Visual Observation vs Imaging

[glend (Glen)]

Can someone help me understand how visual observation and imaging seems to produce vary different views of the same object? I get that the human eye can't do long time exposures, and have various filtered exposures overlaid on it, but the differences are amazing. What is the true rendition?

For example, I am working through O'Meara's Southern Gems book and last night (finally a clean clear night sky) was viewing: M83 (NGC5236) (Gem64), NGC5128 (Gem 61) , NGC3918 (Gem 54), and NGC 5139 (Gem 62).

I like O'Meara's photos because being in black and white they are close to what I can see through my scope, but they (and my observations) lack the stunning colour renditions and detail that the imaging guys seem to be able to produce with the same aperature size. Is this what drives people to astrophotography?

My son likes to dismiss imaging because his view is that it's often artificial in outcome and he want to see the photons from that object directly, and I get that.

[ZeroID (Brent)]

Colours can quite often be someones interpretation of what they expect ( or would like ) to see. Longer wavelengths in the Infrared region can be discerned by filters but can be 'shifted' to a visble red in an image whereas visually they don't exist for the human eye. Similarly for Ultraviolet wavelengths, measurable by instrument only. Sure there are visible colours in nebula but they are also so faint that the eye cannot register them as such, hence your 'black and white' view.
I have seen faint colours in some of the major nebs, green and pink can be seen in M42 for example with a big aperture scope and good conditions. And during processing it is easy to shift colours to another wavelength to make them stand out from other characteristics of the image.
You can see this in peoples interpretations during processing. There are accepted conventions which we expect to see but they are not hard rules for sure.
I understand the direct photons viewpoint but it means the viewer may miss out on details that only show up with the long exposures required to see them.
Personally, I like both options. I get a thrill when I finally find/see/identify some obscure target dim and elusive but then I get another thrill when I capture it in detail and get a better unerstanding and more knowledge of what I have found.
It's all good fun..

[mental4astro (Alexander)]

Originally Posted by ZeroID

I understand the direct photons viewpoint but it means the viewer may miss out on details that only show up with the long exposures required to see them.

I would have to disagree with you, Zero, here - first time I think I ever have, . I don't think ANYONE is missing out on detail, be it through visual or photo. What one "sees" is pretty much dictated by the gear they have, including their own eyes and experience. The challenge for both is the get as much out of their gear as they can, and it is all an interpretation. I'll explain it this way:

Me, I am a dedicated visual fellow. Yes I have a big 17.5" dob, but I also have an 80mm refractor that I love to bits just as much as my 17.5". I can't expect to see the faint arms of a small galaxy with the 80mm, but I certainly can't fit the Coal Sack and Jewel Box in the same field of view with the 17.5". What I'm getting at is you maximise the capability of the gear you have, and spank the heck out of it to do so. That I think is the challenge for both visual and photo. I certainly wouldn't expect the same type of imagery to be produced by an 80mm refractor compared to a 12" RC.

I can follow Glen's son's view that "dismisses" photo. I wouldn't say that, but it is a different interpretation on the one hobby. The challenge for both photo and visual is the make the most of the time they have and the gear they've got.

While I'm a visual exponent of this hobby, I still troll through the wonderful photos posted by the imaging mob for admiration of their skills, picking up star hopping hints to objects, help decide on future observational targets, and to compare what I've laid down detail wise in my sketches to what they've picked up in their cameras. Happy medium for me, . Earlier this year there was a supernova in NGC 1365. I managed to spot it in my 17.5" from home (crappie conditions too), but I was only able to do so by exploiting the photos posted by fellow IISers, .

I hope this goes some way to satisfying your question.

Glen, if you want a more "realistic" reporting of how things are seen through a scope, have a look through the Obs. Forum sticky "Solar System & DSO Sketches". There you'll find a fabulous array of sketches done using a variety of instruments, both large and small.

[Wavytone]

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[Kunama]

The simple answer is that the cone cells in the human eye are mostly non responsive at low light level therefore you do not see the colours present, the rod cells which are what you utilise for low light vision only give you grayscale vision.

