ASI294MC Pro: Which filters have you used, liked, did not like & why?

[oymd]

Hello everyone

After jumping head in last May into this wonderful new hobby to me, I suffered a bicycle accident, fractured ribs, followed by COVID, so had to drop the whole hobby for almost a year!

I'd like to get back, but I think I forgot everything I've learnt last year!

So, as the title says, which filters have you used with said camera, with good results?

I currently have the ZWO 2" filter drawer, and only have the IDAS LPS-V4. I gather it is good for Emission nebula? What about refelection Nebula and planets?

Can you please provide suggestions for a good LP filter for Galaxies?

Any other filters you suggest would be great as well?

I live in Central-ish London, Zone 3, so LP is bad.

Have you tried Ha filters on this OSC at all?

My setup: SW ED80 + 0.85FR, ASI294MC Pro, 2" filter drawer

Many thanks

[souls33k3r]

I'm truly sorry to hear the troubles you've been through but it's good to have you back and feeling better. 

Optolong L-eXtreme filter is a much better bet which works on Ha and OIII at a generous bandpass. 

[oymd]

2 minutes ago, souls33k3r said:

I'm truly sorry to hear the troubles you've been through but it's good to have you back and feeling better. 

Optolong L-eXtreme filter is a much better bet which works on Ha and OIII at a generous bandpass. 

Thank you for your kind words...

Yes, I'm eager to get back. Carrying the AZEQ6 and setting up was out of the question when I was recovering...

As for the filter, can you please expand? DO you mean the L Extreme is a better option for Emission nebula than the LPS V4 that I already have?

With regards to galaxies and reflection nebulae etc.. what do you advise? Like I mentioned above, I have really bad LP in London

[souls33k3r]

I live in London myself (Zone 4 - East) and L-eXtreme will give you a 7nm bandpass in Ha and OIII which will be far effective than trying to use the 294 as an OSC from Zone 3. Galaxies are RGB targets with a hint of Ha for which you will most definitely need some kind of a LP filter (I'm not too clued up on that side of things) but my answer was. Specifically aimed towards you wanting to use Ha filter with this camera. 

[vlaiv]

V4 is UHC type filter

L-Extreme is sort of two band narrowband filter

Both are good choices for emission type nebulae but not for broadband targets like galaxies or reflection type nebulae.

Btw, IDAS also has these duo band filters:

https://www.firstlightoptics.com/idas-filters/idas-narrow-band-nebula-nb2-filter.html

For those - best filter is general type LPS - light pollution suppression filter.

https://www.firstlightoptics.com/optolong-filters/optolong-l-pro-light-pollution-broadband-filter.html

or IDAS variant:

https://www.firstlightoptics.com/idas-filters/idas-lps-p3-light-pollution-suppression-filter.html

You won't be needing filters for planets - they are generally not affected by LP

[oymd]

20 minutes ago, vlaiv said:

V4 is UHC type filter

L-Extreme is sort of two band narrowband filter

Both are good choices for emission type nebulae but not for broadband targets like galaxies or reflection type nebulae.

Btw, IDAS also has these duo band filters:

https://www.firstlightoptics.com/idas-filters/idas-narrow-band-nebula-nb2-filter.html

For those - best filter is general type LPS - light pollution suppression filter.

https://www.firstlightoptics.com/optolong-filters/optolong-l-pro-light-pollution-broadband-filter.html

or IDAS variant:

https://www.firstlightoptics.com/idas-filters/idas-lps-p3-light-pollution-suppression-filter.html

You won't be needing filters for planets - they are generally not affected by LP

Thanks Vlaiv

So, for emission nebulae should consider IDAS NB2 or L-eXtreme

For the rest, a general LPS like the L-Pro or LPS P3?

Just to avoid getting myself confused, are the general LPS filters similar to the UV-IR filters like the Baader ones?

[vlaiv]

2 minutes ago, oymd said:

So, for emission nebulae should consider IDAS NB2 or L-eXtreme

Yes, those duo / tree / quad band filters are good solution for emission type targets.

See this graph. L-eXtreme filter will capture OIII and Ha - which are two most prominent wavelengths in emission type nebulae. It will block almost everything else (there will be small "leak" around these wavelengths as filters have some band pass).

