Widefield narrowband M42+Horsehead

[that_guy]

With orion season coming up, I'm looking to get in to widefield narrowband imaging with my AZ GTe mount. Currently I have the set up purring like a kitten, however, my main issue is with the EOS adapter. It's producing weird pinched stars of sorts that aren't consistent through out the image. I'm having a quick guess it's due to tilt. I'm using the recommended spacing that ZWO has for their EOS efw adapters (i.e. no spacers just the efw and camera) so not sure if the spacing needs fine tweaking or not. I'm actually just going to replace the cheap adapter with something more solid. If anyone has any recommendations, I'm all ears.

Astrobin link here (https://www.astrobin.com/full/oydypp/0/?nc=iotd) for those that want to inspect stars (please do)

I know a lot of you are *sick* of starless renditions but cmon you gotta admit this one looks good ;)

Around 1.5 hours of 60 sec exposures guided (no dec guiding due to heavy dec backlash of the AZ GTe

[strongmanmike]

That's a nice field Tony, some great vistas to be collected with that rig :thumbsup:

Mike

[gregbradley]

Very nice widefield.

It does not look like tilt. Tilt affects one corner or one side not all 4 sides.

It may have slight tilt as the left side seems worse than the right side but I would say its mostly a spacing issue.

Which Canon lens is it? Is it possible the lens is at fault?

Greg.

[that_guy]

I'm using a canon 70-200mm f4L. I've used the lens with my 5D mk ii and it has some field curvature issue but its even throughout.

[gregbradley]

I have that lens also but haven’t tried it for astro.
As you first said the adapter may be flexing
Or spacing is a bit off.

I have found adapters can vary in length although that affected ultra
Wide angle lenses more.

Greg

[CalvinKlein]

Tony have you checked the lens for de-centering ?

This guy explains it very well and has a simple test.
(you dont need to print the test pattern out by the way - you can display it on the monitor)

https://www.youtube.com/watch?v=QVD2Q-3HbVo

[batema]

Tony I have taken a few DSLR images with 200mm f2.8 but would be ok telling me roughly what price you set up is worth so i have an idea of cost.
I love the starless one as well. Beautiful part of the sky.
Mark

[that_guy]

Thanks for the link Kelvin, interesting! From what I can tell from the test, my lens is centred by the looks of it. I'm having a look at the astromechanic lens adapter with EOS focus control which is a lot of solid compared to the cheap 50 bucks zwo adapter. Hopefully this will eliminate the tilt.



The AZ GTe cost me around $450 however, I'd personally get the AZ GTi for an extra $100 just for having double clutches as opposed to a single DEC clutch.

The camera ZWO ASI1600MM Pro with EFW and narrowband astronomic filters would be around $3500 (the most expensive bit)

Mini ZWO 30mm guidescope $100 and ZWO ASI290MC guide camera $450.

This is assuming everything is bought brand new.

[RobF]

Great image Tony. Really enjoyed this one! :thumbsup: