FIrst try out of Lodestar Live Stacking

[RobertI]

Hi all,

Managed a very brief session using Paul's new Lodestar Live V0.9. Very rushed with moon and light pollution, so pictures not perfect, but the software worked without fault. Tried to test stacked versus non-stacked views on M15 (possibly not a good target?) and came up with the following, however I had to apply stretch to each (during the session) to make the results more visible, but stretches are unequal so cannot really compare them. Probably of no help, but thought you may be interested!

Unstacked then stacked:

[RobertI]

This is of course M13 not M15!

[Paul81]

Nice to hear the application behaved itself and you had a good first light use! 

Out of curiosity what stacking settings did you use? I found in testing that (bright) Messier globs were best stacked with median stacking and that the stacking was really about reducing noise than resolving extra details as the object is bright enough to give good detail even on single exposures.

I am interested to see over time what kind of options people find most useful for different types of object too. I think this will also change as the other hybrid stacking and display scaling modes become available.

[laser_jock99]

Nice to hear the application behaved itself and you had a good first light use! 

Out of curiosity what stacking settings did you use? I found in testing that (bright) Messier globs were best stacked with median stacking and that the stacking was really about reducing noise than resolving extra details as the object is bright enough to give good detail even on single exposures.

I am interested to see over time what kind of options people find most useful for different types of object too. I think this will also change as the other hybrid stacking and display scaling modes become available.

So the stacking program is potentially more useful on faint objects than GC's?

[RobertI]

Nice to hear the application behaved itself and you had a good first light use! 

Out of curiosity what stacking settings did you use? I found in testing that (bright) Messier globs were best stacked with median stacking and that the stacking was really about reducing noise than resolving extra details as the object is bright enough to give good detail even on single exposures.

I am interested to see over time what kind of options people find most useful for different types of object too. I think this will also change as the other hybrid stacking and display scaling modes become available.

Hi Paul,

The example shown was with stacking set to mean. I did also try one with stacking set to Median and could not see an obvious difference, but I was really playing with the settings in an unstructured way at that point. I will try post that one later on.

Rob

[Martin Meredith]

Nice one Rob. Since we're discussing globs here's M4 from last night. The left panel is a (mean) stack of 4 x 60s while the right is the most recent unstacked. I know 60s is too much for globs but I only collected 60s darks on this occasion.

I noticed that as well as reducing noise the stacked version to some extent reduces the visual appearance of small tracking errors (a different kind of noise).

Inevitably the stacked version has a 'softer' look which takes some getting used to and might not add much in the case of globulars until quite a few more exposures are stacked. I'm looking forward to more experimentation...

Martin

[Paul81]

The stacking will currently soften the image - this is due to the fact that part of the stacking process is the transformation of the new exposure to the key frame - i.e. warping the new exposure to match the orientation of the key frame. This involves resampling, which to get things progressing I used a simple bilinear interpolation in the initial version. In truth this is pretty low-end and tends to soften (blur) an image - but is quick to implement. As mentioned in the main post I am working on using a higher quality algorithm (Lanczos or bi-cubic for those interested) which should mean the result of the transformation is much sharper. I suspect at the moment some of the extra subtle detail gained by stacking is being lost by the bilinear transformation, but should be more evident when I have sorted a higher quality transformation.

I am very pleased it all seems to be working quite well though and some nice results are coming through!