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The total movement range is not sufficient, you stay too near the focus but this Vcurve method need very defocused image to work.
In the message "Cannot reach near focus HFD, please increase Half Width or better center the curve" I must replace "Half Width" by "Max offset" to match the label in the Vcurve window.
Try 200 or 300 for Max offset, so it can reach a HFD of 20.
For the first try you can reduce the "Number of steps" from 30 to 10 to speedup the process.
And in the Preference/Autofocus you can also try to increase n.step from 3 to 5 to better leverage the seeing variation.
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Hallo Patrick, thanks for your suggestions. I will try it next time, now it snows here in bavaria and tomorrow it turns to rain.
My focus is at 300, so setting "Max offset" to 300 can be critical. Are there successful autofocus situations with a HFD of 20 with a newton or cassegrain?
I will try a greater offset next time. |
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Sure, be careful to not set a negative focuser position that will not work.
The program correctly handle a defocused reflector star image with central obstruction.
This V curve is a real one I do with my 150mm F6 Newtonian:
https://www.ap-i.net/ccdciel/_detail/en/documentation/learn_vcurve.png
The HFD of 20 is only an indication, as you can see in above image it work fine for me, but this can also be 15 or 10.
The important point is you get a sufficient linear part in and out of the focus point because this focus method use a linear regression to guess the focus position.
This is not the case in your screenshot, it look like your are zoomed in a narrow area around the focus. |
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Thank you for clarification. I will give feedback after the next clear night.
Thomas |
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No clear nights here in germany. Thomas |
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Hello Patrick,
there were clear skies for a couple of hours last night. So I followed your suggestions and finally I got a sufficient v-curve with long linear parts. Thanks for your intructions.
Manual triggered autofocus worked most of the time. Once again I struggled with HFD settings. Setting "Autofocus tolerance" higher made it work. Issue can be closed.
Thomas
Attachments:
Bildschirmfoto vom 2017-12-25 23-14-53 -> first try with fewer points
V-Curve-Generation- 2017-12-25 23-21-45 -> final curve
V-Curve-Success.log -> manual triggered v-curve autofocus
V-Curve-Success.log (4,660 bytes)
2017-12-26T00:31:06.340 Autofocus start Vcurve
2017-12-26T00:31:06.341 Focuser temperature: 20.0
2017-12-26T00:31:06.342 AutoFocus started, initial position: 285
2017-12-26T00:31:06.675 ZWO CCD ASI1600MM-Cool: [DEBUG] Requested CCD Frame is (2122,1840) (600 x 600)
2017-12-26T00:31:06.676 ZWO CCD ASI1600MM-Cool: [DEBUG] UpdateCCDFrame ASISetROIFormat (600x600, bin 1, type 2)
2017-12-26T00:31:06.677 Camera frame x=2122 y=1840 width=600 height=600
2017-12-26T00:31:06.678 ZWO CCD ASI1600MM-Cool: [DEBUG] Setting frame buffer size to 720000 bytes.
2017-12-26T00:31:06.678 ZWO CCD ASI1600MM-Cool: [DEBUG] StartExposure->setexp : 1.000s
2017-12-26T00:31:07.777 ZWO CCD ASI1600MM-Cool: [DEBUG] Uploading file. Ext: fits, Size: 722880, sendImage? Yes, saveImage? No
2017-12-26T00:31:08.128 ZWO CCD ASI1600MM-Cool: [DEBUG] Upload complete
2017-12-26T00:31:08.279 Autofocus running, hfd=4.3 peak:1098.4 snr:28.1
2017-12-26T00:31:08.279 Clear focuser backlash
2017-12-26T00:31:08.619 MoonLite: [INFO] Focuser is moving to position 443
2017-12-26T00:31:14.915 MoonLite: [INFO] Focuser reached requested position.
2017-12-26T00:31:15.867 Autofocus move to start position 383
2017-12-26T00:31:16.194 MoonLite: [INFO] Focuser is moving to position 383
2017-12-26T00:31:18.897 MoonLite: [INFO] Focuser reached requested position.
