60 replies to this topic

[Real14]

Hi,

 

I am starting a new thread as the old presentation thread is getting too long and this one is about the first light with the second CEM 120EC2 I have.

 

This mount has a Takahashi Mewlon 250S mounted on it and works at a focal length of 3210 mm. The nativer focal length is really 3000mm but as I have a custom made 35mm faltterner in it the focal length went up to 3210mm. On the back is a QSI 54owsg camera and so the scope is working at 0.475" arx sec per pixel. Unfortunately due to my excitement of seeing, well at least for me, such low RMS numbers that I forgot to set up an autosave sequence in MaxIM DL, but believe me, I have never seen such a beautiful M14 with a 900 second exposure time taken by me 

 

I hope I have clear sky tonight and I will try again. I already noted on the message board in the observatory " DO NOT FORGET TO START AUTOSAVE "  

 

I had to start up from scratrch that means make a Polar aligment as I do not see Polaris and as I had a very good experience making a polar alignment using pHD2 drift align i used that method. After half an hour 45 minutes it was done and a pointing model with 3 stars with the iOptron Handbox bgave me vales of about 30" arc sec per axis and there I left it. BTW, it is a piece of cake the Azimuth and altitude adjustment with this CEM 120 mounts. As you perhaps know my mount os loaded with about 85 lbs of telescopes and 119 lbs of counterweights.

 

The Altitude adjustment is smooth as butter. Having a scale at the turning knob helps a lot as you can use them for checking how much arc min or arc sec you are raising or lowering the mount. The best method I found for adjusting altitude is to only make adjustments up as there you have the full weight of the mount on the adjustment worm. If you overshoot, just remember the position number you had, lower the mount and raise it again to a near value and so you can get nearer step by step to the altitude adjustment.

 

Another beauty of this mount is the internal cabling. I have a total of 3  focuser electronic boards which need power, then a camera which needs power and a total of five USB cables, three for the focusers, one guide camera and the main imaging camera. For the other 2 cameras I will use the QSI cable as they are used during day for Sun imaging. All is connected though the Hub on the DEC head in my case with the custom made holder and head raiser or on the saddle plate as original from iOptron.. No more problems with hanging cables from the end to the control as I had before.

 

Some images below

 

 

thanks for reading and looking and next message has the first results of guiding and I owe you the images 

Edited by Real14, 08 August 2018 - 04:13 PM.

[Real14]

Hi,

 

Here the info about the very first guiding of mount #2 at 3210 mm focal length. At the end of the session high dense clouds rolled in and PHD2 lost the star, but before that it lost the star for a few minutes and then when PHD2 found a new one it was totally off ... I think this is a flaw in PHD2.

 

Some graphs of the session. RMS values of 0.22" for RA and 0.26" for DEC I have not seen them on my mount #1. Having started with mount #1 helped me to get some experience and well for #2 it was easier to get good adjustments.

 

First calibration after polar alignment. A calibration before polar alignment was totally off. No idea why 

 

 

Statistics and Drift fro mount #2

 

 

and here a 1 h guiding graph. The greyed out are at the end is the star loss

 

 

Here the data:

 

Guiding Begins at 2018-08-07 22:35:58
Dither = both axes, Dither scale = 1.000, Image noise reduction = 2x2 mean, Guide-frame time lapse = 0, Server enabled
Pixel scale = 0.53 arc-sec/px, Binning = 1, Focal length = 3210 mm
Search region = 30 px, Star mass tolerance = 50.0%
Equipment Profile = Mi Equipo
Camera = SX Lodestar, full size = 752 x 580, have dark, dark dur = 3000, no defect map, pixel size = 8.3 um
Exposure = 3000 ms
Mount = iOptron ASCOM Driver for CEM120,  connected, guiding enabled, xAngle = -88.7, xRate = 14.062, yAngle = 1.3, yRate = 14.156, parity = +/-,
X guide algorithm = Hysteresis, Hysteresis = 0.100, Aggression = 0.700, Minimum move = 0.250
Y guide algorithm = Resist Switch, Minimum move = 0.150 Aggression = 40% FastSwitch = enabled
Backlash comp = disabled, pulse = 20 ms
Calibration step = phdlab_placeholder, Max RA duration = 2500, Max DEC duration = 2500, DEC guide mode = Auto
RA Guide Speed = 7.5 a-s/s, Dec Guide Speed = 7.5 a-s/s, Cal Dec = -0.0, Last Cal Issue = None, Timestamp = 8/7/2018 10:13:14 PM
RA = 17.64 hr, Dec = -3.3 deg, Hour angle = 0.32 hr, Pier side = East, Rotator pos = N/A, Alt = 64.2 deg, Az = 191.2 deg
Lock position = 434.019, 468.152, Star position = 434.019, 468.152, HFD = 4.57 px

