General Light Pollution Filter for Bortle 3?

Most light pollution maps have my location as a Bortle 3; I would class it to be Bortle 4 myself and my garden is surrounded by some very annoying lights; one LED street light, one sodium street light and 3 bright unshielded warm-white domestic light bulbs on the house opposite. I can protect my imaging rig using simple tarps, but would anyone still bother with something like an Optolong L-Pro or would I simply be wasting my money?

I am not sure what kind of telescope you are using, but if you are worried about stray light I think a dew shield would be better in your case.

Light pollution filters are (in my opinion) really only useful from bortle 6 and above. Below that you are just kind of wasting your money. Below I linked an image where about half the data came from a Bortle 4 campsite where the main building had a super annoying sodium light shining off to the side. It didn't really affect the image. Also, it was at about 10 degrees on the horizon so I am shooting through whatever lights might be shining up from the ground for a loooooooooooong ways.

Vistors From Down Under

That's a rather good shot and also very encouraging! I have an 8" f4 Newt and a 72mm refractor. I do have a dew shield for the Newt but so far have only used it on really cold nights to protect from dew. If that would be as effective as the tarps in stopping any stray light reaching the inside of the scope, or remove the need for a light pollution filter, that would be better for me.

Currently, my only filter is a NBZ nebula one…I just feel under-equipped!

Piers Palmer:
Most light pollution maps have my location as a Bortle 3; I would class it to be Bortle 4 myself and my garden is surrounded by some very annoying lights; one LED street light, one sodium street light and 3 bright unshielded warm-white domestic light bulbs on the house opposite. I can protect my imaging rig using simple tarps, but would anyone still bother with something like an Optolong L-Pro or would I simply be wasting my money?

Bortle 3/4 is good! I suspect it's rather better than most of us have. I am in a Bortle 5/6 and manage to get decent broadband images even against a moon (see attached which was against a full moon).

I do use an Optolong L Extreme for bright nebulae and I like the results.

But I would suggest you don't really need filters where you are.

NGC 3628

Piers Palmer:
That's a rather good shot and also very encouraging! I have an 8" f4 Newt and a 72mm refractor. I do have a dew shield for the Newt but so far have only used it on really cold nights to protect from dew. If that would be as effective as the tarps in stopping any stray light reaching the inside of the scope, or remove the need for a light pollution filter, that would be better for me.

Currently, my only filter is a NBZ nebula one...I just feel under-equipped!

You got some decent telescopes, a great camera and the best equipment of all, dark skies. I think you are well on your way to taking some good pictures.

If you are confident regarding your skills on flat frame acquisition and calibration, and the gradient removal tools of your favorite image processing software but you find yourself spending way too much time removing gradients, then a filter will help. Otherwise it is a waste of money and it may introduce other headaches.

I am under Bortle 5 skies and I don't feel the need for a filter. I tend to image when the object of interest is near its highest altitude. Most of the times, a low-order polynomial (2nd-order or even 1st-order) in PixInsight's ABE gradient removal tool provides very satisfactory results. If you don't speak PixInsight

this simply means that light pollution in my case is very smooth thus easy to model and to remove via any decent software.

Thanks both - I took this last night (just with an STF applied in Pixinsight), but suspect light was somehow getting into the tube? That's probably fairly easily remedied.

The shot I took the previous night of Bode's Nebula is more typical of what I generally get.

M81 (Bode's Galaxy)

Die Launische Diva:
If you are confident regarding your skills on flat frame acquisition and calibration, and the gradient removal tools of your favorite image processing software but you find yourself spending way too much time removing gradients, then a filter will help. Otherwise it is a waste of money and it may introduce other headaches.

I am under Bortle 5 skies and I don't feel the need for a filter. I tend to image when the object of interest is at its highest altitude. Most of the times, a low-order polynomial (2nd-order or even 1st-order) in PixInsight's ABE gradient removal tool provides very satisfactory results. If you don't speak PixInsight this simply means that light pollution in my case is very smooth thus easy to model and to remove via any decent software.

I've not really got to grips with flat frames yet, but I had applied dark and bias frames to the above. I've tried taking flat frames before using my ipad as a light source, but it didn't seem to work very well! Something I definitely need to sort out.

Piers Palmer:
Die Launische Diva:
If you are confident regarding your skills on flat frame acquisition and calibration, and the gradient removal tools of your favorite image processing software but you find yourself spending way too much time removing gradients, then a filter will help. Otherwise it is a waste of money and it may introduce other headaches.

