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First time EAA Epic Fail

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#1 Class-M-Planet

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Posted 29 October 2020 - 12:56 AM

Dear Mighty Ones,

 

I have attempted my first EAA with high hopes, but it ended up as epic failure.  First of all, despite stacking live images via SharpCap Pro, I saw zero nebula or galaxy colors except bloated/overexposed stars.  When I did see colors, it is because I manually changed the histogram RGB colors in the histogram controls menu.  Second thing I noticed from all the images I took are large dark rings that are only noticeable with fully stretched histogram (please see the attached image of a cluster).  I am wondering how I can get rid of those rings.  This imaging session was done under a bortle 6 sky (San Diego), under a very bright moon (3/4 waxing gibbous), and without any filters (only Anti reflective window on the ASI224MC).  Also, I only did rough focusing via an overexposed Mars and slew to my imaging targets.  I felt like the OTA was well collimated since Mars and the Moon looked tact sharp at 250x.  I did notice some vignetting at the very edges, but didn't notice severe comas.

 

Here is the list of what I used:

 

LX90-ACF 8" SCT telescope (Alt-Az mount and OTA)

Optec's Nextgen 0.33x Focal Reducer with proprietary spacer from Optec for ASI224MC (1.89" T-adapter)

ASI224MC ver.1.3

SharpCap Pro ver.3.2 (raw8 and raw16, 300-350 gain, 5-10 sec exposures, 10-50 stacks)

 

It would be great if I can solve some of the problems I am having and get some wonderful EAA images.

 

I'd very much appreciate your responses or suggestions.

 

Clear Skies~~

 

Attached Thumbnails

  • EAAEPICFAIL.jpg

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#2 cmooney91

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Posted 29 October 2020 - 07:13 AM

The darker corners are caused by vignetting and dark rings are shadows of dust in the optical train. 

 

Using flat frame calibration will counteract their effects.  Essentially you  point the scope at an even illumination(or cover it with a LED "tracing tablet"), and take a picture  exposed for a 50% histogram(Grey).  That picture is a flat frame, it is an accurate representation of how the telescope's illumination varies at the sensor. sharp cap can use it like a map to automatically boost the darker areas so the whole image is normalized in brightness. Having an even illumination really helps to isolate and show dim nebula.

 

 

I'm not sure about the color. Check the camera setting on the right side panel for anything that might be a color vs digital mono setting or a saturation setting. On the right side of the main live stacking histogram, there are RGB sliders and also a saturation slider on the right. 



#3 nic35

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Posted 29 October 2020 - 08:15 AM

I'm in Bortle 6 skies and find observing during bright moonlight is less than optimal, unless I'm using some form of filter - preferably narrow band.  Otherwise, everything seems washed out.

 

For some general help, try looking at the unofficial sharpcap users guide - see post 91 here  https://www.cloudyni...al#entry9581288

 

And, of course the sharpcap documentation.

 

Keep at it.  If these are your first images, you are not far from success.

 

It is often helpful to post a screenshot of the live stack, with its histogram.  It provides a lot of useful diagnostic information. 

 

j


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#4 RazvanUnderStars

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Posted 29 October 2020 - 10:14 AM

First, try to focus properly, SharpCap has built-in aids for this even if you don't have a Bahtinov mask. Stacking may fail if stars are out of focus and even if it works, when the scope is not in focus you get blobs. If you want to image faint objects, then use a gain and exposure time combination that does not saturate the pixels where are stars. There are programs to help but you can simply experiment - I'd suggest to reduce the gain first. 



#5 Alien Observatory

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Posted 29 October 2020 - 10:50 AM

Start with some of the basics...

 

Go to Mars and see if it is RED, if not then SC settings are not correct....

 

Without an UV/IR filter (minimum) stars will be Bloated.  Bortle 6 skies, Moon, LP , High Gain and High Stretch are all issue that lead to vignetting and washed out colors.  In the attached ZWO AR coating graph image you can see nothing is blocked after 700 nm and little is blocked below 400 nm, as opposed to the attached ZWO UV/IR Filter image.  Get the ZWO UV/IR filter for about 25 bucks and you will have better results. 

 

The size of the Large Black Rings (Dust Bunnies) suggests they are on the AR Window (not the sensor), so try to clean off the AR widow (Air, Lint Free wipe, Clean micro fiber cloth).

