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Is there a way to correct it?
And is it a mechanical thing?
https://www.cloudynights.com/topic/714964-advice-on-this-off-set/?p=10298236
Really, it isn't so much a bother to me because I simply crop it away.
But the consistency of it is interesting.
I'm operating in a realm I never have before, because my GM811G allows me to image through the meridian.
So this edge shadow is something I've never seen before.
But it is absolutely consistent, and just becomes more prominent with time.
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SonnyE
(I suggest viewed in full screen)
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It's not a shadow, it's from your autostacking software.
You must be using a piggyback autoguiding system.? The piggyback scope and autoguider are centered on a spot not exactly the same as your main imaging camera.?
And you are not exactly drift aligned for polar alignment.??
So what happens is this: the autoguider system is keeping it's target in the cross hairs, but the earth will appear to be rotating around a different spot.
You can also have "differential flexure" ,? a fancy name for all the mechanical shift in the mounting of the piggyback scope system.
There are some good solutions to try:
1. Center the autoguider system on the center of your main camera image, if possible.
2. Drift align the mount.? This takes time but the PHD2 program has a nice Drift Align tool...you just use that to make the DEC axis line horizontal.
3. Get an OAG and then the guiding will be on the main scope image...
As you said, you can always crop the final image!
Stay well and have fun,
Michael
Is there a way to correct it?
And is it a mechanical thing?
Really, it isn't so much a bother to me because I simply crop it away.
But the consistency of it is interesting.
I'm operating in a realm I never have before, because my GM811G allows me to image through the meridian.
So this edge shadow is something I've never seen before.
But it is absolutely consistent, and just becomes more prominent with time.
--
SonnyE
(I suggest viewed in full screen)
|
The guide scope and imaging camera don¡¯t need to be pointed in exactly the same direction, if he has an equatorial mount that¡¯s reasonably well-aligned. The size of the border here looks too big to just be due to a small polar mid-alignment.?
The sharp edges are odd. I would expect a slow drift to produce a much more gradual transition. Also, drift should cause the shadow to get wider over time. If it¡¯s just getting more intense, that sounds like something else is going on, maybe an artifact from the alignment and stacking or something weird in the image capture.?
It would be interesting to look at sub stacks, say 200 at a time from the sequence of 1300.?
What kind of guider do you have ¡ª separate guide scope, or OAG? What is the size of that image in degrees? What happens with a single long exposure on the order of 10-30 minutes ¡ª is there a shadow or trails?
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On Jul 1, 2020, at 9:17 AM, Michael Herman <mherman346@...> wrote:
? It's not a shadow, it's from your autostacking software.
You must be using a piggyback autoguiding system.? The piggyback scope and autoguider are centered on a spot not exactly the same as your main imaging camera.?
And you are not exactly drift aligned for polar alignment.??
So what happens is this: the autoguider system is keeping it's target in the cross hairs, but the earth will appear to be rotating around a different spot.
You can also have "differential flexure" ,? a fancy name for all the mechanical shift in the mounting of the piggyback scope system.
There are some good solutions to try:
1. Center the autoguider system on the center of your main camera image, if possible.
2. Drift align the mount.? This takes time but the PHD2 program has a nice Drift Align tool...you just use that to make the DEC axis line horizontal.
3. Get an OAG and then the guiding will be on the main scope image...
As you said, you can always crop the final image!
Stay well and have fun,
Michael
Is there a way to correct it?
And is it a mechanical thing?
Really, it isn't so much a bother to me because I simply crop it away.
But the consistency of it is interesting.
I'm operating in a realm I never have before, because my GM811G allows me to image through the meridian.
So this edge shadow is something I've never seen before.
But it is absolutely consistent, and just becomes more prominent with time.
--
SonnyE
(I suggest viewed in full screen)
|
As the others have said ¨C that looks like drift to me too. ? You can simply get rid of it by using ¡°Intersection¡± mode stacking (DeepSkyStacker for one offers that). ? David ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Sonny Edmonds
Sent: 01 July 2020 17:06
To: [email protected]
Subject: [Losmandy_users_io] Was told this is Drift... ? Is there a way to correct it?
