Date   

Re: Difference between Recalibrate and Sync

Nick Iversen
 

I once did a Solve & Sync in Sequence Generator Pro and the mount refused to do it saying something about something being more than 5 degrees. What was happening there?


Re: Difference between Recalibrate and Sync

Lee Dodge
 

Thanks Roland.  I understand the difference more clearly now.  Very helpful.

Lee 


Re: First light for a new camera

Bruce Donzanti
 

Nice comparative list, Luca.  I also went from the 1600MM Pro to the 294MM Pro and my 2600MM Pro arrives on Wednesday.  I am hoping it does have the characteristics, as you described, for the 6200MM Pro and if it does I'll part with the 294MM Pro.  I am anxious to compare the 2 side by side in my suburban skies. 

Bruce

On Mon, Feb 8, 2021 at 3:46 PM Luca Marinelli <photo@...> wrote:

 As I mentioned above, I have been imaging with the ASI294MM Pro since the end of December. It replaced a ASI1600MM Pro on a TS ONTC 10in f4 Newtonian astrograph.  These are the main differences between the two cameras as I see them:

ASI1600MM Pro:

Pros:

- It has been around for a long time, everyone can help you if you run into trouble

- Less expensive

- Very little amp glow even for narrowband imaging

- Data calibration is robust and straightforward


Cons:

- It has been around for a long time: it may get discontinued in the not too distant future. the ASI294MC took the place of the ASI1600MC.

- Microlensing artifacts around bright stars are obnoxious and difficult to eliminate (this is really an issue only around magnitude 2-3 stars or brighter)

- QE is modest (~50% @ Ha)

- 12bit ADC

 
ASI294MM Pro:

 Pros:

- New sensor with probably long life in front of it

- Two pixel sizes in one camera (2.3um, 4.6um)

- Extremely high QE (it's an amazingly sensitive camera, 80% @ Ha)

- very low noise and high dynamic range when high gain mode kicks in
- no microlensing artifact

- 14bit ADC instead of 12bit

 

Cons:

- More expensive than ASI1600MM

- Calibration is a bit trickier and requires some getting used to (flats have some swirly patterns that some people have had trouble with)

- Amp glow is pretty significant. It calibrates out well but again it requires flawless calibration practice to ensure high quality data is produced.

 
Low read noise combined with high sensitivity and 14bit ADC of this camera makes it compelling vs the older 1600MM. The questions Roland asked about speed compared to CCD cameras comes down to two factors:

1) QE: How sensitive is the camera? In comparison to the numbers above, the FLI ML16200 has QE of 45% @ Ha - quite a stark difference.
2) Read noise: Low read noise is meaningful in relation to noise from sky glow. That's why with CCD cameras subexposure times for narrowband imaging can be 20, 30 minute or even longer. With the ASI294MM even imaging faint targets I have found that I can achieve optimal exposure levels for narrowband imaging with 3nm filters under Bortle 5 skies in less than 8 minutes per sub. This means that I can guarantee not to lose any SNR efficiency in image integration and accumulate SNR as fast as total integration time. 

I recently completed an imaging project of an extremely faint planetary nebula (HFG1) that I started in September 2020. I collected most of the 82 hours of data with an ASI1600MM Pro but during the last month of data collection I switched to the ASI294MM. For the purpose of illustrating differences in sensitivity of the two cameras, I integrated 20x6 minute subexposures of OIII  signal from each of the two cameras. Pixel size is a bit different (3.8um vs 4.6um) and I registered all the images to the higher-resolution ASI1600MM data before image integration to try and reduce the effect of bigger pixels in the ASI294MM on image SNR. You can see the results of the experiment here:

https://astrob.in/tbilkr/B/

I am also imaging with an ASI6200MM Pro and while the sensitivity is comparable to the ASI294MM Pro (IMX455 sensor), the noise profile is even more favorable with lower read-noise, 16bit ADC, and no amp glow. The new APS-C sized IMX571 is expected to have similar characteristics.

