Crazy idea or not HOO approaches Soul neb

[fmeireso]

I

From looking up APT's instructions, when dithering via PHD2 it seems to have the same third-party instructions that BYN does. Meaning it sends PHD2 a number from 1 to 5. 1 = 0.5 pixels. 2 = 1 pixel. 3 = 2 pixels. 4 = 3 pixels. and 5 = 5 pixels. You can then scale that in PHD2.

You said your scalar is 3, but...there is no 6! So I'm not sure exactly how much you have been dithering. Can you check your APT settings and let us know what it says? And as a check on things working, have you watched subs come in to your screen and noticed the image shift due to the dithers?

No Mike, dithering in APT goes way further then setting 5. I have used v3.82 and now v3.88. I believe it used to be like that but that has been updated since quite a while.
Also you have a scaling factor in PHD2 , kind of multiplier for those setting in APT, as far as i know.
But i am lacking time now, but will send in some screen shots tomorrow...

[Mike in Rancho]

No Mike, dithering in APT goes way further then setting 5. I have used v3.82 and now v3.88. I believe it used to be like that but that has been updated since quite a while.
Also you have a scaling factor in PHD2 , kind of multiplier for those setting in APT, as far as i know.
But i am lacking time now, but will send in some screen shots tomorrow...

Hi Freddy,

Yeah I suppose APT does go much higher, but the question is what does that mean, and is it what you think it means?

And is the developer's name really Ivo too? I didn't know that was a thing.

Anyway, despite your troubles, I am glad you started this as it made me start digging into stuff some more. "Information" on dithering settings is really all over the place out there, so I am skeptical of a lot of it.

For example. My Backyard Nikon has dither aggressiveness (distance) settings from 1 to 5. Those are the only options. According to the developer on the Backyard EOS/Nikon website, those settings correspond to guide pixel moves from 0.5 to 1.5. It is opined, but not confirmed, that the between settings are evenly spaced. Thus...0.5, 0.75, 1.0, 1.25, and 1.5. The scale value in PHD2 would then multiply that. This explanation is quite old, but has not changed, and as far as I can tell in their forums they have stuck to it.

But, I have my BYN set at level 2. My PHD2 scalar is 4. And if I look at my PHD2 logs, I can see that my max pixel movement during a dither was 3.998 pixels. Well, that doesn't make sense, does it? If setting 2 = 0.75 pixels, the max should be 3 using a scalar of 4.

APT's online instructions state as I noted earlier. Their setting number 2 corresponds to 1 pixel. This would match the results I am seeing, so it's possible BYN and APT actually have the same dither distances. I will need to experiment more.

Also, check out this earlier CN post, where it is opined that all the third-party connections to PHD2 use this same 1 to 5 scheme and scale: https://www.cloudynights.com/topic/6852 ... try9813440

Even more interestingly, the author of BYE/BYN hit "like" on that post! Well...what the???

So who knows? And I also noticed in my logs that every single time I do a new session, the dithers follow the exact same sequence and are 100% identical. Every. single. time. Guess they didn't seed the random number generator! Oops.

Anyway, if you have the PHD2 log viewer you can check your session and see what the dither distances were, in guide pixels. Look and see what your max was during the soul sessions. I'm curious if it will be the 18 you were expecting, or something else.

[fmeireso]

I just like investigating and figuring things out.

Now, I just need to do the same when it comes to luminance and color spaces. Ugh.

Freddy, I think you noted that this was taken with a 76EDPH and .8 reducer. Some more googling indicates your mono mod is a 600D/T3i. So astronomy tools says that is 2.66"/pixel. Likewise, more google (all of CN stuff, of course) leads me to believe you are guiding with an ASI290 and 60/280 scope. That would be 2.67"/pixel. So, basically identical movement will be achieved pixel to pixel.

From looking up APT's instructions, when dithering via PHD2 it seems to have the same third-party instructions that BYN does. Meaning it sends PHD2 a number from 1 to 5. 1 = 0.5 pixels. 2 = 1 pixel. 3 = 2 pixels. 4 = 3 pixels. and 5 = 5 pixels. You can then scale that in PHD2.

You said your scalar is 3, but...there is no 6! So I'm not sure exactly how much you have been dithering. Can you check your APT settings and let us know what it says? And as a check on things working, have you watched subs come in to your screen and noticed the image shift due to the dithers?

See my setting is 6, you can go to 90!

[fmeireso]

No Mike, dithering in APT goes way further then setting 5. I have used v3.82 and now v3.88. I believe it used to be like that but that has been updated since quite a while.
Also you have a scaling factor in PHD2 , kind of multiplier for those setting in APT, as far as i know.
But i am lacking time now, but will send in some screen shots tomorrow...

Hi Freddy,

Yeah I suppose APT does go much higher, but the question is what does that mean, and is it what you think it means?

And is the developer's name really Ivo too? I didn't know that was a thing.

Anyway, despite your troubles, I am glad you started this as it made me start digging into stuff some more. "Information" on dithering settings is really all over the place out there, so I am skeptical of a lot of it.

For example. My Backyard Nikon has dither aggressiveness (distance) settings from 1 to 5. Those are the only options. According to the developer on the Backyard EOS/Nikon website, those settings correspond to guide pixel moves from 0.5 to 1.5. It is opined, but not confirmed, that the between settings are evenly spaced. Thus...0.5, 0.75, 1.0, 1.25, and 1.5. The scale value in PHD2 would then multiply that. This explanation is quite old, but has not changed, and as far as I can tell in their forums they have stuck to it.

