Light Pollution

[Astro]

I live in just about the worst location for anyone interested in astronomy and astrophotography, Birmingham UK and 3 mile from Birmingham International Airport and the National Exhibition Centre (NEC).

The light pollution levels are amongst the highest in the UK (and I think Europe generally).

So I like a challenge

The image below is of the Orion Nebula taken over 4 nights in February. It is definitely not the best image ever captured. It is probably the best I can hope to achieve given my location, but it most definitely gives me a buzz getting this result.

Equipment used Canon 5DsR body attached to a Vixen 105mm refractor, on an a guided (GEM) mount.
A total of 619, 25 second exposures, were selected for stacking using Astropixelprocessor. Post processing in Photoshop CC.

[Shadowman]

Nicely captured.

[rpcrowe]

My neighbor who is a budding astro-photographer is experimenting with a filter which is touted to reduce/remove much light pollution. He has not given me his opinion of this filter. I am not sure what type filter he is using...

https://astrobackyard.com/filters-for-astrophotography/

I tend only to like sky images when they have a terrestrial subject like a cactus or an old adobe ruin in the foreground. I mention desert subjects because our deserts have the best sky views.

[1claire]

Wow, this photo left my mouth hanging, it's one of a kind.

[george013]

I live in just about the worst location for anyone interested in astronomy and astrophotography, Birmingham UK and 3 mile from Birmingham International Airport and the National Exhibition Centre (NEC).

The light pollution levels are amongst the highest in the UK (and I think Europe generally).

So I like a challenge

The image below is of the Orion Nebula taken over 4 nights in February. It is definitely not the best image ever captured. It is probably the best I can hope to achieve given my location, but it most definitely gives me a buzz getting this result.

Equipment used Canon 5DsR body attached to a Vixen 105mm refractor, on an a guided (GEM) mount.
A total of 619, 25 second exposures, were selected for stacking using Astropixelprocessor. Post processing in Photoshop CC.

Interesting. I don't know what you mean with the light pollution. Is it the lighter bottom of the picture? I first was looking to the blue circle around some white circle.
If you used a total of 619 pictures of 25s, then you've an exposure of nearly 4.3 hours.

Last week I was in Norway Tromso for shooting polar light. It was a present. The first night in the harbour people said there it starts. I couldn't see anything but when taking a picture I saw it too. Only 1.3 s. The other settings I don't know at the moment. It's amazing what can be made visible with a camera. And in your case with the used gear.
Next day we went on a "polar light saphari", what means driving in the evening to the right site of the mountains hunting for a clear sky. And then hoping for more in a temperature of -10 till -12. What a difference when living in a town!!

If I would live in another place I might get interested in astro photography.

George

[Astro]

Hi George, Light pollution is defined as

excessive, misdirected, or obtrusive artificial (usually outdoor) light. Too much light pollution has consequences: it washes out starlight in the night sky, interferes with astronomical research, disrupts ecosystems, has adverse health effects and wastes energy.

The practical impact in my case is that creates a background light threshold that is brighter than a lot of stars, nebulae and other astronomical objects I would be able to see, say, if I were in a 'dark sky' location.

The attached link takes you to a map (of the UK) which shows the relative intensity of lighit pollution and you can see that Birmingham like other major cities is basically 'floodlit' in this context.

https://www.nightblight.cpre.org.uk/maps/

Richard's point about using a light pollution filter is valid, but the point is that they filter out specific frequencies (mostly in the red area).

I am considering getting one for my Canon EOS mirrorless camera. Speaking to friends who are 'serious' astrophotography practitioners, they tell me that they are useful.

The light at the bottom of the picture is a combination of light pollution and faint background nebula which is actually in the red are of the spectrum.The Blue haloes around the brighter stars are an artefact of the post processing.
I still have a lot of work to do in terms of processing technique to limit these, in part by improving my focus, but also in terms of post processing.

I agree with you about what is achievable using modern digital camera technology combined with stacking software to remove noise. I started out with this genre, with fairly low expectations of success, and am still astounded at what is possible. I still need to improve both my capture and processing though... I'm sure I can with practice, and a bit of luck with the weather etc, improve on what I have posted!

