[gregbradley]

I have been quite happy with my 5nm Ha Astrodon filter. But it is slightly damaged and I need to replace it.

I am wondering if I should look at getting the 3nm Ha filter in its place.

I will be using it at F3.8 so that is factor. Do these 3nm Ha filters work ok at fast F ratios?

Is there much of a difference between 3nm and 5nm Ha?

Is the difference more for when the moon is up filtering out more moonlight?

My main concern is whether its suitable at F3.8.

Greg.