Jupiter and Saturn 20/07/2020

[skybadger]

Hi all 

Two of my latest  - not done much of these this year, maybe 2. So re-learning my way and experimenting. 

These are taken with the Vixen NA140 semi-apo using a TV x2.5 and ASI 178 mono camera with LRGB Astrodon filters from my observatory. They are so low they barely graze the neighbours rooftops. Focusing is via robofocus but eyeballed manually and filterwheel is manual too.

Capture using Firecap for 30seconds resulting in 2500 or so frames per filter.

Processing is using AS3 for stacking, resulting in 30% stacks and then maxim for colour re-combining and wavelets sharpening.

I did try LRGB but adding the L just made it worse so now I stick to RGB only on planets. 

Saturn clearly has an over-blue element I need to shift. 

 

The first of two - a few minutes apart. 

I was hoping I could reduce the image scale a touch to get a brighter image and thus faster frame rates for better resolution. Then I worked it out: 

The effective focal length is 2000mm, I should aim to get the pixel resolution to something just under Nyquist to get optimal frame rates.

At the moment at 2000mm (800*2.5)EFL I am getting (206265/2000) * (2.8/1000)= 0.3"/pixel.

The Telescope Dawes limit is 11.6/14cm = 0.8" so the Nyquist limit is 0.4 ".

Which means I'm already pretty close and changing from 0.3"/pixel may be more hassle than its worth. 

 

I am using the refractor because the other scope is an RC and can just about see the planet is a disk. 

Comments and suggestions for improvement sought... !

 

 

Jup_225532.txt

[Pete Presland]

Very nicely captured.