I will be heading to the west coast of Ireland, later in the year and will be taking my telescope and trying a few captures in true 'dark skies'.... Life is good

[xpatUSA]

I live in just about the worst location for anyone interested in astronomy and astrophotography, Birmingham UK and 3 mile from Birmingham International Airport and the National Exhibition Centre (NEC).

The light pollution levels are amongst the highest in the UK (and I think Europe generally).

Interesting. I am reminded of when my parents moved from SE13, London, in 1953 during the smog era. We moved to Woolstone in what was then Berkshire and I remember looking up at the clear night sky in absolute awe, there were so many stars visible ...

[tbob]

Very impressive. I am amazed, given the ambient light, haze and reflected light that you could get any image, let alone one this clear

[Tri Danimal]

I live in just about the worst location for anyone interested in astronomy and astrophotography, Birmingham UK and 3 mile from Birmingham International Airport and the National Exhibition Centre (NEC).

I live in a similar situation as you, but on the west coast of the US

The image below is of the Orion Nebula taken over 4 nights in February. It is definitely not the best image ever captured. It is probably the best I can hope to achieve given my location, but it most definitely gives me a buzz getting this result.

Awesome image, I am going to start working on mt Orion Nebula this weekend, assuming good weather.

I just received my Orion Sirius EQ-G mount last night. I am so excited to set it up and learn it. I'm hoping to get polar alignment tonight or friday night. I should have no issues with weight as Im only imaging on a Sont A7iii and Sigma 150-600mm lens for the near future. My wife said I cant get a scope until 2020, or until I sell off some other gear from other hobbies. It looks like im going to wait until 2020.

Equipment used Canon 5DsR body attached to a Vixen 105mm refractor, on a guided (GEM) mount.

Can you please share a photo of your imaging setup?

[Astro]

Hi Daniel... be warned... frustrating ... trial and error, long processing times... and totally addictive once you get going....


Vixen A105M 4inch refractor with NEQ3 SynScan guider and Canon 5DsR body attached using T ring,


Synscan guider




Camera attached and flip mirror used to change from eyepiece to camera



Focus is achieved using a Bahtinov mask. and the drive is powered using a Lithium battery (which sits on the centre tray when connected.

Camera settings are 'simple', ISO 6400, Bulb setting and an inervalometer to get exposures up to 30 seconds+

Trial and error suggested that lengthing exposure times past 30 secs gave diminishing returns on final image quality (because of the backgroung sky glow from the city), but increasing the number of captures per session really made a difference. For the kinf of light pollution Iexperience I try to get a minimum of 60 per session. The other 'problem' particularly this seasonhas been poor weather. I think I there have only been about 8 clear nights over the last 3 months. (Though a lot more nights with and hour or two of clear sky...hence the multiple sessions over a few nights!)

One thing I found is worth spending time on, is getting a good polar alighnment for the mount, since it will limit the amount of star drift you can get during a session. If you are trying for exposures of minutes it is important, and if you are looking for exposere times of 30 mins say, it is critical. (..remember I mentioned frustration earlier! )

Also, I found that it is really worth spending the time to get good dark, bias and flat frames, I try to take 40 of each for 60 actual exposures.)

As regards processing software, I have used DeepSkyStacker and found it very good, particularly since it is free, though I now use AstroPixelProcessor which is not free, but not too expensive either... it is a relatively new kid on the block, but I think a real improvement on DSS. It does however take a very long time to process large stacks of images (60+).

The image I posted of a 619 image stack took approximately 36 hrs to complete. (I have a 64gb memory, 8 thread desktop with oodles of scratch disk and it churned away using 7 threads and about 850gb of scratch disk!)

Hope this helps.... and clear skies ..... (wish I had a lot more of them here in the UK!!!)

[Astro]

Trevor,

Very impressive. I am amazed, given the ambient light, haze and reflected light that you could get any image, let alone one this clear

I'm quite surprised myself, but I did a fair bit of research on a number of dedicated astrophotography sites, and came to the conclusion that although there is a 'threshold' maximum exposure time, due to light pollution, stacking/noise reduction is the critical factor to getting the best images. Although taking large numbers of 'short' exposure images is a pain, as opposed to taking fewer 'long' exposure images, having a larger number of images for the stacking and noise suppression to work seems to generate better results.

I'm not sure I totally understand everything yet, but I seem to have got myself a reasonable capture process for the conditions here.

