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OAG pain in Maxim and PHD

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This is more of a story about last nights efforts than a cry for help.

I went out at ten to focus the OAG on the scope fitted with a lodestar and align the guiding axis to the telescope. The ultimate aim was to calibrate the PEC on the SS2K to start to take decent pictures with the mount. It was a glorious night.

But my lodestar seems to have grown duff bright pixels by the dozen over summer. Even using full autocalibration in Maxim didn't seem to remove them. So I created a bad pixel map and applied it to my auto calibration groups but still with no effect.

Meanwhile I soldiered on, using a brighter star in the OAG to focus and align axiis on.

That done, I discovered there seemed to be a reflection from the bright star that Maxim insisted trying to guide on. It turned up on the row of the first bright star image and even after subsequent images when the star clearly moved according to movement calibration requests, the false star remained fixed and caused maxim to fail the tracking calibration.

An hour and a half of this I tried, with various combinations of bin ratios, exposure times, star in different quadrants of the CCD and all with no success until I put the star in the top left quadrant and then calibration success! You might think that was it, I was motoring, since Maxim was now seeing the star. But no. Maxim could calibrate on the star but reported 'star faded' when trying to use it a guide star, consistently and persistently. Apparently it needs a different type of star to guide on. There were no others.

So half an hour later I gave up with that and went to PhD2. It had support for the Lodestar and for the ZWI so I persevered with the Lodestar. It could even  see the star Maxim refused to guide on and I could use it to calibrate the movement of the scope for Phd to guide with. I did get a 'ratio difference alert since my motion was very assymetric 'L' shaped but it did calibrate so on I went.

Now I could calibrate my PEC!. Several times I achieved this, repeating it starting at different times on the worm since the ss2K will even out the measured with the already recorded. And then Puff! the star had gone - nothing to guide on and the duff pixels were there polluting the image as before. Where did it go ? The sky was still clear and the dome slot was right there where the scope needed it to be.

Now I tried a few exposures at 3mins just to get a feel on what quality had resulted from all my efforts. Its an 8" 1800mm so its was optimistic but the evening conspired further  - the camera intervalometer battery was flat. Not to be deterred I dug out the spare. That'll teach it. But that one has a duff lead that causes the camera to turn off occasionally and it wanted to play. It was now 1.30, I was freezing and not thinking about swapping batteries so it was time to hit the sack.

Only up at 6 for work.

I love these succesful evenings. Gotta have more of them.

Better luck to every one else, and if you have a solution to the Maxim problem I'm interested.


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Mmmm - I had Maxim running a couple of night ago and it kept showing the images I taken 2 or 3 frames before the one I'd just taken - right pain when trying to align things and making adjustments on the wrong image...

Edited by fwm891

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The 'star faded' thing has been a persistant problem with Maxim for years, not sure they ever fixed it. The rest is par for the course and the Gremlins have to be knocked on the head individually (sometimes more than once!) Eventually it starts to work but it can be hard going...


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MaxIm seems to be one of those programs that you either love or hate (a bit like PixInsight perhaps :evil::grin: :grin: :grin: ). Me? I love it and the only time I have ever had a 'Star Faded' error message has been when, errr, ummm, the star has faded because of cloud cover! I have had stars that have mysteriously failed to calibrate and the 'L'-shaped red calibration trace has produced a diamond or some other shape so I simply re-run the calibration, manually choosing a different star by clicking on it before clicking on 'calibrate'. On the rare occasions that I have to do this, I choose a star that is as far away as possible from other stars.

You'd have to take me kicking and screaming to get me away from MaxIm for capture, guiding and stacking! Don't get me wrong, it isn't by any means a perfect program but it does guide beautifully with my LodeStar guide camera........

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I love & loathe it I'm afraid Steve... It's jam packed with so much I think that's becoming a problem for them to maintain.  I wish they had a cut down version as I'm tied in to just use it for capture because I use ACP which I really can't praise high enough.

What version of Maxim are you using skybadger?

