AS!2 alignment point sizes

[Space Cowboy]

Here is a very interesting article posted by Christophe Pellier demonstrating the different results produced when using small or large alignment points on as!2:

http://www.planetary-astronomy-and-imaging.com/en/autostakkert2-comparing-alignment-point-sizes-for-jupiter/

[Freddie]

Interesting. I found that for me 70-80 works best which ties in well with these findings.

[cgarry]

Thanks for posting, very interesting.

Cheers,

Chris

[Space Cowboy]

Yep Emil said a while ago that small points produce less contrast and this shows that very well. To me these make a bigger difference than derotating 2-3 min avis.

[Olorin]

Interesting I always use APs around 35. I'll try bigger ones now.

Thanks for posting

Dror

[neil phillips]

I have been using 70. Looks to me like 50 is worth trying, it does seem to have the sharpness. would like to have seen 70 blinkered with 50

will you be trying 50 Stuart. when your running again ?

The blur seems to soften the noise too. Anyone notice that.

[neil phillips]

Emil also said stay away from the edges. and showed a example. Yet the example here shows points quite close to the edge ? To edge or not too edge ?

[Space Cowboy]

Good point Neil yes I remember the edge rule. That requires manually placing them which often produces cracks for me unless I only use a handful of points.

50 is the smallest I use though recently I've used 100 so looking at these results I shall try 50 again on my last couple of captures. My gut feeling is that larger points work better on smaller stacks so if seeing is below average and you only stack say 10% then its best to use larger points else you get those cracks. 

So many variables depending on the stack size, APs , wavelets and seeing conditions.

[neil phillips]

Good point Neil yes I remember the edge rule. That requires manually placing them which often produces cracks for me unless I only use a handful of points.

50 is the smallest I use though recently I've used 100 so looking at these results I shall try 50 again on my last couple of captures. My gut feeling is that larger points work better on smaller stacks so if seeing is below average and you only stack say 10% then its best to use larger points else you get those cracks. 

So many variables depending on the stack size, APs , wavelets and seeing conditions.

Well I am trying AP size 50 next.  Might compare against 70. Always been 70 75 for me. Wonder what the optimum amount of points is on a image around 6meters ?

[Space Cowboy]

Any excuse to do some repro work lol 70 could be the sweet spot Neil.

[si@nite]

Very intresting & informative Stuart, I tend to use 40-50s & have also used variable sizes so certainly worth experimenting to get that extra detail!

[knobby]

Great thread chaps !

Just a little note for newbie imagers (note to self) ...

After sifting through the info here, I kind of feel that I could have got more from the avi.s I've captured so far.

Unfortunately I deleted them to save space on my lappy  

Dont delete captures until you really are sure you're done ! 

[JamesF]

I have in the past wondered if the AP size should relate to the overall image size at all.

James

[neil phillips]

I have in the past wondered if the AP size should relate to the overall image size at all.

James

That could be True James. But don't forget many of us are working at  FLs that we use time and again. So unless a big jump in FL is used  the settings for a lot of us tend to remain constant I would have thought. Though yes ive read what your saying from Emil himself too.

[Space Cowboy]

Just done my own comparrison using 50,70 & 100 APs.

Attached zip file containing 2 pipp avis.

All settings were identical apart from the APs (using auto placement mode).

50 is clearly sharper across the whole disc but has cracks (seeing was too wobbly for this setting).

AS!2 APs.zip

[si@nite]

Nice comparative Stuart,i agree 50 seems slightly sharper to me, at least on my lappy anyway!

[Space Cowboy]

Interestingly when I used the latest version of as!2 the 50 AP setting did not produce any cracks.