Will the Mach 2 support .....
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Roland Christen
Hello AstroNuts,
We get this question many times, "will the Mach2 support my scope, camera etc." I can't really answer specific setups since I don't have infinite variety of scopes at my disposal. However, to give you some idea I am presently testing two scopes piggybacked on the Mach2.
Here is my present setup. I am using it to test
various optics, cameras and field flatteners. It consists of a 160EDF
refractor with QTCC and a full frame ZWO 6200 color camera, which provides a very
wide field. On top rides an oldie but excellent 130 EDF refractor with
2.7" focuser, 67PF562 Flattener and my QSI 683WSG camera, Lodestar
off-axis guider and an 8x50 Baader finder for good measure. Both scopes
sit in rings that are attached to dovetail plates. When you add up all
the parts, the whole shebang weighs close to 70 lb with the weight
centered about 9 inches from the top of the Dec axis. I have
approximately 75lb worth of counterweight which includes the weight of
the standard Mach2 cwt bar and the shorter extension.
Is
it stable and does it slew, track and guide effortlessly? Yes on all
counts. It does need to be closely balanced, but not ridiculously so.
Using MaximDL6, in poor seeing i get on the order of 0.4 arc sec rms
guiding. In good to excellent seeing I get 0.1 to 0.15 arc sec rms
guiding. My guide exposure is between 2 and 5 seconds with 1.5 seconds
between exposures. Best guiding seems to be when the exposures are 4 to 5
seconds, and I get very few excursions that are larger than 0.5 arc sec
pk.
By the way, I don't usually guide with one scope and image with another. In this case I am guiding with the lighter weight 130EDF and I am getting perfect round stars with the 160 below. The 160 is shooting at 960mm focal length with a 3.75 micron/pixel camera, 0.8 arc sec per pixel. ZWO 6200 camera. resolution with this camera in medium seeing has yielded 1.4 arc sec FWHM stars in a 5 minute exposure.
I will be shooting tonight if the weather holds, and I can record some guide graphs for anyone interested. Seeing is supposed to be good (4 out of 5) but transparency will be poor. I'm doing a shootout between the CMOS camera with 3.75 micron pixels and my older QSI683 CCD camera with 5.4 micron pixels. Which camera records images faster? Which has better contrast? Any bets on the winner?
Rolando
 -- Roland Christen Astro-Physics |
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Thanks for showing us this imaging setup Roland, and yes, please share your results including your guiding graphs.
Mike |
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Marcelo Figueroa
What!!!, you don't have an infinite number of telescopes, what kind of world is this where you can't have an infinite number of telescopes ??? :D
Great setup, we will be watching for the results. Here we are betting on the ASI 6200. These new cameras are ridiculously sensitive. |
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Greg McCall
Hi, would that setup still be OK if you built and loaded a tracking model from APPM in place of guiding?
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Roland Christen
Yes indeed. In fact I have run it both with a model and with guiding. The model tracks a bit smoother since it's not chasing a twinkling star. But the outcome is the same.
Rolando
-----Original Message-----
From: Greg McCall <emailgregnow@...> To: main@ap-gto.groups.io Sent: Tue, Jun 1, 2021 9:08 pm Subject: Re: [ap-gto] Will the Mach 2 support ..... Hi, would that setup still be OK if you built and loaded a tracking model from APPM in place of guiding?
-- Roland Christen Astro-Physics |
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Roland Christen
Result #1: CMOS vs CCD
The 683 has an 8300 chip that's not very efficient but it's monochrome. There are better CCD chips with much higher quantum efficiency such as the Starlight Xpress Pro36, which is a full frame camera with exceptional low noise. It has a 7.4 micron pixel size.
The ZWO 6200C is a color CMOS camera with very low noise, but is it as sensitive as a monochrome CCD? It turns out that it isn't as sensitive as the 8300 monochrome chip. In a side by side test of these two cameras, the ZWO produced a peak intensity of the core of M106 that was only 75% as high as the QSI camera. And that's with a 50% greater light grasp of the 160 EDF vs the 130 EDF that the QSI was attached to. The CMOS did have a signal/noise advantage because of the low noise chip, but part of that was due to the higher light grasp of the 160 mm aperture.
See image below:
Rolando
 -----Original Message-----
From: M Hambrick <mhambrick563@...> To: main@ap-gto.groups.io Sent: Tue, Jun 1, 2021 7:51 pm Subject: Re: [ap-gto] Will the Mach 2 support ..... Thanks for showing us this imaging setup Roland, and yes, please share your results including your guiding graphs.
