taking long exposures with heavy light polloution

[oldpink]

for me it will have to be with the camera on as I don't own a lens for it, for now its purely for astro
no chance of me getting out in the foreseeable future, even the best long range forecast says cloud, rain and windy for the next week
so frustrating, pity someone can't invent a cloud filter for us optical asrtonomers
I could always revive my old hobby of amateur radio and get into that side of astronomy, Sat dishes are easy to get just need to figure out a receiver (goes off to investigate)

[lensman57]

Lensman - I don't think I'll ever be able to do such long exposures here with whatever lp filter I have! It never gets dark where I am near the city centre - obviously a white zone for lp. Maybe I'm wrong but I think I'm doomed to relatively short exposure imaging... Here's a single 120s/ iso800 sub I took last night (of M3).

L_5234_25pc.jpg

If I were to try and do a 5 minute one it would be pretty much a whiteout, I think. Maybe there could still be some useable data and with stacking/darks/flats and processing maybe I'd still be able to get quite a lot out. Tbh, I don't know as I've never tried processing beyond 3min subs yet... 120s subs as above, I've been able to use ok. Guiding with the lp interference is also problematic but I'm not giving up yet!

Oldpink - sympathies! Maybe you could arrange some sort of screen to cut out the direct lp? I have a piece of cardboard on my window sill which shields the scope from the direct light caused by a street lamp about 8m away.

Louise

Hi Louise,

This the is processed data of the Leo Triplet. Dealing with the gradients caused by the Moon and the LP was a nightmare but here it is anyway, I have not had a great dealsuccess with teh IC405 yet but all is not lost yet despite the severe LP levels.

Regards,

A.G

[ardbeg74]

Still a lot of thin bands of cloud hanging around, trying to get the whirlpool tonight, but cant even see the stars near it i was using as a guide. Did see what i call the "flag pin" asterism ( its shaped like a P ) near the sunflower galaxy that might be worth a shot though, as a comparison of the last failed attempt to get good data on it

I know what you mean about the radio astronomy. I made a joke on a post about trying to create aricebo from lots of sky dishes, but in all seriousness it would be really interesting to get in to... but it means buying more kit that i dont have a clue about

Lensman... nice job mate!!!    Inspired now.   I tried the leo triple last week, While i got all 3 in frame, it was a nightmare evening from start to finish. Everything that could go wrong went wrong.  And the results were... well not post-able here

If you dont mind me asking, what was your total integration time for that?

All the best

Mark

[lensman57]

Still a lot of thin bands of cloud hanging around, trying to get the whirlpool tonight, but cant even see the stars near it i was using as a guide. Did see what i call the "flag pin" asterism ( its shaped like a P ) near the sunflower galaxy that might be worth a shot though, as a comparison of the last failed attempt to get good data on it

I know what you mean about the radio astronomy. I made a joke on a post about trying to create aricebo from lots of sky dishes, but in all seriousness it would be really interesting to get in to... but it means buying more kit that i dont have a clue about

Lensman... nice job mate!!!    Inspired now.   I tried the leo triple last week, While i got all 3 in frame, it was a nightmare evening from start to finish. Everything that could go wrong went wrong.  And the results were... well not post-able here

If you dont mind me asking, what was your total integration time for that?

All the best

Mark

Hi,

This was 14 X 900s with Bias and Flats, no darks. Ascension 80mm Apo triplet, Televue TRF2008 and an Atik 428EXc with IDAS D1 filter. Processed in PI and PS.

