Recent....ish astro imaging

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RRconway
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Recent....ish astro imaging

Post by RRconway »

Hi all,

My main photographic interest is astrophotography and I really got back into it during Covid isolation. It is frustrating and rewarding in equal measures but very addictive.
I thought I'd share some results with you all.

There are two types of star clusters, globular and open.
Globular star clusters are literally spheres of stars that are held together by their own gravity, while open clusters drift apart not having enough gravitational force to hold them together.
The good thing about imaging stars and clusters is that because they are so bright you don’t need to take nearly as many frames as you do imaging nebula and galaxies, although The Pleiades below is a slight exception because of the dust clouds within the cluster.

Beehive Open Cluster (M48)
1,500 light years from Earth, and no I can never really see a beehive πŸ˜‚
Image

Herculean Globular Cluster (M13)
Containing over 100,000 stars and 25,000 light years from Earth.
The thing I like about this image is the differences in the distances of each element.
The large blue star in the 4 o’clock position is only 425 light years away.
The large yellow star in the 8 o’clock position is 1,200 light years away.
The β€˜faint fuzzy’ (galaxy NGC 6207) on the left in the 9 o’clock position is 64 million light years away.
Now that’s what I call depth of field πŸ˜€
Image


Double Open Cluster (NGC869)
6,800 light years from Earth
Image

Pleiades Open Cluster (M45)
444 light years from Earth.
These are a cluster of hot young stars, hence the vivid blue colour and commonly referred to as the Seven Sisters and surrounded by dust that reflect their blue light.
Image

I hope you like them.

Cheers,
Jeff
I know you think you understood what I said, but I'm not sure you realise that what I said is not what I meant.

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psquiddy
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Re: Recent....ish astro imaging

Post by psquiddy »

Interesting stuff - thanks.

What is the significance of the different colours of the stars?
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psquiddy
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Re: Recent....ish astro imaging

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And what set up do you have for this?
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Paulish
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Re: Recent....ish astro imaging

Post by Paulish »

Brilliant photographs. I understand that there is quite a bit of work involved with layering etc. I especially like the Pleiades. This is one of my favourite patches of sky, and they do look beautiful even when just looking through binoculars. Thank you for sharing.

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RRconway
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Re: Recent....ish astro imaging

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psquiddy wrote: ↑
Mon 10 Oct 2022, 8:23 am
Interesting stuff - thanks.

What is the significance of the different colours of the stars?
Paulish wrote: ↑
Mon 10 Oct 2022, 8:57 am
Brilliant photographs. I understand that there is quite a bit of work involved with layering etc. I especially like the Pleiades. This is one of my favourite patches of sky, and they do look beautiful even when just looking through binoculars. Thank you for sharing.
Thanks for the comments psquiddy and Paulish.
The star colour relates to the temperature of the star and it ranges from the dimmest and coolest red dwarfs up to the brightest and hottest blue stars such as we find in the Pleiades cluster. The cooler dimmer yellow / orange stars have a longer life in general. The Sun currently resides about a third from the bottom of the cool red end of the scale.

Paulish, you are correct about the layering, we call it stacking but the stacks for star images are quite small. The Pleiades one here was 45 x 30 second exposures but my galaxy and nebula pictures can be 4, 5, or 600 exposures and if I can dial my mount in accurately enough will often be 60 seconds each, but when I can afford to upgrade to more accurate tracking 3, 4, and 5 minute exposures will be possible.
The more 'data' you can collect the more detail is resolved and noise reduced.
psquiddy wrote: ↑
Mon 10 Oct 2022, 8:23 am
And what set up do you have for this?
The latest 'family' photo from last year.
The front one is my 5D MK4 with the Canon 100-400. Whilst the lens is very good for terrestial or aviation its not best suited to astro as it has too many glass elements which cause star distortion around the edges, but I use it now and then as it is more portable. The mount it is sitting on is the Skywatcher Adventurer Pro which is a portable star tracker allowing for long exposures but it is compact and lightweight.

The second mount is a manually controlled German Equatorial Mount (GEM) which tracks the sky in altitude and azimuth to prevent star trails but isn't really portable so I seldom use it now. The white and yellow telescope on it is the best scope I have quality wise. It is an APO doublet meaning it only has two elements so very little distortion. It actually has less reach than the Canon 100-400 but the quality is far better. The Herculean cluster and Double open cluster above were taken using this scope.
The camera on the end of it is a Canon 600D which has been astro modded to capture more red light which occurs in Hydrogen Alpha which is common in deep sky objects that I photograph. When I can afford it I will replace it with a dedicated astro camera, (not for a while yet).