Mike -- Roland Christen Astro-Physics |
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Roland Christen
Result #2: Tracking with 2 refractors piggyback
The sky unfortunately was not pristine during my imaging session. High level clouds continued to drift thru the image, so the tracking was at times a bit unsteady, but overall not too bad. Here is one tracking graph that was typical of the evening. 1 pixel = 1.45 arc sec in this graph. In this 15 minute period the tracking was less than 0.5 arc sec pk, and approx 0.14 arc sec rms.
Rolando
 -----Original Message-----
From: Roland Christen via groups.io <chris1011@...> To: main@ap-gto.groups.io <main@ap-gto.groups.io> Sent: Tue, Jun 1, 2021 11:47 pm Subject: Re: [ap-gto] Will the Mach 2 support ..... Result #1: CMOS vs CCD
The 683 has an 8300 chip that's not very efficient but it's monochrome. There are better CCD chips with much higher quantum efficiency such as the Starlight Xpress Pro36, which is a full frame camera with exceptional low noise. It has a 7.4 micron pixel size.
The ZWO 6200C is a color CMOS camera with very low noise, but is it as sensitive as a monochrome CCD? It turns out that it isn't as sensitive as the 8300 monochrome chip. In a side by side test of these two cameras, the ZWO produced a peak intensity of the core of M106 that was only 75% as high as the QSI camera. And that's with a 50% greater light grasp of the 160 EDF vs the 130 EDF that the QSI was attached to. The CMOS did have a signal/noise advantage because of the low noise chip, but part of that was due to the higher light grasp of the 160 mm aperture.
See image below:
Rolando
 -- Roland Christen Astro-Physics |
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Luca Marinelli
Thank you for sharing your results, Roland. I was imaging with the Mach2 and my solid tube 10in f4 reflector last night (40lbs fully loaded but with a fairly significant moment arm) and the absolute encoders on the mount make it track smoother and easier than when I use the same scope on my AP1100 without encoders. The difference encoders make in ease of use of a mount is truly remarkable. Obviously imaging results are the same, provided one guides the non-encoder mount appropriately, but it certainly takes a bit more finesse and knowledge with the non-encoder mount.
With regards to the comparison between the QSI683 and the ZWO 6200MC, I wanted to offer some considerations to keep in mind: 1) In spite of the larger diameter of the 160mm optics, the etendue per pixel is 1.76x larger for the 130mm scope given the bigger effective pixel size of the binned KAF8300 sensor. This means that the solid angle of sky seen by each pixel of the KAF8300 sensor is almost twice as big as the ZWO 6200MC system and signal will accumulate accordingly, even before taking into account quantum efficiency. 2) The ZWO 6200MC has a Bayer matrix in front of the signal. You did not mention what filter you were using with the QSI683 camera but if it was a luminance filter, you are allowing up to about 4x more wavelength bandpass than any of the R, G, or B filters in front of each of the pixels of the ZWO ASI6200MC. 3) The ZWO 6200MC is a variable gain camera. You did not mention what gain setting you were using. If you were using the camera with default gain in the ASCOM driver, it is probably gain 0 (CMOS gain 0.8 e/ADU), which corresponds to the highest full well capacity and dynamic range, but the lowest sensitivity of the camera (signal accumulation measured in ADU per unit time). It should be noted that the camera circuitry changes acquisition mode at gain 100 (CMOS gain 0.28 e/ADU) with a step change in read noise from 3.5e to 1.5e per read. This is a particularly useful gain setting when large full well capacity is not the paramount concern. Best, Luca |
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Roland Christen
Thanks for your reply,
I did not adjust the gain in the 6200M. I could not find any way to do that in MaximDL. Perhaps I need to read the manual more closely.
The 160 EDF has 51% more light grasp, so the signal/noise is considerably higher. A real test of course would be to run each camera on the same scope with similar pixel size. I will do that when I test the Starlight X-Press Pro 36 on the 160 refractor. That camera has much higher efficiency than the QSI, and the 7.4 micron pixel size will be a good match for the 6200C binned 2x2 at 7.5 microns. That said, i suspect that the 6200M would be the clear winner, not only because of the lower noise and somewhat higher efficiency, but also because you can run it binned at 1x1 on those very steady nights to get the highest resolution.
Running this 6200C on my laptop presented some interesting challenges. I could not do an automated run of consecutive images because the laptop ran out of memory after the first image was downloaded. I don't know why that is, the laptop has lots of memory but for some reason had trouble with the 359 megabyte images and would crash each time. I also could not calibrate dark frame and flat frame in one step without MaximDL crashing. Even though I was very careful to get good flat frames, the results were really strange, especially when more than 2 calibrated images were combined. All of these problems went away when I used only 80% of the chip area for each image.