I am under Bortle 5 skies and I don't feel the need for a filter. I tend to image when the object of interest is at its highest altitude. Most of the times, a low-order polynomial (2nd-order or even 1st-order) in PixInsight's ABE gradient removal tool provides very satisfactory results. If you don't speak PixInsight this simply means that light pollution in my case is very smooth thus easy to model and to remove via any decent software.

I've not really got to grips with flat frames yet, but I had applied dark and bias frames to the above. I've tried taking flat frames before using my ipad as a light source, but it didn't seem to work very well! Something I definitely need to sort out.

In this case please include flats and dark flats into your workflow as a first measure. I support the claim that a lens hood or dew shield is another important measure. In case none of this solves your problem 5 midsized stones may be another approach - at your own risk :-)

Have fun and clear skies
Wolfgang

Just to avoid confusion: The flats and dark flats won't solve light polution issues but they will help your images a lot in general.

CS Wolfgang

In case none of this solves your problem 5 midsized stones may be another approach - at your own risk :-)

Absolutely not necessary. You will lost data. Bortle3 is excellent.

Just make shorter expositions (120/180s instead 300s) .

ricardo leite:
Absolutely not necessary. You will lost data. Bortle3 is excellent.

Just make shorter expositions (120/180s instead 300s) .

There is some virtue in being background limited, so not sure whether this will be the case with 120/180s in a Bortle 3 zone.

Clear skies
Wolfgang

Don't need it in Bortle 3/4 unless you're maybe shooting lower than 25/30 degrees towards some light pollution.

Do they hurt? If I go to Bortle 2 would it matter if I left them in my Reducer?

Dan Kearl:
Do they hurt? If I go to Bortle 2 would it matter if I left them in my Reducer?

In order to cut out some of the worst light pollution offenders, LP filters cut off wide swaths of the color spectrum to eliminate them. Pretty great if you are in a city, but almost useless outside of one. You are going to want all that signal its cutting out when you are in Bortle 2, because its not being polluted (as much) as it would be in town to be a real issue.

I am lucky enough to live in Bortle 3 class. I am occasionally bothered by stray light at some orientations (sometimes of my own making), but I find a dew shield helps cut that stuff out.
CS Brian

Thanks everyone. I shan’t bother. I’ve rigged up some windbreaks which can act as light screens and I’ll be more consistent with using the dew-shield on the Newt. I’ve ordered on for the Frac too as it’s dew-shield is quite short.

Piers Palmer:
Thanks both - I took this last night (just with an STF applied in Pixinsight), but suspect light was somehow getting into the tube? That's probably fairly easily remedied.

M81 (Bode's Galaxy)

This looks like vignetting, which a good flat should eliminate. I'm also fairly new at this, so I sometimes prepare a range of flats of different intensity, and test to see which one work best to eliminate vignetting. It's worth spending sometime experimenting with different flat exposures. It will make a big difference.

Yeah - I think my belligerence in not doing them is proving costly! I wonder if it's worth investing in a flat-panel to make my life easier.

Piers Palmer:
Yeah - I think my belligerence in not doing them is proving costly! I wonder if it's worth investing in a flat-panel to make my life easier.

Flats are n.1 item you shuld take care of when processing astronomical imagery, even in Bortle 3 skies. What the heck, even in Bortle 1! Flat panels are to be avoided if possible (some times isn't) and dusk flats to be much preferred.

Piers Palmer:
Yeah - I think my belligerence in not doing them is proving costly! I wonder if it's worth investing in a flat-panel to make my life easier.

A flat panel is not essential, I just cover the tube (14 " inch Dobson) with a white T shirt and point to the sky at dusk. I use Sharpcap's flat creator. NINA's flat wizard also works well.

If I need to redo flats during the night, I've also improvised a ceiling light panel (50 euros) with exactly the same diameter as my tube. I cover this with an IKEA bed cover and it gives me decent flats at about 30 ms exposures 0 gain for my ASI 294MCpro.

Dan Kearl:
Do they hurt? If I go to Bortle 2 would it matter if I left them in my Reducer?

If you're lucky enough to have access to Bortle 2 skies you should definitely remove your filters!

You could give it a try with GradientXTerminator by Russell Croman. It's a plugin for PS. Otherwise if you have MaximDL, they have a nice gradient removal tool. CS.

Piers Palmer:
Most light pollution maps have my location as a Bortle 3; I would class it to be Bortle 4 myself and my garden is surrounded by some very annoying lights; one LED street light, one sodium street light and 3 bright unshielded warm-white domestic light bulbs on the house opposite. I can protect my imaging rig using simple tarps, but would anyone still bother with something like an Optolong L-Pro or would I simply be wasting my money?

Optolong L-eNhance and L-eXtreme

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