Got it!
But 0.15 RMS feels unreal. What RMS are you getting when you do not use 4x4 binning, but 1x1 binning?

There used to be a mistake in the algorithm in which the reported RMS was simply divided by the binning factor, without making any difference to the real RMS. Both Wouter and I were mislead by this for a good while, as we were using 2x2 binning which neatly cut the reported RMS almost in half while actually worsening the true RMS through reduced resolution of guide star movement.

I wonder whether that problem has been resolved or possibly crept back in again.

Jo

Could be, not really sure. But I don't have a tracking issue imaging at 1956mm focal length. Examples seen above.
I have not tried 1-1 yet. But since I see no tracking issues, I'm not sure I need to. I can see errors at 0.4" easily and right now I rarely get those anymore. I am keeping about 90% of my images.

Not sure if it makes a difference, but I am in central NM at 7,000 feet altitude.

Seeing is definitely superior at that altitude and dry atmosphere. And whatever works!

Still, 0.15 looks unreal. At 10s exposure, you should have no problem reducing the binning to 1x1 on your guide cam without affecting the SNR much.
It would be interesting to see whether your RMS changes when you change the binning while leaving everything else the same. Testing that would only take you 20 min or so.

Jo,

Hy had been correcting this quite a while ago and since that day the RMS displayed made much more sense as it was basically stable no matter what binning was used. Unless that problem creeped back in.

 

Actually it was 10 monts ago that the issue was solved.
indilib.org/forum/ekos/6690-dubious-drif....html?start=12#51440

I know. I just want to make sure that the flaw has not crept in again.
An RMS of 0.15 seems too good to be true, which means it usually is....
Easy enough for Peter to test, though. Doesn't affect me, I am using 1x1 binning for guiding anyway.

The error has definitely crept back in.  When I guide with 1-1 I can't get close to 0.15 arc second RMS.   It's closer to 1 arc second - because it was fighting with the encoders.
With the dual encoders on the CEM120 EC2, having the error in EKOS prevented frequent guide pulses and actually made the tracking MUCH better.

But all these experiments showed me something else…. with improved Polar Alignment I no longer guide at all with met C11 at f/7 (2,000mm).  I can let the mount just track on its own with no guiding and get nice round stars even with 5 minute subs!  Here's my latest Ha image of M57 - made with 28 5-minute subs - all unguided.   If I had EKOS guiding at 1-1 - this image would have been a mess.  The mount had to have been tracking well below 0.8 arc seconds or better - consistently over 2 1/2 hours to achieve this.   These 28 frames were all that I captured.  None were tossed out from this imaging session.

 

• C11 EdgeHD @ f/7 (1956mm focal length)
• ASI1600MM Pro -10C
• iOptron CEM120 EC2
• Esatto Focuser 

Very nice! Don’t forget to dither though.

Peter

I found your post here very interesting. Thanks for sharing. I live in North Albuquerque Acres at 5850ft which is Bortle Class 5 so I am probably near your location. Looks like maybe you are in Edgewood. I just got my PlaneWave CDK 12.5 two days ago and set it up on my CEM70EC.

   

I am thinking that it might be too much for the CEM70 and as I was expecting the scope is not really suitable for a portable setup. This leads me to  think I need a dome and a new mount. So I had a couple of questions that you might be able to give me some guidance on. Right now I am running Kstars on a Mac Mini at the mount which works well. My first question is how well does your dome automation work? I am assuming you bought the stock 2.2M rotation and shutter automation kit.

My second question is regarding your CEM120EC2. My CEM70EC has gotten some pretty good performance if I am careful in the polar alignment. I have found that the iPolar scope in the CEM70 is off by about 4 arc-minutes but I can get unguided exposures of 5 to 10 minutes at 454mm focal length. I have been using PHD2 for most of my guiding.
 

So I am wondering if you have anything to share on the unguided or guided performance of your setup. If I use my 0.66 reducer there isn't enough back focus to put in an OAG so I need to use a guide scope or go unguided.

My current equipment  setup is:

CEM70EC
PlaneWave CDK 12.5 2541mm with optional 0.66 reducer
Sagitta OAG w/ASI224MC
MoonLite Nightcrawler WR30
Sony A7R4

Thanks
Kurt








 

Hey Kurt, yeah I’m in Edgewood, about 40 minutes away. You should just stop by and we can get all your questions answered, see the dome in action and examine the CEM120 EC2 working.