Regards,

A.G

[oldpink]

radio astronomy is something I have looked into before
it can be done very cheaply with a few easily available components
lots of satellite TV equipment can be used and there is software available
it seems a shame to waste all that study I did getting my Radio Amateur certificate / OU degree in electronics
I also have background in computers and electronics in general so a lot of the equipment I can build or adapt

I also run my own PA & lighting company where I use equipment from low frequency audio, through to very narrow band laser shows mixing RGB laser beams
at very high scan rates to create 3 dimensional images via protecting them through lots of smoke with lots of other lighting effects via a computerised control system

you might say I have an interest in lots of parts of the spectrum

[Thalestris24]

Hi Louise,

This the is processed data of the Leo Triplet. Dealing with the gradients caused by the Moon and the LP was a nightmare but here it is anyway, I have not had a great dealsuccess with teh IC405 yet but all is not lost yet despite the severe LP levels.

Regards,

A.G

Nice image! I'd like to be able to achieve something similarly as good one day! I have lots of things/issues to sort out though and the weather is rubbish at the moment anyway. I just got a qhy8l osc  and I'm hoping that I'll be able to exploit it's higher QE and get better images. At the moment I have no lp filter for it so will try it out without first. I see you have the idas d1 . It seems to have a good reputation - at a price!

Louise

[lensman57]

Thank you  Louise, given the imaging conditions I am quite pleased with the image . I have now processed the IC405 from the same night and it is in the "deep Sky imaging" section the forum, it only took 3 days to process.

Regards,

A.G

[Thalestris24]

So I had my first go with the qhy8l on Sat/Sun but have no lp filter for it so had to resort to processing to remove the lp and other gradients. Stacked 4 out of 5 240s subs in dss and processed in StarTools. Here are results before and after processing:

Single sub with amp glow and lp:

Stacked and processed:

I should mention that these are both screen grabs using the Windows 7 snipping tool. Still, you can see that the lp has been eliminated. There is a problem with the image being out of focus on one side. This must be a camera problem that I'll have to try and sort out next time.

Louise

[wxsatuser]

That looks good with the LP gone, should get some nice data with the new cam.

[Dave_D]

Some good advice here... going to see if i can apply some of it at my location. I stumbled on the custom white balance totally by accident when i was messing with my camera settings. I'd love to be able to do 5 minute subs but 2 minute has been my limit so far. Might try to see if i can get a lp filter to fit on my baader mpcc as a clip filter is out of my financial range at the moment being one of camorons 'scroungers' But anyway, got a gpusb sat here, never been used or even plugged in so i might try a swap on astrobuysell.

[toxic]

may have to go to a clip filter

can't find anyway to get my 1.25 LPF mounted unless I use the barlow

I like the looks of the Astronomik Deep Sky & LP filter

or get a decent 2" LPF and mount it with the Coma corrector that I need to buy

hi

you say that you have a 1.25 lpf why not just unscrew your lens from the bottom of the barlow and screw the lpf on to it. i have a 2" skywatcher lpf and i screw it to the com corrector and it works fine i admit its not the best lpf but it works for me.

my images are all orange without it

[oldpink]

hi

you say that you have a 1.25 lpf why not just unscrew your lens from the bottom of the barlow and screw the lpf on to it. i have a 2" skywatcher lpf and i screw it to the com corrector and it works fine i admit its not the best lpf but it works for me.

my images are all orange without it

I did think about that

but it means I need to use the 1.25 adapter in the focuser instead of the camera attached directly

not sure if I will be able to focus with the extra inch or so the 1.25 adapter will add but worth a try

[oldpink]

I've just had an Email from Juan at cheap astrophotography about the settings to use as I didn't get it initially
first thing I did was to set up a custom white balance (first mistake) and use that for AP

apparently the best setting for my modded camera is Daylight for the WB 

that coupled with the other technique I found via this thread (using the sky as a custom WB)I will need to get out and try
even if I only get a few subs it will allow me to see what works best

[oldpink]

tried mounting the LP filter onto a nose piece and as I suspected the extra distance the 1.25 adapter adds stops me from getting to focus
forecast says a few hours of clear sky just after sunset so hopefully I can try out some White Balance settings to see what works best
while I await the purchase of the Astronomic filter

[ianpwilliams]

I'm new to astronomy, and I will have light pollution to deal with in my back yard (and no car to go anywhere better).

