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AT65EDQ and triangle stars

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#26 CapnRon

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Posted 09 January 2012 - 08:19 PM

Robert,
I am new at this level of AP and my capture and processing techniques have a long way to go. But I also appreciate the scale of the imaging of this scope.

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#27 David Ault

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Posted 09 January 2012 - 08:37 PM

Mine was definitely a problem with the scope and not fixable (by me at least). I really liked the scope in all other respects and with everyone's help on Cloudy Nights, I finally decided to ask OPT to exchange it. I also asked them to confirm that the quality control card had been filled out and signed as well as doing an artificial star test before shipping it too me. They were very helpful and willing to work with me, so my replacement scope should be shipping out later in the week after they receive the defective one.

I'm keeping my fingers crossed that there are no problems with this one by the time it gets to me.

Thanks,
David

#28 zerro1

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Posted 09 January 2012 - 11:39 PM

Robert,
I am new at this level of AP and my capture and processing techniques have a long way to go. But I also appreciate the scale of the imaging of this scope.


I spent pretty much the last 2 years expending most my effort on data collection. I figured if I didn't have that part figured out, I wouln't have anything worth processing anyway. So now I struggle with processing. :smirk: If it wasn't for Sal, Tonk, and Jerry, wouldn't have what few processing skills I do have.

You're ahead of me working with Mono/filter imaging. I'll be on OSC and DSLR for some time to come

#29 CapnRon

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Posted 11 January 2012 - 12:16 AM

Robert,
I have a long list of people to thank here also, but I have not kept track of their names! Originally I was planning on going the DSLR route, what not to like about using one camera body for multiple tasks. What scared me off was the size of the image files and the concern about storing, manipulating and processing all that data. I figured the mono data was more manigable and you could bin the sensor when you needed to. And I have to admit the purist in me said that mono data with filters was the historical approach. I also have to thank people for steering me into a starting with a short focal length scope. The C9.25 I originally purchased collects a lot of light and looks impressive, but I would be still trying to get past 30 second exposures (if that) if I had not purchased the AT65EDQ to work my way slowly into tracking and guiding. I think your signiture line should read "The more I learn, the less I know I know!"

#30 zerro1

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Posted 11 January 2012 - 12:28 AM

I know :grin:

#31 CapnRon

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Posted 16 January 2012 - 08:43 PM

Why I don't think it is focuser sagg on the AT65EDQ.
First, my camera arrangement is pretty tight and is held well by the focuser. The SBIG is threaded directly to the filter wheel, the OAG mounts on the filter wheel, there is 25mm long adapter on the OAG that is held by a centering Bader ClickLock adapter. The ClickLock has an almost 2" long extension barrel that slides into the focuser and is clamped by two screws on opposing compression rings. All of the screws on the focuser are tight and I don't sense any motion of the cameras by hand.

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#32 CapnRon

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Posted 16 January 2012 - 08:51 PM

The above picture was taken with the cameras mounted on my C5, but the arrangement is the same on the AT65EDQ.

Second. I took images East and West of the Meridian, as suggested by OPT (their resident imagers). I imaged Bellatrix, Menkar and Menkib on the evening of the 12th. Bellatrix was at Alt 140 deg from my location, Menkar was at 220 deg. Menkib was also West of the Meridian but nearly at my Zenith. I imaged at exposures up to 20 seconds without tracking or guiding (all exposures look similar, just some better than others naturally). Here is what the raw data (Dark Subtracted) looks like for the three fields (note: I cropped similar magnitude stars from each field) for the 10 second exposures.

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#33 CapnRon

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Posted 16 January 2012 - 08:57 PM

All three images produce the same shape (as far as I can tell) even though the cameras were in three different orientations; for Bellatrix it was lying on its right side, for Menkar it was lying on its left side and for Menkib it was lying almost on its back. So, if I have this right in my mind (and that is always a question at my age). It seems that it is something locked into the imaging train that is producing this effect and not somthing that is shifting as the scope moves around.

I have sent this off to OPT and they are looking at the raw data on DropBox, to make their own determination.

Any comments or suggestions here are welcome, I will wait and see where this goes from here.

Ron

#34 zerro1

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Posted 16 January 2012 - 09:16 PM

All three images produce the same shape (as far as I can tell) even though the cameras were in three different orientations; for Bellatrix it was lying on its right side, for Menkar it was lying on its left side and for Menkib it was lying almost on its back. So, if I have this right in my mind (and that is always a question at my age). It seems that it is something locked into the imaging train that is producing this effect and not somthing that is shifting as the scope moves around.

I have sent this off to OPT and they are looking at the raw data on DropBox, to make their own determination.