 

 

Thanks for reading and looking

 

All in all the best investment I made for the remodeling of my Observatory.

 

regards Rainer

 

 

[Real14]

Hi,

 

Here you can see a Automatic Meridian flip done by the CEM 120EC2 mounts.

 

I set the flip to be made after 1 degree past meridian. You can set it up to 14 degrees past meridien. Of course you have to check if nothing hits anything 

 

Meridian flip takes at MAX speed about 1minute 28 seconds 

 

The videos are about 1min 50 seconds in duration

 

I measured the noise under closed roof and they make about 60dB at a distance of 1.5 meters ~ 5 feet which I think is very acceptable.

 

 

Mount SN # GB20001

 

https://vimeo.com/283973153

 

 

Mount SN # GB20002

 

https://vimeo.com/283973378

 

Thansk for watching

 

regards Rainer

Edited by Real14, 08 August 2018 - 04:15 PM.

[bmhjr]

Very impressive Rainer. You do nice work!

[Real14]

Very impressive Rainer. You do nice work!

Thank you bmhjr. It was a long journey but this time I took my time in order to avoid foolish mistakes due to trying to hurry up the set up.

 

regards Rainer

[bmhjr]

Hi,
 
Here you can see a Automatic Meridian flip done by the CEM 120EC2 mounts.
 
I set the flip to be made after 1 degree past meridian. You can set it up to 14 degrees past meridien. Of course you have to check if nothing hots anything 
 
Meridian flip takes at MAX speed about 1minute 28 seconds 
 
The videos are about 1min 50 seconds in duration
 
I measured the noise under closed roof and they make about 60dB at a distance of 1.5 meters ~ 5 feet which I think is very acceptable.
 
decibel.png
 
Mount SN # GB20001
 
https://vimeo.com/283973153
 
 
Mount SN # GB20002
 
https://vimeo.com/283973378
 
Thansk for watching
 
regards Rainer

That flip is interesting. I have very limited experience having only used the CEM60, but it rotates DEC and RA at the same time as it flips. Do all your slews work like that?

[Real14]

Hi,

 

For those who have not seen my custom DEC head raiser and relocating the connection HUB on the saddle here some pictures

 

https://www.cloudyni...0ec2/?p=8616069

 

https://www.cloudyni...0ec2/?p=8631306

 

and here the prototypes. I designed a high profile and a low profile connection HUB relocation

 

High Profile which gives you more clearance for passing over the meridian

 

 

Low profile

 

 

In both cases the cables on a side by side setup are distributed from the center of the dovetail plate to the right and the left.

 

 

 

 

 

[suvowner]

Hi,

 

Here the info about the very first guiding of mount #2 at 3210 mm focal length. At the end of the session high dense clouds rolled in and PHD2 lost the star, but before that it lost the star for a few minutes and then when PHD2 found a new one it was totally off ... I think this is a flaw in PHD2.

 

Some graphs of the session. RMS values of 0.22" for RA and 0.26" for DEC I have not seen them on my mount #1. Having started with mount #1 helped me to get some experience and well for #2 it was easier to get good adjustments.