Rolando
-----Original Message-----
From: Luca Marinelli <photo@...> To: main@ap-gto.groups.io Sent: Wed, Jun 2, 2021 5:09 am Subject: Re: [ap-gto] Will the Mach 2 support ..... Thank you for sharing your results, Roland. I was imaging with the Mach2 and my solid tube 10in f4 reflector last night (40lbs fully loaded but with a fairly significant moment arm) and the absolute encoders on the mount make it track smoother and easier than when I use the same scope on my AP1100 without encoders. The difference encoders make in ease of use of a mount is truly remarkable. Obviously imaging results are the same, provided one guides the non-encoder mount appropriately, but it certainly takes a bit more finesse and knowledge with the non-encoder mount.
With regards to the comparison between the QSI683 and the ZWO 6200MC, I wanted to offer some considerations to keep in mind: 1) In spite of the larger diameter of the 160mm optics, the etendue per pixel is 1.76x larger for the 130mm scope given the bigger effective pixel size of the binned KAF8300 sensor. This means that the solid angle of sky seen by each pixel of the KAF8300 sensor is almost twice as big as the ZWO 6200MC system and signal will accumulate accordingly, even before taking into account quantum efficiency. 2) The ZWO 6200MC has a Bayer matrix in front of the signal. You did not mention what filter you were using with the QSI683 camera but if it was a luminance filter, you are allowing up to about 4x more wavelength bandpass than any of the R, G, or B filters in front of each of the pixels of the ZWO ASI6200MC. 3) The ZWO 6200MC is a variable gain camera. You did not mention what gain setting you were using. If you were using the camera with default gain in the ASCOM driver, it is probably gain 0 (CMOS gain 0.8 e/ADU), which corresponds to the highest full well capacity and dynamic range, but the lowest sensitivity of the camera (signal accumulation measured in ADU per unit time). It should be noted that the camera circuitry changes acquisition mode at gain 100 (CMOS gain 0.28 e/ADU) with a step change in read noise from 3.5e to 1.5e per read. This is a particularly useful gain setting when large full well capacity is not the paramount concern. Best, Luca -- Roland Christen Astro-Physics |
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George
The ASI 6200 camera is also looking through colored filters.
Regards,
George
George Whitney Astro-Physics, Inc. Phone: 815-222-6538 (direct line) Phone: 815-282-1513 (office) Email: george@...
From: main@ap-gto.groups.io <main@ap-gto.groups.io>
On Behalf Of Roland Christen via groups.io
Sent: Wednesday, June 2, 2021 11:03 AM To: main@ap-gto.groups.io Subject: Re: [ap-gto] Will the Mach 2 support .....
Thanks for your reply,
I did not adjust the gain in the 6200M. I could not find any way to do that in MaximDL. Perhaps I need to read the manual more closely.
The 160 EDF has 51% more light grasp, so the signal/noise is considerably higher. A real test of course would be to run each camera on the same scope with similar pixel size. I will do that when I test the Starlight X-Press Pro 36 on the 160 refractor. That camera has much higher efficiency than the QSI, and the 7.4 micron pixel size will be a good match for the 6200C binned 2x2 at 7.5 microns. That said, i suspect that the 6200M would be the clear winner, not only because of the lower noise and somewhat higher efficiency, but also because you can run it binned at 1x1 on those very steady nights to get the highest resolution.
Running this 6200C on my laptop presented some interesting challenges. I could not do an automated run of consecutive images because the laptop ran out of memory after the first image was downloaded. I don't know why that is, the laptop has lots of memory but for some reason had trouble with the 359 megabyte images and would crash each time. I also could not calibrate dark frame and flat frame in one step without MaximDL crashing. Even though I was very careful to get good flat frames, the results were really strange, especially when more than 2 calibrated images were combined. All of these problems went away when I used only 80% of the chip area for each image.
Rolando
-----Original Message----- Thank you for sharing your results, Roland. I was imaging with the Mach2 and my solid tube 10in f4 reflector last night (40lbs fully loaded but with a fairly significant
moment arm) and the absolute encoders on the mount make it track smoother and easier than when I use the same scope on my AP1100 without encoders. The difference encoders make in ease of use of a mount is truly remarkable. Obviously imaging results are the
same, provided one guides the non-encoder mount appropriately, but it certainly takes a bit more finesse and knowledge with the non-encoder mount.
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Khushrow Machhi
Hi Roland,
Prior to this guiding run do you have a model built in APCC? Khushrow |
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Roland Christen
No model in APCC.
Roland
-----Original Message-----
From: Khushrow Machhi via groups.io <kmachhi@...> To: main@ap-gto.groups.io Sent: Wed, Jun 2, 2021 11:46 am Subject: Re: [ap-gto] Will the Mach 2 support ..... Hi Roland,
Prior to this guiding run do you have a model built in APCC? Khushrow -- Roland Christen Astro-Physics |
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Luca Marinelli
Roland,
I don’t know if you can charge gain in Maxim DL but you can certainly change the gain of the ASI6200MC in the ASCOM driver. Modern image acquisition software (NINA, Voyager, SGP) will also allow you to change the gain dynamically (per filter,
per target, or whatever you want).
