63 replies to this topic

[DanB]

Hi again,

I fixed my latitude bolts, the new ones are so much nicer. Guiding seems fine now but 4 times I lost calibration in really good conditions, meaning I had good stars, good skies, the scope and mount is solid tonight but..
PHD failed in RA 3 times with the error "star did not move enough in RA" calibration failed (Or rreally close to that verbage), the last time it failed to calibrate DEC with the same sort of message and stated PHD was "turning off DEC guiding", its guiding outside right now but thinking something isnt right.
Let me know what you experts think, I'm clueless and I cant find anywhere. Thanks for anything, Dan

[Fabio Papa]

This means that PHD expects x pixels of movement before declaring the direction calibrated, and the star never gets there in the allotted amount of "pulses" sent. But I guess you already got this part, right?

The only thing one can adjust (as far as I know) is the length of those pulses. Click on the brain icon, you should see the pulse length. Try doubling that. That should do the trick. This usually happens with short FL guide scopes. What FL are you guiding with?

[mhamren]

I'm no expert but I'll give it a shot.

If polar alignment is off, drift may exceed the movement of the calibration pulses. Also, I've had to adjust the autoguide rates on my CGE to get it to respond to the calibration pulses.

Hope this is of some help.

[DanB]

Hi Fabio thanks. I'm using the AT80ED. I stepped it up by double but that didnt seem to do it. My polar alignment could be a bit off as I havent mastered that yet. Its close but definately not perfect.

No matter whether I'm pointing to the southern sky or the northern sky the drift is the same in phd, straight up and down, it seems to have the side to side captured as the star stays on that verticle line of the crosshair pretty good. I went all the way up to 1,500 with the stepper settings (500 was default)and I didnt notice any improvement. Unfortunately I had to give up for the night, got work in the morning.

People say to balance a little heavy on the east side, I dont think I'm getting that either, not sure what it means or how it helps. I think I have my cables under control and the weight off of the ota's so I'm not sure if its software settings or my setup. I never did have a grasp on good polar alignment and it should be easy but I never know for sure just how close I really am with that polar alignment scope on the eq6. I just spin it to the approximate position that the program polarfinder shows and put the little circle on the star.. the way I understand I should be close and PHD should guide pretty well from there.

Well, I'm sure I'll get it someday soon with the help around here:-) Thanks guys, Dan

[DanB]

Hi,
You mean in my hand paddle for the mount where there are guide settings? or in the phd software?

I've seen that in there.. All my backlash and pec and any tracking settings are all default from the factory, I'm not brave enough yet lol! Maybe I should step it up one setting whatever that is?

Thanks I appreciate the suggestions!! Dan

[DanB]

I stepped it up by double

Sorry, I meant to say I stepped up the number calibration steps from 500 to 1000 and that didnt work so I tried 1500 and that didnt work.

Not sure about RA aggressiveness and all of those settings in phd but its at 100 anyway.
Thanks again. Dan

[Fabio Papa]

That's strange. During calibration, PHD sends a number (don't remember the maximum) of pulses of a predetermined length (which you already modified) until its happy about the movement obtained. In your case, this never happens, which is strange. All the other settings, like aggressiveness, are not taken into consideration so soon by the program, so that's not at fault.

I know it may sound silly, but does the star move at all during calibration? I mean, do you physically see it move in the screen?

[Gary BEAL]

Or, furthering on from Fabio, can you make the star image move on the screen (capturing all the time so you actually see it move)?
There is a "Move" command in the Tools section IIRC. Try that. Also while you have the "Brain" symbol open, make sure it is checked to move in both RA and Dec. I guide with an old 50mm finder, minus the eyepiece, with the QHY5 where the eyepiece used to be, so way shorter focal length than you. Most of the time it works, with all the default settings except a bit more calibration steps.
Gary

[Domerman]

Make sure you aren't trying to guide on a hot pixel. Take dark frames in PHD. I have hot pixels with my DSI that always stay in the same place and I make sure to avoid those, as they obviously are not stars.

[chicot]

For better polar alignment, try doing a software-aided drift align with your camera. I use the polar alignment wizard with pempro (you can download a free trial version) and that tells me exactly how good my polar alignment is.

[mhamren]

Hi,
You mean in my hand paddle for the mount where there are guide settings? or in the phd software?

In the hand controller, the default on the CGE was 50, I've cranked it up to 80-90.

You must have decent polar alignment or PHD and/or your mount won't be able to keep up with the drift.

Good Luck!

[Fabio Papa]

I would discard bad polar alignment. The error message clearly states that not enough movement was detected. If he was so poorly aligned, the star would drift out too fast, hence too much movement. The error would also be different, something along the lines of "Guide star lost" or something like that.

+1 on hot pixel. Happened to me also. With the DSI, it's very easy to mistake.