The threshold will be different for different people and is affected by age etc. so some people do see some colour in nebulae etc where others, particularly older eyes have to contend with shades of grey

As for the reasons some are drawn to AP ???? that's anyone's guess.

I'm into "astrophotography-by-proxy" that is I love seeing the results of the hours of effort the AP afficionados put into gathering data but prefer my own time to be with my eye to the eyepiece.

[ZeroID (Brent)]

Originally Posted by mental4astro

I would have to disagree with you, Zero, here - first time I think I ever have, .

Blimey !! A disagreement!! What's it going to be ? Large aperture scopes at 20 paces ??

As I said. it's all good fun...

[astroron (Ron)]

IMHO astro imagers are really only astro image processors.
One only has to have a look at the many different colours too Eta Carina and M42 to see what I mean
Most of the colours are only representations and and not the true colours.
A Big percentage of imagers haven't looked through a telescope in years,and a lot don't know what the object they are imaging looks like in an eyepiece.
One only has too watch the beginners thread to see this.
First question?
What telescope can I get to take pictures?
Not what can I see in the eyepiece.
They should not be called Telescopes,but big Telephoto lenses.
Cheers

[Steffen]

My astro-imaging setup is cheap and gets me the best images to be had these days – Internet access and a web browser

Cheers
Steffen.

[Bill.davey (Bill)]

I love looking at the beautiful images taken by the world class experts on IIS. They are stunning but sometimes suffer from the restrictions of the equipment used.
What the eye lacks in sensitivity it more than makes up for in dynamic range. M42 to me through my 10" dob with an ES 20mm 68 eyepiece looks fantastic. I can see all the bright stars in the trapezium AND the nebulosity and details in the fish mouth region. Astro images show more detail but the bright stars are always blown out.
NGC 2070 is a fantastic complex visual object. I have seen some great sketches but not many great images. Images of NGC 2070 to me look like beautiful abstract art, not at all the fantastic object I see through my eyepiece.

Bill

[Poita (Peter)]

Whether using a telescope and eyepiece or a CCD, neither is a 'true rendition. Both are using technology to enhance our visual perception in ways our eyes cannot achieve on their own.

To me the best innovation ever is video astronomy. It combines the immediacy of visual with some of the colour and detail of astrophotography.

Basically you have a specialist video camera in place of the eyepiece and you get full colour images with lots more detail than visual alone, but in real-time, wither on a screen attached to the scope, or from the warmth of the living room! The colours are also not 'made-up' by the person doing the processing if that is something that bugs you. And it works great with something cheap like a fast ED80. To me, this is closer to what the objects would look like if I could stand close enough to see them with my naked eye, and with the colours to match.

There is always room for both visual and CCD imaging, but with light pollution and physical constraints on scope-size I find I am doing neither more often, and using video astronomy instead, and keeping visual for the Moon and Solar obs.

[MichaelSW (Michael)]

It must be very satisfying to produce those beautiful astro images of the heavens above, and to all the IIS members who do, I say, "thank you very much" for all your effort.

My passion for astronomy lies more in my heart than my head. I struggle with understanding and remembering the science and the technology, but never tire of the view.

Cheers to you all.

[madbadgalaxyman (Robert)]

I was a dedicated visual deep sky observer for two and a half decades; it was never boring.

That isn't my thing anymore, though I still like to kick the four inch refractor or the Celestron C8 onto the verandah for a quick look-see.

Personally, I believe that what initially gets people most excited about astronomy is the visual views; later on, we tend to become more specialized e.g. astro-imaging, telescope making, viewing very faint galaxies, understanding how stars and galaxies work, etc.

[moonunit (Joe)]

Would love to see a cost comparison between viewing and imaging. What would it be a ratio of 1 to 10?

[ZeroID (Brent)]

Originally Posted by moonunit

Would love to see a cost comparison between viewing and imaging. What would it be a ratio of 1 to 10?

Scary !!!

I DON'T want to see a cost comparison.
Or more likely I don't want my wife to see a cost comparison...