PureNight Light Pollution Reduction Filter Comparison for Astrophotography

Man, that post title's a mouthful.

Anyway, back in May I received my PureNight filter and had a chance to test it out during a late night hike into the hills surrounding the bay. I was personally quite impressed but received the reasonable request from Reddit for a side-by-side comparison with and without the filter. Thus, as part of a trek down to Natural Bridges State Beach this weekend I did some side by side shots to compare.

    But first, let's take a look at the final result.

    Milky Way over Natural Bridges. Cool, right!?

    Why Natural Bridges? Well a) it's gorgeous and b) it's on 5-6 on the Bortle Scale looking out over the ocean and then back towards Monterey (another 5-6 zone). Which is to say that there was going to be some noticeable light pollution to deal with.

    Alright. So, let's do some side by sides. Both photos are from a Sony a7Sii, 18mm f/2.8, 25s, ISO 6400, Daylight WB.

    BTW, grab the raw files here and here to try your hand at editing both and let me know your results!

    No filter. Only lens correction applied.

    PureNight Filter used. Lens correction applied.

    PureNight Filter used. Lens correction applied. 0.7EV boost to exposure to bring the histogram in line with the one with no filter.

    As expected the filter cut out a significant amount of the yellow and orange. Which is basically what it promises to do.

    Now, time to adjust the white balance.

    No filter. Lens correction applied. White balance adjusted.

    PureNight. Lens correction. 0.7EV boost. White balance adjusted.

    It looks like the PureNight did manage to pull out more contrast from the galactic core and more warmth. Not bad. However, I did find myself fighting to tone down the blue both in white balance and throughout the entire editing process.

    Unfortunately, past here it starts to get rather subjective as you can take the edits in a bunch of different directions and I'm uncertain if side by side comparisons would be that useful.

    I'm going to leave this post as a <WORK IN PROGRESS> as I'd like to experiment with a few things in the future. Such as boosting the ISO or uping the exposure in camera when using PureNight (vs in post) and doing a comparison of stacking images with and without PureNight.

    Anyway, if you have any other testing ideas, let me know. And I'll update this post as we go. In the meantime, I'll leave you with a higher res vertical pano from that same night. :)