Photographing Orion is really just about over for this season, so I'm starting to look for some new fainter targets to concentrate on. Problem is that the bug season is also starting, and I know I now need less sleep than I used to but ...... I reckon as the days lenghten I'm going to become seriously sleep impoverished... that life... a continuous unstable juggling act!

[george013]

I'm pretty sure you know these kind of pictures but for others to get an impression of light pollution.
Just googled and picked a suitable picture.
http://www.allesoversterrenkunde.nl/...edverlichting/. And from this site

A lot of the Dutch light pollution is flower related

George

[Tri Danimal]

Hi Daniel... be warned... frustrating ... trial and error, long processing times... and totally addictive once you get going....

Vixen A105M 4inch refractor with NEQ3 SynScan guider and Canon 5DsR body attached using T ring,

That is a beautiful imaging rig. I really like the slick idea of using a mirror be able to move between a camera and eyepiece, I'll have to remember that if/when I step up to a scope.

Trial and error suggested that lengthening exposure times past 30 secs gave diminishing returns on final image quality (because of the background sky glow from the city), but increasing the number of captures per session really made a difference. For the kinf of light pollution Iexperience I try to get a minimum of 60 per session. The other 'problem' particularly this seasonhas been poor weather. I think I there have only been about 8 clear nights over the last 3 months. (Though a lot more nights with and hour or two of clear sky...hence the multiple sessions over a few nights!)

One thing I found is worth spending time on, is getting a good polar alignment for the mount, since it will limit the amount of star drift you can get during a session. If you are trying for exposures of minutes it is important, and if you are looking for exposere times of 30 mins say, it is critical. (..remember I mentioned frustration earlier! )

Also, I found that it is really worth spending the time to get good dark, bias and flat frames, I try to take 40 of each for 60 actual exposures.)

I just recieved my Orion Sirius EQ-G (goto mount with controller) last night (I just posted about it in anohter thread under photography equipment), I have not had the chance to try to polar align it, yet. I also need to see if I can mount my camera with my standard ballhead plate or do I need to get a dovetail. I didnt realize how many little pieces there are to getting this thign imaging. So fars its been a fun journey.

As regards processing software, I have used DeepSkyStacker and found it very good, particularly since it is free, though I now use AstroPixelProcessor which is not free, but not too expensive either... it is a relatively new kid on the block, but I think a real improvement on DSS. It does however take a very long time to process large stacks of images (60+).

The image I posted of a 619 image stack took approximately 36 hrs to complete. (I have a 64gb memory, 8 thread desktop with oodles of scratch disk and it churned away using 7 threads and about 850gb of scratch disk!)

Hope this helps.... and clear skies ..... (wish I had a lot more of them here in the UK!!!)

I have not even considered paying for a program just yet. I am completly happy withthe performance of DSS, Autostakert2, Registax6, and StarStax for my needs. I mean I still have photoshop and lightroom but I had those before I got into astro.

THanks for your detailed response. I look forward to reviewing more of your images. Clear skies my friend!!!

[rudi]

.....

The light pollution levels are amongst the highest in the UK (and I think Europe generally).....
Equipment used Canon 5DsR body attached to a Vixen 105mm refractor, on an a guided (GEM) mount.
A total of 619, 25 second exposures, were selected for stacking using Astropixelprocessor. Post processing in Photoshop CC.....

Hi James, this is indeed a very nice result given the circumstances....
I can recommend a CLS clip in filter to tackle the light pollution, It is maybe not galaxy friendly,but so far I am happy with it...
AFAIK you are over the payload limit for the mount with this setup. I just wonder how 'stable' this setup is. The 25 sec exposures are unguided I suppose. Have you an idea how long subs you can make unguided??

[Astro]

Hi Rudi, good to hear from you.

I can recommend a CLS clip in filter to tackle the light pollution, It is maybe not galaxy friendly,but so far I am happy with it...

I am familiar with the Astronomic clip in CLS filter but they do not do one for the Canon 5Ds R.
I have a Canon M5 mirrorless which I am considering using with a Clip in filter (Astronomic have one for this range of cameras)
There is a problem though with the intervalometer function which I am investigating at present. As I understand it exposures over 30 seconds are compromised.. I picked this up from the Astronomik web pages, but have not had much time to follow up yet.

