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Starting from scratch - Pulled everything but the camera

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#1 dcaponeii

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Posted 04 August 2020 - 11:57 PM

I thought I had the collimation dialed in this evening.  Focus looked good seeing wasn't too bad either.  After capturing a few videos of Jupiter I did some test stacks and wavelets before coming inside and they were TERRIBLE!!!  Pulled the entire optical train out except for the camera at prime focus and began collimation again.  Got that dialed in and shot this 20% stack.  Better resolution than I've been getting to date.  Clouds rolled in so I couldn't start putting the other optics back in place to see if I can figure out what is causing the soft focus.  Still feels like collimation but how many times can I dial it in and still not get good images.  This is a 20% stack from a 22000 frame capture.  Gain = 185 and 8 ms exposure.  Yielded a 63% Green Histogram

 

2020-08-05-0357_1-U-L-Jup_AP24_3xAS_206148w.jpg


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#2 Tulloch

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Posted 05 August 2020 - 12:13 AM

I dunno why you are having the problems you are - have you tried imaging something a good distance away during the day, like a car number plate, a stop sign, something that's not moving and less affected by the atmosphere? If you can get a really sharp focus on small details, then it might indicate that the problem is in your seeing when imaging the planets. If you can't get a good focus on the terrestrial object, then look again at your optical train.

 

Just my 2c ...

 

Andrew


Edited by Tulloch, 05 August 2020 - 12:14 AM.

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#3 sg6

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Posted 05 August 2020 - 02:08 AM

22000 frames at 8ms is 176 seconds and that might be too long for Jupiter. Jupiters rotation speed mens that details on it's surface move during "long" videos, and rather unfortunately long is not apparently that long. gaah.gif

 

Just that in photography sharpness is often a case of both good focus and the object, person or planet, not moving. And telling Jupiter to hold still for 3 minutes isn't going to accomplish much.

 

Try half the length so around 10000 frames end to end, the 80 to 100 second duration, assuming the same 8ms.



#4 Kokatha man

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Posted 05 August 2020 - 03:02 AM

22000 frames at 8ms is 176 seconds and that might be too long for Jupiter. 

Sorry - but this is simply incorrect!

 

sq6, apologies if I'm wrong but I think you have propagated that myth on this forum a few times: to the OP, look at our website in the link below & try telling me that 180 seconds is too long for the very hi-res examples of Jove you will find in abundance therein..! :lol:


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#5 Tom Glenn

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Posted 05 August 2020 - 04:23 AM

When you say you have the collimation "dialed in", what is your evidence?  If you take a short video of an unsaturated star, both in focus, and slightly out of focus, stack the video and post it, people could tell you whether you are collimated.  We've seen it happen many times on this forum where somebody will say they were collimated, only to post an image that shows otherwise.  Also common is that people are collimating while deeply out of focus, and using the secondary shadow, which is unsuitable.  You need to be in focus, or very close to it.  And what evidence do you have that you don't have bad seeing conditions most of the time?  Was the diffraction pattern stable in live view, and could you see an Airy disk in focus?  Looking at your image, it looks like fairly typical poor seeing, although collimation and focus and also masquerade as this.  


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#6 dcaponeii

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Posted 05 August 2020 - 08:42 AM

When you say you have the collimation "dialed in", what is your evidence?  If you take a short video of an unsaturated star, both in focus, and slightly out of focus, stack the video and post it, people could tell you whether you are collimated.  We've seen it happen many times on this forum where somebody will say they were collimated, only to post an image that shows otherwise.  Also common is that people are collimating while deeply out of focus, and using the secondary shadow, which is unsuitable.  You need to be in focus, or very close to it.  And what evidence do you have that you don't have bad seeing conditions most of the time?  Was the diffraction pattern stable in live view, and could you see an Airy disk in focus?  Looking at your image, it looks like fairly typical poor seeing, although collimation and focus and also masquerade as this.  

Good idea.

 

What I mean by dialed in is: 1:  Concentric donut at far focus.  2: Concentric diffraction circles at near focus with a central point of light.  3)  At very near focus there are no "flares" in any direction around the central star.

