Flats for narrowband?

[Joeistotalycool]

Is it necessary to take flat frames for narrowband filters? I could not find many useful sources online. 

[Ibbo!]

Yes flats will help if done properly.

[alexbb]

Doesn't make any difference compared to other lights and will correct the narrowband images in the same manner

[Notty]

yes, and during my admittedly short foray into NB before licking my wounds and going back to DSLR, the vignetting particularly on the weaker signal like SII was even worse that the lum/rgb channels so definitely needed!

[Skipper Billy]

I tried using my Lum flats for Ha, Sii and Oiii images but when I stopped being lazy and took flats with the narrowband filter the results were definitely superior.

 

[fireballxl5]

Big +1 for flats for NB filters (as per BB really). They especially help if your camera (Sony CCDs only?) causes a banding pattern across the image as my QSI690 does. It's particularly obvious in Ha, see master flat example below...

 

[ollypenrice]

Flats don't remove light pollution gradients but only the uneven illumination of the optical system. This being so, and because we stretch NB data harder (or I certainly do!) flats are probably  even more important in NB than in broadband.

Olly

[wimvb]

How else to get rid of dust motes? A definite YES for flats for all kinds of astro imaging