wide angle dslr bahtinov mask

thingiverse

I had a hard time finding a functional bahtinov mask that would work for a wide angle lens on my camera for when you want your milky way photos to be pin point sharp, so I made this one. The bars are .22mm wide with a gap of .78mm and I've tried it on a 12mm (18mm full frame equivalent) f4, 18-140mm (27-210mm full frame equivalent) f3.5 at 18mm, and a 35mm (52mm full frame equivalent) f1.8 lenses. My camera is a Nikon D5500 so it has a 1.5x crop factor. The longer the focal length the better the diffraction spikes were, but I was able to get distinct diffraction spikes at 12mm and f4 with my iso set at 6400, but the best effect was around 75mm on my 18-140mm at the widest aperture, or the 35mm at 1.8 because it's a faster lens. At the shorter focal lengths sometimes it's easier to take an exposure and zooming in on the playback to find the spikes if you can't see them that well just zooming in on live view. I've included a 100X100X2mm square mask for the popular filter holding systems, as well as one that is threaded for a 77mm filter, and cases for both to protect them in the camera bag, and also the template of the bars and gaps in case it's needed to be modified for different situations. I chose to print everything out of petg so if it gets left in the car it's not as big of a deal. The masks work better in a darker filament. All done in Tinkercad and there should be a total of 6 .stl files