Do light pollution filter improve astro imaging from moderately light polluted sites?
The theory is clear: These filters help to reduce the sky glow from warm light sources, especially sodium vapor streetlights, but they will not help much against the newer generation of LED lights. While you therefore cannot expect wonders, you should be able achieve better contrast from sites with a fair amount of older streetlights.
On the other hand, I have never done a comparison of what I can achieve with and without one of these filters. While taking my first Milky Way core shots of this season from a Bortle class 4 site, I took the chance and shot same panorama back to back, first without and then with my light pollution filter.
During post processing, I independently processed both panoramas with my normal workflow. The results show that it is possible to correct moderate light pollution during post processing to a big extent, but processing the unfiltered image was more difficult and there still is slightly better contrast in the filtered image.
In the filtered image however, the bright Jupiter on the very left has slightly more glare and if there is stray light, I have a hard time controlling reflections, as I cannot attach the lens hood with my 150mm filter holder in place.
Another drawback of any filter is that it reduces the light arriving at the sensor. With the light pollution, I lose about halve an f-stop and have to expose about 50% longer. This is not a big problem if you are tracking the sky, but might be a deal breaker if you shoot from a fixed tripod
So wat do you think? Are light pollution filters worth the price and hassle?
Canon EOS 6D, astro modified
Samyang 24mm f/1.4
iOptron SkyTracker Pro
Low Level Lighting
nachtlicht° light pollution filter
5 x stack of 3 images @ ISO1600, tracked for the sky
30s filtered / 20s unfiltered