The third one is just a visual telescope that I rarely use now as astrophotgraphy has taken over from visual for me.

The fourth one at the back is an 8 inch reflector which I used to image the Beehive and Pleiades above and the sunspot images that I posted a while back. Its sitting on my main mount which is another GEM mount but it is motorised and tracks the sky in altitude and azimuth and is the one I use most.
I use the 600D for 95% of my astro, I dread to think what the shutter count is on it πŸ˜‚

The Rudolph isn't essential but it keeps you company during the night πŸ˜‚

Thankyou again for the interest. I will post some more soon.

Cheers,
Jeff

Image
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psquiddy
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Re: Recent....ish astro imaging

Post by psquiddy »

Thanks for the info.

Do you go out to find a "dark sky" area or do you just go into the garden? If so - how dark is it?
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RRconway
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Re: Recent....ish astro imaging

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psquiddy wrote: ↑
Tue 11 Oct 2022, 8:26 am
Thanks for the info.

Do you go out to find a "dark sky" area or do you just go into the garden? If so - how dark is it?
I will occasionally try to find somewhere darker and every summer we go to the south coast which has Bortle 4 skies, the scale goes from 1 (no light pollution) to 9 (lots of light pollution) think central London.
I live in West London about 1 mile from RAF Northolt which is Bortle 7-8. It was worse earlier in the year with HS2 site lighting being ridicuosly bright but they seem to have calmed down now.

Cheers,
Jeff
I know you think you understood what I said, but I'm not sure you realise that what I said is not what I meant.

Andy'll do
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Re: Recent....ish astro imaging

Post by Andy'll do »

Thankyou for these incredible photos. I won't pretend to understand all the technical stuff, but thats an incredible setup & trying to get to grips with something that is 64million light year away is simply mind blowing !!!

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Rick
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Re: Recent....ish astro imaging

Post by Rick »

Very impressed with these images.
Obviously a lot of time, effort and expense has gone into them.
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Tomorrow.

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RRconway
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Re: Recent....ish astro imaging

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Andy'll do wrote: ↑
Wed 12 Oct 2022, 1:30 pm
Thankyou for these incredible photos. I won't pretend to understand all the technical stuff, but thats an incredible setup & trying to get to grips with something that is 64million light year away is simply mind blowing !!!
Thanks Andy, all the measurements and figures in space are completely unimaginable, for example 1 light year is 6 trillion miles, try timesing that by 64 million πŸ˜‚

Cheers,
Jeff
I know you think you understood what I said, but I'm not sure you realise that what I said is not what I meant.

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RRconway
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Re: Recent....ish astro imaging

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Rick wrote: ↑
Wed 12 Oct 2022, 6:38 pm
Very impressed with these images.
Obviously a lot of time, effort and expense has gone into them.
Thanks RIck, its not cheap but thankfully the cameras are ones I already had for other photography, the telescopes (compared to the cameras) are considerably cheaper. My wife is very understanding but currently future upgrades are currently embargoed as we deal with the current financial situation.

The time is the real battle. I can spend all night outside and get really rubbish results, but then having identified what went wrong it might be 2 months before I can try again. Clearly I can't do it on a work night so it tends to be weekends but then I need clear skies and preferably no moon.
This summer under Bortle 4 skies I was out most nights but still had to satisfy the family requirements for days on the beach, trips out etc etc, I needed another holiday to recover πŸ˜‚
Don't get me started on the conversations that took place when it was discovered that the telescopes and cameras in the car meant there was no room for suitcases and forced us to take two cars, and that was after I inisted that the dates for said holiday co-incided with no/new moon cycle πŸ™„

Thanks again for the kind comments, I will share more soon.
Cheers,
Jeff
I know you think you understood what I said, but I'm not sure you realise that what I said is not what I meant.

Andyph
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Re: Recent....ish astro imaging

Post by Andyph »

Jeff those are fascinating -

Inspired me to get get a better understanding of the night sky - I'm lucky I live in rural New zealand and its both pretty dark and lots to see I think. The Milky way really stands out here.

Just wondering with the photos if they would have more UMPHHH if your Blacks were well Black - seems to me the background on your shots isn't as dark as I feel it should be.
Certainly the last shot you posted above and lots of your shots on Flickr I feel could be processed with darked black levels or more contrast


Anyone else have thoughts on that?
Last edited by Andyph on Thu 13 Oct 2022, 7:56 am, edited 1 time in total.