I think though that once I'm sure about being able to program bulb exposures effectively, I will switch to the mirrorless camera with a cls clip filter. I would then expect to be able to extend my exposure time considerably for individual subs.
Aditionally, I suspect integrations will not take as long since it is a 22megapixel camera rather than the 50Megapixels of the 5Ds R!

AFAIK you are over the payload limit for the mount with this setup. I just wonder how 'stable' this setup is. The 25 sec exposures are unguided I suppose. Have you an idea how long subs you can make unguided??

Interesting... I took advice from a small but well respected Astronomy retailer (Tring Astronomy) when I bought the telestope.

They knew I was attaching a canon 5D body for photography and they recommented the configuration that I ended up buying. I've been using it for 15 months and as far as I can ascertain there are no stability issues.
Assuming I switch successfully to using the M5 camera, it will reduce the load somewhat, but I will check back on loadings with Tring Astronomy when I contact them to get the CLS filter.

The rig is guided but unguided exposures above 15 show oval stars.

This winter season, there have been very few 'long' nights of clear sky. The norm has been clear periods from about an hour up to about 3 max.

I set up the telescope before each session and polar align followed by 1,2,or 3 star alignment depending on how the intiial weather conditions seem. (If I think I'm only going to get 1 to 2 hours of clear sky I go for single star alignment )
I have settled for the present on a max of 30 second exposures because I seem to get better integretions with exposures under 30 secs.

I do get some drift over about an hour, (approximately 5%)

It is still a learning curve. Logically, I keep thinking about looking into switching to a CCD camera, but I keep coming back to the view that there is a good bit further to go with DSLR /mirrorless.

[rudi]

Thanks for the clarification James.

AFAIK, the load capacity limit mentioned in the specs is for visual observation. For better stability this should be divided by two for astrophotography.
In 2011 (I think) I had an EQ3 like mount, which was prone to vibrations iff loaded with a +/- 4 kg OTA.
So I guess the specs have changed drastically....

What guiding equipment do you use ?

[Astro]

What guiding equipment do you use ?

Rudi, I have a ZWO 30F4 Miniscope with a ZWO ASI Planetary CCD Camera replacing the eyepiece. I'm using Phd (Stark labs) as the control software.

I'm still getting to grips with the setup, but I'm hoping to be confident of exposures of 30 mins or more by the time I head over to the West Coast of Ireland later this year.

[rudi]

.... exposures of 30 mins or more ....

Allow me to add my 2 cents worth....

Very long exposures (+10 minutes) are typically used with cooled narrowband CCD cameras.

The length off a sub depends on many factors like used equipment, seeing, light pollution,....

With a DSLR camera the sensor temperature, and thus the thermal noise, increases a lot during an hour or more imaging....

I live in a red zone on the light pollution map. And I typically use exposures around 2 to 3 minutes (guided), because to my experience, in my case, longer subs would not ad more usable data, only unwanted noise. To me the quality off one sub is more important.

For 10 minutes subs, sky conditions have to be really good and in my case, plane trails are a problem. Throwing out one 10 min sub is a lot compared to one 2 min sub, in a total imaging time off lets say one hour.
A lot more can go wrong in a 10 min sub compared to a 2 min sub.

A lot has been written about the optimum sub-exposure, but I believe it is best to try out what works best for you in a given situation.
HTH.

[Astro]

Hi Rudi, thanks for this, it really helps. The last two years has been one long learning curve and it has been an exercise in experimenting to find what works best. My 30 minute 'aspiration' is precisely that, and is/was a target for my trips to Ireland later this year (where there are true dark skies)

[QUOTETo me the quality off one sub is more important.][/QUOTE]

This I have definitely leant a this winter. Apart from the fact that there is a virtual threshold of about 30 secs here before sky glow/light pollution blocks further improvement in detail, I've had to work with shorter exposures to optimise the number of good captures. The weather has been very 'shut down' over the winter and there have been only a couple of nights which have been relatively cloudless. I did find myself keeping to exposures less than 30 sec to make best use of the short periods of clear sky.

Your point about thermal noise and long shoots is an issue I was aware of, but had not considered properly
I think it may actually be worth going back over all the sessions (32) since Dec and maybe select the first 20 or so subs from each session and combine them, then repeat for the last 20 or so in each session. Comparison of the results will probably give me a time limit to maybe optimise run times and limit thermal noise.
Madness lies before me!!!