But, I have my BYN set at level 2. My PHD2 scalar is 4. And if I look at my PHD2 logs, I can see that my max pixel movement during a dither was 3.998 pixels. Well, that doesn't make sense, does it? If setting 2 = 0.75 pixels, the max should be 3 using a scalar of 4.

APT's online instructions state as I noted earlier. Their setting number 2 corresponds to 1 pixel. This would match the results I am seeing, so it's possible BYN and APT actually have the same dither distances. I will need to experiment more.

Also, check out this earlier CN post, where it is opined that all the third-party connections to PHD2 use this same 1 to 5 scheme and scale: https://www.cloudynights.com/topic/6852 ... try9813440

Even more interestingly, the author of BYE/BYN hit "like" on that post! Well...what the???

So who knows? And I also noticed in my logs that every single time I do a new session, the dithers follow the exact same sequence and are 100% identical. Every. single. time. Guess they didn't seed the random number generator! Oops.

Anyway, if you have the PHD2 log viewer you can check your session and see what the dither distances were, in guide pixels. Look and see what your max was during the soul sessions. I'm curious if it will be the 18 you were expecting, or something else.

You are right Mike, the dither setting are a very gray zone.
But what i am gonne do :
In my Heart stack when i made the images i forgot to alter the APT setting cause it was a setting for my 102 mm. There was more strange big noise in , not really streakes like typical walking noise but agian a sort of pattern, forgot what Ivo (from ST) called it.
In the Soul stacks this is not there anymore or at least not to that degree.
I guess for the next session i will put a higher value for dithering and just see where it gets me...
However it bothers me to not be able to calculate or to know for sure the exact dithering distance

[Mike in Rancho]

But you can!

In fact yours is really easy, at least for the Soul, since your guiding and imaging pixel scales are essentially 1:1.

Can you upload and link the PHD2 log for your Soul imaging session(s)? I'll run it through the log viewer (you can download it too). It tells you on the graph (and text if you open that) what the dither pixel distances were.

Of course, the dithers are "randomly" sized from -/+ 0.000 to max, within the parameters you set. But with enough dithers there's a fair chance that we'll see enough of the range to make a good guesstimate of what the calculations will be between APT and PHD2.

[fmeireso]

But you can!

In fact yours is really easy, at least for the Soul, since your guiding and imaging pixel scales are essentially 1:1.

Can you upload and link the PHD2 log for your Soul imaging session(s)? I'll run it through the log viewer (you can download it too). It tells you on the graph (and text if you open that) what the dither pixel distances were.

Of course, the dithers are "randomly" sized from -/+ 0.000 to max, within the parameters you set. But with enough dithers there's a fair chance that we'll see enough of the range to make a good guesstimate of what the calculations will be between APT and PHD2.

Stupid me , why did i not think of that myself!

hmm seem not to be able to upload a txt file here?

I will try to sent it through CN

[Mike in Rancho]

Well Freddy's PHD2 file looked okay to me. APT does in fact send what you put in the distance (at least outside of the 1-5), so his max dithers are 6 x 3 = 18 guide pixels. His first one was even 17.x in the RA.

The guide errors were a bit over half a guide pixel, slightly high IMHO, but in arc-seconds about 1.3", which is half of his pixel scale of 2.7".

So, if some kind of pattern is ending up in Freddy's stack...what could be the source?

[fmeireso]

@Mike and Ivo

https://www.dropbox.com/s/w50qzi8amxqkrbv/M13.fts?dl=0

This is an OSC stack from M13 from late april.
Can you verify if there is some noise pattern in too.
Cause Ivo stated both Soul stacks had pattern noise.
Do you see some in this M13 stack. This is a clean OSC stack no filters , FF in place, camera Canon 800D unmodded. Bigger scope 102 mm F/7

thanks

[Mike in Rancho]

Hi Freddy,

I took at look at the M13, and also the "OSC" of the Soul again too. Both being the same unmodded camera, just one was with the L-eN, if I have that correctly.

Honestly I'm not seeing much trouble in either. Some defects, sure, like anybody's, including some dust spots. If anything, there's maybe some large scale striation in the background, but not that I would think would end up as something problematic. And maybe I'm just seeing things.

What I try to do is an AutoDev and keep, then just zoom in and out. Then I rotate it 90 degrees and see if it holds up. Sometimes stuff looks like it's there just due to the way the graphics or monitor are displaying things, and it will change with zoom or rotation.

Mostly your "OSC" stuff seems primarily random to me, as I think it should be.

The mono Ha, however, seems different. It really does seem like a smaller scale imprinting of patterns, all over the place where the white of the nebula isn't strong enough to overcome it I guess. And here's where it's different from the OSC files -- that pattern holds up and is obviously still there, regardless of how I rotate the image or even zoom in close.

Weird. And seems to me would have far more of an impact in trying to smooth that out, so will leave your image choppy, especially since you want to use a lot of that for your L type detail.

What are the integration times on the Soul's? I wonder also if they might be a little short, and thus we are having to pull up the background more than we would if the integration was greater?

[fmeireso]

Integration time on the Soul stacks were about 3 hr 30 or just over it, so in total a 7 hours of integration.

So a kind of 50 / 50 thing.

ok next session i will augment my dithering settings for the mono, see if that makes a difference at al.
Maybe also take kind of full spectrum mono without filter, to see if the filter throws in some weird stuff or not. One never knows.