 

First calibration after polar alignment. A calibration before polar alignment was totally off. No idea why 

 

002_1erguiado_cali.jpg

 

Statistics and Drift fro mount #2

 

Statistics_002.JPG Drift_002_20180807.JPG

 

and here a 1 h guiding graph. The greyed out are at the end is the star loss

 

002_1erguiado_20180807.jpg

 

Here the data:

 

Guiding Begins at 2018-08-07 22:35:58
Dither = both axes, Dither scale = 1.000, Image noise reduction = 2x2 mean, Guide-frame time lapse = 0, Server enabled
Pixel scale = 0.53 arc-sec/px, Binning = 1, Focal length = 3210 mm
Search region = 30 px, Star mass tolerance = 50.0%
Equipment Profile = Mi Equipo
Camera = SX Lodestar, full size = 752 x 580, have dark, dark dur = 3000, no defect map, pixel size = 8.3 um
Exposure = 3000 ms
Mount = iOptron ASCOM Driver for CEM120,  connected, guiding enabled, xAngle = -88.7, xRate = 14.062, yAngle = 1.3, yRate = 14.156, parity = +/-,
X guide algorithm = Hysteresis, Hysteresis = 0.100, Aggression = 0.700, Minimum move = 0.250
Y guide algorithm = Resist Switch, Minimum move = 0.150 Aggression = 40% FastSwitch = enabled
Backlash comp = disabled, pulse = 20 ms
Calibration step = phdlab_placeholder, Max RA duration = 2500, Max DEC duration = 2500, DEC guide mode = Auto
RA Guide Speed = 7.5 a-s/s, Dec Guide Speed = 7.5 a-s/s, Cal Dec = -0.0, Last Cal Issue = None, Timestamp = 8/7/2018 10:13:14 PM
RA = 17.64 hr, Dec = -3.3 deg, Hour angle = 0.32 hr, Pier side = East, Rotator pos = N/A, Alt = 64.2 deg, Az = 191.2 deg
Lock position = 434.019, 468.152, Star position = 434.019, 468.152, HFD = 4.57 px

 

 

Thanks for reading and looking

 

All in all the best investment I made for the remodeling of my Observatory.

 

regards Rainer

that graph is interesting, johnsoda  also got an ra error of .22" with his cem60ec on his phd graph......to me thats 2 nice examples of the ioptron encoders working very well for very accurate ra tracking 

[Real14]

That flip is interesting. I have very limited experience having only used the CEM60, but it rotates DEC and RA at the same time as it flips. Do all your slews work like that?

Hi,

 

Guess what ? That was the reason to test it as one mount did a single RA and DEC movement and the other as you said did a combined movement and that draw my attention.

 

Look like the auto meridian flips are executed in a different way according to the position of the DEC axis ? I will test it today to see the behaviour. I even wrote an e-mail to iOptron asking about this difference and yesterday when I tried to show the difference both mounts made the same procedure. 

[bmhjr]

Hi,
 
Guess what ? That was the reason to test it as one mount did a single RA and DEC movement and the other as you said did a combined movement and that draw my attention.
 
Look like the auto meridian flips are executed in a different way according to the position of the DEC axis ? I will test it today to see the behaviour. I even wrote an e-mail to iOptron asking about this difference and yesterday when I tried to show the difference both mounts made the same procedure. 

Yes test. Trust but verify.

You could also check the Horizon limits, as set in the hand controller, to see if there is anything that may cause different behavior. Shouldn't, but you never know.

Bill

Edited by bmhjr, 08 August 2018 - 12:03 PM.

[Real14]

that graph is interesting, johnsoda  also got an ra error of .22" with his cem60ec on his phd graph......to me thats 2 nice examples of the ioptron encoders working very well for very accurate ra tracking 

Hi,

 

That is right and I think it is time to kill the Urban Myth that RMS values will be the same day in day out. We will enever get similar atmospheric conditions every day but encoders help a lot to tame a bit the seeing. I think we are getting too obsessed with those RMS values and I write it again. Important are round stars .. One day they will be bigger and the next day they will look smaller ..

So IMHO the purchase of mounts with encoders for me was a good investment ... especially taking into account that the next brand with similar equipment costs more then double then this ones.