And is it a mechanical thing?
https://www.cloudynights.com/topic/714964-advice-on-this-off-set/?p=10298236
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Thanks All!
As far as my stacking, I have very little control over it, that I'm aware of, anyway.
The stacking is a part of the Atik Infinity camera software. The only options I have are to delete a questionable image before the next stacks.
What was odd, and is harder to show, is how this odd edge starts to show, then got more and more pronounced. It didn't change it just kept developing.
In the earlier images it doesn't really show, it just developed like a 5 O'clock shadow. LOL!
My initial thoughts was a misalignment in my imaging train, because it was so square.
I use an Orion ED80T CF as my telescope.
A Manual Filter wheel, and typically a Baader Moon and Sky Glow filter for my area light pollution. (Possible suspect, being in the light path. But the filter is round.)
And then the Atik Infinity, with it's software.
I did a run at the Eagle Nebula, and the same anomaly cropped up.
But in the end, I can easily crop this oddness off the image in Post Processing.
I just had this hair-brained idea to see if I could image through the meridian, and bypass any meridian flip.
Starting off, I had no idea I could go to such an extreme. It just kept going, and the reason I stopped was the telescope was approaching the mount. And it was 03:01 Hrs.
Honestly guys, much of this technical stuff is above my current interest and intellect. It kinda makes me dizzy. LOL! ;^)
But if I can crop away the doo-doo, then do my typical minimal Post Processing, I'm OK with that.
Thank You for your well thought out analytics. I will say, getting into this new realm of imaging is interesting to me.
I can sit there grabbing files at 250 second slices (25, 10 second images) and see this "5 O'clock shadow" develop.
But... it pales in comparison to the detail that builds in the details of the image.
Other friends Post Processing my odd ball imaging method.
But, it's because Scott made the RAEXT and shown the RA flip through after extending the RA. (Sans telescope.) That is the only reason I took this zany path.
And the only reason I got this weird result.
But I do things a bit differently anyway.
Thank You for your inputs!
--
SonnyE
(I suggest viewed in full screen)
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On Wed, Jul 1, 2020 at 09:16 AM, Michael Herman wrote:
3. Get an OAG and then the guiding will be on the main scope image...
Funny you should mention that Michael, I did try for an entire month, with 2 different OAG's to make OAG work with my refractor. Never got it to work. But damn, I sure tried. Because OAG makes excellent sense. And I really wish it did work with a small refractor. But before I returned the second OAG, I chatted with a rep about OAG's and he told me, "Well, OAG's are for reflectors." Like SCT's. Made me feel stupid for trying. But hey, I can do stupid very well. LOL! But, when I finally gave up on OAG, I got an Orion MMAG. in a round about way. I had the camera, then bought the Auto Guider telescope. It was instant success. So I guess I was stupid after all. LOL! ? -- SonnyE (I suggest viewed in full screen)
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>>>?Well, OAG's are for reflectors." Like SCT's.
Haha that's super not true. I use oags on all my refractors including the sky 90
On Wed, Jul 1, 2020 at 09:16 AM, Michael Herman wrote:
3. Get an OAG and then the guiding will be on the main scope image...
Funny you should mention that Michael, I did try for an entire month, with 2 different OAG's to make OAG work with my refractor.
Never got it to work. But damn, I sure tried.
Because OAG makes excellent sense. And I really wish it did work with a small refractor. But before I returned the second OAG, I chatted with a rep about OAG's and he told me, "Well, OAG's are for reflectors." Like SCT's.
Made me feel stupid for trying. But hey, I can do stupid very well. LOL!
But, when I finally gave up on OAG, I got an Orion MMAG. in a round about way. I had the camera, then bought the Auto Guider telescope. It was instant success.
So I guess I was stupid after all. LOL!
?
--
SonnyE
(I suggest viewed in full screen)
-- Brian?
