Here's a shot of Mercury on 18th January from Brisbane. It was 18 degrees above the horizon 6 minutes before sunrise. Angular size would have been 5.8".
I think the colour comes out nicely here. I don't know enough about Mercury yet to know if the shadings on the disc in this image are actually planetary features.
Canon EOS 550D with teleconverters through a Sky-Watcher 12" Autotracking Dobsonian.
Thanks guys. This was made out of the best 150 frames from 10,000 frames (640x480 at 50fps). The atmospheric refraction at 18 deg elevation was nothing compared to 30min earlier when Mercury was 11 deg above the horizon. I've attached singles frames from both times.
I had to start work at 5:30 so I was backing out the car while making the .mov of Mercury. It took 2 minutes to put away the Dob and camera and I was away.
To get that looking clear, you'd need AO and I don't think it would be practical on a dob, but they're good shots despite the low elevation they were at
Thanks guys. This was made out of the best 150 frames from 10,000 frames (640x480 at 50fps). The atmospheric refraction at 18 deg elevation was nothing compared to 30min earlier when Mercury was 11 deg above the horizon. I've attached singles frames from both times.
I had to start work at 5:30 so I was backing out the car while making the .mov of Mercury. It took 2 minutes to put away the Dob and camera and I was away.
Tom
This is not atmospherics this is the teleconverters lense to get a wider view that is causing this. I get this a lot with my Barlow.
Hi Malcolm. I had assumed that it was atmospheric chromatic dispersion, particularly because the dispersion of colours decreased the higher the planet got while the equipment remained the same.
Here is the video of Mercury at 11 degrees elevation, from which the above image was created. http://www.flickr.com/photos/vontom/5397395472/
Due to the distance from the affecting atmosphere and the scope the result would not be as much as you see here. We do need barlows and to get the increase magnification.
You will see many posts on typical issues relating to optic and chromatic abberation.
I am now considering the alternative now in monochrome imaging with RGB filters for this very reason. But what is for sure is this is a lens issue not atmospherics.
Thanks John. BTW love your Saturn images - inspiring and well done! I'm not far away in Wakerley and it's good to know Brisbane skies can offer so much!
Nice one Tom tried Venus and Mercury earlier this week but couldn't get anything on Mercury.Be interested in what your camera shows up on Venus.
Attached is what I got (1000 frames stacked)Gstar vide camera
This is not atmospherics this is the teleconverters lense to get a wider view that is causing this. I get this a lot with my Barlow.
What brand of Barlow Malcolm? I recently purchased a Barlow with this very problem.
Having said that, it looks more like atmospheric dispersion to me, particularly as the effect reduces with elevation.
Atmospheric turbulence usually create wiggly images the RGB is still intact. The barlow depending on the make cause the splitting of RGB onto the CCD sensor at different angles. I don't have a major problem with my barlow but it is noticeable when I expand the image. I have been a bit delayed but I am going to try and manipulate some of my image to show this affect. The only comparison that I am unable to replicate is the magnification which is the whole concept.
I hope one day to decide whether to go with a filter wheel and a mono camera or a Televue Extender which is specifically designed for AP, or both.