--Luca



Re: First light for a new camera

Luca Marinelli
 

 As I mentioned above, I have been imaging with the ASI294MM Pro since the end of December. It replaced a ASI1600MM Pro on a TS ONTC 10in f4 Newtonian astrograph.  These are the main differences between the two cameras as I see them:

ASI1600MM Pro:

Pros:

- It has been around for a long time, everyone can help you if you run into trouble

- Less expensive

- Very little amp glow even for narrowband imaging

- Data calibration is robust and straightforward


Cons:

- It has been around for a long time: it may get discontinued in the not too distant future. the ASI294MC took the place of the ASI1600MC.

- Microlensing artifacts around bright stars are obnoxious and difficult to eliminate (this is really an issue only around magnitude 2-3 stars or brighter)

- QE is modest (~50% @ Ha)

- 12bit ADC

 
ASI294MM Pro:

 Pros:

- New sensor with probably long life in front of it

- Two pixel sizes in one camera (2.3um, 4.6um)

- Extremely high QE (it's an amazingly sensitive camera, 80% @ Ha)

- very low noise and high dynamic range when high gain mode kicks in
- no microlensing artifact

- 14bit ADC instead of 12bit

 

Cons:

- More expensive than ASI1600MM

- Calibration is a bit trickier and requires some getting used to (flats have some swirly patterns that some people have had trouble with)

- Amp glow is pretty significant. It calibrates out well but again it requires flawless calibration practice to ensure high quality data is produced.

 
Low read noise combined with high sensitivity and 14bit ADC of this camera makes it compelling vs the older 1600MM. The questions Roland asked about speed compared to CCD cameras comes down to two factors:

1) QE: How sensitive is the camera? In comparison to the numbers above, the FLI ML16200 has QE of 45% @ Ha - quite a stark difference.
2) Read noise: Low read noise is meaningful in relation to noise from sky glow. That's why with CCD cameras subexposure times for narrowband imaging can be 20, 30 minute or even longer. With the ASI294MM even imaging faint targets I have found that I can achieve optimal exposure levels for narrowband imaging with 3nm filters under Bortle 5 skies in less than 8 minutes per sub. This means that I can guarantee not to lose any SNR efficiency in image integration and accumulate SNR as fast as total integration time. 

I recently completed an imaging project of an extremely faint planetary nebula (HFG1) that I started in September 2020. I collected most of the 82 hours of data with an ASI1600MM Pro but during the last month of data collection I switched to the ASI294MM. For the purpose of illustrating differences in sensitivity of the two cameras, I integrated 20x6 minute subexposures of OIII  signal from each of the two cameras. Pixel size is a bit different (3.8um vs 4.6um) and I registered all the images to the higher-resolution ASI1600MM data before image integration to try and reduce the effect of bigger pixels in the ASI294MM on image SNR. You can see the results of the experiment here:

https://astrob.in/tbilkr/B/

I am also imaging with an ASI6200MM Pro and while the sensitivity is comparable to the ASI294MM Pro (IMX455 sensor), the noise profile is even more favorable with lower read-noise, 16bit ADC, and no amp glow. The new APS-C sized IMX571 is expected to have similar characteristics.

--Luca



Re: First light for a new camera

Dale Ghent
 

I have the ASI1600 with the Panasonic chip, 294 color, and IMX455-based QHY600 which is the same sensor as the ASI6200.

The Panasonic chip that's in the ASI1600 and other cameras has been a fantastic chip over the years and, like you said, the microlensing effect on super bright stars has been the only major complaint about it. The 12bit nature of its ADCs can be compensated with by just making more exposures. For what it is/was, it has been a very good standard in the CMOS realm. It was a sensor designed in the early 2010's with tech of that era, and despite that, it has decently controlled amp glow and dark current. And as a chip of that era, it is a front-illuminated design with a single gain domain. These are outdated designs now.

The IMX294/492 is back-illuminated which means more photons actually fall into the pixels, which raises the QE. The vast majority of current era designs from Sony are back-illuminated. The other thing that many current-era chips have in their corner is dual conversion gain. Dual conversion gain is where a good bit of the magic occurs in these sensors and lets them be flexible. DCG sensors came about to address the need for a sensor that can perform well in both bright and dim settings. The Low Conversion Gain (LCG) domain grants you a large full well, with the trade-off being read noise. The High Conversion Gain (HCG) domain gives you lower read noise at the cost of a shallower well. Both have DR curves that largely mirror each other. LCG is meant for exposing in bright environments where the deep well would be best suited, where the HCG domain is for dark scenes, where sensitivity and low read noise is needed. Both the IMX294/492 and IMX455, as well as others, are dual conversion gain sensors.

