4 replies to this topic

[aeroman4907]

Here is a cropped area around Langrenus that I imaged on 11-2-20.  Captured with an 8" EdgeHD and QHY183C camera for a resolution of 0.23"/px or 451m/px.  Seeing conditions were fair with a Pickering of about 4 with an 8" scope.  Be sure to click on the image for full size.

 

[flt158]

Super image, Aeroman!

Your focus is seriously good and endearing. 

 

Those 2 central peaks in the centre of Langrenus I always find amazing when I see them with my apochromatic refractor. 

 

Kindest regards to you from Aubrey. 

[aeroman4907]

Super image, Aeroman!

Your focus is seriously good and endearing. 

 

Those 2 central peaks in the centre of Langrenus I always find amazing when I see them with my apochromatic refractor. 

 

Kindest regards to you from Aubrey. 

Thanks Aubrey for the compliments.

 

I think many overlook the importance of achieving critical focus.  While seeing is the most important variable with regard to high resolution imaging, it is the element that we can't control for the most part.  What we can control are things like focus, collimation, OTA thermal equilibrium, etc.  Of those items, I think I find critical focus the most difficult to achieve in most seeing conditions where I live and the factor that seems to require amongst the greatest precision.  I find that being minusculely off of focus and processing to get maximum results becomes quite difficult.  Being just slightly off of focus and the effective resolution can easily get cut in half, making my 8" scope like a 4" scope.  Being somewhat off focus and resolution will be cut down by 4x.

 

Seeing is typically variable, which is why "lucky" imaging can be effective.  Being out of focus is a permanent condition.  I've had some very good results even when the seeing was quite bad and precise collimation was difficult to ascertain, as was focus.  Here is a prior posting earlier this year with my first capture of the first quarter moon:  https://www.cloudyni...-after-3-years/

 

Here are also some of my thoughts and findings regarding critical focus: https://www.cloudyni...critical-focus/

 

Best regards!

 

Steve

[Tom Glenn]

Looking good Steve!  Langrenus is a terrific crater, we just get few opportunities to catch it under good lighting, as you have done here.  

[aeroman4907]

Thanks for the compliment Tom!  Yes, getting some of the eastern limb craters and features in good lighting requires imaging at unpleasant hours of the morning (1 or 2 am) to get the maximum results with the Moon close to the Meridian.

 

Steve