Yeah it's a bit too red. I was mainly just messing around with my 50/1.8 that hasn't seen much use lately. Getting the right balance is pretty tricky with bare HeNe tubes. If you get the color it's usually over exposed. If you get the exposure right the color is usually off. The pic I posted was taken at f/1.8, 1/2000 sec @ ISO 1600. I might try again over the weekend. If I get decent results I'll start a thread in the multimedia forum.
Received mine this week. It looks fantastic! I love seeing the emission lines of the gas with a grating:
I also noticed a strange thing. The weak dot that is projected from the HR (anode) side isn't a single dot!
There are at least two laser dots, the second one is much weaker and not aligned with the first one. It also looks slightly "redder", but it's probably due to the power difference (couldn't notice any WL difference with a grating).
I think there's also a third, very weak dot, but I'm not completely sure.
With the exception of the Portahene, gas isn't really my thing, nor is HV. However, I saw these, and thought of this GB, and wondered why you couldn't use one as a $4 power supply for your hene tubes, presumably with a beefier resistor on the output to pull the voltage down a bit to the 1300 V you actually need here.
Yep, you need 5-8mA on average, and it has to be filtered DC (HV caps), and you need an ignition pulse in the neighborhood of 10kV just to ignite the tube, and that's if the tube is healthy. HeNe's are a bit of a bitch to drive, not like CO2 or Argons.