21.09.19 A mottley selection

[Rusted]

Dogh!  I'm a martyr to high frequency, thermal agitation.

[xtreemchaos]

great shots Rusty, nothing from me today seeing was pants the worse ive had this year. well done. charl.

[Davey-T]

Nice set, mine is still chuntering away, hopefully get something worthwhile that hasn't been blown away.

Dave

[Rusted]

Thanks Charl.

I'm still struggling to make the most of my video captures.

[Rusted]

Thanks Dave.

There was tremendous agitation of the image on the monitor.
I'm amazed anything came out of it.
It's been a lovely day here with full sun, 64F and not much wind.
Shame about the poor seeing conditions.
 

[Davey-T]

29 minutes ago, Rusted said:

Thanks Dave.

There was tremendous agitation of the image on the monitor.
I'm amazed anything came out of it.
It's been a lovely day here with full sun, 64F and not much wind.
Shame about the poor seeing conditions.
 

Which camera are you using ? what frame rate are you getting ? mine can only manage around 30fps, been pondering getting something faster, USB3 to try and freeze the wobbles a bit.

Like Charl I've had to use the .5x focal reducer most of the time recently due to poor seeing.

Dave

[Rusted]

ZWO120MC, 24RGB, USB3 to SSD, i7 laptop with 16GB, 120fps.  120/10.
I usually whack a 2x Barlow in when the seeing is rubbish.
2% of 3000 frames of 480x960 and cropped. I used to do 30% but was told off.

Edited September 21, 2019 by Rusted

[Davey-T]

2% ? I use anything from 25% to 50%.

Dave

[Rusted]

18 minutes ago, Davey-T said:

2% ? I use anything from 25% to 50%.

Dave

So did I. But I was told off by somebody here.

[Davey-T]

1 hour ago, Rusted said:

So did I. But I was told off by somebody here.

Not sure what the reasoning is behind that especially with a fast frame rate camera, maybe when 5fps was normal but would maybe make even less sense, what's the point of taking thousands of frames then stacking maybe 50 of them, what would be the difference with those 50 ?

Deep sky imaging dictates the more frames stacked the better from a signal to noise point of view.

I'll do some experiments when I get the time, can't say as I've ever measured the SNR of my solar images so will do that as well.

Dave

[Stub Mandrel]

2 hours ago, Rusted said:

So did I. But I was told off by somebody here.

Well I tell you 🙂 - (1) look at the quality graph in Autostakkert, there's often an obvious cutoff point. (2) use the slider and see where the sub quality starts to decay. (3) stack different percentages. If you get an improvement, try going a bit furtehr in that direction, if it gets worse head the other way.

As you increase the number of subs noise decreases but at a critical point the image starts to 'soften' as you add in poorer subs, it can take several  runs to find the sweet spot and its not always teh same.

I don't think I've ever gone below 5%, with too few subs, however good they are, there's too much noise.

[Merlin66]

OT.

Neil,

Can you help me understand the use of the green cursor in the AS3! quality graph?

Sure, you can move it across the graph but it doesn't automatically pick up that point for stacking etc?

Is there something I'm missing?????
 

[symmetal]

The green graph line is the subs ordered by quality from left to right, left being the best. The green line quickly falls from max quality to a lower quality value and then decreases more slowly across the graph before quickly dropping to very bad quality at the right hand side.

If you choose to stack say 10% that means your using all the green line subs from the left hand side to the point 10% of the distance across to the right hand side. Depending on the seeing the graph quality drops more quickly so choose a point on the green graph where the quality is still fairly high and estimate what percentage of the whole graph that is. This is the percentage to choose to stack. I normally use between 10 and 20 percent.

You have four boxes where you can enter the percentage to stack. You can fill them with say 2, 5, 10 and 20% and it will produce four stacks with the different percentages without having to repeat all the pre-processing, so is quicker. You can then examine the four percentage stacks to see which gives the optimum result in terms of sharpness and noise. The 2% stack should be sharpest with the most noise and the 20% stack should be the softest with the least noise.

See how much sharper (and more noisy) your 2% stack is compared to the others. The others will be less noisy and the sharpness fall off may not be too much to worry about. 

Alan

Edited September 22, 2019 by symmetal

[Merlin66]

Alan,

Thanks got that!

I was more interested in the functionality of the vertical green cursor line ( right click in quality graph).

All I can see is that it shows the frame and frame# at the cursor position.....to do what????

 

[symmetal]

Oops, sorry Merlin. I think it's just as you say, to show the frame at that green line position, and that's all. Left or right click seems to do the same.

Alan

[Merlin66]

Alan,

Thanks. Yeah, that seems to be all it does.........

[Rusted]

I have spent Sunday morning capturing H-alpha videos of the large prom on the SW limb.
In between I have selected one video with good detail and stepped Registax "Best Frames" upwards from 5% in 5% steps, right up to 100%.
Alignment and Stacking were used with each step up in Best frames but NO wavelets.
These still images were each saved and labelled to ensure accuracy.
A short video of these stills, in the correct sequence from 5% to 100%, was made with 1 second duration per still.
If you can see a difference between any of these then you ought to apply to Marvel for a lead part in their next film.

 

Edited September 22, 2019 by Rusted

[Stub Mandrel]

10 hours ago, Merlin66 said:

OT.

Neil,

Can you help me understand the use of the green cursor in the AS3! quality graph?

Sure, you can move it across the graph but it doesn't automatically pick up that point for stacking etc?

Is there something I'm missing?????
 

It shows where the image being previewed is in the quality ranks.

[Rusted]

It's not OT if it expands our knowledge via the hive mind.

[Stub Mandrel]

9 hours ago, symmetal said:

The green graph line is the subs ordered by quality from left to right, left being the best. The green line quickly falls from max quality to a lower quality value and then decreases more slowly across the graph before quickly dropping to very bad quality at the right hand side.

It's not always 'very bad' at bottom right.

Top left is the 'best image'  - sometimes AS3! can assign high quality to really bad images which have strong artefacts, using PIPP to get rid of the 5% worst images can help eliminate these.

Bottom right is the 'worst' image. But if all the images are 'good' the graph will still drop to zero at bottom right. As an example I took 50 stills of the moon the other evening with a dslr on my scope. At 1/400 (2.5ms and through a Ha filter) the subs were virtually indistinguishable and any of them would have been usable but AS3! still ordered them and graped from top left to bottom right.

This is why you shoudl always use the slider to check what the graph is telling you. usually you will see poor subs at one end and better at the other with a 'break' in the curve that helsp you find where the quality changes. This can be a very obvious step if cloud comes in!

This is that moon, 100% of frames stacked:

[Pete Presland]

A fine set of images