They supposedly found a long standing "bug" in Maxim re the guiding & released 6.09 to fix the "star faded".  Such was the "can't believe we missed this" impression I got from the way it came out (on the old yahoo group at least), as I understand it, this was made available to all regardless whether or not you were "in contract".  Until then I'd stuck with 5.24 for my "production" system as it was stable with ACP & mostly didn't have too much trouble with the star faded. But when it happened it ruined the session. Now I've been running 6.09 "in production" for a while now I can say its been much much better & able to use multistar guiding too. It's the first v6 version I've felt was stable enough to trust alone in the Obsy! The only fly in the ointment.... If you have an Atik..  In v6.09 they broke the Atik driver relationship & screwed the temperature reporting. So, I switched to using the Ascom drivers which has worked ok. I hear today they fixed it & will be released in 6.11.

I use an OAG on the C925 seup & the stars are.. well they're not stars they're bananas! It's been guiding fine on those if it can find one that's not too bright otherwise it fails.

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I've had Maxim for a few years now and never got it to guide properly, occasionally give it another try as it seems a waste of money not to, the star faded thing has always been a pain, I even got "star faded" message using the simulator lol.

Recently upgraded to 6. something, probably the last time I'll bother as it seems to have doubled in price from when I upgraded last time, the upgrade cost more than SPG outright purchase.

ATM I can get up and imaging in a few minutes using PHD so don't know if I can be bothered wasting more clear skies getting Maxim to guide :)


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My OAG stars can sometimes be bananas too!

I'm running 5.24 and I sometimes get the fading issue but never once a calibration is successful.

Then again PhD lost the star too.

more practice required



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MaxIm seems to be one of those programs that you either love or hate (a bit like PixInsight perhaps :evil::grin: :grin: :grin: ). 

Alas, I fall into a third category and suspect that I'm not alone. I love and hate Pixisight in equal measure!!!

I wonder if the OP's problems may be more optical than electronic? Is it the star's signal that's the problem or is distortion making it hard for the centroid calculation? And is the prism as deep into the light cone as it can go before creating a shadow? Some older SX OAGs had a problem with tilting once locked in place, too, though that doesn't sound like the problem here.


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What is weird here is that I ONLY use MaxIm DL for guiding and have only ever had a star faded issue when the star has indeed faded - for it to happen using the simulator is banal at worst UNLESS of course, it is part of the 'random errors' setting in the simulator parameter set?

Why, I wonder, am I not seeing this myself? Very strange!

MaxIm DL is not perfect, it can be a challenge at times but rarely is it the software itself, more usually one of the numerous settings that is not set right. I can confirm that I have had a recent issue with v 6.03 and CCD Commander and this made me switch back to v 5.24 which resolved the issue - I am hopeful that the latest V6.09 will resolve this so that I can take advantage of several nice new features in v 6.XX over v 5.XX

I hope you do resolve this issue as MaxIm DL has much to offer.

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Nothing more frustrating than problems like that on a good night!

I've been using Maxim (5.18) for quite some time, guiding with OAG and Lodestar.  Very happy with it and, like Steve, I only seem to get 'star faded' when the clouds roll in or if I've chosen a borderline faint guide star and transparency deteriorates.  I have had occasional guiding problems but these were traced to mechanical issues or to wrong guide settings in Maxim.

I would always start diagnosis by checking the mount's native tracking behaviour with guiding switched off, just to ensure there isn't an underlying basic mechanical issue.  Put a star on the crosswires and take a long series of short exposures with no guiding.  Scan the resulting images and do an unaligned sum.  Check for uniform gradual drift in Dec and moderate PE oscillations in RA.  If you see anything sudden or erratic, investigate that first.

Then do a run with guiding on, but with it disabled in one axis.  After a while switch to guiding on the other axis only. Lastly switch guiding on in both axes.  Make a note of the time any odd behaviour happens and at the end of the session, look at the guide log around and just before that time.  Sometimes you can get a clue as to how the problem started and developed (sudden large displacement, repeated failure to correct, large over-correction oscillations etc etc.) and that may help to narrow down possible causes.


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I've found I get better guiding results if under Options/Track box size/ select multi star guiding. The error numbers reported dropped a few percent for me. I'm running DL 6.10 pro if that helps

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