 

Pat Utah smile.gif

Attached Thumbnails

  • AR-clear-window1.jpg
  • ZWO UV:IR-Window-graph1.jpg

Edited by Alien Observatory, 29 October 2020 - 11:14 AM.

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#6 GazingOli

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Posted 29 October 2020 - 11:04 AM

I am using the same type of scope and the same camera, however the .63 reducer from celestron. No vignetting issues with my combi. Just darks and propper focus and everything works fine with SharpCap. 

 

See my gallery - link in the signature.

 

With the ASI 294 I have also serious vignetting which neans: learn how to do flats and do not change anything in the lightpath after having done the flats, which I do not like. 

 

CS.Oli



#7 DSO_Viewer

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Posted 29 October 2020 - 11:35 AM

Dear Mighty Ones,

 

I have attempted my first EAA with high hopes, but it ended up as epic failure.  First of all, despite stacking live images via SharpCap Pro, I saw zero nebula or galaxy colors except bloated/overexposed stars.  When I did see colors, it is because I manually changed the histogram RGB colors in the histogram controls menu.  Second thing I noticed from all the images I took are large dark rings that are only noticeable with fully stretched histogram (please see the attached image of a cluster).  I am wondering how I can get rid of those rings.  This imaging session was done under a bortle 6 sky (San Diego), under a very bright moon (3/4 waxing gibbous), and without any filters (only Anti reflective window on the ASI224MC).  Also, I only did rough focusing via an overexposed Mars and slew to my imaging targets.  I felt like the OTA was well collimated since Mars and the Moon looked tact sharp at 250x.  I did notice some vignetting at the very edges, but didn't notice severe comas.

 

Here is the list of what I used:

 

LX90-ACF 8" SCT telescope (Alt-Az mount and OTA)

Optec's Nextgen 0.33x Focal Reducer with proprietary spacer from Optec for ASI224MC (1.89" T-adapter)

ASI224MC ver.1.3

SharpCap Pro ver.3.2 (raw8 and raw16, 300-350 gain, 5-10 sec exposures, 10-50 stacks)

 

It would be great if I can solve some of the problems I am having and get some wonderful EAA images.

 

I'd very much appreciate your responses or suggestions.

 

Clear Skies~~

Start off with a proper focus and get rid of the terrible vignetting by taking flats or making the focal ratio slower.

 

Steve



#8 garyhawkins

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Posted 29 October 2020 - 11:37 AM

I'm also in San Diego - are you a member of SDAA?

 

This is far from an epic failure smile.gif .  A lot has to hang together with EAA and it will take time.  In fact (except for the B&W) the image does not look bad and the 224MC/0.33 focal reducer combination is working well.  I use a 533MC/0.63 combination with my C8, but I also have the parts to replicate your system and based on those results might give it a try one day.  A C8/224MC/0.33 focal reducer combination is a very cost effective solution - nice.

 

Your issues: Dark ring are dust bunnies.  Either remove the dust or calibrate out with flats.  The vignetting will be calibrated out with the same flat.  A UV/IR filter would be a good add and reduce star bloating.  I use a CCD/CLS filter from Optolong as I'm Bortle 8 here in North County.

 

Your FOV is small so acquiring your target is going to be a challenge.  How did you go about target acquisition?  With such a small FOV a plate solver like ASTAP or ASPS will be very helpful but, of course, it's another s/w package to setup.

 

Personally, I think your gain is fine.  I typically use 300 to 400.  Check out tutorials of SharpCap, Carl Smith does some great ones.  If you want to see what I'm doing  check out my YouTube page - link in signature.

 

I think you've got off to a decent start so hang in there - Rome was not built in a day!

 

CS Gary

 

 

Dear Mighty Ones,

 

I have attempted my first EAA with high hopes, but it ended up as epic failure.  First of all, despite stacking live images via SharpCap Pro, I saw zero nebula or galaxy colors except bloated/overexposed stars.  When I did see colors, it is because I manually changed the histogram RGB colors in the histogram controls menu.  Second thing I noticed from all the images I took are large dark rings that are only noticeable with fully stretched histogram (please see the attached image of a cluster).  I am wondering how I can get rid of those rings.  This imaging session was done under a bortle 6 sky (San Diego), under a very bright moon (3/4 waxing gibbous), and without any filters (only Anti reflective window on the ASI224MC).  Also, I only did rough focusing via an overexposed Mars and slew to my imaging targets.  I felt like the OTA was well collimated since Mars and the Moon looked tact sharp at 250x.  I did notice some vignetting at the very edges, but didn't notice severe comas.