You can spot these types of sensors by looking at the graphs commonly posted by ZWO, QHY, and others. They have two distinct areas, like this one for the IMX455-based ASI6200MM:

https://astronomy-imaging-camera.com/wp-content/uploads/ASI6200-Performance.png

You can see the two domains clearly in the DR and Read Noise charts. LCG is on the left, starting at gain=0, and then the transition to HCG happens at what looks like gain=100. You can see that LCG and HCG start out more or less similarly, with the LCG having a larger well. Once you get to gain=100, the read noise drops, DR (mostly) recovers, and the downward progression resumes as gain increases. The difference is that at gain=0, you have a 50k e- well, and at gain=100 (the start of the HCG domain) you have what looks like a ~15k well. These charts aren't the greatest but that's my guess assuming they're on a log scale. But you can see the difference nonetheless.

So what does this mean in practice? You can shoot in two different ways:

1. At gain=0 and with long exposures
2. At gain=100 and with shorter exposures

both will yield effectively equivalent results. Which one is best to use (note: I'm purposefully avoiding the word "better" here) largely comes down to personal preferences. Personally I shoot at the start of HCG (the equivalent of gain=100 here) because that's where the sensor performs its best. The very slight hit to DR compared to gain=0 is more than made up by the larger number of exposures I can rip through. People doing photometry or planetary with these kinds of sensors might find the LCG domain a more useful place for their purposes. In this way, you can look at LCG vs. HCG more in terms of what's best for the use case.

If you have one of these kinds of dual conversion gain sensors and are not entirely sure where the LCG->HCG transition is on the gain scale, it's easy enough to figure out for yourself. Cap off the camera and run bias exposures in loop. Look at the histogram or image stats as you steadily increase the gain. As you increase the gain, you will likely also see an increase in the measured standard deviation. At some point, the stddev will suddenly drop. The gain value in which that drop in stddev happens marks the entry into the HCG domain, as stddev is a representation of the read noise.

As for IMX294/492 vs. IMX455, the 455 (and its APS-C analog, the IMX571) are hands-down the best we have on the consumer market right now. With zero amp glow, a good middling pixel size that applies to a wide range of focal lengths, QEs in the mid-70s for Ha/Sii and mid-80s for Oiii, and 16bit ADCs, they're really cement the fact that modern and highly compelling CMOS tech has arrived and is available. There's not much left to want for the amateur. These sensors are absolute monsters on fast optics as well.

On Feb 8, 2021, at 10:55, Terri Zittritsch <theresamarie11@gmail.com> wrote:

[Edited Message Follows]

Dean, thanks for posting the information.
Can you say what you think you're getting by replacing the ASI1600MM with the ASI294MM? I have the ASI1600 and many great images are taken with this camera. The biggest downside that I've noticed is the micro-lensing effect you can get on bright stars. I know the ASI294 shows deeper well depth, and better DR, but do these directly relate to better images? I know that some poo poo-ed the ASI1600 because it only has 12 bits of depth, but that didn't keep people from producing great images. Since you've owned both, what are the benefits that you can see in the images?
Maybe a tough question. I wonder if there is any micro-lensing?

I've recently purchase an ASI6200MM which is on my stowaway now.. and waiting to get a first image.

Terri


Re: How Good Can Guiding be With Non-AE Mount

Mike Dodd
 

On 2/8/2021 12:14 PM, Roland Christen via groups.io wrote:

The problem with MaximDL is that in RA the calculated arc seconds are
divided by CosineDec. So as you go higher in the sky towards the pole,
the calculated value of 1 pixel will be a large number of arc seconds
compared to what it would be at 0 Dec. I consider this a bug in the
program which affects the guide graph but not the guiding.
Thanks, Roland; I didn't know this.

