Testing out the viability of my recently purchased Canon 70-200mm f4L IS lens for astro use in this image.
At 200mm on bright objects I noticed some central vignetting which was solved with Flats calibration - this gradient seems to be absent at the 70mm part of its range though.
I wanted to use this lens with my 2600MM and 7x36mm EFW - this presented a challenge with the currently available ZWO accessories. The smallest (optical thickness) EOS to M42 adapter provided a backfocus distance in excess of the 44mm required for Canon lenses.
A cloudy nights forum post suggested the availability of a TS adapter which would be perfect (albeit with a spacer) - I managed to get one delivered to Australia, and here we are!
Pushed the exposures to 1000sec on this image to see how the lens might perform at extremes.
Next purchase on its way from PhotAstro in Germany is a 3D printed 'On OTA' frame which will house the lens like a mini scope allowing the addition of mounted AsiAir, EAF and guidescope (see pic)
12x1000s Ha
9x1000s Oiii
HOO palette and Seti Astro NB to RGB stars script for more realistic looking NB stars (enjoying these scripts)
Bigger version
https://astrob.in/fr9k07/0/
Thanks for looking
Doug