 

Note:  Can only detect these features when using a 5-10 frame average in Firecapture.

 

Before checking in FC I used Metaguide and had the red dot centered in the center of the Airy disk again with MG set to about a 1.5s integration time to stabilize the image.



#7 dcaponeii

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Posted 05 August 2020 - 08:51 AM

I dunno why you are having the problems you are - have you tried imaging something a good distance away during the day, like a car number plate, a stop sign, something that's not moving and less affected by the atmosphere? If you can get a really sharp focus on small details, then it might indicate that the problem is in your seeing when imaging the planets. If you can't get a good focus on the terrestrial object, then look again at your optical train.

 

Just my 2c ...

 

Andrew

Great idea and I've not noticed any issues in the past when looking at the light pole about 0.5km out that I align my finder scope with.

 

I did notice this morning that the FC capture data indicated that I was imaging at f/24!!  This might actually be a lot of my problem since for my ASI290MC camera and the 12" LX-600 I should be shooting (given the 5x pixel size criteria) at f/15.  The scope is an f/8 and with a 2x Barlow I expect to achieve f/16 which should be just about right.  The projection distance to the chip must be a lot larger than it should be (not sure how to fix that yet with this Barlow.  However, that being said, the image with the camera at Prime Focus should be at the scope's design f/8 value.  The FC data indicates f/9 which is reasonable close to the expected value.  But even the prime focus image above is not in sharp focus (at least not what I expect of a 12" aperture scope.  It's certainly possible I'm doing something during stacking or wavelets but I doubt that.   The f/8 image above is certainly not a high resolution image by any stretch of anyone's imagination.  I appreciate all the help that you and the other in the forum have been providing.  I'll get it sorted eventually I'm sure.



#8 dcaponeii

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Posted 05 August 2020 - 08:53 AM

Sorry - but this is simply incorrect!

 

sq6, apologies if I'm wrong but I think you have propagated that myth on this forum a few times: to the OP, look at our website in the link below & try telling me that 180 seconds is too long for the very hi-res examples of Jove you will find in abundance therein..! lol.gif

It clearly true based on your's and other's imaging that 180s is NOT too long for Jupiter.


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#9 RedLionNJ

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Posted 05 August 2020 - 09:00 AM

I'm with all of the above opinions (except for one).

 

What you display as a sample, above, is fairly typical for poor seeing due to a combination of jet stream and low elevation.

 

You need to get EVERYTHING in alignment for hi-res imaging such as is demanded of for planetary imaging.

 

non-excessive f-ratio (ok, you probably have that - aim for no more than 400 pixels for Jupiter)

close to perfect collimation (show us evidence)

finely-tuned ADC  (again, evidence would be nice)

perfect focus (harder to provide evidence except for the finished product)

and last but incredibly importantly - good or better seeing

 

I get maybe two really good nights of seeing a year where I live.


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#10 dcaponeii

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Posted 05 August 2020 - 09:10 AM

I'm with all of the above opinions (except for one).

 

What you display as a sample, above, is fairly typical for poor seeing due to a combination of jet stream and low elevation.

 

You need to get EVERYTHING in alignment for hi-res imaging such as is demanded of for planetary imaging.

 

non-excessive f-ratio (ok, you probably have that - aim for no more than 400 pixels for Jupiter)

close to perfect collimation (show us evidence)

finely-tuned ADC  (again, evidence would be nice)

perfect focus (harder to provide evidence except for the finished product)

and last but incredibly importantly - good or better seeing

 

I get maybe two really good nights of seeing a year where I live.

I'll image some diffraction images this weekend.  I've got several cloudless evenings coming up starting tomorrow.  I'm using the ClearDarkSky website to gauge seeing and last night was reported as "average" on my app.  I agree with the 2 or 3 nights a year of really good seeing but you can see my images for yourself and they are consistently poor so far.  I'm certainly not done working the issue and I appreciate everyone's helpful suggestions I take them to heart and am trying to implement them.  FC data file indicated I was imaging at f/24 with the 2x Barlow which might be part of the challenge I'm fighting.  When I imaged last night at prime focus FC data file showed f/9 which is pretty close to the f/8 specification for the scope.  f/24 is quite a bit outside the "normal" range of f/number if I use the factor of 5x pixel size criteria.  Even 7x pixel size only yields f/21 for my scope.