 

As I say, we buy our equipment with what is left after taxes and professional astronomers buy their equipment from our taxes 

Edited by Real14, 08 August 2018 - 04:12 PM.

[Real14]

Yes test. Trust but verify.

You could also check the Horizon limits, as set in the hand controller, to see if there is anything that may cause different behavior. Shouldn't, but you never know.

Bill

Hi Bill,

 

Yes that could be a reason. I have set the horizon at 0°. First I will use that and then lower the horizon and see if it affects it.

 

Rainer

[alphatripleplus]

Rainer,

 

Do you have a PHD plot with just the RA and Dec corrections visible as bars superimposed on the RA and Dec trendlines? I'm just curious to see how large and how often the RA guide pulses are. My guess is they are very minor. Thanks.

[suvowner]

Hi,

 

That is right and I think it is time to kill the Urban Myth that RMS values will be the same day in day out. We will enever get similar atmospheric conditions every day but encoders help a lot to tame a bit the seeing. I think we are getting to obsessed with those RMS values and I write it again. Important are round stars .. One day they will be bigger and the next day they will look smaller ..

So IMHO the purchase of mounts with encoders for me was a good investment ... especially taking into account that the next brand with similar equipment costs more then double then this ones.

 

As I say, we buy our equipment with what is left after taxes and professional astronomers buy their equipment from our taxes 

yep thinking through this has certainly taught me some things about how the seeing affects what phd thinks is going on......I think we are probably "chasing the seeing" when guiding more often or to a greater degree than we realize 

 

it seems when guiding with encoders one should back way off on what phd does to the mount, a "best practice" document for guiding with encoders would be a nice thing for either ioptron or even the phd team to write up.....it seems like you would only need phd to watch for drift or any weird flexure ??

 

this should be required reading prior to a night of imaging especially the last slide:

https://openphdguidi...stPractices.pdf

Edited by suvowner, 08 August 2018 - 12:32 PM.

[John Miele]

Looks fantastic Rainer!

Edited by John Miele, 08 August 2018 - 12:30 PM.

[StephenW]

yep thinking through this has certainly taught me some things about how the seeing affects what phd thinks is going on......I think we are probably "chasing the seeing" when guiding more often or to a greater degree than we realize 

 

it seems when guiding with encoders one should back way off on what phd does to the mount, a "best practice" document for guiding with encoders would be a nice thing for either ioptron or even the phd team to write up.....it seems like you would only need phd to watch for drift or any weird flexure ??

I'm not sure in general that there is anything new or different that needs to be done to the PHD2 settings for mounts with encoders.   PHD2 already recommends setting the guiding parameters so you are not chasing the seeing - and this remains the same for mounts with encoders. (i.e. the upper bounds on PHD2's settings should still be set based on your local seeing conditions)

 

There has been some discussion on the PHD2 forum on whether for mounts with encoders there should be an option is disable RA guiding completely (i.e. let the encoder manage that) and just guide in DEC (to handle PA drift).  But then you still have the possibility of flexure, mirror flop etc that the encoders can;t handle, so I think guiding in RA would probably still be a safe option for most people.

[Real14]

 

I'm not sure in general that there is anything new or different that needs to be done to the PHD2 settings for mounts with encoders.   PHD2 already recommends setting the guiding parameters so you are not chasing the seeing - and this remains the same for mounts with encoders. (i.e. the upper bounds on PHD2's settings should still be set based on your local seeing conditions)

Hi Stephen,

 

Well the PHD suggestions are good but I had always to back off in DEC as the corrections were too aggressive. Since I turn them down My DEC guding comes closer to the RA result.

 

 

There has been some discussion on the PHD2 forum on whether for mounts with encoders there should be an option is disable RA guiding completely (i.e. let the encoder manage that) and just guide in DEC (to handle PA drift).  But then you still have the possibility of flexure, mirror flop etc that the encoders can;t handle, so I think guiding in RA would probably still be a safe option for most people.

