KenGS wrote: ↑Mon Mar 22, 2021 10:38 am
Hi Henk
I think you are limited by your guiding focal length. Your overall RMS is just 0.24 pixels which is pretty good. Also, your MinMo on each axis is 1.7 pixels which at 6.62"/pixel is 1.1". That means that PHD2 ignores any deviations less than 1.1" which sets the floor for your guiding. You can see on the graph how any deviation less than that results in no guide pulse.
That is something I can change next time I try. Thanks for pointing that out.
KenGS wrote: ↑Mon Mar 22, 2021 10:38 am
The smaller pixels of the ASI120 should help a bit.
I ordered the ASI120MM mini because it was cheap and had good reviews but it's not going to be loads better than my QHY5 at 120 mm
FL unfortunately. Maybe I can separate the sensor and attach my 4.5" supermarket Newt as a guide scope. Orion documented that this guider configuration should work up to 1500 mm while the Newt is 1200 mm (and of course it works reasonably well for taking decent images just not 0.5" RMS).
If it helps, I did try the multi-star guiding in Ekos. It did not change things much but also did not make it worse. One would think that using more guide stars should reduce the measurement noise levels and may make a shorter
FL more capable.
KenGS wrote: ↑Mon Mar 22, 2021 10:38 am
Unfortunately, on the screen shot the HFD value is not visible. That would indicate if the guide scope could be better focussed.
It's 4.64 px. Here is the complete text:
Calibration Begins at 2021-03-22 06:42:22
Equipment Profile = My Equipment
Dither = both axes, Dither scale = 1.000, Image noise reduction = none, Guide-frame time lapse = 0, Server enabled
Pixel scale = 6.62 arc-sec/px, Binning = 1, Focal length = 162 mm
Search region = 32 px, Star mass tolerance = 50.0%
Camera = QHY 5, gain = 40, full size = 1280 x 1024, no dark, no defect map, pixel size = 5.2 um
Exposure = 1000 ms
Mount = INDI Mount [LX200 OnStep], Calibration Step = 750 ms, Calibration Distance = 25 px, Assume orthogonal axes = no
RA Guide Speed = 15.0 a-s/s,
Dec Guide Speed = 15.0 a-s/s
RA = 9.95
hr,
Dec = 69.1 deg, Hour angle = -9.95
hr, Pier side = West, Rotator pos = N/A, Alt = 16.0 deg, Az = 10.9 deg
Lock position = 207.538, 552.056, Star position = 207.908, 551.998, HFD = 4.64 px
West calibration complete. Angle = 86.7 deg, Rate = 0.861 px/sec, Parity = Even
North calibration complete. Angle = 176.5 deg, Rate = 1.674 px/sec, Parity = Even
KenGS wrote: ↑Mon Mar 22, 2021 10:38 am
Also not visible is whether there were any calibration issues. The normalized RA rate of 16"/s is odd.
I had a calibration issue the first time when the box was 15 pixels. It instantly lost the guide star in
DEC when testing the backlash. This happened repeatedly, by the same amount. The problem went away after I set the box to 32 pixels. I was pointed at Bode's galaxy, which may be why more steps were needed in
RA. I was very pleased with the calibration graph, I can't recall seeing such a nice one ever before with my AVX.
I'm glad that there was nothing glaringly obvious wrong (except the minimum movement perhaps). I will read up on the various issues in the documentation and on CN so I can hopefully diagnose it myself, try again with the MN and normal guide scope mounting, and will let you know if I achieve improvement.
... Henk.
Telescopes: GSO 12" Astrograph, "Comet Hunter" MN152, ES ED127CF, ES ED80, WO Redcat51, Z12, AT6RC, Celestron Skymaster 20x80,
Mounts and tripod: Losmandy G11S with OnStep, AVX, Tiltall,
Cameras: ASI2600MC, ASI2600MM, ASI120 mini, Fuji X-a1, Canon XSi, T6, ELPH 100HS,
DIY: OnStep controller, Pi4b/power rig, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles,
Accessories: ZWO 36 mm filter wheel, TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, QHY OAG-M, EAF electronic focuser, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50,
Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK,
Computers:Pi4b, 2x running KStars/Ekos, Toshiba Satellite 17",
Website:Henk's astro images