Brian Valente portfolio
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Hi Sonny,
I try to avoid meridian flips....and if I image through a flip, I label my sub images slightly?differently, and stack them separately.
I can then stitch the two final images together in Photoshop or equivalent, or overlay them.??
To avoid a meridian flip, when the mount, scope, and target permit, I'll start my scope west pointing east but upside down if necessary ....that is counterweights above the scope center.? Then the object is tracked through the meridian, and into the West like sunset.? (Not "to infinity and beyond!" as Buzz would say, but maybe 52 million light years or so. )
Have fun with your wonderful equipment!
Michael
Thanks All!
As far as my stacking, I have very little control over it, that I'm aware of, anyway.
The stacking is a part of the Atik Infinity camera software. The only options I have are to delete a questionable image before the next stacks.
What was odd, and is harder to show, is how this odd edge starts to show, then got more and more pronounced. It didn't change it just kept developing.
In the earlier images it doesn't really show, it just developed like a 5 O'clock shadow. LOL!
My initial thoughts was a misalignment in my imaging train, because it was so square.
I use an Orion ED80T CF as my telescope.
A Manual Filter wheel, and typically a Baader Moon and Sky Glow filter for my area light pollution. (Possible suspect, being in the light path. But the filter is round.)
And then the Atik Infinity, with it's software.
I did a run at the Eagle Nebula, and the same anomaly cropped up.
But in the end, I can easily crop this oddness off the image in Post Processing.
I just had this hair-brained idea to see if I could image through the meridian, and bypass any meridian flip.
Starting off, I had no idea I could go to such an extreme. It just kept going, and the reason I stopped was the telescope was approaching the mount. And it was 03:01 Hrs.
Honestly guys, much of this technical stuff is above my current interest and intellect. It kinda makes me dizzy. LOL! ;^)
But if I can crop away the doo-doo, then do my typical minimal Post Processing, I'm OK with that.
Thank You for your well thought out analytics. I will say, getting into this new realm of imaging is interesting to me.
I can sit there grabbing files at 250 second slices (25, 10 second images) and see this "5 O'clock shadow" develop.
But... it pales in comparison to the detail that builds in the details of the image.
Other friends Post Processing my odd ball imaging method.
But, it's because Scott made the RAEXT and shown the RA flip through after extending the RA. (Sans telescope.) That is the only reason I took this zany path.
And the only reason I got this weird result.
But I do things a bit differently anyway.
Thank You for your inputs!
--
SonnyE
(I suggest viewed in full screen)
|
On Wed, Jul 1, 2020 at 09:50 AM, Les Niles wrote:
What kind of guider do you have ¡ª separate guide scope, or OAG? What is the size of that image in degrees? What happens with a single long exposure on the order of 10-30 minutes ¡ª is there a shadow or trails?
Separate guide scope, Les. Size in Degrees? Heck if I know.? I did do a run at the Eagle Nebula, 30 second exposures, End result: Same funny anomaly. 12,000 seconds of data (June Gloom closed me out. LOL!) ? I thought it was kind of odd. ? -- SonnyE (I suggest viewed in full screen)
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On Wed, Jul 1, 2020 at 03:53 PM, Brian Valente wrote:
Haha that's super not true.
Well, that's what the guy told me 5 years ago. I was very disappointed it didn't work. ? -- SonnyE (I suggest viewed in full screen)
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On Wed, Jul 1, 2020 at 03:59 PM, Michael Herman wrote:
To avoid a meridian flip, when the mount, scope, and target permit, I'll start my scope west pointing east but upside down if necessary ....that is counterweights above the scope center.? Then the object is tracked through the meridian, and into the West like sunset.? (Not "to infinity and beyond!" as Buzz would say, but maybe 52 million light years or so. )
?
Well, what I've been experimenting with basically starts East of the meridian, and I just image until the scope bangs the mount. 8^0 (Not really. But it swings from over there, to way over there.) I'm always thinking outside the box. In elementary school they wouldn't let me in the sand box. ? -- SonnyE (I suggest viewed in full screen)
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Michael Herman
David C. Partridge