PEC training confusion

[vlaiv]

That's about it - it's now recorded and stored in EQMod - it will be applied each time you select Sidereal + PEC (and it will be selected by default unless you change it).

Approach that you used for recording is "automatic" - meaning EQMod records curve based on issued corrections and now knows how to "preempt" corrections by variable tracking speed - this will lessen the load on guider and enable you smoother guiding as well.

[Anthonyexmouth]

6 minutes ago, vlaiv said:

That's about it - it's now recorded and stored in EQMod - it will be applied each time you select Sidereal + PEC (and it will be selected by default unless you change it).

Approach that you used for recording is "automatic" - meaning EQMod records curve based on issued corrections and now knows how to "preempt" corrections by variable tracking speed - this will lessen the load on guider and enable you smoother guiding as well.

Just set of on a 10 min test sub. See what happens now. 

[Anthonyexmouth]

Not sure if its really made a difference, but this 10 min sub looks better than any before it, but that might be the 1 ton of concrete in the pier that i never had before

[vlaiv]

4 minutes ago, Anthonyexmouth said:

Not sure if its really made a difference, but this 10 min sub looks better than any before it, but that might be the 1 ton of concrete in the pier that i never had before

I'm almost certain that much concrete won't hurt (unless dropped on someone)

 

[vlaiv]

It also looks like you had a small jolt in DEC - probably wind.

[Anthonyexmouth]

How do you tell it's the Dec that got nudged?

Will the belt mod change the pec curve?

[vlaiv]

1 minute ago, Anthonyexmouth said:

How do you tell it's the Dec that got nudged?

Will the belt mod change the pec curve?

That's cause I'm certified pixel peeper

If you examine your image, you will see that almost all stars have small "ghost" image:

This happens when image is "displaced" for a few seconds and star ends up next to where it is supposed to be. If signature is really faint (like above) - that means it stayed very short time at that position. If signature is smeared - there were probably more than one "excursions", but clear ghost image is indicative of single one.

Direction of jolt is easy to find - just look which way RA and DEC go. With Orion's nebula, three stars in nebulosity are pretty much matched with direction of RA:

And if you look at ghost image, you'll notice it's perpendicular to it, and that would mean DEC.

If you do belt mod, your pec curve is going to change, no question about it. Both in shape, but also in "position" (you will remove step motor to fit belt). Btw, to keep PEC properly working, you need to always park your scope to home at end of session. You also should not use your scope with hand controller. If you change RA step motor "position" (or rather worm position in respect to what EQMod thinks it's home), you will need to redo PEC curve. There is option to "resync" PEC curve by shifting phase - but I don't think it can be done with any real success.

 

[Anthonyexmouth]

Can anyone decypher this and tell me whats good and whats bad here?

Cloud came over during backlash test and ruined that bit

 

[Anthonyexmouth]

got the backlash graph now

[vlaiv]

I marked out bad:

P2P error is large - you want that to be smaller - with guiding you want your p2p to be less than 2".

Second thing marked is max drift rate - you want it to be lower, so that drift limiting exposure is something like 8-10s. You want to guide at about half to full drift limited exposure. Meaning that your guide exposure should be anywhere from half to full max drift rate. Longer guide exposure helps with seeing, but you can't have it be larger than drift limited exposure (about half is max really when you have "smooth" mount).

Belt mod should sort both of these issues, and a bit of backlash as well.

[Anthonyexmouth]

6 minutes ago, vlaiv said:

I marked out bad:

P2P error is large - you want that to be smaller - with guiding you want your p2p to be less than 2".

Second thing marked is max drift rate - you want it to be lower, so that drift limiting exposure is something like 8-10s. You want to guide at about half to full drift limited exposure. Meaning that your guide exposure should be anywhere from half to full max drift rate. Longer guide exposure helps with seeing, but you can't have it be larger than drift limited exposure (about half is max really when you have "smooth" mount).

Belt mod should sort both of these issues, and a bit of backlash as well.

i struggle to see anything with a lower exposure, in a fairly dark location too. 

what can i do in the mean time , before i get the belt mod? 

can i do anything to make my guide cam/scope more sensitive?

[vlaiv]

What does your guide graph look like now with PEC?