--- Mike


Re: Mach2 question

Harold
 

Thanks for the response, somehow SkySafari move my mount to someplace in France. After correcting for this the RA was much better and DEC error was down to 1.3 degrees but I’m not sure the elevation is spot on. Also not sure that the axis of the dovetail is aligned with the DEC axis or how important that is.


Re: First light for a new camera

Dean Jacobsen
 

Emilio,

The camera and the ASCOM driver seems to work fine.  It has been on the bench taking dark frames and I have probably taken 90 test images with it.  No problems with the camera in the 2x2 or the "unlocked" 1x1 bin mode.  No hangups.  No weird artifacts or anything.
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ


Re: First light for a new camera

Dean Jacobsen
 

Hi Terri,

I have only had the camera out for one session.  Based on that single data point it does seem to be an excellent performer.  However, I haven't had a chance to use it very much.

There were several things [mostly theoretical at this point] that prompted the purchase of the camera though:

1.  I had been using my ASI1600MM for 3.5 years or so.  Thus, I thought I might have been approaching end of life for some of the camera's components so perhaps it was time to upgrade to a newer camera.

2.  I had seen the microlens effect with my telescope-filter-camera combination so I wanted to eliminate that.  There were objects that I had been avoiding because of the bright stars in the field,

3. I wanted to get the more sensitive camera.  The ASI1600 mono works great but the new back side illuminated detectors are quite a bit more sensitive so I want to take advantage of that and be able to convert more photons to electrons per unit time.  The QE data for the camera has been published on ZWO's product page for the camera.  They also have an ASI294MM vs. ASI1600MM QE graph. 



4. The ASI294MM has a much larger full well capacity at the gain that I will be using it at [~20k e- at unity gain  vs. ~ 8k e- for the ASI1600 at 76 gain] so I wanted to take advantage of that for preservation of the colors of the brighter stars in the field in my color filtered images.

--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ


Re: How Good Can Guiding be With Non-AE Mount

Roland Christen
 


I use arc seconds because an arc second is an an arc second on both
cameras. No mental gymnastics to go from one to the other.
The problem with MaximDL is that in RA the calculated arc seconds are divided by CosineDec. So as you go higher in the sky towards the pole, the calculated value of 1 pixel will be a large number of arc seconds compared to what it would be at 0 Dec. I consider this a bug in the program which affects the guide graph but not the guiding. You can turn off the Auto Dec feature, but most people don't and then get a wild RA graph when imaging objects toward the north.
When I suggested using pixels, I was of course referring to use of an off-axis guider which looks at star motion from the same scope as the imaging camera. Of course it isn't the same if you use a separate guide scope with short focal length.

Rolando


-----Original Message-----
From: Mike Dodd <mike@...>
To: main@ap-gto.groups.io
Sent: Sun, Feb 7, 2021 10:38 pm
Subject: Re: [ap-gto] How Good Can Guiding be With Non-AE Mount

On 2/7/2021 10:13 PM, M Hambrick wrote:

> Yes, I use MaxIm DL Pro for imaging and guiding. [...]
>
> I recently set up configurations for all of my scope / camera
> combinations in MaxIm so that I can set up the guiding graph to display
> the error in arc-seconds, but until now I have not done this.

I recommend doing that; see below.

> I think I
> saw a recent comment from Roland where he stated that he normally
> displays his guiding graph in pixels because that is what the camera sees.

I displayed pixels, but then it occurred to me that pixels and plate
scale on the guide camera have no relation to pixels and plate scale on
the imaging camera, so why display guide camera pixels?

I use arc seconds because an arc second is an an arc second on both
cameras. No mental gymnastics to go from one to the other.

I know what the plate scale is on my ASI-1600 imaging camera (0.8
arcsec/px) so if I see a guiding error of 0.6 arcsec RMS, I know that's
less than one pixel on the imaging camera, and that's what I care about.

> I have also been experimenting with the guide exposure time and exposure
> delay to see if I can do better.

I use ACP automation software, and it sets the exposure based on guide
star brightness. It also doesn't begin an exposure until the error is
within a specified limit. Then MaxIm applies a settling delay before
opening the shutter.