[Will]

Dan,
I'm with Fabio on the simple thing first. When you begin calibration do you see the selected star move away from the crosshair center during the calibration process? If not then you need to check some of the basics like cables. I can agree with the hot pixel suggestion too. I have three on my DSI and they've fooled me once or twice.

[LLEEGE]

Are you using a GPUSB or ASCOM to guide? It sounds like a bad cable or connection. If you are using the GPUSB, download the port checker. You can manually pulse the RA?DEC axes and verify star movement on the screen or with an EP.
Most likely, you have a bad cable. One other thing, if you are using an ST4 cable, is it the one that came with the DSI? If so, that will not work without modification. I had to swap out one end to make it a cross connect instead of straight through.

[DanB]

Hi all,

I'm using GPUSB. Its all relatively new but it could be a bad cable I guess, new doesnt always mean functional as we all know:-) I'll download that port checker and try that.

I havent read anywhere about having to modify the DSI cable but I'm pretty sure I changed cables a few years back with this DSI. I dont even think I bought the usb cable I just had it laying around so its not the original. That could be it too I guess.
Is there anything to read concerning this cable problem with the DSI?

Thanks a lot LLEEGE! Dan

[DanB]

I think I'm close to PA but I know I'm not perfect. One friend uses phd and says he rarely does any more than a rough alignment like I said above and he gets beautiful 15 minute and 30 minute images with PHD. He could be lying his backside off lol...
About the hot pixel. I did try a few different times to calibrate and with different stars and I get the same thing, mostly the star drifts away (after it is guiding) in the vertical.

When doing the calibration steps I can see the star move out of the crosshairs then back again but mostly only in the horizontal across the screen and not the vertical as much (if any at all). I honestly dont THINK its hot pixels but I've been fooled before and more than once:-)

The first night out it didnt seem to do all of this. The calibration didnt fail and I could have sworn I saw the star move in X and Y both but again, I could be mistaken.
I need to take more notes I can see now. One last thing is, I seem to track a lot better towards the southern or south eastern sky. When looking towards Andromeda (northeast for me)the tracking is worse if that means anything at all. The only reason I'm confident that both axis' are moving is the sound of the motors and my slewing which all seem smooth and ok. Not sure what else I can add right now but if I think of anything I'll post.

Thanks everyone, really appreciate all of this experience! Dan

[LLEEGE]

The cable that comes with the DSI is intended to be used with Autostar. It is a straight through cable. If you put the two ends together, end to end, (to form a loop) the wire colors will match up. 1-1, 2-2, etc..
For the GPUSB, it needs to be 1-6, 2-5, 3-4, 4-3, 5-2, 6-1.
I bought some repair ends for Radio shack, cut one end off the cable and replaced it.

[yock1960]

Do you have DEC Guiding set to Auto? If so, try just North or South. It seems to work better if you have a lot of backlash in DEC (having it North or South). If the guide star is being lost during guiding, then you need to know if it's moving north or south, then set the DEC guide method to the opposite direction. I think I'm remembering that right. There is a document over on the LXD75Telescopes Yahoo group that explains it step by step (guiding.pdf).

Steve

[LLEEGE]

This should help you check your cable wiring.

[DanB]

Well at first I looked in there and that "DEC guiding" was set to off. I set it to auto to see if it changed anything and it didnt seem to. I wasnt sure about the "north/ south" settings so I didnt try that.
This sounds like something I can try on my next outing though, thanks Yock! Dan

[DanB]

That cable looks fine to me. I got that when I got the GPUSB from Shoestring (not saying its good because of that but...), the colors and positions of the wires look right according to that diagram. If anything it could be that DSI cable though, havent ruled that out yet. Thanks LLEEGE, Dan

[Gregk]

I had this twice Once because I was on a bad Pixel instead of a star and the other the cable was bad or connection can't remember which,,,could be the guide pulse width setting also

Stark Labs Has a Yahoo group

Greg

[Mark Sibole]

Dan
The 2 main things to check for this error is make sure you are not using a hot pixel to guide on and make sure there is a connection between your scope and PHD.
By using a 3x3 mean filter in PHD you can eliminate 90 % of the hot pixels or taking a dark frame to rid them.
Also make sure there is a connection from PHD to the scope.
PHD may have an option to manual guide via buttons and you can confirm that PHD id moving the scope.
Ive been using PHD since it was a baby and have great success with it.
What every problems you are having is very minor and 1 of the 2 suggestions should get you going.

[lawrie]

I agree with LLEEGE and Mark, I had the same issue a few months ago, it was a cable problem. All that PHD is saying with the error message is that it can't move the mount, so it can't calibrate.
Hope this helps.

[DanB]

Hi LLEEGE,

Do you know if this cable can be bought? Some things I dont mind doing but wiring to my camera's I dont really feel like tackling. I will if I have to though of course:-)

How did you identify which wires to switch? I cant find any information about this anywhere. I'm now on starks yahoo group and have the question there but figured while I wait that I could ask you.
Thanks for anything further... Dan