With the first clear night in ages here in Sydney, I waited until the wee small hours for the moon to set and headed out to try my wide field shots using a couple of Bahtinovs on a couple of lenses.
Despite researching, I couldn't find a definitive answer, so I was unsure of their efficacy on short/small lenses - in my case 35mm and 12mm. Bintel had the 52mm for my stock 35mm f/1.4 lens, but didn't have stock of the 67mm needed for my Samyang 12mm f/2.0 lens, so I made one myself with a craft knife and some rigid black plastic from Eckersleys.
Here are the two most apparent results - after focusing as best I could using Live View at 10x digital zoom, I got pretty close.
A tiny tweak later fixed the slight focus issue and the focus was perfect. (Until I bumped the focus while putting some Blu Tac to fix the focus ring!)
My home made wasn't the best, but still assisted, and by the time I'd shot and marveled at my focus on 35mm, the series using my 12mm could only grab 7 minutes of exposures (28x15") before light cloud rolled in!
Minimal processing (thanks to Sydney's light pollution dome and the general haze...)
https://flic.kr/p/2eeNGeR