Light Pollution Filter needed ?

[PaulR1]

Hey folks

Anthonyexmouth's thread here :

 

Prompted me to ask this question , in his thread he posted a RAW file which looked pretty nice , I understand he is using a CLS filter.

Here is one of my subs ( 3 min @ 800 ISO ) of the same object.

Im using a modded 450D dslr so Im wondering here if the pinkness is due to light pollution or just because I have a modded camera and if a light polution filter would help.

Or does this image look pretty "normal" for a sub through a modded dslr?

The images do get darker as the night progresses.

Thanks

[david_taurus83]

Where are you imaging from? Is there streetlights in your area?

[PaulR1]

There are street lights 3 of them pretty close to me but they are actually lower than the scope, as Its all installed on a flat roof here.

( I live above a shop in a maisonette)

When I look at the sky it doesnt look too bad in terms of glow on the horizon.

[david_taurus83]

It's definitely LP then. The glow radiates up. It's like trying to image from within a dome of light. You would definitely benefit from a filter. It helps but doesn't eliminate it altogether. There's no way I could take a 3 min sub here without a filter. It would be completely washed out. I have a Skytech CLS CCD filter that works quite well. I'll dig up the review and you can see the difference they make.

 

Edit: Here you go.

 

[teoria_del_big_bang]

3 minutes ago, david_taurus83 said:

It's definitely LP then. The glow radiates up. It's like trying to image from within a dome of light. You would definitely benefit from a filter. It helps but doesn't eliminate it altogether. There's no way I could take a 3 min sub here without a filter. It would be completely washed out. I have a Skytech CLS CCD filter that works quite well. I'll dig up the review and you can we the difference they make.

I have just had my DSLR modified but not had chance to use it yet since the modification. Now the filter removal makes it much more sensitive to red light, which when trying to get all the light we can from DSOs is a good thing, BUT does that also mean it makes them more suseptable to LP as well ?

Steve

[PaulR1]

13 minutes ago, david_taurus83 said:

It's definitely LP then. The glow radiates up. It's like trying to image from within a dome of light. You would definitely benefit from a filter. It helps but doesn't eliminate it altogether. There's no way I could take a 3 min sub here without a filter. It would be completely washed out. I have a Skytech CLS CCD filter that works quite well. I'll dig up the review and you can see the difference they make.

 

Edit: Here you go.

 

thanks mate

[PaulR1]

7 minutes ago, teoria_del_big_bang said:

I have just had my DSLR modified but not had chance to use it yet since the modification. Now the filter removal makes it much more sensitive to red light, which when trying to get all the light we can from DSOs is a good thing, BUT does that also mean it makes them more suseptable to LP as well ?

Steve

Good question that

[david_taurus83]

9 minutes ago, teoria_del_big_bang said:

I have just had my DSLR modified but not had chance to use it yet since the modification. Now the filter removal makes it much more sensitive to red light, which when trying to get all the light we can from DSOs is a good thing, BUT does that also mean it makes them more suseptable to LP as well ?

Steve

I'm not sure Steve. Removing the infrared filter lets more of that wavelength of light through so if there are infrared lamps for local cctv etc then I suppose it's more susceptible to that also. It will behave just like visible light pollution only our eyes can't pick it up but the camera will.

[Marci]

Combination of light pollution and the camera just being generally red-heavy now due to no longer having it's colour-correcting hot mirror, so it’s white balance will now be off. Yes, a CLS CCD filter will improve things... but ultimately the white balance of anything getting thru the filter will likely still be slightly red-heavy and need correcting out. Quick fix: head to Image > Autotone in photoshop will re-align the histogram and correct the white balance... then process as per normal.

[toxic]

looking at the pinkness of your image you could do 6 minutes it wont matter if your image looks washed out so long as its not completely blown and an easy way to tell is to load a test shot into dss and look at what it shows on the screen without stacking.

i had a quick go at your single sub and you suffer some vignetting and the rest is just colour ballance.

 

[cletrac1922]

First of all welcome from land down under

Some of my club members have been experimenting with narrow band filters

Most common been H-Alpha, Oiii and Sii

We now have another problem emerging, with introduction of LED street lighting, which casts light across a bigger area

John

 

 

 

[PaulR1]

2 hours ago, Marci said:

Combination of light pollution and the camera just being generally red-heavy now due to no longer having it's colour-correcting hot mirror, so it’s white balance will now be off. Yes, a CLS CCD filter will improve things... but ultimately the white balance of anything getting thru the filter will likely still be slightly red-heavy and need correcting out. Quick fix: head to Image > Autotone in photoshop will re-align the histogram and correct the white balance... then process as per normal.

Thanks for this tip I just tried it and it works a treat

 

[PaulR1]

43 minutes ago, toxic said:

looking at the pinkness of your image you could do 6 minutes it wont matter if your image looks washed out so long as its not completely blown and an easy way to tell is to load a test shot into dss and look at what it shows on the screen without stacking.

i had a quick go at your single sub and you suffer some vignetting and the rest is just colour ballance.

 

Many thanks , tried what you suggested with DSS , very cool .

?