On the other hand, UHC type filter - passes more of the light:

or Optolong version:

It passes both Hb and OIII but lets in more light. Such filters are better in moderate to strong light pollution but not as good in extreme light pollution. In general Hb is about 1/4 of Ha in strength or less and SII is often very faint. Those are worth including only if one does not include as much light pollution as well.

This does not mean that you can't use your V4 - it will just have slightly worse performance than L-eXtreme (and on some targets it might be better if Hb is strong enough).

8 minutes ago, oymd said:

For the rest, a general LPS like the L-Pro or LPS P3?

Just to avoid getting myself confused, are the general LPS filters similar to the UV-IR filters like the Baader ones?

No, they are different. They also block some of the light, but much less than UHC / NB type filters. Here, look at Optolong version of this filter:

It tries to cover most of the spectrum between 400-700nm with exception of few gaps - and these few gaps contain most of light pollution (of certain type - like those old yellow street lamps - in above graph marked with orange lines).

Good LPS filter will block that unwanted light but let all other light pass. Problem is of course that these days, our light pollution is no longer concentrated in these few lines - but also spread over whole spectrum (due to LEDs replacing those old sodium lamps).

 

[drjolo]

I am currently also trying to make similar decision - select filter for 294 color camera under moderately polluted sky. I am thinking about Optolong L-Pro filter.

There is one more aspect of filter if we consider OSC camera - color balance in the result image. If the filter passes broad lines, then color balance is affected less. For UHC filters color balance is affected more, and for extreme duo/thee narrowband even more. At least it appears to me like that basing on some internet research and findings. 

Found at https://www.cyclopsoptics.com/filters/optolong-l-pro-filter/

 

[oymd]

2 hours ago, souls33k3r said:

I live in London myself (Zone 4 - East) and L-eXtreme will give you a 7nm bandpass in Ha and OIII which will be far effective than trying to use the 294 as an OSC from Zone 3. Galaxies are RGB targets with a hint of Ha for which you will most definitely need some kind of a LP filter (I'm not too clued up on that side of things) but my answer was. Specifically aimed towards you wanting to use Ha filter with this camera. 

With regards to the L-eXtreme, I had a look on Astrobin...

I saw this:

Heart Nebula with L-eXtreme filter

This cant be right? The stars have almost disappeared from the image? I know that's a characteristic of the filter, but isn't that just too much? Sure, the nebulosity seems to be enhanced, but where are the stars!!?

Edited January 25, 2021 by oymd

[vlaiv]

20 minutes ago, oymd said:

With regards to the L-eXtreme, I had a look on Astrobin...

I saw this:

Heart Nebula with L-eXtreme filter

This cant be right? The stars have almost disappeared from the image? I know that's a characteristic of the filter, but isn't that just too much? Sure, the nebulosity seems to be enhanced, but where are the stars!!?

Many people now start to process starless version of their images (look up StarNet++ - software for removing stars from the image) and then put back in stars later on.

In fact - I was going to suggest that as a way of processing nebula images with these UHC/Narrowband filters  that alter color heavily.

If you look at above example posted by @drjolo far right color checker has only two colors that are almost as they should be - red and teal which are colors of Ha and OIII (or close enough). This means that these filters don't need color correction when shooting nebulosity.

They do change star color very much, but you can take some exposures without filter and then use StarNet++ to create starless version of image taken with filter and stars only version of image taken without filter and combine the two. That would give you proper color in both nebulosity and for stars.

[oymd]

5 minutes ago, vlaiv said:

Many people now start to process starless version of their images (look up StarNet++ - software for removing stars from the image) and then put back in stars later on.

In fact - I was going to suggest that as a way of processing nebula images with these UHC/Narrowband filters  that alter color heavily.

If you look at above example posted by @drjolo far right color checker has only two colors that are almost as they should be - red and teal which are colors of Ha and OIII (or close enough). This means that these filters don't need color correction when shooting nebulosity.

They do change star color very much, but you can take some exposures without filter and then use StarNet++ to create starless version of image taken with filter and stars only version of image taken without filter and combine the two. That would give you proper color in both nebulosity and for stars.

I see...that's interesting...

There's nothing straightforward in this hobby..