With my setup, I get good guiding with a 1-second exposure and a guide
star SNR above 50.

--- Mike







--
Roland Christen
Astro-Physics


Re: First light for a new camera

Emilio J. Robau, P.E.
 

The read noises are significantly lower than most CCDs.  Although I hate to admit it, CCD technology is not keeping up with the broader used CMOS technology.  The two new cameras are very interesting, but I would wait a little longer to purchase them as the end users finish up being beta testers for both QHY and ZWO.

The ASI 2600 and QHY 268 (Sony IMX 571) Mono are not widely available yet.  The first batch is being shipped now.   They are APS-C chips and look very very promising.  I will probably trade out my 16200 chip for this shortly when the first user adopters work out the bugs.   The difference in read noise and sensitivity is pretty stunning.  I will give up the size for being able to do NB with much much shorter exposures. 

I purchased the QHY 294 pro camera (Sony IMX492) Mono for the small pixel size at 2.3 or so microns but returned it and am waiting until the bugs are worked out to potentially repurchase it.  It is a very sensitive camera with a quirky chip.

I think these two cameras and price points are pretty dramatic advancements.  If we could only get the manufacturers to actually finish developeing their products before slinging it at the pay for testing user base, that would be great. 


Re: Dec limit in Mach2

Roland Christen
 

Thanks for the update. We just heard from another user of the Mach2 who had stalling problems. He did the same thing: complete un-install of APCC from a previous mount and a new clean install. His stalling problems went away also.

Rolando



-----Original Message-----
From: Luca Marinelli <photo@...>
To: main@ap-gto.groups.io
Sent: Sun, Feb 7, 2021 9:12 pm
Subject: Re: [ap-gto] Dec limit in Mach2

Circling back on the runaway Dec axis issue when APCC connects to the mount. On Friday, I went ahead and completely uninstalled APCC, including deleting the folders with all the APCC data and log files - I only copied the horizon and meridian limit files to the Desktop so I could reload them later. I then proceeded to reinstall APCC from scratch. I reloaded the meridian and horizon limits and then tested the mount. Everything worked fine, APCC connected to the mount without inducing a Dec axis rotation. I imaged on Friday, Saturday nights and I just launched another imaging run tonight. In all cases APCC connected to the mount without problems.

At this point, it appears that a plausible explanation for the behavior I encountered was an instability in APCC due to some stale files when I switched from the Mach1 to the Mach2. Hopefully reinstalling APCC has taken care of the problem for good. 

Thank you to everyone for the advice!

Luca

--
Roland Christen
Astro-Physics


Re: Difference between Recalibrate and Sync

Jeff B
 

👍👌🔭

Great explanation.  Thanks Roland.

Jeff

On Mon, Feb 8, 2021 at 11:48 AM Roland Christen via groups.io <chris1011=aol.com@groups.io> wrote:
Recalibrate: when you send the mount to an object via keypad or planetarium program, the mount receives RA/Dec co-ordinates for that object and stores them in the memory. Now as you center the object, the internal co-ordinates change slightly because you moved the mount via the buttons. Now the position where the mount thinks it is pointing does not agree with the original stored position of the object. Pressing "Recal" updates the new position to equal the original co-ordinates. This is now a new reference point from which you can send the mount via GoTo and find other objects nearby with high accuracy.

Sync: when you loosen the clutches and move the mount manually to a known object or star, the mount has no information where you moved (there are no encoders on the axes). The only information that is in the mount's memory is the last position where it was pointed before you moved the mount manually. These co-ordinates might be off by 100 degrees! So, there is nothing in the mount to recalibrate on. Therefore you must tell the mount what the co-ordinates are where you are pointing. Example: you set up the mount and telescope for an evening of observing. There are no co-ordinates in the mount memory because this is a new setup. You loosen the clutches, and manually point the telescope at Sirius. Then you bring up Sirius in your keypad or planetarium program and "Sync" on the co-ordinates of Sirius. Now the mount has those co-ordinates in the memory and can find all other objects from that reference point with high accuracy.

