Adding a light pollution filter?

[cjdawson]

Hi all.

I'm thinking about how I'd go about adding a light pollution filter into my optical train.   The main problem is the question of which size filter, and how to mount it into the optical train.

My current setup working from my scope is....

 

SCT Thread F6.3 Focal reducer

SCT Thread to T2 adapter

ZWO Filter wheel

ZWO ASI1600MM-Cooled

 

I'm sure that the place to insert the Light pollution filter will be between the Filter wheel and the SCT to T2 adapter.    The alternative being something that has an SCT Thread and can go scope side of the FR.     Any ideas?

[michaelmorris]

I know that it doesn't answer your question, but why not put the filter in your filter wheel?

[cjdawson]

1 minute ago, michaelmorris said:

I know that it doesn't answer your question, but why not put the filter in your filter wheel?

It's a legit question.  However the problem with doing so means that I can't make LRGB images, As those are the filters already in the wheel. I'd want this filter to be in place as well as, so that I can still do the LRGB thing.

[jed2i]

What LRGB filters do you have?

[teoria_del_big_bang]

There are quite a few old threads on this if you search the forum so a fairly common practice by the looks of it ,such as:

https://stargazerslounge.com/topic/198998-lp-filter-used-with-lrgb-filters-good-idea/

I think most seem to put them behind the flattener or coma corrector.

Steve

[geordie85]

2 hours ago, cjdawson said:

 

I'm sure that the place to insert the Light pollution filter will be between the Filter wheel and the SCT to T2 adapter.    The alternative being something that has an SCT Thread and can go scope side of the FR.     Any ideas?

I wouldn't have any filters load bearing. It'd probably be best to have it as you suggested, at the scope end of your focal reducer

[cjdawson]

9 hours ago, jed2i said:

What LRGB filters do you have?

It's been a long time since I've seen the filter (only saw them on purchase day)   iirc it's these

https://www.firstlightoptics.com/rgb-filters-filter-sets/zwo-125-lrgb-filter-set-optimised-for-asi1600.html

[cjdawson]

Ah ha.  Found the solution to the LP problem....

 

https://www.firstlightoptics.com/light-pollution-reduction/idas-d1-lps-sct-filter-adaptor-set.html

going to add that to my wish list, then again maybe not as they're talking about changing all the street lights in my area to LED