 

Here is the list of what I used:

 

LX90-ACF 8" SCT telescope (Alt-Az mount and OTA)

Optec's Nextgen 0.33x Focal Reducer with proprietary spacer from Optec for ASI224MC (1.89" T-adapter)

ASI224MC ver.1.3

SharpCap Pro ver.3.2 (raw8 and raw16, 300-350 gain, 5-10 sec exposures, 10-50 stacks)

 

It would be great if I can solve some of the problems I am having and get some wonderful EAA images.

 

I'd very much appreciate your responses or suggestions.

 

Clear Skies~~


Edited by garyhawkins, 29 October 2020 - 11:38 AM.

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#9 roelb

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Posted 29 October 2020 - 04:45 PM

Focus with Bathinov mask on a star above 50° altitude, not on Mars

Decrease focal reduction: 0.5 x --- 0.63 x to avoid vignetting: "flats" not required, only "darks" to avoid "hot pixels" and "amp glow" with the 224MC

Do your first EAA without the moon disturbing (no filter necessary)

Clean the "AR window" to remove "dust bunnies"

SharpCap: don't touch the "real time" "Display Histogram" at the right / use the "Auto Color Balance" on the "Live Stack Histogram"

For SC help, use https://forums.sharpcap.co.uk/ and look for the "Unofficial SC Guide from Astrojedi": https://spideroak.co.../Astro - share/

Gain: 350 OK

 


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#10 alphatripleplus

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Posted 29 October 2020 - 07:26 PM

You can also consider using ASILive software with your ASI224MC as an alternative to  SharpCap - ASILive runs under both Windows and Mac OS. Some find it simpler to start with than SharpCap for someone beginning EAA, although it has fewer features than SharpCap. I like ASILive personally, and use SharpCap mostly for its great polar alignment routine (which you won't need if you are on an Alt-Az mount). 



#11 Class-M-Planet

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Posted 29 October 2020 - 11:09 PM

Wow, thank you all for so much useful information and words of encouragement!  I have bookmarked all those links that were provided. The Unofficial SharpCap Quick Start Guide (.pdf and Cloudy Nights link) by Astrojedi is exactly what I've been looking for--thank you!  I'll also look into Carl Smith's work.  I got lured into EAA after looking at the following image gallery.

https://www.cloudyni...-image-gallery/

 

I'll do my best to clean out those dust bunnies on my AR window and optical train first thing; this is the first time that dust actually bothered me pretty significantly.  As for cleaning the sensor itself, I will go as far as using a rocket blaster for now. 

 

Somehow I understood that SharpCap captures flats and darks on the fly once I begin live stacking.  What I didn't understand is that I actually need to set it up prior to live stacking! I really need to carefully read the official and the unofficial SharpCap Pro documentation.  I do have additional questions regarding darks and bias frames.  I know that ASI224MC is an uncooled camera, so exposure times are set in the magnitude of seconds.  My guess is that, therefore, the camera doesn't heat up that much.  Would taking darks substantially produce cleaner images for this camera setup?  Under SharpCap, bias subtraction is an option.  Would taking bias frames significantly help produce cleaner images for this camera setup?

 

I've put off purchasing filters except for a cheap 1.25" UV/IR filter until now after reading Cory Schmitz' blog on astrophotography for beginners.

https://photographin...inner-mistakes/

As a beginner with little experience, it made sense to me that if I collected enough photons over a long period that SNR will eventually shift in favor of the signal.  However, for near real-time EAA, I am wondering if I should invest in a light pollution or narrow-band filter, since time is not on my side.  I do have conflicting doubts about light pollution filters in general, without substantial proof, because I believe San Diego light pollution now spans across all visible spectrum.  Perhaps this is a discussion for another day.  What filter do you recommend/not recommend based on your EAA experience (optolong CLS is duly noted), and what filter size would you recommend?  I have 2" filter thread on the Optec 0.33x reducer, but I know I won't need anything larger than 1.25" for my set-up.  If I do go with an 1.25" filter, then the filter placement will become more tricky.  I do plan on doing large DSO imaging in the near future with a small refractor+eq mount+DSLR.

 

Yes, I'll use the auto color balance and don't touch the real-time display histogram.  I'll double check my color balance settings and experiment further as to why I am not seeing any color on my stacked images.  I've clicked on debayer preview as well.  I will also try imaging without the moon.

