Jump to content

NLCbanner2024.jpg.2478be509670e60c2d6efd04834b8b47.jpg

The night it all went wrong

jgs001

Recommended Posts

jgs001

jgs001

Posted
Posted

I'm sure everyone has been there... last night I had one of those nights.

All seem to go well, PA'ed, all linked together, tried to align using sync, but that didn't work, so I put the tubes up, weights down and started the normal align process (think I've resolved the Sync now). Got it all aligned, slewed to target, spot on, could even see it on the PHD window from the QHY5v. went to take a test shot to check framing, and 60 seconds, getting massive trails. That's not right, tried again... 30 seconds, still big trails. All powered up and tracking, I could hear the motors working, eqmod showing as sidereal tracking. So I powered down and tried again. Rebalanced and ran through the whole process including PA again. Same thing... Tried a third time, not so bad, so I setup for guiding. PHD ran through it's processes, this is when I noticed something else...

The west movement, took 41 steps to move the required amount, the east movement, of 41 steps moved twice the distance.. odd.. still guiding came up. Tried imaging, 50s looked ok, so I set for 5 minutes. within 5 minutes the guide star was lost. the guide graph, stared out ok, and gradually got bigger and bigger, and the OSC reach 0.01

I gave up. Had enough... 2.5hours and achieved precisely nothing.

I've checked the gears, they are all lubed and turning freely. I've checked my cable, and that's all ok... I can find nothing wrong, except I must have done something wrong.

Anyone have any ideas ?? Apart from perhaps jealousy... using the portable eq1 instead of the HEQ5 the other night ...

Link to comment
Share on other sites
  • Replies 27
  • Created
  • Last Reply
brianb

brianb

Posted
Posted

Yeah, I think most of us have cursed our equipment for not working properly at one time or another....

Anyone have any ideas ??

Clutch slipping? Tight cable restricting movement?

Link to comment
Share on other sites
jgs001

jgs001

Posted
  • Author
Posted

I did update eqmod, but I'm not sure when... I'm running 1.16J

RA Rate is set to 0.1 and Dec rate to 0.2

In PHD Dec guide mode is set to Auto.

I checked all the clutches, screws, bolts etc for anything that might be loose. And then tightened them a bit anyway.

Link to comment
Share on other sites
Ant

Ant

Posted
Posted

You know what? That sounds like exactly the sort of issue I had a few weeks ago that Steve and Jon kindly helped me sort.

Which Steve has detailed below.

Good luck John.

Ant

Link to comment
Share on other sites
Ant

Ant

Posted
Posted

Surely having the ASCOM Pulse guide settings set to anything other than 1.00 during the PHD calibration routine means that the setting are redundant...

I have to admit that I have them set to 0.7 on both and have calibrated like that, but it occurred to me last night that all that does is inform PHD that the star is moving less for the calibration pulse that it sent...

Does that make any sense?

Ant

Link to comment
Share on other sites
SteveL

SteveL

Posted
Posted

It means that it wants EQMOD to move the mount during pulseguidng at + or - 0.7x sidereal rate from the current tracking rate.

i.e.

RA Lower limit 1x - 0.7x = 0.3x

RA Upper Limit 1x + 0.7x = 1.7x

DEC rate is static unless told to guide, so its really just + or - 0.7x sidereal rate

The guiding rate is adapts the current tracking rate to speed it up or slow it down as required. For some longer FL OTA, high guiderates can cause the mount and OTA to flex and oscilate (sp?), whereas short tubes can guide quite happily at 1x adaption to the current rate.

Link to comment
Share on other sites
SteveL

SteveL

Posted
Posted

no, its the adjustment to the underlying tracking rate (as per the descriptions of DEC Rate and RA rate in the EQMOD window)

but isnt that the same thing? Track at 0.7 +/- sidereal, or track at 70% of 1x sidereal?

Link to comment
Share on other sites
SteveL

SteveL

Posted
Posted

Yes, Agressiveness is just the percentage of the calculated guide move that actually gets sent, so you dont correct the full amount. This is useful to stop overcorrection, especially with longer FL systems and on windy nights wher the thing is flapping around like a flag :D

Link to comment
Share on other sites
jgs001

jgs001

Posted
  • Author
Posted

But as far as I know, unless the install of the eqmod update changed these settings, I've never changed the guiding settings, and have never had a problem with guiding, 20 minutes with the C80ED and a 2xTC for 1200mm..

I guess it must have been one of the other options you mentioned Steve, but I couldn't find anything. I've been having a play and nothing seems to be binding on the mount, all axes move freely, I've tweaked the balance and it's all now balanced every which way... around the polar axis (Still not got Dec and RA sorted out in my head), and with the tubes horizontal and veritcal, with the C80ED on top and underneath (side by side mounting).

Having said that, the settings discussion is very interesting

Link to comment
Share on other sites
jgs001

jgs001

Posted
  • Author
Posted

But as far as I know, unless the install of the eqmod update changed these settings, I've never changed the guiding settings, and have never had a problem with guiding, 20 minutes with the C80ED and a 2xTC for 1200mm..

I guess it must have been one of the other options you mentioned Steve, but I couldn't find anything. I've been having a play and nothing seems to be binding on the mount, all axes move freely, I've tweaked the balance and it's all now balanced every which way... around the polar axis (Still not got Dec and RA sorted out in my head), and with the tubes horizontal and veritcal, with the C80ED on top and underneath (side by side mounting).

Having said that, the settings discussion is very interesting

Link to comment
Share on other sites
Psychobilly

Psychobilly

Posted
Posted

The trouble is with problems like this we dont get a decent run of clearish skies to systematically work through all the possible causes... its bad enough when the mounts in the obs so you can leave it set up....

I'm still trying to get my head around how to mount the camera on the EQ3 so that the long axis of the sensor is always parallel to DEC...

I'm expecting the CPC to sulk as well....

Peter...

Link to comment
Share on other sites
steppenwolf

steppenwolf

Posted
Posted

Ironically, I too had problems with EQMOD last night and although everything looked to be correct, I was unable to do an automatic star centring using MaximDL via EQMOD. I manually centred instead using a gamepad but when I slewed to my target (M81), having arrived, it stopped tracking in RA. On a whim, I went to the telescope control menu in C du C and turned the tracking 'off' then 'on' and lo and behold it all started working just fine so it was a software glitch - yours could have been something similar?

Link to comment
Share on other sites
jgs001

jgs001

Posted
  • Author
Posted

And tonight it all worked like a charm... I got a short hour or so gap in the clouds tonight... so I managed to get setup, ignoring the twinges from me back and left knee... I double checked everything before even getting started... level PA etc... I used the hand controller and checked the tracking on Arcturus... no problems there... so I setup guiding and ran some test shots... I deliberately made it hard, with the 2xTC as well... so 1200mm... first test, 60 seconds, no problem. 2nd test, 300 seonds, no problem... so I went for my real test... and 20 minutes no problem...

The guiding calibration was even in East and West also, and the graph was pretty smooth and OSC at about 0.4

The only thing I can think is that I messed up PA really badly last time out. I think that the amount of adjustment in Alt I had to make to put Polaris near the right point bears this out I think...

Here's the 20 minute sub at ISO800, I've tweaked it a bit in Aperture to adjust for the LP filter and remove a bit of skyglow. I think the odd comet I seem to have discovered :) is internal reflections from the TC or perhaps the LP filter.

IMG_3648.jpg

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.