Hi from Scotland Bobobirder, I have the exact same set up as you, and founfd the vignetting a problem until I sorted out the aspect ratio etc.
I use the G1 on the following settings so give it a try:
Aspect ratio - 16:9
Picture size - L
Ex.Opt Zoom - On
Digital zoom - either 2x or 4x (2x is better i find)
Keep zoom on telescope low and the camera zoom up to about 35mm. I also use the swaro DCA adapter
Thanks for the feedback, Dave. I can't get the digital zoom or extended digital zoom to work with RAW format without vignettes. It works fine for JPEGs, but JPEGs on the G1 aren't great.These digital zoom techniques simply reduce the effective resolution. RAW just delivers what the sensor picks up. This allows a lot more flexibility as JPEG is a compressed lossy format. Compare an original RAW with a JPEG without modification and you'll see what I mean. Perhaps the JPEG algorithm on the G1 isn't great, I don't know.
I realized today that the issue is that DCA Zoom keeps the G1 kit lens a bit too far from the 20-60x eyepiece for the G1. If you hold teh G1 with kit lens up close by hand, you can eliminate the vignette even in RAW. Next I'm going to measure how much closer it needs to be and see if I can eliminate the vignette at all zooms and find to what the lens zoom needs to be set to achieve that and if it varies.
It looks like the DCA could be modified by trimming the length of the outer female section and cutting away a similar amount from the step on the male piece.
Before I go to that trouble, I'm wondering if anyone has tried the Panasonic Lumix 20mm f1.7 ASPH "pancake" lens. My thinking is that the short but wide lens would not only reduce vignetting, and let in more light, but also lower the weight and the lever arm on the scope. The kit lens and G1 plus the DCA all hanging off the scope makes it quite floppy. Having a balance rail seems mandatory, but I've already dropped a wad of cash and trying to make progress without more expensive toys. I could sell the kit lens and buy the pancake if that would be all I need, but I fear it won't be so easy. The alternative is to cut down the DCA and buy (or build) a balance rail and stick with the 12-45 kit lens. In that case, I'm committed. My goal is to not lose resolution or view. Better said, I want to use the full RAW image capture and retain the maximum field of view of the scope and eyepiece. Any suggestions appreciated.
Bob
PS: The attached shows a JPEG made from the original RAW file taken in relatively low light and maybe 150 meters at 60x zoom on the eye piece and max focal length of 45mm on the lens with 800 ISO, 1/500 and f 5.6. The second image is only cropped and zoomed. This was a long shot with extreme zoom and low light late in the day (and rig balanced only on my car window). Nonetheless, I was happy to get the belted kingfisher shot, even though of such poor quality. I'm wondering what the pancake and or the 30x eyepiece could have done to improve this tough image? I don't expect miracles and at a point it's really about getting closer to the birds in better light and getting the shot you really want. My goal is to get descent tools first then spend plenty of time to learn to use them. That's the lasting fun!