For the focusing issue problem, I'll invest in a Bahtinov mask or print a DIY mask. I'll also look into the SharpCap's aided focusing--this sounds like a cool feature.

 

For slewing to my targets, I use Stellarium after aligning my LX90.  The GOTOs are not dead on, but small planets such as Uranus do come into view once I synchronize that part of the sky.  At 660mm focal length, I find that gotos are good enough for me to identify and center via the hand controller.  However, I do struggle somewhat with a 2x barlow for planetary imaging.

 

I am just a lone/casual sky observer/imager for now.  Perhaps one day I'll gather up my courage and venture into SDAA :)

 

Yes, I've heard many good things about ASILive.  I may also try it out.

 

Thank you so much for your responses and suggestions.  I'll keep you posted.

 

Clear Skies~~



#12 biomedchad

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Posted 30 October 2020 - 06:14 AM

Stick with sharp cap. Way more info and users out there for help. Look at their forums for complete info on how to correctly capture flat images. I use t shirt and a cheapo Led panel off amazon. Once you get a good flat and darks don’t touch a thing or you will need to do it all over again. But before you do any of this you need to get a proper focused image and set your gain. You can use the same flat for any gain or exposure time but you’ll need dark for each time and gain. Sharp cap will put these into specific folders for you. I just received a new camera and have to do all of this over again tonight. So an hour or so of work before
I can start observing objects.

#13 alphatripleplus

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Posted 30 October 2020 - 07:25 AM

I used to have an uncooled ASI224MC and yes, you will notice the difference darks make, particularly with removing hot pixels. Try to match temperature, gain and exposure for your darks. You can set up a dark library of saved darks for later use. Flats may be important if you have noticeable vignetting - with a small sensor camera, like the 224MC, that will depend on the scope you are using and how much focal reduction you use. In some set-ups you will not notice vignetting with a small sensor.



#14 GazingOli

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Posted 30 October 2020 - 07:38 AM

Please be aware that you will get live stacking issues without darks!

 

CS.Oli



#15 raylinds

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Posted 30 October 2020 - 09:00 AM

I have to agree with Gary- this was in no way an epic fail. I have had disappointing sessions, but try to come away with one or two positives.  You've learned something and have gotten hands-on experience with your hardware and software.  Be satisfied with baby steps, there is a pretty sharp learning curve.

 

You mentioned Carl Smith- have you seen his excellent video on SharpCap workflow? Also, check out the videos produced by Gary Hawkins and SDAA- I have learned a lot from them.  If I were in San Diego I would definitely join and get involved.



#16 RazvanUnderStars

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Posted 30 October 2020 - 06:05 PM

To the OP: I'd highly recommend you watch two talks by Dr Robin Glover (SharpCap's author): Deep Sky Astrophotography With CMOS Cameras and its follow-up, Choosing the right gain for Deep Sky imaging with CMOS cameras. You'll see them recommended very often here and they are equally applicable to EAA. 


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#17 Class-M-Planet

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Posted 30 October 2020 - 08:23 PM

Yes, I still plan on using SharpCap Pro for EAA, Polar aligntment, and planetary imaging; I'll try to get my investments worth :)  Thank you for your tutorial suggestions--I have bookmarked all the YouTube tutorials (Carl Smith and Dr. Robin Glover).

 

I am now trying to figure out how people take their flat and dark frames.  T-shirt method sounds like a popular method taken during dusk or dawn, but the LED method is brilliant; you can do it pretty much at any time.

 

I am wondering if these frames would suffice for EAA:

 

20 Dark Frames (same settings as light frames, but place a cap on the telescope)

 

20 Flat Frames (same settings as light frames, but provide uniform light source and decrease exposure time to 10-30 milliseconds).  I will have to get optimal exposure time via trial and error.

 

Thank you very much.

 

Clear skies~~



#18 RazvanUnderStars

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Posted 30 October 2020 - 10:24 PM

I don't have a ASI224MC but the key thing is that you ought to take the darks at the same sensor temperature as the main images. Since the ASI224MC is not cooled (and therefore thermo-stabilized), that temperature will vary (and will be higher than the ambient because of the heat from the circuits). Given that the camera has very low read noise, I think I wouldn't bother with darks and simply use that time at the scope to observe more. From a theoretical/imaging perspective, the SNR will decrease with the square root of the number of frames so if do take them, I'd take more.