The problem with using Sync happens if you point to a star with the counterweights higher than the scope. Then all subsequent slews will place the telescope below the mount. This can cause pier crashes.

Rolando



-----Original Message-----
From: Vladimir Steblina <vsteblina@...>
To: main@ap-gto.groups.io
Sent: Sun, Feb 7, 2021 12:23 pm
Subject: [ap-gto] Difference between Recalibrate and Sync

My friend and I have just about given up on the difference between Sync and Recalibrate with the AP900.

Can somehow explain the difference in terms we can understand?? 

What difference does it make??  When is it appropriate to use one versus the other??  Thanks.

Yep, we read the manual.  English is my fourth language and that is my excuse and I am sticking to it.....however, my friend is a native English speaker!!

Vladimir

--
Roland Christen
Astro-Physics


Re: How Good Can Guiding be With Non-AE Mount

Roland Christen
 

Guiding is going to depend on your seeing as well as the parameters that you set in the guide software. If you have a good PE curve it can help a lot in RA.

Rolando

-----Original Message-----
From: M Hambrick <mhambrick563@...>
To: main@ap-gto.groups.io
Sent: Sun, Feb 7, 2021 6:23 pm
Subject: [ap-gto] How Good Can Guiding be With Non-AE Mount

I  have a 1100 GTO mount without absolute encoders, and I have been wondering how good I can expect the guiding to be. The guiding graph below is pretty typical of what I get. Is this pretty typical, or should I be able to do better than this ?

Suggestions are welcome.

Mike


--
Roland Christen
Astro-Physics


Re: Mach2 question

michaeljhanson@...
 

Hi Harold,

Park 4 has dependency on latitude.  So, the first thing to check is that the (software) location matches the mechanical adjustment of the mount.  Sky Safari allows you to program your site information in to the mount from the "Scope Setup" screen, but the default is to NOT update the mount upon connect.  When you've connected with the "Set Time & Location" box checked, the mount will be updated.  The mount will remember this "site" forever, so you do not need to leave the box checked.  Make sure the altitude adjustment is consistent with the latitude reported by Sky Safari.

When the mechanical setup and the site information are in agreement, you can choose "Find Home" on the disconnect menu.  Home is in the Park 3 orientation.  Make sure "Home" matches park 3.

I hope you enjoy your new toy!

Regards,
Mike Hanson


Re: First light for a new camera

Roland Christen
 

How much faster is this camera versus CCD technology?

Rolando



-----Original Message-----
From: Dean Jacobsen <deanjacobsen@...>
To: main@ap-gto.groups.io
Sent: Sun, Feb 7, 2021 5:28 pm
Subject: [ap-gto] First light for a new camera

Hi All,

A couple of new mono CMOS cameras have come out over the last few months.  First a 4/3" sized camera using the back illuminated IMX492 and then most recently cameras using the back illuminated APS-C sized IMX571 sensor.

Both offer a substantial upgrade from my well loved ASI1600MM.  I ended up purchasing the ASI294MM-Pro with the 4/3" sized sensor.

The weather here in coastal Southern California hasn't been cooperating with me the last week or so but I did manage to get about 1.9 hours [29 x 240s] parked on the Rosette as a first light for the camera.  The conditions were less than optimal - greater than 85% humidity with milky white skies from the light pollution and the moisture in the air.  Had to shut down after 2 hours before everything got soaked when the approaching fog rolled in.

Here is a link to my 2 hour hydrogen alpha shot of the Rosette taken with the ASI294MM Pro and the FSQ-106 at f/5.  The full resolution image has been posted.  This image was just stacked and stretched.  No noise reduction or deconvolution.

https://www.astrobin.com/full/0ffdnz/C/ 

The ASI294MM Pro does a nice job, and at $1480 it gives great performance for the price in my opinion.  The body of the new camera has the same dimensions as my ASI1600MM so I was able to simply unscrew the ASI1600 from the filter wheel and screw the ASI294MM on.

The Mach2 and APCC performed flawlessly as usual.