#11 dhammy

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Posted 05 August 2020 - 09:14 AM

Upload the video clip to google drive - we’ll be immediate able to put the seeing issue to rest.

Are you are using a dew heater or allowing the scope time to reach ambient temperature before imaging? If you live somewhere with large temperature swings during the night, your scope may be chasing the temperature which of course causes tube air currents...


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#12 dhammy

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Posted 05 August 2020 - 10:00 AM

Also if you are using a diagonal - don’t. 


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#13 RedLionNJ

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Posted 05 August 2020 - 10:20 AM

I've got several cloudless evenings coming up starting tomorrow.  I'm using the ClearDarkSky website to gauge seeing and last night was reported as "average" on my app.  I agree with the 2 or 3 nights a year of really good seeing but you can see my images for yourself and they are consistently poor so far. 

Alas, cloudless is only one of the sky factors when you're looking to bring out detail as small as 0.15 arcsec or less. Everything which rolls into "seeing" is just as important.  David points out equilibrium as another factor. I often find my "seeing" is so-so when I first open up the roof/scope, then it degrades for an hour or so, then improves again. I am sure this is entirely due to lack of local equilibrium and the steep gradients during the stabilization period to get there.

 

CSC is close to meaningless for seeing conditions. It only takes into account the lowest 4,000 feet or so of atmosphere.  That's due to the data source.

 

It's also quite possible you just haven't hit one of those 2 or 3 really good nights, yet. I look to spring and fall as the best potential seasons for these.  Yet a cool day in summer or a warm day in winter can have great results, too.  Out of our control - just get out on every clear night and give it a go.

 

 

I also have a 12" SCT, but mine's (nominally) F/10.  That's a better fit for the 290MC, and when I add my 1.5x barlow, it's an excellent fit.

 

But a 2x barlow on the F/8 shouldn't be too far off. Certainly good enough.

 

Grant


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#14 dcaponeii

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Posted 05 August 2020 - 10:56 AM

Alas, cloudless is only one of the sky factors when you're looking to bring out detail as small as 0.15 arcsec or less. Everything which rolls into "seeing" is just as important.  David points out equilibrium as another factor. I often find my "seeing" is so-so when I first open up the roof/scope, then it degrades for an hour or so, then improves again. I am sure this is entirely due to lack of local equilibrium and the steep gradients during the stabilization period to get there.

 

CSC is close to meaningless for seeing conditions. It only takes into account the lowest 4,000 feet or so of atmosphere.  That's due to the data source.

 

It's also quite possible you just haven't hit one of those 2 or 3 really good nights, yet. I look to spring and fall as the best potential seasons for these.  Yet a cool day in summer or a warm day in winter can have great results, too.  Out of our control - just get out on every clear night and give it a go.

 

 

I also have a 12" SCT, but mine's (nominally) F/10.  That's a better fit for the 290MC, and when I add my 1.5x barlow, it's an excellent fit.

 

But a 2x barlow on the F/8 shouldn't be too far off. Certainly good enough.

 

Grant

I usually open the roof as soon as direct solar heating is no longer present.  Last night that was at about 8:10 pm.  I then began my imaging around 9:20 pm a little over an hour later.  Very possible that I'm not giving things enough time to stabilize.  Setting sun shines directly on the side of the observatory which then shines directly on the scope if I open up too much earlier.  I was imaging until nearly midnight last evening and didn't notice any continued improvement.  A cloud deck moved over top of me while I was processing a few test images and cut off my work.  I'm working with my images now to see what's really been captured.


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#15 Tom Glenn

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Posted 05 August 2020 - 11:52 AM

In both this thread, and your other one, you mentioned that you think luck alone would have yielded you good seeing thus far.  This is not the case.  Most people have terrible seeing, all the time.  In fact, for many people, the image you posted above for Jupiter is an example of the best outcome in years.  This forum (and others) can easily give beginners the wrong impression about planetary imaging, because it tends to overrepresent the best examples of images, which are not common.  Jupiter is very low in the sky now too, which makes a huge difference.  