There are some very good before and after LP images in this thread, but they tend to be wide angle shots. Does anyone know if it's possible to get decent DSO shots under heavy light pollution with light filters, image processing etc?

[Thalestris24]

I'm new to astronomy, and I will have light pollution to deal with in my back yard (and no car to go anywhere better).

There are some very good before and after LP images in this thread, but they tend to be wide angle shots. Does anyone know if it's possible to get decent DSO shots under heavy light pollution with light filters, image processing etc?

I posted this earlier on another thread:

http://stargazerslounge.com/topic/212381-getting-somewhere-i-hope/#entry2271451

Bad lp, no filter, processed with StarTools

Louise

[Thalestris24]

I posted this earlier on another thread:

http://stargazerslounge.com/topic/212381-getting-somewhere-i-hope/#entry2271451

Bad lp, no filter, processed with StarTools

Louise

ps the previous image I posted above wasn't widefield - it was a random group of stars seen through my 150pds....

[Alien 13]

I'm new to astronomy, and I will have light pollution to deal with in my back yard (and no car to go anywhere better).

There are some very good before and after LP images in this thread, but they tend to be wide angle shots. Does anyone know if it's possible to get decent DSO shots under heavy light pollution with light filters, image processing etc?

It depends somewhat on the type of LP you have if its the standard orange glow that i have then processing can be very effective in removing it.

There are other factors involved, for me it is the maximum sub length my mount/scope will allow so if i can go to this maximum without overexposure then i believe i can get better images without the use of a filter.

Alan

[ianpwilliams]

Yes I get the orange glow too. But it sounds like filters and processing would be able to help. I would be interested to see a photo of the Orion Nebula (or similar) taken with light pollution, with a before and after shot, if anyone has posted anything like that.

[oldpink]

you can also play with custom white balance to take out a lot of glow
I found that can take a fair bit out with a bit of experimenting and the type of light your dealing with
I have a mixture of red Sodium and white "Eco" lamps to deal with which makes it more difficult to deal with

[Alien 13]

This was my orion nebula the 1st image is a single sub 2nd the processed image.

Alan

[RikM]

Yes I get the orange glow too. But it sounds like filters and processing would be able to help. I would be interested to see a photo of the Orion Nebula (or similar) taken with light pollution, with a before and after shot, if anyone has posted anything like that.

Here's another one:

60 second sub without filter

90 second sub with SkyWatcher Light pollution filter

About 40 or so 90 seconds subs, with filter, after stacking and processing

[oldpink]

afraid I'll be on Beans & toast for a couple of weeks
I'm ordering my Astonomik CLS filter tomorrow, but it will be worth it

[ianpwilliams]

Well that's amazing. I would have thought that in would be hard to remove the orange glow from DSO shots, particularly if the nebula is different colours, some of which would be similar to the orange glow. But this really gives me hope.

I was considering starting with a cheaper scope setup to start with just to see how badly the light pollution would affect things, and then intend to upgrade later, but it seems that with a good light filter, and plenty of image processing (which I would be more than happy to do do), that it would hopefully be an entirely avoidable problem.

[Thalestris24]

Well that's amazing. I would have thought that in would be hard to remove the orange glow from DSO shots, particularly if the nebula is different colours, some of which would be similar to the orange glow. But this really gives me hope.

I was considering starting with a cheaper scope setup to start with just to see how badly the light pollution would affect things, and then intend to upgrade later, but it seems that with a good light filter, and plenty of image processing (which I would be more than happy to do do), that it would hopefully be an entirely avoidable problem.

I'm afraid it's not _entirely_ avoidable and nothing compares to dark skies. However you can compensate to a certain extent. I think if you want to seriously image nebulae then a mono ccd and narrowband filters are the way to go. That's expensive, and probably a later upgrade, but you can still achieve quite a lot with an astro modded Canon dslr or a good osc cooled ccd.

Louise