Thanks for looking.
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ

--
Roland Christen
Astro-Physics


Re: Difference between Recalibrate and Sync

Roland Christen
 

Recalibrate: when you send the mount to an object via keypad or planetarium program, the mount receives RA/Dec co-ordinates for that object and stores them in the memory. Now as you center the object, the internal co-ordinates change slightly because you moved the mount via the buttons. Now the position where the mount thinks it is pointing does not agree with the original stored position of the object. Pressing "Recal" updates the new position to equal the original co-ordinates. This is now a new reference point from which you can send the mount via GoTo and find other objects nearby with high accuracy.

Sync: when you loosen the clutches and move the mount manually to a known object or star, the mount has no information where you moved (there are no encoders on the axes). The only information that is in the mount's memory is the last position where it was pointed before you moved the mount manually. These co-ordinates might be off by 100 degrees! So, there is nothing in the mount to recalibrate on. Therefore you must tell the mount what the co-ordinates are where you are pointing. Example: you set up the mount and telescope for an evening of observing. There are no co-ordinates in the mount memory because this is a new setup. You loosen the clutches, and manually point the telescope at Sirius. Then you bring up Sirius in your keypad or planetarium program and "Sync" on the co-ordinates of Sirius. Now the mount has those co-ordinates in the memory and can find all other objects from that reference point with high accuracy.

The problem with using Sync happens if you point to a star with the counterweights higher than the scope. Then all subsequent slews will place the telescope below the mount. This can cause pier crashes.

Rolando



-----Original Message-----
From: Vladimir Steblina <vsteblina@...>
To: main@ap-gto.groups.io
Sent: Sun, Feb 7, 2021 12:23 pm
Subject: [ap-gto] Difference between Recalibrate and Sync

My friend and I have just about given up on the difference between Sync and Recalibrate with the AP900.

Can somehow explain the difference in terms we can understand?? 

What difference does it make??  When is it appropriate to use one versus the other??  Thanks.

Yep, we read the manual.  English is my fourth language and that is my excuse and I am sticking to it.....however, my friend is a native English speaker!!

Vladimir

--
Roland Christen
Astro-Physics


Mach2 question

Harold
 

My Mach2 arrived on Saturday, I have set it up in the family room to get used to it’s operation. During this process I connected it to SkySafari and was pleasantly surprised that the mount  connected and work. Before disconnecting I had SkySafari send the mount to park position 4. The mount stoped with a 2.5 degree error in RA and 10.5 in DEC. I was expecting much better results than this. Any suggestions would be helpful, not overlooking the strong possibility of operator inexperienced or error.


Re: First light for a new camera

Terri Zittritsch
 
Edited

Dean, thanks for posting the information.
Can you say what you think you're getting by replacing the ASI1600MM with the ASI294MM?     I have the ASI1600 and many great images are taken with this camera.   The biggest downside that I've noticed is the micro-lensing effect you can get on bright stars.     I know the ASI294 shows deeper well depth, and better DR, but do these directly relate to better images?     I know that some poo poo-ed the ASI1600 because it only has 12 bits of depth, but that didn't keep people from producing great images.     Since you've owned both, what are the benefits that you can see in the images?
Maybe a tough question.    I wonder if there is any micro-lensing?

I've recently purchase an ASI6200MM which is on my stowaway now.. and waiting to get a first image.   

Terri


Re: What is the current status for Linux / Mac support via INDI or similar?

Bob
 

On Mon, Feb 8, 2021 at 10:59 PM, Ray Gralak wrote:
I notice there is an active thread on the Indi forums at the moment about this. I find the attitude of a couple of the
(I think) Indi devs to be rather surprising, complaining of a lack of support from AP. They seem to think that just
because they are open source, everybody else should be.

While it would be great if there was an sdk for the GTOs, I can understand why AP hasn't released one
This comes up every once in a while. All of the necessary commands to do imaging with an Astro-Physics mount have been documented for a long time. I think some newer commands will be made available, if they haven't been already.

-Ray Gralak
Author of PEMPro
Author of APCC (Astro-Physics Command Center): https://www.astro-physics.com/apcc-pro
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver
For my own interest, aside from the basic mount command set which is documented in the cp4 manual, are there any of the algorithms or pseudo code that make up specific functions available? Or is this hitting the ip area?

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