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#16 Stricnine

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Posted 05 August 2020 - 12:50 PM

I'll image some diffraction images this weekend.  I've got several cloudless evenings coming up starting tomorrow.  I'm using the ClearDarkSky website to gauge seeing and last night was reported as "average" on my app.  I agree with the 2 or 3 nights a year of really good seeing but you can see my images for yourself and they are consistently poor so far.  I'm certainly not done working the issue and I appreciate everyone's helpful suggestions I take them to heart and am trying to implement them.  FC data file indicated I was imaging at f/24 with the 2x Barlow which might be part of the challenge I'm fighting.  When I imaged last night at prime focus FC data file showed f/9 which is pretty close to the f/8 specification for the scope.  f/24 is quite a bit outside the "normal" range of f/number if I use the factor of 5x pixel size criteria.  Even 7x pixel size only yields f/21 for my scope.

I've found "Seeing" predictions to be profoundly inaccurate.  To get some rough idea on the turbulence I'll watch stars, the more they're twinkling the worse the seeing is.  Keeping in mind that "seeing" can/will vary across the sky.  Given the light pollution I video under I can't really see stars near Jupiter and Saturn right now.

 

Check out DMach's Astrobin account (link below) he's included a link to get the SER files (and image stacks) he used for the image, along with restrictions on the use of his data.  Watching/stepping through the SER videos will give you a really good idea of what great seeing looks like and the resulting image that is possible from it.  The raw stacked images in the link are clearer/sharper then any of my post-Registax versions.

 

https://www.astrobin...ff2x/C/?nc=user



#17 dcaponeii

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Posted 05 August 2020 - 04:01 PM

In both this thread, and your other one, you mentioned that you think luck alone would have yielded you good seeing thus far.  This is not the case.  Most people have terrible seeing, all the time.  In fact, for many people, the image you posted above for Jupiter is an example of the best outcome in years.  This forum (and others) can easily give beginners the wrong impression about planetary imaging, because it tends to overrepresent the best examples of images, which are not common.  Jupiter is very low in the sky now too, which makes a huge difference.  

You are making me feel more encouraged.

 

I'm still a bit worried about Firecapture calculating that I was imaging at f/24.  I'm thinking I'll slip my f6.3 flattener/reducer (that I used to use on my f/20 Meade 2120) into the mix (yields f/5 for this scope) and see if I can bring that f/number down.  By calculation that should drop the f/24 to f/15 which is where i should be.

 

I'll be back at this weekend.  Things will hit one of these nights.  I'm really trying to get tuned up in time for the Mars opposition.



#18 dcaponeii

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Posted 05 August 2020 - 04:07 PM

I've found "Seeing" predictions to be profoundly inaccurate.  To get some rough idea on the turbulence I'll watch stars, the more they're twinkling the worse the seeing is.  Keeping in mind that "seeing" can/will vary across the sky.  Given the light pollution I video under I can't really see stars near Jupiter and Saturn right now.

 

Check out DMach's Astrobin account (link below) he's included a link to get the SER files (and image stacks) he used for the image, along with restrictions on the use of his data.  Watching/stepping through the SER videos will give you a really good idea of what great seeing looks like and the resulting image that is possible from it.  The raw stacked images in the link are clearer/sharper then any of my post-Registax versions.

 

https://www.astrobin...ff2x/C/?nc=user

I'll take a crack at collimating with a nearby star.  I'm south of Dallas so the light pollution I mostly fight is on my northern horizon (except when the football stadium lights are on!)  I'll have to remember my onedrive password to get a look at the raw data.  I'll give that a shot through as it would be very useful to see what "good" data looks like.



#19 DMach

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Posted 06 August 2020 - 10:34 AM

I'll take a crack at collimating with a nearby star.  I'm south of Dallas so the light pollution I mostly fight is on my northern horizon (except when the football stadium lights are on!)  I'll have to remember my onedrive password to get a look at the raw data.  I'll give that a shot through as it would be very useful to see what "good" data looks like.

