Lucky imaging is the next step to high resolution images

  • Posted on: 13 January 2022
  • By: tihomiry

Comparison Pentax K5 and IM178

Atmosphere is the worst nightmare of the ones, who would like to get hight resolution images. Small telescopes can not have adaptive optics but could benefit of there small aperture and the statistical chance to get a clear view for a fraction of a second. The best fit for this is aperture of 100 - 150 mm. It is like being on the bottom of a pool and looking up. You will see a blurred view but for a fraction of a second you have a chance to get a clear view and you could catch this exact moment.
Generally it should be between 10 milliseconds to 2 second depending on the elevation and the state of the atmosphere.
How to estimate it? Record a video and count how much frames is it take before the image change.

frame comparison Almak

For example if you have a change each 10 frames and you shoot 20 frames per second, then you have half a second clear view and your exposure best be set to 0.5x2/3=0.33s. You could use 0.5s of course, but you will have to discard more frames as you are not sure as the state change will be in sync with the exposure interval. For star system use the lowest exposure that you could and for deep sky the highest.

This is image of Almak with my 3 small telescopes in comparison. You could see the differences of the oprical system and how their diffraction limitation looks like:

Almak different scopes

Also SharpCap software have live stack functionality that can stack only frames that are above predefined focus quality FWHM. Witch is best for deep sky. This one is taken under bad seeing conditions due to wind:

Live stack SharpCap

Here is Jupiter with Vixen VMC 110L. No post-processing

Jupiter VMC 110L

VMC 110L

The best thing is that you do not need precise equatorial mouth or autogiding to do that. You need a high speed, low noise, high QE camera that is now becoming cheeper as the advance of the sensor development. More on this topic will come this year as this will be the primary development of my largest telescope SW200pds!

Recently I got one very good lens the Asahi Takumar 135mm 1:2.5. This is fast telephoto lens and from my point of view a good lens should be with aperture from 1:1,2 to 1:2,8.

Moon at 45% illumination and 70x magnification. With aperture of 200mm,14,1 stops dynamic range, color depth of 23.7 bits at this image there are slight color variation on the moon surface that reveals it’s structure.

This is the beginning of my research on how dark the sky could be and what is benefit of a dark sky for astrophotography. I was inspired from those 2 sites. First one presents mathematical model of how dark the sky is.

You can find my last DSLR Astrophotography article in Bulgarian at page 76. I am sharing my last findings for this publication, Specially written for the Institute of Astronomy.

Satellites, cosmic trash or UFOs, the moving spots are everywhere on the sky. Typical satellite behavior is to reflect sun light. It should be yellow or white and could fade and shine due to its rotation.