M45

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Here is my latest astro photo... Messier 45 aka Pleiades aka the Seven Sisters. Well, it is 7 sisters and their parents…. Trivia fact: This cluster was mentioned in the works of Homer (Iliad and Odyssey) in the mid 700 BC.

Native American cultures used the cluster to measure keenness of vision by the number of stars the observer could see it in. The Aztecs based their calendar on the Pleiades, with the cluster’s heliacal rising marking the beginning of the year. A number of other indigenous peoples of the Americas associated the Pleiades with various myths and legends.

This cluster is a mere 444 light years from earth in the constellation Tarus the Bull. It is seen in the winter time, and you can see it with the naked eye., and binoculars will show it well. This was a combination of 315 x 30 second exposures taken mid November this year using a D5300, 300mm f/2.8 VR @ f/5.6 and ISO 400. What I did not expect to see was the 'halo' or 'star burst' effect on the medium to large stars. Clearly that was because I stopped the lens down - but I would have expected to see this at f/8 or higher.

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That's a very impressive photo, especially to be obtained with such modest equipment. Obviously you must be using a star tracking system for your camera.

Do you use special software for combining so many images?
 
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Very nice indeed. I am always fascinated by astro photography.
Thanks! When I was a kid, I bought a Bausch & Lombe (probably butchered that name) to view the heavens. What I really wanted to do was take pictures of what I saw... it took me about 40 years to get there.



That's a very impressive photo, especially to be obtained with such modest equipment. Obviously you must be using a star tracking system for your camera.

Do you use special software for combining so many images?
Thanks! That would be what is behind the curtain... :) Tracking is done with this kit mounted on a Meade telescope and another camera used for tracking (+ sw). Post processing is done using a product called Pixinsight. I found the learning curve on Pix higher than the learning curve for photoshop...
 

kilofoxtrott

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Wow Ken.
I just did the first feasibility study with my 200-500mm on Orion nebula.
The size is OK, but my tripod is terrible...

I'm waiting for the next clear day
Klaus
 
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Kevin I know it's complicated but as an introduction to a novice like me, can you outline the workflow so that I can have a better understanding of the procedure? Thank you very much.
 
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I will try.... I use a product called Pixinsight for all of this. I have estimated some times - these are CPU processing times.

1) Besides just taking the photos of your target (lights), there are 3 other types of files you need. Darks, flats and bias. Darks get rid of the thermal noise. They are taken at same ISO and hopefully temperature and exposure with the lens covered - so black and about 25. Flats are taken with a light source (I have an LED panel) that are used to get rid of any anomaly's like dust bunnies, etc. I take about 25 of these. Bias are used to get rid of electronic noise and are taken at as fast a shutter speed as the camera will allow. For the most part darks and bias are put in a library as they rarely change. Flats change on focus so are taken often.

2) Next is to calibrate your lights. Software is used to look at each light and remove the noise from above. This is where the dust bunnies are removed. Time: 15 minutes

3) At this point the files are grey scale. Next is a process to debayer the files to create an RGB file. Time: 30 minutes

4) Now it is time to review the lights to trash any outliers. For example, with long exposures planes travel through your FOV are a problem. With SW, I rank the files 100 and down and that value is written into a keyword on the file. Lights that don't meet my expectations are removed. Time: 25 minutes

5) Next comes alignment. You pick the very best light from above and sw runs to align each light with that one. After that, you need to stack the files. SW looks at the weight above and then stacks all the lights into one. The result is referred to as a linear file (i.e. not stretched). But, there is a process that can be applied that will stretch the image and give you an idea of what it will look like in the non-linear world (like the image above). Time: 5 hours

6) Next is a series or processes that remove noise, plate solves the image from a WW database to color correct it and then tighten or sharpen the stars.

7) Now the image needs to be stretched for real. There are a number of ways to do this, and I try each and take the best.

8) At this point you use curves, saturation and a few other processes to put the final touches on the image. Pix uses masks - similar but different to PS masks - where you can protect the stars to work on the background or vice versa.

This is really a high level view, and some who read this and have done it may disagree. But, like photoshop, there are a lot of ways to get to the final answer.

Any questions, let me know!
 

kilofoxtrott

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Thank you Ken for explaining.
Yesterday we had a clear blue sky and I was Looking Forward to shoot Orion nebula.
But then, in the late evening, the air got foggy...

Kind regards
Klaus
 
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That is a pretty common problem with astrophotography. You go out and take 20-30 minutes setting up only to have clouds move in. I am fortunate to live in the country side and have my equipment mounted in an 8 foot observatory. All I have to do is open the roof.
 
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Not all stars are white. That is HR 1188....

HR 1188 is a 5th magnitude Variable Double Star appearing in the constellation Taurus. It is 184 light years from our solar system. It is a yellow-white main-sequence star of spectral type A2V. Its surface temperature is 9000 Kelvins - 1.6 times hotter than the Sun's - and it is 2.0 times the Sun's diameter in size. This star's total energy output, or luminosity, is 25 times the Sun's, and it has a mass of 2.5 Solar masses.

Lol, so know you know....
 
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Not all stars are white. That is HR 1188....

HR 1188 is a 5th magnitude Variable Double Star appearing in the constellation Taurus. It is 184 light years from our solar system. It is a yellow-white main-sequence star of spectral type A2V. Its surface temperature is 9000 Kelvins - 1.6 times hotter than the Sun's - and it is 2.0 times the Sun's diameter in size. This star's total energy output, or luminosity, is 25 times the Sun's, and it has a mass of 2.5 Solar masses.

Lol, so know you know....
Thanks for the info :) I was thinking I was going to find out it's a red giant or something :)
 

Butlerkid

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Late to this show....but soooooo glad I found this thread! This image deserves to be seen by all...so....voila! Featured!

Kevin, your work is absolutely STUNNING! You show me things I could never see on my own....and then provide such interesting information, too! Keep posting!
 
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And a note in my inbox suggested to feature this, which was my pleasure to do.
Thanks!

Late to this show....but soooooo glad I found this thread! This image deserves to be seen by all...so....voila! Featured!

Kevin, your work is absolutely STUNNING! You show me things I could never see on my own....and then provide such interesting information, too! Keep posting!
Thanks so much for the kind words! I am always amazed by what the heavens can show us.
 

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