15.4.2020 Hedgerow prom at 8 o'clock on SE limb..

[Rusted]

2x WO Barlow, 800x600 in SharpCap. 3.37Ms, Gain 300, 250fps. 
Seeing slowly improving but wind picking up. AS!2, ImPPG, PhotoFiltre7.

 

[Davey-T]

Nice prom' just having a stab at it myself but seeing is a bit wobbly now.

Dave

[AdeKing]

I've been watching this on and off all day. There has been some spectacular detail visually, it's a shame my sketching isn't capable of capturing the detail.

[Freddie]

Nice work. I would be careful with gain/exposure as they are a little blown out particularly at the base of the proms and you will have probably lost a little detail.

[Rusted]

Thanks for the constructive advice Freddie.

I read somewhere that the ideal Gain for my ASI174MM is 300. Previously, I would use zero Gain and adjust the exposure length accordingly.
Often that would be around 1ms with the PST blocking filter. Then I changed to a Lunt B1200S2 blocking filter which is much dimmer.
So I began to use far more Gain in an effort to keep my exposures short to freeze the thermal agitation.

Today I was struggling for clarity in indifferent seeing conditions. There was hidden detail at the threshold of visibility but of relatively low brightness.
So I pushed the processing a little harder to bring out that detail. I'd much have preferred greater clarity to bring the "smoke" out without forcing it.
I captured lots of videos, over the coarse of this afternoon, but they all looked very similar by the time they were processed in ImPPG.

I have appended a "Snapshot" of the prom as seen by SharpCap. No processing at all. This is exactly what I was seeing on my monitor. There is a lot of noise.

[Freddie]

That’s quite a lot of gain, I never have my 174 over 100 and more often than not much lower than that. You are right though that it is a balance between gain and exposure.

Looking at that Sharpcap image I would definitely back the gain off a bit. A good guide is to back it off until you just start to see some darkening of the disc and some surface detail but only just. You can process out and slight surface detail if you still want to present the  final image with a full white disc.

I would imagine with that amount of noise you are having to stack quite a few images to control it which then means you are including a high number of lower quality frames which will have the effect of blurring the detail. Lowering the gain means you can stack fewer frames. I rarely stack more than 100.

[Rusted]

Thanks Freddie.

I still see myself as a beginner at imaging. Always open to advice from an experienced imager.

My routine solar capture is now 3k frames. Of which I choose 40% if the seeing is reasonable. [Early morning.]
If the seeing is very "mobile" I may capture 2k or even 1k. Then I stack 30%.

I was advised to stack far more frames when I mentioned how few I was normally using at first. 5-10%.
The theory being that I was losing lots of potential data. 

I am always wide open to experimentation. So will try stepped variations of gain and exposure times. The same with stacking.

Thanks again for your patience in responding to my posts. 

[Freddie]

No problem.

As long as you don’t have lots of noise in the individual frames to get rid of by stacking lots (reducing gain will help that), I think by stacking lots of frames you are not making sure you are including good data as suggested, you are actually making sure the stack is worse by including many poor quality frames. However good the seeing is, with daytime seeing you are only ever going to get a tiny percentage of the time during the capture where there is truly good seeing. Keeping the number of frames in the stack to the minimum required to control the noise therefore ensures only the best frames go into the stack. I would determine how many frames you need to stack to control the noise from any given gain and then just stick to that number regardless of how long the AVI is. I always stack a set number, not a percentage. I would never stack more than 150 even from a ~3,000 frame AVI and try to keep it nearer 100 as said above.
 

I should probably get my captures from earlier processed and posted so that you can look and decide if I know what I’m talking about!!

[Rusted]

Thanks Freddie.

All taken on board and I will be following your advice.

I think the three SGL medals speak for themselves. 

[Merlin66]

Rusted,

The zero gain for the ASI 174 is 189, I set to this in FireCapture and gamma to 50. Vary the exposure to bring the rhs of the histogram to around 85-90%

 

[Rusted]

6 hours ago, Merlin66 said:

Rusted,

The zero gain for the ASI 174 is 189, I set to this in FireCapture and gamma to 50. Vary the exposure to bring the rhs of the histogram to around 85-90%

 

Really? Thanks.

The obvious questions are:

Where does the 189 figure come from?

As I use SharpCap, do I set that to 189 in the Gain box?  Or some other figure?

EDIT: SharpCap has no Gamma setting.

Edited April 16, 2020 by Rusted

[Merlin66]

On the ZWO website they have all the gain setting for all the cameras...

https://astronomy-imaging-camera.com/product/asi174mm

The zero gain setting gives maximum image depth.....