 

For the flats, it depends on the scale of the objects you observe. If the object is smaller and in the centre, the vignette may not be relevant at all although the camera's smaller field of view may be an issue, i.e. larger objects will be darkened at the edge. Still, I'd suggest to start without them and enjoy observing. There's enough to learn about SharpCap. Later, once you've mastered the process, you can add the flats if you want. I'd focus more on getting plate solving working, for instance, it has a huge benefit in locating targets, especially if out of frame. If it works, you can also use it during star alignment to center the stars - very convenient during alignment. 



#19 alphatripleplus

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Posted 31 October 2020 - 07:55 AM

Darks do not have to be done at the telescope - you can seal the camera and take the darks inside beforehand -  and they can be re-used for several months. As long as you match temperature, gain and exposure your darks will be fine. Don't worry if you can't match  temperature exactly - for EAA a few degrees Celsius difference won't matter. (If you have an unheated garage, or even a refrigerator, you might get close to a night time temp during the day.)

 

I used to own an ASI224MC and darks did make a noticeable difference in the performance I got out of that camera. 



#20 Class-M-Planet

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Posted 31 October 2020 - 05:30 PM

That is good to know that I can reuse dark frames from previous sessions.  This will speed up my observing quite significantly, thank you.  I have heard that some people have had good results with Optec's NextGen 0.33x focal reducers on ACF scopes paired Mallincam and ASI224MC cameras.  So, I decided to take a plunge despite Optec's website stating that it may over-correct for coma and field curvature.  Aside from the vignetting issue, which I can fix with flats, I am content with the 0.33x focal reducer.  However, I'll have to fold my ambition to go with a little larger sensor for this set-up.

 

I am pretty new to plate solving and EQ-MOD in general, so it will take some time to get used to.  I still haven't figured out how to get dead on GOTOs (only acceptable, for now) on my lx90 at high powers, so I believe plate solving will make my life easier.  It appears that SharpCap supports All Sky Plate Solver, AnSvr, and Astro Tortilla for plate solving.  Trying out all of them and picking the optimal sounds like another daunting task.  Does anyone have any recommendation on where I should start?  Thank you for that in advance.

 

Clear Skies~~



#21 alphatripleplus

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Posted 31 October 2020 - 05:51 PM

  It appears that SharpCap supports All Sky Plate Solver, AnSvr, and Astro Tortilla for plate solving.  Trying out all of them and picking the optimal sounds like another daunting task.  Does anyone have any recommendation on where I should start?  Thank you for that in advance.

 

Clear Skies~~

I started with ASPS as a platesolver and then moved to ASTAP, which is extremely fast and seems to require just the basic G17 star database to work well across quite a range of fields of view. There are a couple of topics in this Forum on using ASTAP with SharpCap that you might want to look at if you choose to try ASTAP.

 

One other comment on focal reduction, is that it is possible the reducer might give you less vignetting if used with a little less focal reduction. So perhaps you could experiment operating at f/4 instead of  f/3.3, i.e. bring the reducer a little closer to the camera. This may or may not help with aberrations, but less focal reduction would mean less vignetting. Of course, flats, if you do them will take care of vignetting too.



#22 Class-M-Planet

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Posted 31 October 2020 - 06:49 PM

Thank you very much.  I'll look into how to plate solve with ASTAP.


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#23 jrsm

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Posted 05 November 2020 - 01:38 PM

Wow, thank you all for so much useful information and words of encouragement!  I have bookmarked all those links that were provided. The Unofficial SharpCap Quick Start Guide (.pdf and Cloudy Nights link) by Astrojedi is exactly what I've been looking for--thank you!  I'll also look into Carl Smith's work.  I got lured into EAA after looking at the following image gallery.

https://www.cloudyni...-image-gallery/

 

I'll do my best to clean out those dust bunnies on my AR window and optical train first thing; this is the first time that dust actually bothered me pretty significantly.  As for cleaning the sensor itself, I will go as far as using a rocket blaster for now. 

 

Somehow I understood that SharpCap captures flats and darks on the fly once I begin live stacking.  What I didn't understand is that I actually need to set it up prior to live stacking! I really need to carefully read the official and the unofficial SharpCap Pro documentation.  I do have additional questions regarding darks and bias frames.  I know that ASI224MC is an uncooled camera, so exposure times are set in the magnitude of seconds.  My guess is that, therefore, the camera doesn't heat up that much.  Would taking darks substantially produce cleaner images for this camera setup?  Under SharpCap, bias subtraction is an option.  Would taking bias frames significantly help produce cleaner images for this camera setup?

