Don,I had mixed results while I was using Phase One getting the best results with the IQ1-100. I now use the GFX50s which has been a huge upgrade in Milky Way shots.
There is the rule of 500 when shooting night shots and wanting crisp stars. Divide 500 by the focal length in order to get a shutter speed long enough to capture the stars. This works well on any full frame sensor. What I've done is factor the 80% crop into the equation.
Full frame at 24mm I works out something like 20.83 seconds so I use 20-seconds on a Sony A7rIII beginning the ISO at 800 and working up and down till I like it.
The GFX is a tad more complicated - that same 24mm forks like this. Divide 500/24=20.83*80%=16.666 seconds. I would use 16-seconds and since I'm using the GFX I'd set the beginning ISO at 1000 and work upwards. It works for me.
Look for the darkest nights of the month which usually begin a couple days prior and after the new moon. Clear cool nights works well and expect to be outdoors between 2 and 4 am.
I've stabilized a camera on a telescope (XF/IQ) I've also used a small tracker using the Sony/GFX all of which allow for long shutter times while tracking. I reduced it all to just a tripod, no sleep and the 500 rule.
Thanks! That is great information! The rule of 500.... who knew?:toocool:
How would I factor the H5D-50c with an 80mm lens?