.5" dob on a few occasions. It has been the most challenging object to repeatedly see. I saw it easily one night from my usual dark sky site on one occasion, and on another, when atmospheric transparency was poor I could not see it to save my life. Seeing the Horsie is an excise in trying to spot a black wart on a black background. When you do manage to see this 'wart', it is just a soft black featureless faint bulge that cuts into a slightly less dark background. No red colouration, and no distinct equine features.

I have not had the chance to sketch the Horsie. The night I did see it most clearly I was not able to do a sketch. And knowing how well I am able to see it, I really need to wait for the best of conditions to come around again, otherwise I am just shortchanging myself with it.

Atmospheric conditions? Transparency? What the hell?

Best way to help you understand is with an example. Below are two sketches I've done of Thor's Helmet. Both were done using my 17.5", both when Thor's Helmet was overhead. The one on the left was done first, and as it turns out when transparency was not too crash hot. The one on the right is more recent, but transparency happened to be exquisite that night, and I was able to see a whole lot more detail.

'Seeing' refers to the thermal stability of the atmosphere. When seeing is poor, the stars shimmer more. In a telescope, as one increases magnification, atmospheric thermal currents begin to become more apparent. Poor seeing and an image shimmers and swims around at low magnification. Great seeing (thermally cool and stable atmosphere), and magnification can be pushed all the way to the telescopes' limits.
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Last edited by mental4astro; 27-11-2015 at 12:05 PM. Reason: more info
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