Yes I am the one which would like to disable completely the RA guiding but the purpose is for testing and learning how the mounts react with encoders only and so far I have not been able to see how the encoders do move the RA axis and so I can not make me a picture of it. This is for learn to know the mounts and make some posible deductions.

 

I think up to now the whole encoder philosophy has been a bit in the dark or mistified and now while we are talking more and more about this added technology I think a lot of people will do more tests and bring a bit more light into this matter.

 

IMHO the producers of mounts with encoders have kept this as a deep secret and honestly there is no big secret in what encoders do, but the real secret is what do I do with the encoders and if that is kept secret I understand it. Nobody will release the algorythms used for using encoders but we users can learn a lot if we can put through the paces the mounts with encoders and learn from that how they help us.

 

regards Rainer

[StephenW]

Hi Rainer,

 

>Well the PHD suggestions are good but I had always to back off in DEC as the corrections were too aggressive. Since I turn them down My DEC guding comes closer to the RA result.

 

I think there is a distinction between 1) the general recommendation to set guiding parameters to match your local seeing conditions (which is something the user has to determine) and 2) the specific recommendations Guiding Assistant makes.  I was referring to 1) and I think you are referring to 2), but I could be wrong  .

 

The latest dev release has some changes in Guiding Assistant, but I haven't had a chance to test it yet to see if it now recommends less aggressive MinMove settings.

 

Steve

 

p.s. congrats on getting both of your mounts set-up and running.  looking really good!

[Real14]

Yes test. Trust but verify.

You could also check the Horizon limits, as set in the hand controller, to see if there is anything that may cause different behavior. Shouldn't, but you never know.

Bill

Hi Bill,

 

Coming back to the Auto Meridian Flip I just made some tests and yes it does it always do sequential. First RA and then DEC. No idea why ?

 

regards

[ac4lt]

Yes I am the one which would like to disable completely the RA guiding but the purpose is for testing and learning how the mounts react with encoders only and so far I have not been able to see how the encoders do move the RA axis and so I can not make me a picture of it. This is for learn to know the mounts and make some posible deductions.

I’m still a novice when it comes to phd2 so I might be way off the mark or misremembering the settings. But, wouldn’t it be possible to effectively disable RA guiding by setting the RA minmove to a large number like 10 or the RA aggressiveness to 0?

[StephenW]

>wouldn’t it be possible to effectively disable RA guiding by setting the RA minmove to a large number like 10 or the RA aggressiveness to 0?

 

Yep, that is exactly right.  I think there was some chatter on the PHD2 forum on whether this actually turned off all guide input or not, but that is what it should do.

[bmhjr]

Hi Bill,
 
Coming back to the Auto Meridian Flip I just made some tests and yes it does it always do sequential. First RA and then DEC. No idea why ?
 
regards

Thanks, good info.

[Real14]

Rainer,

 

Do you have a PHD plot with just the RA and Dec corrections visible as bars superimposed on the RA and Dec trendlines? I'm just curious to see how large and how often the RA guide pulses are. My guess is they are very minor. Thanks.

Hi Errol,

 

Here a crop of the graph with visible guide corrections. The PHD Log Viewer has no trendlines.

 

Hope this helps

 

 

[dhaval]

I am impressed by these mounts delivering solid results! 

 

Gives me thoughts!!

 

CS!

[Real14]

>wouldn’t it be possible to effectively disable RA guiding by setting the RA minmove to a large number like 10 or the RA aggressiveness to 0?

 

Yep, that is exactly right.  I think there was some chatter on the PHD2 forum on whether this actually turned off all guide input or not, but that is what it should do.

But it does not do it as when I set RA agressiveness to 0 it is defaulted it in the basic program to 0.1 and with the MinMo there is a defaulted value of 10 pixels and when I reached the drift of 10 pixels it started to guide with the defaulted RA agressiveness ...

 

Here is the proof ...

 

I wanted to let it go with ZERO RA guiding for a few hours and then compare the first and the last image ... 

 

regards

 

Edited by Real14, 08 August 2018 - 02:20 PM.