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GeorgeP
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Re: Recent....ish astro imaging

Post by GeorgeP »

A quartet of outstanding images, Jeff!

I, too, have been fascinated by the night sky but have not pursued it due to work and family commitments. Now that I have retired, I might get a little more time to try it. I can't imagine that my long-suffering wife will be too pleased.

In answer to Andy's question re: the blacks, they look fine to me and my 60 y.o. eyes.
Cheers,

George

Melbourne, Australia.

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Re: Recent....ish astro imaging

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Andyph wrote: ↑
Wed 12 Oct 2022, 10:28 pm
Jeff those are fascinating -

Inspired me to get get a better understanding of the night sky - I'm lucky I live in rural New zealand and its both pretty dark and lots to see I think. The Milky way really stands out here.

Just wondering with the photos if they would have more UMPHHH if your Blacks were well Black - seems to me the background on your shots isn't as dark as I feel it should be.
Certainly the last shot you posted above and lots of your shots on Flickr I feel could be processed with darked black levels or more contrast


Anyone else have thoughts on that?
To be fair Andy, Jeff did state
surrounded by dust that reflect their blue light.
so that would explain that particular image.

Lovely stuff though Jeff.

I went out to get some pictures of Comet Neowise but as it was July, the sky didn't really get dark enough, still had fun though.

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RRconway
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Re: Recent....ish astro imaging

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GeorgeP wrote: ↑
Thu 13 Oct 2022, 5:07 am
A quartet of outstanding images, Jeff!

I, too, have been fascinated by the night sky but have not pursued it due to work and family commitments. Now that I have retired, I might get a little more time to try it. I can't imagine that my long-suffering wife will be too pleased.

In answer to Andy's question re: the blacks, they look fine to me and my 60 y.o. eyes.
Thankyou George.
I'm really lucky that my wife is so patient especially when you consider her hobbies are knitting and needlecraft and generally cost a fiver a month and I've been allowed to invest in all my gear.
Down in Austrailia you have some really dark skies so I am really jealous, it makes such a difference πŸ˜€

Cheers,
Jeff
I know you think you understood what I said, but I'm not sure you realise that what I said is not what I meant.

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RRconway
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Re: Recent....ish astro imaging

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Lovely stuff though Jeff.

I went out to get some pictures of Comet Neowise but as it was July, the sky didn't really get dark enough, still had fun though.
Thanks Wes, glad you like them. Comet Neowise was fun, I dragged my kids out of bed at 2am to view it, I think they appreciated it πŸ˜‚

Cheers,
Jeff
I know you think you understood what I said, but I'm not sure you realise that what I said is not what I meant.

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RRconway
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Re: Recent....ish astro imaging

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Andyph wrote: ↑
Wed 12 Oct 2022, 10:28 pm
Jeff those are fascinating -

Inspired me to get get a better understanding of the night sky - I'm lucky I live in rural New zealand and its both pretty dark and lots to see I think. The Milky way really stands out here.

Just wondering with the photos if they would have more UMPHHH if your Blacks were well Black - seems to me the background on your shots isn't as dark as I feel it should be.
Certainly the last shot you posted above and lots of your shots on Flickr I feel could be processed with darked black levels or more contrast


Anyone else have thoughts on that?
Hi Andy,
Thanks for the comments and glad it inspired you.

Quick answer, no πŸ˜‚ but let me explain.
The Pleiades image as Wes mentioned is a relection nebula which is a cloud of dust that reflects nearby starlight so a black sky would look completely un-natural.

In astrophotography the widely accepted standard is not to completely blacken the background. The process of capturing the 'data' which is how the multiple exposures are referred to is a time consuming and technical process aimed at capturing as many photons of light as possible. These exposures get combined to cancel out 'noise' and increase signal to noise ratio. The output from the software that combines those exposures looks nothing like the end result and requires a lot of really gentle processing which can take hours as you learn the processes involved.
When you reduce the background too much, (and you do have to reduce it) you risk 'clipping' the dark end of the histogram and it starts to take the really faint details that you've teased out, and reduce the overall detail of the image.
When I process my images I will use the RGB values to reduce the dark areas down to about R 20, G 20, B 20. To make them blacker will damage the overall image and in any case when you start doing this hobby you realise that space is rarely black πŸ˜€

I hope this exlpains things a bit. I will post some pictures to help illustrate the above at some point.
BTW, really jealous of your location and dark sky, it must be great.

