Diffusion / Star Glow / Black Mist filters for astro photography

Camera Lens Astrophotography 2 replies219 views
HR_Maurer avatar
Hi there,
some time ago i've been researching a lot, trying to fiddle out which diffusion fiter to buy. THis wasn't easy at all, so my idea is to collect some data across the community, and build up some knowledge which can help in future decisions. 
There are so-called "star glow" filters, which should be identical to normal diffusion filters. At least from my point of understanding. The "star glow" filters weren't available when i was looking for them, so i went on looking for "Black Mist" filters.
From my understanding, a diffusion filter is characterized by the amount of diffusion, and by the angle of diffusion. Of course, diffusion can also be anisotropic. So one thing to consider, when comparing such filters, is focal length.

CS Horst
HR_Maurer avatar
Kenko - Pro 1 Digital - Pro Softon-A(W)
Sony A7III
Sony FE 20mm f/1.8 G

This filter is not magnetic, but available with typical filter threads.From my finding, the diffusion at 18mm was rather strong, diffusion is also affected by distortion effects, resulting in a deformation in radial direction.
Here i show intermediate stacks. My Final Result is a more subtle blend of registered sub-stacks with and without filter.
Edit: There was some thin clouds. I got a second stack of 12 images without filter (after passing the register reference), showing a lot of haloes from clouds. In the image shown below, there is a faint halo around Rigel even without filter.

Top: 6x 13s with filter, registered
Bottom: 12x 13s without filter, registered  
Wei-Hao Wang avatar
I use Cokin Diffuse 1.  For wide-angle lenses, its intensity is about right.
examples:
https://www.astrobin.com/b1g6q1/
https://www.astrobin.com/cosujy/?nc=&nce=
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