maxim & PHD minimum motion

[libraryman]

Just a quick question about min motion parameters.

Is there a relationship between Maxims time based min motion settings and PHD's Pixel based setting?

for eg, PHD defaults at 0.15 pixels and Maxim defaults at 0.01 seconds, is there any correlation in these settings?

Ray 

[Astroboffin]

Hi,

I think there is a difference in those two parameters, as far as I know, the PHD setting you are referring to, is the amount the star moves on one of the camera pixels before a signal is sent to the mount to move back, so if it drifts 0.15 of a pixel in any direction the mount will be told to move back.

The setting in maxim, I think as I am no expert with maxim, is the minimum duration of pulse to move the mount, so if you look in PHD it has settings for minimum and maximum duration for pulses to move the mount, and think that the maxim setting you are referring to is that.

So one is movement of the star before mount is told to move, and the other is the length of pulse, usually in milliseconds, sent to the mount to correct the alignment.

Hope that helps, and more importantly makes sense, I am no expert and am sure others will jump in and correct me if I am wrong, although I am certain about the PHD settings, but not 100% about the maxim.

AB

[libraryman]

Ahh, OK, thanks for that, I have found PhD more intuitive than maxim, i have changed my guidescope and I struggle with maxims min motion parameters.

If I use PhD, I just use the default setting but in maxim, I have no idea what to put in.

PhD does appear to give me a lower fwhm and rounder stars but I'm sure its just because I haven't got the setting correct in maxim.

Ray

[sloz1664]

Hi AB,

I've been looking for this link for the past two days......Age & memory giving up on me 

It helped me with Maxim

http://www.ccdware.com/resources/autoguidercalcv4.cfm

Steve

[libraryman]

Hehe, sorry Steve, i have seen that link many times, it is a good guide, and its very good of you to look for it.

the original question was about similarities in the Min motion setting of Maxim and PHD, i have seen a suggestion that Maxim uses 1 sec motion as a movement of 10 pixels but of course that depends on the size of the pixels !!! and since i use the smaller pixels of the QHY5L-ii 

The calculator suggests a setting of 0.111 i ended up using 0.08  and apart from the poor seeing, it guided far better than iv'e had before, i also took the time to align the calibration axis and that helped me to see what was really going on.

Ray