I think you don't need to log into Onedrive to access the data, should be publicly available. If you have trouble accessing it, just let me know or PM me - good things should be shared!

 

Seeing like that is a rare bird indeed, even here at the equator - once a year so far. (Actually it probably occurs more frequently than that, but it's cloudy so often here I wouldn't know it ... 17 straight cloudy nights and counting as I write this.)  :(

 

Andrew/Tulloch also shared one of his data sets a while back!



#20 dcaponeii

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Posted 07 August 2020 - 05:33 AM

When you say you have the collimation "dialed in", what is your evidence?  If you take a short video of an unsaturated star, both in focus, and slightly out of focus, stack the video and post it, people could tell you whether you are collimated.  We've seen it happen many times on this forum where somebody will say they were collimated, only to post an image that shows otherwise.  Also common is that people are collimating while deeply out of focus, and using the secondary shadow, which is unsuitable.  You need to be in focus, or very close to it.  And what evidence do you have that you don't have bad seeing conditions most of the time?  Was the diffraction pattern stable in live view, and could you see an Airy disk in focus?  Looking at your image, it looks like fairly typical poor seeing, although collimation and focus and also masquerade as this.  

Spent about 90 minutes last night shooting collimation captures of the star Nunki in Sagittarius prior to capturing Jupiter and Saturn.  I'm not sure how to interpret what I'm seeing at the camera but here it is.

 

All images are 60% stack of about a 200 frame capture.  400 Gain and 40 ms exposure with 10 frame Averaging ON.  I reinstalled the optical train which is My JMI Crayford focuser on the back plane.  The 1.25 threaded adapter.  The ADC (collimation was done in the neutral position) a 2x Barlow and finally the ASI290MC with it's 1.25" nosepiece inserted into the barlow.  Note:  It took about 30 minutes to get the optics back to the same image size as I've been using so far (Barlow won't thread onto the camera.)

 

ROI = 800x600.

 

My initial donut is shown here.

 

2020-08-07-0323_7-U-L-StarAS_6061 - Donut.jpg

 

I thought this was a good starting point so I changed focus to near focus range and got this result.

 

2020-08-07-0326_2-U-L-StarAS_6061 - Near focus before.jpg

 

Narrow on the bottom so began making adjustments and got to here:

 

2020-08-07-0329_0-U-L-StarAS_6061 - Near closer.jpg

 

Very close to focus is in this image and you can see the asymmetry in the image as you approach focus.

 

 2020-08-07-0331_6-U-L-StarAS_6061 - very near focus before.jpg

 

So I made a couple of very small inputs on the secondary to bring the very near focus to this point.

 

2020-08-07-0331_6-U-L-StarAS_6061 - very near focus before.jpg

 

So at this point I went thru focus to see what it looked like on the other side and got this result which is clearly asymmetric once again.

 

 2020-08-07-0341_6-U-L-StarAS_6061 - thru focus went too far.jpg



#21 dcaponeii

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Posted 07 August 2020 - 05:44 AM

So I started again from the point in Post #20.  If I adjust the secondary to give a symmetric result with the "donut" then the near focus star image has a sickle shape.  When I adjust the near focus image to a symmetrical circular shape then the "donut" becomes asymmetric again.

 

I decided on making a donut near focus symmetrical and here's the final star image I left with to start imaging.  I think maybe I shouldn't worry about the asymmetry in the donut and go with a symmetric very near focus image but your comments would be helpful in this regard.

 

Very near focus image

 

2020-08-07-0408_7-U-L-StarAS_6061 - vnf.jpg

 

Adjusted to here:

 

2020-08-07-0413_4-U-L-StarAS_6061 - adj 2.jpg

 

Which yields this donut which CAN'T be correct:

 

2020-08-07-0416_2-U-L-StarAS_6061 - back to asymmetric.jpg

 

Decide to make my final adjustment with the focus halfway between the above image and on focus.

