Combining broadband & narrowband data

[RugbyRene (Rene)]

Hi,

I have a ZWO ASI294MC-Pro and am looking at getting some filters to combat light pollution. I would also like to add narrowband data to bring out more detail.

I'm settled on the IDAS D2 QRO LPS filter from First Light Optics. This will take care of the light pollution.

I'm now trying to figure out if I should get some narrowband filters to capture specific wavelengths of light which I can them add to my broadband data.

The thing is I've looked at the transmission lines for the light pollution filter and compared that to the transmission lines form the narrow band filters and for a given wavelength they pretty much match.

So my question is, am I wasting my money by buying narrowband filters if the light pollution filter already covers the wavelength of light I'm interested in.

Rene

[casstony]

The IDAS D2 is a broadband filter which gives a mild reduction in light pollution.

Narrow band filters such as a Baader 7nm Ha and 8.5nm OIII are much better at cutting out light pollution and the result from the two filters can be combined to make a bi-colour image that is better than the IDAS D2. You can also add the Ha image to a broadband image.

An easy way to go is to use a dual band narrow band filter like the L-Enhance or STC Duo; these filters pass both Ha and OIII.

The narrower the filter passband is, the better it will reject light pollution. NB filters aren't useful on all objects but are very handy for emission nebulae under light pollution or when the moon is up.

[Nikolas (Nik)]

L-Enhance would be your best option at a decent price to cover all of this.

[ChrisV (Chris)]

Or STC duo filter. I'm in northern Sydney suburbs and have an OSC. I swap between this and a plain old UV/IR filter depending on the target

[AnakChan (Sean)]

Have a look at the Helix Nebula with different filters. Most are IDAS but there’s also the STC Duo-narrowband thrown in there.

The “narrowband” IDAS ones would be the LPS-V4, NB2 and NB3.

[ChrisV (Chris)]

Here's what the STC Duo does.
The first two are from the duo filter, splitting red & green channels
The final is them combined with stars put back in