Cheers,
Jeff
I know you think you understood what I said, but I'm not sure you realise that what I said is not what I meant.

Andyph
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Re: Recent....ish astro imaging

Post by Andyph »

Hi Jeff

Thanks for taking the time for a reply - I follow your reasoning.
But it reads to me as if the artificially high black level (at 20) to not lose data makes perfect sense – BUT should only apply to the intermediate steps .
It seems to me – once you have a final image though surely you can darken black to being black (at 0) as anything darker is just noise?


Maybe it is just I like high contrast images – and when i think of space I think of Apollo missions to the moon and descriptions of the deep blackness of space and super bright Moon surface etc.

useless information alert
Anyway one of the few constellations I can recognise is the Southern Cross – Our bedroom is on the south of the house and we usually have the curtains up so I see the cross most nights – its super obvious.
I’m sure you know that the cross is not at the pole but two of the stars point at the pole
The NZ Flag has 4 stars which represents the Southern Cross – Easy – although we recently had a referendum on changing of the flag ( We have referendums on important stuff here – No trifling Brexit nonsense downunder!)
And the Ex Convicts from our West Island (Sometimes called Australia) have 6 stars on their flag – 5 representing the cross and also the pole star – but otherwise they stole our flag – did I mention they are Ex- Convicts .

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GeorgeP
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Re: Recent....ish astro imaging

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Andyph wrote: ↑
Sun 16 Oct 2022, 8:38 am
...And the Ex Convicts from our West Island (Sometimes called Australia) have 6 stars on their flag – 5 representing the cross and also the pole star – but otherwise they stole our flag – did I mention they are Ex- Convicts .
There's nuthin ex- about the status of the population over 'ere. :rofl:
Cheers,

George

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RRconway
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Re: Recent....ish astro imaging

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Andyph wrote: ↑
Sun 16 Oct 2022, 8:38 am
Hi Jeff

Thanks for taking the time for a reply - I follow your reasoning.
But it reads to me as if the artificially high black level (at 20) to not lose data makes perfect sense – BUT should only apply to the intermediate steps .
It seems to me – once you have a final image though surely you can darken black to being black (at 0) as anything darker is just noise?


Maybe it is just I like high contrast images – and when i think of space I think of Apollo missions to the moon and descriptions of the deep blackness of space and super bright Moon surface etc.

useless information alert
Anyway one of the few constellations I can recognise is the Southern Cross – Our bedroom is on the south of the house and we usually have the curtains up so I see the cross most nights – its super obvious.
I’m sure you know that the cross is not at the pole but two of the stars point at the pole
The NZ Flag has 4 stars which represents the Southern Cross – Easy – although we recently had a referendum on changing of the flag ( We have referendums on important stuff here – No trifling Brexit nonsense downunder!)
And the Ex Convicts from our West Island (Sometimes called Australia) have 6 stars on their flag – 5 representing the cross and also the pole star – but otherwise they stole our flag – did I mention they are Ex- Convicts .
When we talk about 'blacks' what we are actually talking about is the dark end of the histogram, so we adjust the image to what the individual thinks looks good while monitoring the 'black' parts of the image. The varioius changes that we make span areas of the historgram so reducing the dark to 0, 0, 0, not only drags other areas of the image down but clips the blacks which in effect just dumps all the data in the left of the histogram, so given the effort that is required to gather the data in the first place astrophotgraphers don't want to dump any of it.
It must be remembered that some of the really faint dust and nebulosity in these images is really close to the left of the histogram and easily lost.

Ultimately, as you say it is a personal preferance but astrophotgraphers will normally opt for less black black in the image πŸ˜‚

The reason the Apollo images look as contrasty as they do, is, I think, because the subject of the image, be it the Earth or the Moon is incredibly bright with very well defines edges compared to the background of space with strong contrast, hence you can drag the blacks right down. Deep Sky Objects (DSOs) are nowhere near as bright and don't have the hard defined edges, hence the difference in appearance when imaged.

The Southern Cross is as you say your version of Polaris the pole star. Down there they use plate solving to align their mounts for astrophography, we have it relatively easy aligning to the Pole Star.
The one thing I would like to see are the Small and Large Magallenic clouds, two galaxies that should be naked eye visible, one day maybe πŸ˜€

I'll be adding other examples of my images over the next few weeks which will show examples of what we are discussing, I hope you enjoy them.

Cheers,
Jeff
I know you think you understood what I said, but I'm not sure you realise that what I said is not what I meant.

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