BIG problems with Optolong L-Pro Filter!

[wesdon1]

Hi all. Basically I've been using my new 1.25" L-Pro Filter for some weeks now, and in the few imaging sessions I have done so far, I'm struggling to understand a few things...

1 - Why is the filter making my subs so blue?

2 - Why are my subs and subsequently my final DSS stacked images terribly vignetted? Is it because the filter is 1.25"? 

3 - Why are my subs so blown out, even though I'm only doing 1 minute subs, and have a decent LP Filter, the L-Pro, which is supposed to really help with LP and Sky Glow?

Any advice would be greatly appreciated. Thanks You.

*As a side note, for those who may recall my earlier posts regarding Polar Alignment, I am now quite good at getting Polar Alignment really dialled in, but I can't do longer exposures than roughly 1 minute because of the above problems with Sky Glow, Vignetting, and the awful Blue Cast over my images.

[900SL]

The L pro only cuts out certain bands of LP, and may not deal with some LED light pollution

Seriously, it would help posting this as a sticky for the N00bs but you need to post more information if you expect an answer:

Camera, gain / ISO / exposure length

Scope and f ratio

Bortle scale/location

and probably some other stuff but it's been a long day..

[Elp]

I find the optolongs make the image more green, I had a CLS filter prior which caused a blue tint. Regarding vignette, likely the filter is too small to cover the camera sensor but are you taking and applying flats as these are required to remove vignettes and dust in your images.

[rnobleeddy]

Quote

 1 - Why is the filter making my subs so blue?

I don't know why more blue, but any time you chop out vast chunks of the light spectrum, it's best to assume you'll need to rebalance the colours when processing. You can seem from https://www.firstlightoptics.com/light-pollution-reduction-imaging/optolong-l-pro-light-pollution-broadband-filter.html that's it's going to make a significant difference.

 

Quote

Why are my subs and subsequently my final DSS stacked images terribly vignetted? Is it because the filter is 1.25"? 

That would depend on the camera size primarily, as well as where the filter is placed. More worrying is that your flats should correct this unless you're using a filter that's way too small. In which case all you can do is crop.

 

 

[wesdon1]

17 hours ago, 900SL said:

The L pro only cuts out certain bands of LP, and may not deal with some LED light pollution

Seriously, it would help posting this as a sticky for the N00bs but you need to post more information if you expect an answer:

Camera, gain / ISO / exposure length

Scope and f ratio

Bortle scale/location

and probably some other stuff but it's been a long day..

Thanks for advice. I've sorted the issues. basically I need a 2" filter, instead of a 1.25", I also wasn't doing Flat frames, and I also need a field flattener for 'scope. Finally, I also now know how to calibrate RGB properly in processing.

[wesdon1]

17 hours ago, Elp said:

I find the optolongs make the image more green, I had a CLS filter prior which caused a blue tint. Regarding vignette, likely the filter is too small to cover the camera sensor but are you taking and applying flats as these are required to remove vignettes and dust in your images.

I've found out my mistakes now thanks. I wasn't doing lights/flats, and I need a 2" filter to adequately cover my sensor on camera. Finally, I now know how to do RGB properly in processing. Thank You for your great advice and suggestions!

Wes.

[wesdon1]

16 hours ago, rnobleeddy said:

I don't know why more blue, but any time you chop out vast chunks of the light spectrum, it's best to assume you'll need to rebalance the colours when processing. You can seem from https://www.firstlightoptics.com/light-pollution-reduction-imaging/optolong-l-pro-light-pollution-broadband-filter.html that's it's going to make a significant difference.

 

That would depend on the camera size primarily, as well as where the filter is placed. More worrying is that your flats should correct this unless you're using a filter that's way too small. In which case all you can do is crop.

 

 

Thanks for great advice and suggestions, I have worked everything out now ( I hope! LOL ). Basically I wasn't doing flats, i'm using the wrong sized filter for my setup, and I wasn't doing RGB calibration in processing! Thanks again! 

Wes.