Autoguiding with MaximDL and CCD Commander

[Euan]

I've noticed quite a few people capture using MaximDL, but having tried to autoguide and been frustrated with the complexity, they have went back to PHD. I was one of these people until I had to bite the bullet and learn how to do it or else CCD Commander couldn't guide during automated sessions.

Here is a little explanation of how I got it to work and a few pitfalls, hopefully it will help some people who are in the same situation.

Let's start with the config of Maxim and using that standalone, then I will cover how to make this work with CCDC.

Maxim Configuration:

I tried quite a few different ways of controlling the mount. First using the ST4 ports of my QHY5 by selecting "Guider Relays" (this failed), I then wasted quite a lot of time using "ASCOM Direct" thinking this was the best way to connect to the mount, it would pop up with your usual ASCOM chooser and it looked like it should work. This was a mistake, what worked was to choose "Telescope", then select the mount in the Observatory control window in Maxim. This allows normal pulse guiding, which is the same thing I've been using with PHD.

Calibration:

As with PHD, Maxim has to calibrate to know how much to move the mount relative to the pixel movement on the guider. From what I have read this only has to be done once, although time will tell if it really works on all points of the sky.

First off, start with a single exposure. Try and get a resonably bright star, as it has to follow it after quite a few seconds of movement. You can set how many seconds you want to move the mount in the settings window above, this really depends on your focal length as you don't want to move it out of the FOV or move it so much it can't tell what star it is. When you have a bright star, click on it and then use "Calibrate". It will then move the mount for the number of seconds you have selected in each of the 4 directions till it ends up back where it started.

Guiding:

You should now be ready to start guiding. As with PHD, you need to set the exposure time to match what star you want to use, increase for dimmer stars, decrease for brighter ones.

There is quite a big pitfall here that had me stumped for a while. Because Maxim calibrates once, rather than where PHD users (usually) calibrate before each session, it has to know which side of the mount the scope is on, so that it knows to reverse the RA pulses after a pier flip (you see this when your images are flipped upside down after a pier flip). You have to pay attention to the boxes "Pier Flip" and "Auto Pier Flip". "Auto Pier Flip" takes the information from the mount driver to determine what side the scope is on, and "Pier Flip" is a manual setting to either check or un-check depending on whether or not you want to reverse the RA pulses. I found "Auto Pier Flip" never worked for me, and I had to set it manually. You will know very quickly if you have the wrong setting on this, as the guiding will quickly push the guide star out of the FOV

Select the guide star and hit "Track" and hopefully it should all start working. As with PHD it may take a bit of playing about with the aggressiveness

OK, now that it works on it's own, let see how this ties in with CCD Commander...

CCDC uses a lot of it's own settings over the Maxim settings, and it also automatically chooses a guide star

CCD Commander Settings:

CCDC will use Maxim to star off at a set exposure length, and try to find a guide star while stepping up through longer exposures. Have a play with the Auto Guide Star settings to see what works best for your set up, you will need to set the lower and higher ADU thresholds so that it can find a star at these levels. These are the setting that work best for me. The "Ignore Hot Pixels" option is very good for the QHY5, as there are quite a lot of hot pixels!

You should also pay attention to the "Autoguider calibrated in" setting as this is related to the "Pier Flip" setting in Maxim, I found I had to set this correctly or else I would get the same issue with the RA going in the wrong direction

You can also set the "Max Error to Start" in the take images action, this will make sure the guiding error is below a set threshold before images are taken. This takes a bit of playing with to get right. There is a backup option of "Max Guide Cycles to Wait", after this number of guide cycles, the images will be taken reagardless

What you should have at the end should be something that is more powerful than PHD, I've found my guiding is actually better in Maxim and the automation of the guiding works quite well.

[moocher]

Nice one Euan!!!!! I actually find Maxim by far the best software to guide with i`ve ever used. It is a bit of a learning curve but when you`ve done it a few times it becomes second nature...and its far more accurate than say PHD...

Alan:)

[gost]

Thanks! I've been looking for some guides on this program.

Anyone know if there are any video tutorials on MaximDL? Other than the few ones on the homepage.

[syd_malicious]

Maxim is a complete PITA to first start using but once cracked, and Maxims irritating quirks learnt, there is nothing I have used that comes close. Plus as noted above it is necessary for automated programs. It is worth persevering - trying the simulators first helps and after a few pennies in the swear box it will become fairly clear.

As to calibration I would strongly recomend the "Pinpoint Guider Calibration plugin" plugin from John Winfield. You have to be sure all the Maxim parameters are correct, mainly the side of pier settings, but it simply works and saves so much hassle.

regards

Paul

[ncjunk]

Good explanation, i had exactly the same problem with having to set up the mount connection in the observatory section of maxim.

Also if you dont get enough movement of the star you may need to increase the calibration time (cant remember what it is called)

[roundycat]

I use a 10s cal time on a 600mm scope, 30s seems like a very long time.

Roland Christen says not to use 'scope dec' as the guider software copes with the change of movement required without any bother. I have it switched off now and no problems.

Your guide exposure seems to be 0.2s? If you live in the Atacama desert that may be ok but in England you will be constantly chasing the seeing. I use 4-6s.

I regularly swap guide scopes from an FSQ @ 530mm focal length to a TMB and reducer for 600mm focal length. I calibrate every few months whether I need it or not.

Dennis

[Euan]

I'm really glad I wrote this now as it's been so long since I did any imaging I need to remind myself

Your guide exposure seems to be 0.2s? If you live in the Atacama desert that may be ok but in England you will be constantly chasing the seeing. I use 4-6s.

That's just where CCDC starts looking for a guide star at, if it's set too high to begin with and on a really brings star it can fail to find one

[barkis]

That is a most useful write up Euan, and I will no doubt be familiarising myself with the details . Maxim is a bit daunting, but I think it's reputation as being one of the best is sound.

Why can't it cope on it's own, without CCD Commander being involved though, or is that a question only a numpty would ask?

Numpty Ron.

[Euan]

Why can't it cope on it's own, without CCD Commander being involved though

It does, just follow it down to just before the CCDC settings to get it working

It's just that CCDC can't use PHD for guiding, it has to do it all through Maxim, which is the reason for me having to get to grips with it

It does take a bit more thought than programs like PHD, but once your there it is worth it. I get the feeling my guiding is actually better in Maxim, although I haven't done any pixel-to-pixel accurate comparisons

[barkis]

It does, just follow it down to just before the CCDC settings to get it working

It's just that CCDC can't use PHD for guiding, it has to do it all through Maxim, which is the reason for me having to get to grips with it

It does take a bit more thought than programs like PHD, but once your there it is worth it. I get the feeling my guiding is actually better in Maxim, although I haven't done any pixel-to-pixel accurate comparisons

Gotcha!, thanks for clearing that up for me.

[George]

Thanks Euan, Ive always shied away from Maxim for guiding as PHD has always worked for me, Im slowly starting to use Maxim for other things, Im finding plate solving a great boon especially as its sometimes weeks between imaging sessions so it makes framing on your last target dead easy.

Anyone care todo a workflow for using a DSLR with Maxim?

[blinky]

Yeah, would love to see that too George!