Depending on the color correction of your scope you may use a wider spectral window for the Luminance data. The L1 filter has the widest spectral window, the L2 is about the same as our current L-Filter and the L3 is much narrower. If you use an optical system that is completely free of any chromatic aberration you should get an L1 filter for your setup. For general use the L2 filter is well suited to most optical systems with a corrector, flattener or reducer in the optical train while the L3 filter is designed for users of refractors with a less-than-perfect color correction and in combination with the new Deep-Sky RGB filters, the L3 filter will minimize the problem of bluish halos around stars. [img]https://cdn.astrobin.com/ckeditor-files/28834/2022/391fc88a-844b-4de3-aeb4-17667450b2e9.png[/img]