2017-12-26T00:31:20.494 ZWO CCD ASI1600MM-Cool: [DEBUG] StartExposure->setexp : 1.000s
2017-12-26T00:31:21.497 ZWO CCD ASI1600MM-Cool: [DEBUG] Uploading file. Ext: fits, Size: 722880, sendImage? Yes, saveImage? No
2017-12-26T00:31:21.736 ZWO CCD ASI1600MM-Cool: [DEBUG] Upload complete
2017-12-26T00:31:21.903 Autofocus mean frame 1/3, hfd=5.6 peak:248.9 snr:9.6
2017-12-26T00:31:22.466 ZWO CCD ASI1600MM-Cool: [DEBUG] StartExposure->setexp : 1.000s
2017-12-26T00:31:23.585 ZWO CCD ASI1600MM-Cool: [DEBUG] Uploading file. Ext: fits, Size: 722880, sendImage? Yes, saveImage? No
2017-12-26T00:31:23.818 ZWO CCD ASI1600MM-Cool: [DEBUG] Upload complete
2017-12-26T00:31:23.963 Autofocus mean frame 2/3, hfd=5.8 peak:234.7 snr:9.1
2017-12-26T00:31:24.524 ZWO CCD ASI1600MM-Cool: [DEBUG] StartExposure->setexp : 1.000s
2017-12-26T00:31:25.647 ZWO CCD ASI1600MM-Cool: [DEBUG] Uploading file. Ext: fits, Size: 722880, sendImage? Yes, saveImage? No
2017-12-26T00:31:25.880 ZWO CCD ASI1600MM-Cool: [DEBUG] Upload complete
2017-12-26T00:31:26.032 Autofocus mean frame 3/3, hfd=5.1 peak:249.7 snr:9.6
2017-12-26T00:31:26.033 Autofocus running, hfd=5.6 peak:234.7 snr:9.1
2017-12-26T00:31:26.034 Autofocus move to near focus 394
2017-12-26T00:31:26.357 MoonLite: [INFO] Focuser is moving to position 394
2017-12-26T00:31:26.976 MoonLite: [INFO] Focuser reached requested position.
2017-12-26T00:31:28.571 ZWO CCD ASI1600MM-Cool: [DEBUG] StartExposure->setexp : 1.000s
2017-12-26T00:31:29.712 ZWO CCD ASI1600MM-Cool: [DEBUG] Uploading file. Ext: fits, Size: 722880, sendImage? Yes, saveImage? No
2017-12-26T00:31:29.953 ZWO CCD ASI1600MM-Cool: [DEBUG] Upload complete
2017-12-26T00:31:30.117 Autofocus running, hfd=5.1 peak:201.9 snr:8.0
2017-12-26T00:31:30.117 Autofocus measurement1 : HFD=5.115 position=378
2017-12-26T00:31:30.795 ZWO CCD ASI1600MM-Cool: [DEBUG] StartExposure->setexp : 1.000s
2017-12-26T00:31:31.791 ZWO CCD ASI1600MM-Cool: [DEBUG] Uploading file. Ext: fits, Size: 722880, sendImage? Yes, saveImage? No
2017-12-26T00:31:32.025 ZWO CCD ASI1600MM-Cool: [DEBUG] Upload complete
2017-12-26T00:31:32.174 Autofocus running, hfd=4.7 peak:184.7 snr:7.4
2017-12-26T00:31:32.175 Autofocus measurement2 : HFD=4.927 position=380
2017-12-26T00:31:32.775 ZWO CCD ASI1600MM-Cool: [DEBUG] StartExposure->setexp : 1.000s
2017-12-26T00:31:33.781 ZWO CCD ASI1600MM-Cool: [DEBUG] Uploading file. Ext: fits, Size: 722880, sendImage? Yes, saveImage? No
2017-12-26T00:31:34.113 ZWO CCD ASI1600MM-Cool: [DEBUG] Upload complete
2017-12-26T00:31:34.268 Autofocus running, hfd=3.9 peak:153.8 snr:6.4
2017-12-26T00:31:34.269 Autofocus measurement3 : HFD=4.739 position=381
2017-12-26T00:31:34.269 Autofocus move to focus position 381
2017-12-26T00:31:34.591 MoonLite: [INFO] Focuser is moving to position 381
2017-12-26T00:31:35.128 MoonLite: [INFO] Focuser reached requested position.
2017-12-26T00:31:36.724 ZWO CCD ASI1600MM-Cool: [DEBUG] StartExposure->setexp : 1.000s
2017-12-26T00:31:37.622 ZWO CCD ASI1600MM-Cool: [DEBUG] Uploading file. Ext: fits, Size: 722880, sendImage? Yes, saveImage? No
2017-12-26T00:31:37.967 ZWO CCD ASI1600MM-Cool: [DEBUG] Upload complete
2017-12-26T00:31:38.116 Autofocus finished, POS=382 HFD=4.5 PEAK:153.4 SNR:6.4 TEMP:20.0
2017-12-26T00:31:38.429 AutoFocus successful
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Yes this is a good curve and it must work now.
Now I return at home and can work again on the program. Don't hesitate if you have other questions.
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