If Maxim DL is a 32bit application, it will likely suffer greatly from the large files produced by these small pixel, full-frame cameras. That was the case with Sequence Generator Pro before they released a 64 bit version and now there are no
data issues.
Luca
On Jun 2, 2021, at 12:59 PM, Roland Christen via groups.io <chris1011@...> wrote:
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Hi Roland
359 MB per image !? Wow ! I guess that the image size must go up exponentially with the number of pixels. The images from my old 2.7 megapixel camera are something like 1.9 MB. From my 16 megapixel camera they are 31 MP. What is the image download time for your camera ? Although the image download time is supposed to be a lot shorter for CMOS cameras, I have been told that all kinds of weird things can happen during these downloads. I also seem to recall the folks at Diffraction Ltd telling me that it is not the permanent memory on your hard drive but rather the RAM that is the issue during the image downloads. If you have a lot of different processes running at the same time that could be causing the MaxIm crashes. Mike |
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It's a different world with CMOS sensors. I've been shooting CCD's for 20 years and CMOS for about 1 1/2 years. Fast computers mounted on the telescope, SSD drives, lots of disk space etc. Learning the ins and outs of CMOS gain curves and modes. It's a new world. And they have their issues including flat frame calibrations. But they are here to stay and the performance can be incredibly awesome in certain configurations for certain purposes. In dark skies with good mounts and tracking, all this is less important. The 5.94u pixels on my new QHY400C OSC seem to be a pretty good match for my AP155EDF too. And I just like the simpler work flow. And the raw file size for this full frame larger pixel sensor is a reasonable 48 MB before debayering. I don't think Sony has released a mono version of this sensor. That would be great. The IMX410 is the sensor used in the Nikon Z6. |
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John Jennings
The attached image was just a test shot during flattener collimation. Not the best processing etc., and was shot in my bortle 8 / 2" + sky. It's to illustrate how fast CMOS cameras can be.
37 subs@ 120s - 74 min Allen Texas - Bortle 8 MaximDL, ASTAP, StarTools, Photoshop AP Mach1, AP155 f/7.18 with flattener, 1.11 asecs/pix, big crop QHY410C full frame CMOS color 5.94U pixels IDAS P3 filter |
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Great post John, thanks for the perspective.
toggle quoted message
Show quoted text
TJF Mobile On Jun 3, 2021, at 15:53, John Jennings <johnrogerjennings@...> wrote:
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The following is my post to our clubs Facebook page. (Texas Astronomical Society of Dallas) An example of fairly fast image acquisition with a OSC CMOS camera. I'm trying to get efficient with my time as I'm getting older.
IC443 the Jellyfish Nebula
1/15/2021 - Nebula stack - LeXtreme Pro
1/18/2021 - Stars stack - IDAS P3
From my backyard in Allen, Texas:
MPSAS 17.8-18.2 / Bortle 8-8.2 (Measured with SQM meter)
Finally got the results of my science project I've been working on for the last 3 months. Did not spend more than 2 hours on the work flow today... not including stack time. This is not an attempt at narrowband with shrunk or no stars, but rather a composite RGB image from a OSC camera with colorful background stars. Did spend a month or so on refreshing my math for sky background vs sub length calculations and doing a boatload of testing with filters and my SQM meter.
63 subs @ 240secs (4.2hrs) LeXtreme Pro
156 subs @ 30 secs (1.3hrs) IDAS P3
Total integration for my Bortle 8+ sky was 5.5 hours.
Can probably cut the broadband down to about 35 mins of 30sec subs for a total integration of 4.8 hours. Anything more doesn't improve the image for me. This will allow me to shoot more than 1 nebula per night sometimes depending on their brightness, but IC443 is fairly dim.
QHY268C @ Bin1- 1.26 "/pix, 3.76u pixels, AP130 @ f 4.725, APMach1 unguided. https://ap-gto.groups.io/g/main/photo/264814/3238572?p=Created,,,20,2,0,0 |
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On 6/3/2021 6:43 PM, John Jennings wrote:
This is not an attempt at narrowbandIs there a link where we can see the image? --- Mike |
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Joseph Beyer
Thanks for posting John. Very nice image. Even taken in a fairly light polluted environment it came out well. Images like this make the decision to move away from a OSC camera more difficult. Glad to see you’re able to image unguided with your Mach1/130. Joe On Jun 3, 2021, at 3:43 PM, John Jennings <johnrogerjennings@...> wrote:
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