Don't know about SharpCap settings, sorry.

 

Edited April 16, 2020 by Merlin66

[Rusted]

Just now, Merlin66 said:

On the ZWO website they have all the gain setting for all the cameras...

The zero gain setting gives maximum image depth.....

Don't know about SharpCap settings, sorry.

Thanks again.

Don't apologise! I just can't seem to cope with Firecapture.
I learn more every day.  Usually, the lesson is how little I know.
Thank goodness for helpful experts like you!
You are our patient Sherpa on the steepest inclines of the learning curve.

[Freddie]

Some interesting comments there by “Merlin66” and obviously everyone has to find the settings that works with their particular setup.

My thoughts and experiences however are that with a gain of 189 the benefits of max image depth are imperceptible but boy can you see the extra noise in the frames. The extra noise meaning you are going to have to stack more frames to control it, including poorer quality ones that will blur the final result. Also, when you are just concentrating on the proms as you are, setting the histo to 85-90% is going to be too low as to expose the proms correctly you will have to blow out the surface and hence the histo is going to be 100%.

As said though, everyone has valid thoughts and it is best to think about which ideas may work for you, try out a number and see what works best for your particular setup.

[Merlin66]

Freddie,

I was thinking of surface features...

I agree 100% for proms you need to push the histogram to give the best exposure for the individual prom.

 

[Rusted]

Thank you gentlemen.

I shall apply your advice depending on my target. Proms v surface features.

EDIT: Image attached: See label for details.

 

 

 

Edited April 16, 2020 by Rusted

[Rusted]

And another: 2.6ms, G262, 100 of 2k.

More subtlety to the "smoke."

[Merlin66]

Rusted,

Compare 100/2000 "quality frames" with say 500/2000 or even 1000/2000.

I find in AS3! that sometimes the best 30 or 50% give as good results....

 

[Rusted]

14 minutes ago, Merlin66 said:

Rusted,

Compare 100/2000 "quality frames" with say 500/2000 or even 1000/2000.

I find in AS3! that sometimes the best 30 or 50% give as good results....

Thanks. As I have the videos saved I can run them through AS!2/3 using various % stacks.
They will, of course, be dependent on the original video settings: Re: Gain and exposure.
I'll be back.
 

[Rusted]

Okay. Three stills from the same video with identical, but minimal processing and with different numbers of stacked frames.
The most obvious difference, to me, is the darkness of the background with 1000 of 2k frames.
I manually cropped the individual frames around the prom but couldn't make them identical.

 

[Merlin66]

Rusted,

Look at the background noise in the 10 frame image..... it improves with 100 frames and almost disappears with a 1000.

I'd start with 100/2000 and look at 300-500/2000.

Just my 2c.

 

[Freddie]

You say these have minimal processing. It looks to me that includes sharpening. There is however clearly far more detail in the proms in the 10 stack than in the 100 stack. As I suggested, the additional frames have blurred the detail. As we are interested in the proms and not the background, then the 10 stack is the one to stick with but sort the background and the way to do that is through processing not by just stacking more frames and losing detail in the thing you are interested in.

Let us know if the processing has included sharpening and if so, I can give you some pointers. Knowing what you use to sharpen (hopefully imppg) would be useful.

[Rusted]

16 minutes ago, Merlin66 said:

Rusted,

Look at the background noise in the 10 frame image..... it improves with 100 frames and almost disappears with a 1000.

I'd start with 100/2000 and look at 300-500/2000.

Just my 2c.

Thanks to you both.
Well, now I have just had to delete my initial response to Merlin.

I really liked the darker backgrounds but saw the 10 frame example as rather "overdone."
It lacked the "smokey" subtlety of the other two. Now I look again it may have slightly more detail.

I ran the same video through a new download of AS!3. Previously I had AS!2 on my imaging laptop.
Nothing was changed between runs except the number of stacked frames.
ImPPG was left open to ensure no change between separate runs.

Out of respect to both of you, as experienced and successful imagers, I really ought to have another trial.
This time with a completely different video with a wider variety of stacked frame numbers.
I can even leave ImPPG completely out of the equation and post the resulting stills separately and unchanged in size or cropping.
Which might easily have resulted in unintended changes in these posted examples.
 

[Freddie]

I wouldn’t worry about a new trial. Now that you have confirmed you used imppg to sharpen as I suspected, I am pretty certain I know what the problem is and how to solve it. However, dinner must come first so will be back in 30 mins!!!

[Peter Drew]

Waiting with bated breath!, I'm not an imager but I like images, specially solar.  I have a bit of a "horse" in this race having goaded Rusted into this position for some time.   😀