Filter question

[ebdons]

Hi, has anybody seen this filter, is this a "good" LP filter as I've never seen this type, think these are seconds from Omega filters then? do you think it blocks out too much? https://www.ebay.co.uk/itm/312234297478

Edited February 1, 2019 by ebdons
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[vlaiv]

It looks like a very good filter if it matches response curve in the image - but it is certainly not LPS filter and Galaxy improvement of 95% is just ridiculous.

This is very good UHC filter by the looks of the spectral response curve. It should pass following wavelengths:

486.1um - H beta

495.9um & 500.7um - OIII

And it has peak that is probably passing:

656.28um - H alpha

maybe even

671.7nm und 673.0nm - which are SII, but that peak looks rather narrow to be ~20um wide (on second image it looks like it has FWHM of about 10um in that second peak, so maybe not SII lines).

If you want "comparison curve" - take a look at other UHC filters and their curves. Such filters are best suited for imaging emission nebulae (or observing them).

BTW, one can't judge filter only by it's transmission curve - surface accuracy, anti reflective properties and durability all play a part in overall usefulness of filter.

 

[ebdons]

Hi thankyou sir, it just came up from a search of various filter tables and never knew about it, but it sort of looks like a UHC type but narrow, I'm interested but not willing to take a leap unless some folks have positive or negative opinion on it, I'm still maybe leaning towards a idas p2 for modified OSC? Ton

[vlaiv]

Someone recently reviewed such "double" NB filter - I can't remember what's the name of filter nor manufacturer - but you can maybe find it somewhere in SGL via search.

If you want broadband general purpose LPS filter - then IDAS P2 is very good choice - I have it and use it on both OSC and Mono cameras (for luminance). I'm pleased with it so far.

[vlaiv]

Found it - here is filter:

https://www.cyclopsoptics.com/astronomy-filters/stc-astro-duo-narrowband-filter-48mm-2/

and here is the thread about it:

 

[ebdons]

Yes I reckon so, I had a chat with you about a month ago and was still undecided about the idas, but after some research and opinions, I was looking at the optolong l-pro and skytech l-pro which are the same I think, but not many folks are using them so that tells me about them then? idas d-2 for LED light pollution which is near me, but I want it also for my mono cam as well. Ton

[ebdons]

Hi All, I finally made up my mind and pulled the trigger on this combo, IDAS NGS-1 and IDAS NB-1 which I can use as a combo or single on some objects. this is the new version which replaces the V4 type I think?  Hopefully I could also use these as special luminance and add these to RGB maybe. clear skies.

Edited July 12, 2019 by ebdons
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