 

I've put off purchasing filters except for a cheap 1.25" UV/IR filter until now after reading Cory Schmitz' blog on astrophotography for beginners.

https://photographin...inner-mistakes/

As a beginner with little experience, it made sense to me that if I collected enough photons over a long period that SNR will eventually shift in favor of the signal.  However, for near real-time EAA, I am wondering if I should invest in a light pollution or narrow-band filter, since time is not on my side.  I do have conflicting doubts about light pollution filters in general, without substantial proof, because I believe San Diego light pollution now spans across all visible spectrum.  Perhaps this is a discussion for another day.  What filter do you recommend/not recommend based on your EAA experience (optolong CLS is duly noted), and what filter size would you recommend?  I have 2" filter thread on the Optec 0.33x reducer, but I know I won't need anything larger than 1.25" for my set-up.  If I do go with an 1.25" filter, then the filter placement will become more tricky.  I do plan on doing large DSO imaging in the near future with a small refractor+eq mount+DSLR.

 

Yes, I'll use the auto color balance and don't touch the real-time display histogram.  I'll double check my color balance settings and experiment further as to why I am not seeing any color on my stacked images.  I've clicked on debayer preview as well.  I will also try imaging without the moon.

For the focusing issue problem, I'll invest in a Bahtinov mask or print a DIY mask. I'll also look into the SharpCap's aided focusing--this sounds like a cool feature.

 

For slewing to my targets, I use Stellarium after aligning my LX90.  The GOTOs are not dead on, but small planets such as Uranus do come into view once I synchronize that part of the sky.  At 660mm focal length, I find that gotos are good enough for me to identify and center via the hand controller.  However, I do struggle somewhat with a 2x barlow for planetary imaging.

 

I am just a lone/casual sky observer/imager for now.  Perhaps one day I'll gather up my courage and venture into SDAA smile.gif

 

Yes, I've heard many good things about ASILive.  I may also try it out.

 

Thank you so much for your responses and suggestions.  I'll keep you posted.

 

Clear Skies~~

You should not do anything with the sensor as it will required disassembling the camera.  Your dust is on the AR window, not on the sensor.  Opening the camera may create more problems than it is worth.  The sensor is small so aligning a finder scope to match the field of view is essential. You can start with aligning a distant object and then if you have a star in the middle of the sensor, fine tune the alignment of the finder scope to center on that star.  It will help.  For that size sensor almost any flattener reducer will do but I think .33x is a bit to radical.  A.5x reducer should work better, but your field of view will be smaller.  You can enter your telescope, reducer and sensor in Stellarium to get a picture of what field of view you have.  

 

You might want to get another telescope with a shorter focal length; there has been some discussion on this board about the st80 which would give you a much wider field of view for not much money.  You can piggy back it on the existing scope and then you would have the best of both worlds.  A wide angle scope for larger objects like m42 and m 45 and the meade for small objects like the crab nebula m1.



#24 Class-M-Planet

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Posted 07 November 2020 - 02:04 AM

I haven't gotten a chance to go out for another imaging session.  With rain and still bright moon out, it will be at least a week before I can go out again.  Yes, I'll try not to open the camera and clean the AR window outside first; hopefully this will get rid of those dust motes. 

 

Yes, you are right about the 0.33x reducer being a bit radical in the traditional sense, but I did it for a different reason.  I started this project to make something similar to a poor man's eVscope with existing items that I already had in hand, and a 0.33x reducer seemed to fit the bill.  Also, a hyperstar system was out of the question on a Meade ACF SCT I had.  I wish Meade's ACF SCTs are hyperstar compatible.

 

I do have an evostar80 for larger DSOs, but I haven't figured out what focal reducer to use on it.  Anything less than a 0.63x reducer will undersample a bit, but using anything greater than that won't fit M42.  I run into the same problem with an ST-80.

 

Thank you for hinting me about the Stellarium's customizable FOV feature.  I'll have to give that a try.  I've been only using the default FOV to identify interesting targets before slewing.

 

Clear Skies~~



#25 alphatripleplus

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Posted 07 November 2020 - 08:07 AM

Good luck and let us know how it works out.




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