[Anthonyexmouth]

[vlaiv]

Your RA graph shows quite strong 13.8s period - and this is motor gear meshing period - it looks like motor gear on RA is not meshing properly. You can try to adjust this by changing how the motor is seated in housing.

Because of this, you need lower guide exposure 1s or 1.5s. What sort of gain are you using with your camera? Can you increase it? Maybe use ASCOM driver instead of native one in PHD2 and select 16 bit output and higher gain.

Also, your RA corrections are rather small - I can hardly see them on the graph. Not sure why is that. What guide rates do you use on your mount? x0.5 of sidereal or less (down to x0.3) should be good.

[Anthonyexmouth]

1 minute ago, vlaiv said:

Your RA graph shows quite strong 13.8s period - and this is motor gear meshing period - it looks like motor gear on RA is not meshing properly. You can try to adjust this by changing how the motor is seated in housing.

Because of this, you need lower guide exposure 1s or 1.5s. What sort of gain are you using with your camera? Can you increase it? Maybe use ASCOM driver instead of native one in PHD2 and select 16 bit output and higher gain.

Also, your RA corrections are rather small - I can hardly see them on the graph. Not sure why is that. What guide rates do you use on your mount? x0.5 of sidereal or less (down to x0.3) should be good.

Do I increase the gain somewhere in phd2?

Pretty sure it's set to .5x but I'll check. 

Just ordered the belt mod, late night shopping is expensive,  so will that eliminate the meshing issue?

While I was at it I also ordered a baader click lock and Altair flattener/reducer

[vlaiv]

2 minutes ago, Anthonyexmouth said:

Do I increase the gain somewhere in phd2?

Pretty sure it's set to .5x but I'll check. 

Just ordered the belt mod, late night shopping is expensive,  so will that eliminate the meshing issue?

While I was at it I also ordered a baader click lock and Altair flattener/reducer

Belt mod will certainly remove gear meshing problem. Be careful to put enough tension on the belt. I had similar problem with belt because of low tension - it also did not mesh properly, and 13.8s was there, although smoother than yours - more sine like. After I adjusted tension - it went away.

Camera gain is under camera tab of advanced settings:

[Anthonyexmouth]

Just checked and I think I'd updated eqmod and it looks a little different to what I remember. 

Is it the ascom pulse guide settings? Ra and Dec were set to .9 so I've just changed the Ra to .5

[vlaiv]

1 minute ago, Anthonyexmouth said:

Just checked and I think I'd updated eqmod and it looks a little different to what I remember. 

Is it the ascom pulse guide settings? Ra and Dec were set to .9 so I've just changed the Ra to .5

Change both to x0.5 or x0.4 - you will need to recalibrate your PHD2 after that.

[Anthonyexmouth]

1 minute ago, vlaiv said:

Change both to x0.5 or x0.4 - you will need to recalibrate your PHD2 after that.

Yeah, phd just got proper annoyed. Might wrap it in soon. Getting cold and not run all the wiring into the workshop yet. Waiting until everything is working. 

[Anthonyexmouth]

Camera gain was set to 95. I am using the zwo driver. Would the ascom driver be better?

[vlaiv]

Just now, Anthonyexmouth said:

Camera gain was set to 95. I am using the zwo driver. Would the ascom driver be better?

Only difference that I noticed is ability to use 16 bit (12bit in this case) capture with ASCOM driver. It makes my stars have significantly higher SNR - tens of times as much as with native - SNR of 200-300 is not uncommon vs 20-30 (max 50) with native.

[Anthonyexmouth]

this is the graph after changing to .5x and recalibrating

 

[vlaiv]

2 minutes ago, Anthonyexmouth said:

this is the graph after changing to .5x and recalibrating

 

I'm still confused - RA corrections now seem a bit larger, but still fairly small for some reason, and mount looks like not responding to guide commands (or it's responding but guide commands are so "small").

Here is a piece of mine guide graph - notice length of both blue and red correction bars:

Your red bars are of "normal" height, but blue seem so small in comparison.

At what DEC did you calibrate your mount, and do you have DEC compensation turned off by any chance?

[Anthonyexmouth]

Calibration was done about 5°

Dec compensation is on

[Demonperformer]

Great for a permanent setup, but is this worth doing on a temporary setup that has to be dismantled at the end of every session?