Any comments or suggestions here are welcome, I will wait and see where this goes from here.

Ron


Hope they get it figured out..

Sent you a PM

#35 David Ault

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Posted 18 January 2012 - 01:30 AM

Just got my replacement scope today. OPT did an artificial star test before shipping it to me and said it looked good. I did my own test first thing and found the same result so, I was excited to try it out. I did some short exposures on a bright open cluster and found triangle stars again. Feeling disheartened I decided I had nothing to loose by adjusting the retaining rings. This time I had a little more experience and knew that if I let the ring slip to far I'd be back in potato star country, so I very carefully loosened the ring on the primary optics a millimeter at a time until I saw no further improvement. At this point I still had a triangle stars with two points of the triangle almost in line with the star centroid. Now I started on the retaining ring of the flattener and the ends of the triangles slowly got closer to the centroid until I ended up with stars that were as round as I could perceive. The best case test image showed a FWHM of 2.97 and and aspect ratio of 11. So, I am now a happy camper! Now to actually start imaging with it. :) Thanks everyone for the help and advice.

Thanks,
David

#36 David Ault

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Posted 18 January 2012 - 10:20 AM

For those that are interested, here's my first real image with the new AT65EDQ:

http://astrobin.com/3795/

In this longer exposure I'm starting to notice some star distortion again. I may loosen the retaining ring of the flattener just a bit more (after waiting until the scope is cold). Even after all the adjustments I made last night the rings are still extremely tight. I just have to be careful and not let anything slip.

#37 gapalp

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Posted 20 January 2012 - 04:15 PM

Stinks a different AT65EDQ needing the same adjustments. Let us know if you make anymore and the results. The stars do look good in the pic but I do see what you are talking about.

I haven't had a chance to image with mine since my testing. Weather and sick babies :(

#38 David Ault

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Posted 20 January 2012 - 09:21 PM

I did get some time a couple nights ago to do some actual imaging with the new scope, but I've been busy with work so I haven't had a chance to post. Here are the two images I was able to take:

http://astrobin.com/3875/
http://astrobin.com/3873/

This was after one additional minor adjustment with the retaining ring on the flattener.

Regards,
David

#39 sullij1

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Posted 20 January 2012 - 09:49 PM

Looks like it's all patched up.

#40 gapalp

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Posted 21 January 2012 - 01:39 PM

Yep, looks like you are in business now!

#41 David Ault

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Posted 21 January 2012 - 02:27 PM

Thanks Guys! :)

Regards,
David

#42 BKBrown

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Posted 09 January 2013 - 07:14 PM

I recently started imaging with an AT65EDQ I acquired some time ago. It is a sweet scope and provides simple and superb wide field imaging...but I have a problem. The image below is clipped from a series I shot of the Double Cluster last night and it appears to have the dreaded triangular stars that I had not noticed before. Now I am a newbie DSO imager, but it sure looks to me like the issue discussed in this thread. What do folks here think? If it could be something else, I would definitely like to know, if it is the retaining ring thing I am not shy about fixing stuff. Thanks for any thoughts or suggestions!

Clear Skies,
Brian :question:

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#43 David Ault

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Posted 09 January 2013 - 08:01 PM

Brian,

It's hard to say if this is the same problem. It looks out of focus, was that intentional to highlight the issue? How long is this exposure? I used very short exposures to rule out tracking (5 seconds if I remember correctly).

Once everyone helped me diagnose the issue with mine the fix was quite simple. I had to remove the focuser, then remove the flattener assembly from the back of the OTA (the focuser screws into the flattener assembly which screws into the OTA). Once the flattener assembly is out you can get to the retaining ring on the flattener lens. I loosened mine in very small increments and tested between each change. It took a lot of assembly / disassembly of my rig, but was obviously worth it. I did think it was odd that that it was the flattener lens that was 'pinched' as it is a single lens and not a compound doublet/triplet arrangement, but it did work.

Regards,
David

#44 BKBrown

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Posted 09 January 2013 - 08:57 PM

Thanks David, your info is quite useful. The exposure is 120 seconds at ISO 1600, so it is a long run...and yes it is highly enlarged. Below is the normal version for my reference file.

Clear Skies,
Brian

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#45 Orion58

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Posted 10 January 2013 - 03:09 PM

As David mentioned, loosen the retaining ring on the flattener and that will probably do it - however, also be very careful not to tighten the actual mounting rings too much when putting the scope back on the mount. The rear ring is directly over the flattener.

The mounting rings fit like a glove but can exert a lot of force on the tube if tightened too much. Once I made both of these adjustments the triangular stars basically disappeared.

Hope this helps.






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