 

2020-08-07-0421_9-U-L-StarAS_6061 - adjusted near focus.jpg

 

The final star image is shown here:

 

2020-08-07-0425_2-U-L-StarAS_6061 - final star image.jpg

 

As you can see I seem to be chasing my tail a bit.  All of these adjustments are the result of very small adjustments to one screw at a time and those adjustments are a small fraction of a turn of the screw most of the time only moving the star image about half of the ROI on the chip.  Yes I'm recentering the image after each adjustment.

 

 


Edited by dcaponeii, 07 August 2020 - 05:45 AM.


#22 dcaponeii

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Posted 07 August 2020 - 11:02 AM

Here is my first Jupiter capture after working on the collimation photos above.  A 20% stack at 325 Gain and 8 ms exposure.  180s total capture.  I could not get the f/6.3 reducer into the optics as I didn't have enough focus (got close but ran out of travel from the scope's Crayford).  Did notice an image shift as I got close to running out of travel (counterclockwise which I think is moving the mirror forward so maybe that's to be expected when that weight get's out away from the back of the scope?)  I think this week's feedback has resulted in a better image but I sure would like some pointers on what I'm chasing in collimation if anyone has seen something similar.

 

2020-08-07-0436_8-U-L-Jup_AP64_3xAS_206116w.jpg



#23 RedLionNJ

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Posted 07 August 2020 - 11:29 AM

Spent about 90 minutes last night shooting collimation captures of the star Nunki in Sagittarius prior to capturing Jupiter and Saturn.  I'm not sure how to interpret what I'm seeing at the camera but here it is.

 

All images are 60% stack of about a 200 frame capture.  400 Gain and 40 ms exposure with 10 frame Averaging ON.  I reinstalled the optical train which is My JMI Crayford focuser on the back plane.  The 1.25 threaded adapter.  The ADC (collimation was done in the neutral position) a 2x Barlow and finally the ASI290MC with it's 1.25" nosepiece inserted into the barlow.  Note:  It took about 30 minutes to get the optics back to the same image size as I've been using so far (Barlow won't thread onto the camera.)

 

 

I'm not quite sure I follow all the above.  Just use the exact same optical setup you would use for imaging, when adjusting collimation.  This includes appropriate ADC adjustment for the elevation.

 

There's no subtle way to say this - that collimation looks terrible, in my opinion.



#24 dcaponeii

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Posted 07 August 2020 - 11:54 AM

I'm not quite sure I follow all the above.  Just use the exact same optical setup you would use for imaging, when adjusting collimation.  This includes appropriate ADC adjustment for the elevation.

 

There's no subtle way to say this - that collimation looks terrible, in my opinion.

I agree with your assessment of the collimation.  I was hoping someone would see something in the images that jumps out at that as to the possible cause.  If I collimate far from focus (the donut) I get a distorted star shape near (and at) focus.  If I collimate to make the very near focus image small and symmetrical then the donut is not symmetrical.  I don't think it should be doing that and I'm not sure which to favor.  Last night I collimated with the donut.  Tonight I plan to collimate with the very near focus image.  I think this is the root cause of the differences I've been experiencing with MetaGuide (which uses very near focus) and Firecapture for which I was just doing old school symmetrical donut.

 

What does not come through in ANY of the images is that there is a clearly defined set of diffraction rings easily visible that I use to try and align things.



#25 Kokatha man

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Posted 07 August 2020 - 07:48 PM

...I'm having a hard time reading these images - apart from an obvious heat plume from the optics/primary not being sufficiently cooled, there seems to be an inordinate amount of atmospheric diffraction going on: what is the elevation & what is the camera..? If it is one of the colour cameras switch the viewing to mono output... wink.gif

 

Also, many of the examples above appear as if they are "half images." I understand that some (or all?) of your images are Metaguide outcomes which unfortunately are somewhat alien to me although I can of course interpret images #1,2,3,6 & 9 in your posts above - & a couple of others where they are too over-exposed for me to make any appraisal.

 

Look at the link in our signature below for real-time collimation examples which might give you some direction for what to look for without Metaguide when viewing a defocused star in FireCapture, if it is of assistance. 


  • dcaponeii likes this


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