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PHD Guiding graph


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Hi everyone, 

i'm trying to autoguide, but i'm always getting poor guiding graph.

i did polar aligment with sharpcap, did it to Excellent, then i start guiding with PHD, which stops after while because it's ineffective. here is a Photo of the lines, i did this immediately after polar Alignement without moving the scope. Any ideas why this happening? balancing seems good to me.   

PHD.png

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6 minutes ago, OJ87 said:

Hi everyone, 

i'm trying to autoguide, but i'm always getting poor guiding graph.

i did polar aligment with sharpcap, did it to Excellent, then i start guiding with PHD, which stops after while because it's ineffective. here is a Photo of the lines, i did this immediately after polar Alignement without moving the scope. Any ideas why this happening? balancing seems good to me.   

PHD.png

Hi. Have you calibrated your guiding camera/scope?

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9 hours ago, OJ87 said:

hmm, you mean Darkframe library? or step calibrating?

I mean step calibration. I’ve seen this happen on mine if calibration wasn’t done or guide scope moved or camera rotated after calibration is done 

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2 hours ago, tooth_dr said:

I mean step calibration. I’ve seen this happen on mine if calibration wasn’t done or guide scope moved or camera rotated after calibration is done 

I calibrated it ,  but Maybe i rotated the camera while trying to reconnect the cam. I will try to calibrate again tonight, thanks a lot, I hope the problem would be so easy solved

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3 hours ago, tooth_dr said:

I mean step calibration. I’ve seen this happen on mine if calibration wasn’t done or guide scope moved or camera rotated after calibration is done 

Or after a meridian flip.. 🤔 

It seems that the corrections are actually increasing the error, that is compensating in the oppostite direction. 

Did you calibrate on one side of the Pier and then guide on the other side using ST4 on camera? 

 

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12 minutes ago, FaDG said:

Or after a meridian flip.. 🤔 

It seems that the corrections are actually increasing the error, that is compensating in the oppostite direction. 

Did you calibrate on one side of the Pier and then guide on the other side using ST4 on camera? 

 

Yes I didnt want to confuse the OP, I've experienced this after a flip.

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Calibration is needed to tell PHD which way is up, down, left, right etc. If you calibrate and then move the guide scope or rotate the guide camera then it can end up sending corrections the wrong way. A few key points:

If you move the guide scope or camera in any way, no matter how small a movement, you need to recalibrate.

If you are using an ST4 cable to guide you need to recalibrate everytime you move to a different target in the sky.

If you are using ASCOM pulse guiding (not with and ST4 cable) you dont need to calibrate when you change targets but your EQMod coords need to be accurate. You should sync the mount to your target once you are centred on it.

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4 hours ago, OJ87 said:

I calibrated it ,  but Maybe i rotated the camera while trying to reconnect the cam. I will try to calibrate again tonight, thanks a lot, I hope the problem would be so easy solved

Yes, that will cause this issue, of camera rotated after calibration... 😮

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5 hours ago, david_taurus83 said:

If you are using an ST4 cable to guide you need to recalibrate everytime you move to a different target in the sky.

Well, this is very stringent: I use this configuration on my HEQ5 and I definitely don't recalibrate for each change of target, but only on meridian flips. 

Actually, using ST4 only, I have found out that, when imaging at high dec, better results are achieved by calibrating on stars at lower dec and then slewing to target.  This is due to the lower RA motion for each step at high dec. 

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