I'm continuously astounded by your work Bert... This is an epic task you've set yourself.. Vela is a massive region of sky, with many different objects, all of which are considerably dim, and usually hard to process out against the sea of stars behind them...
If ever someone was to rise to the occasion.. This is it.
Over the last few years I have been tweaking my system to improve my data collection.
The mount is guided by a 1250mm FL Mak even when doing wide fields. Since I built the observatory my polar alignment is and stays about as good as drift aligning can get it.
The signal to noise is very good due to two factors the fridge cooling the camera and dithering between exposures. A futher refinement is using an aperture in front of the Canon 300MM F2.8L lens. An extension on the lens light shield also helps especially for the faint stuff. This even improves narrow band data.
Combining full colour and narrow band data was the trick to getting a 'natural' looking image of a very faint extended object such as the Vela SNR. I used a method that is quite unorthodox.
All the other images I have done were just practice and training for this one.
I will go on practising and one day may get it closer to perfect.
The one thing that really helped was enough nights of clear skies while Vela was at or near the zenith. In the past I have had mosaic interruptus more often than I would like.
Absolutely superb. All your hard work and dedicaton paid off and it certainly shows. I'm amazed at the sharpness of the details for such a widefield. How do you focus?
Absolutely superb. All your hard work and dedicaton paid off and it certainly shows. I'm amazed at the sharpness of the details for such a widefield. How do you focus?
I use a computer controlled stepper motor to focus the lens. The lens is held at a constant temperature by thermostatically controlled dew heaters. Focus is attained by taking test images 1000 steps apart (1000 steps is 0.15mm of focus ring movement). Once best focus is set not only does it not change for the night it is still at best focus for many nights as long as the lens and camera are equilibrated to their set temperatures. Typically 18C and -10C.
There is a reason for heating the lens body as it stops the filter in the lenses rear filter holder getting condensation due to the camera body being at -10C
The other processing trick is because of the random dithering between exposures the stacked exposures if done at x1.6 times the native pixel size of your sensor you effectively more than double the size of your sensor in pixels. This is completely mathematically valid to a factor of the square root of two ie 1.414.
The sensor on my Canon 5DH has 8.2 micron square pixels. When sampling the image produced by the 300MM F2.8L the dim or faint stars are about at best three pixels across. The 300mm F2.8L has far better MTF than this. Another complicating factor is the anti aliasing filter on all one shot colour camera's. This filter stops Moire effects where the fine detail interferes with the sampling interval. This filter intentionally blurs the image so no Moire fringes are produced.
No, I have a 46 LCD upstairs with my PS3 and your pic is waaay too big for my flimsy PC monitor here. Need a big screen to take all the picture in, in one go.
Bert - simply breathtaking. It is a work of Stellar art
David I am glad you like it. When you have your observatory fully set up, you too can think more about imaging rather than being a pack horse carrying equipment in and out.
All your hard work and dedicaton paid off and it certainly shows. I'm amazed at the sharpness of the details for such a widefield. How do you focus?
Will have to check tonight on a 46" flat panel.
No, I have a 46 LCD upstairs with my PS3 and your pic is waaay too big for my flimsy PC monitor here. 
Need a big screen to take all the picture in, in one go.
