Re: New to Mach 1, some newbie help appreciated

Pete Tuson

Rolando, thank you for this. One of the things I want to try is using my EdgeHD 8 at F10 2032mm focal length (I unfortunately can't fit on the 0.70x reducer with my esatto focuser, there's not enough back focus distance). I'm going to be upgrading my guidecam to the ASI 174 as I think this has much bigger pixels than my 290mm. Main imaging camera is a 2600mm. This focal length was impossible for me to consider on my CEM40.

Is guiding at these longer focal lengths within this mount's capability? I'm hoping that binning the 174 guide cam 2x2 (giving 1.2" per pixel) will be enough to handle the Edge HD focal length. Do you foresee any issues with that?

I really don't mind about pointing errors, as you say, slew and centre is pretty good in NINA and that works fine for me. I'm a big fan of KISS in all walks of life.

Saying that, do you suggest I buy a copy of PEMPro? I believe that records multiple revolutions of the worm gear and averages it. I think PHD2 has Predictive PEC - should I use that along side any curve uploaded to the mount from PEMPro?

Thanks for taking the time.


On Sun, 27 Mar 2022 at 17:01, Roland Christen via <> wrote:
Forget pointing models, they do very little for accurate guided tracking for mounts that have to be set up every night. Good tracking is much more dependent on a good PEM for RA and good balance on the Dec axis. Good polar alignment is also important to keep both axes from drifting too much so that the guider doesn't have to work so hard to keep the guide star on track.

PemPro is a great program for creating a good PE curve that can be downloaded into the CP3 controller. It will make guiding so much easier and more stable for the RA axis.

Getting good balance in Dec will reduce the pressure on the gear teeth (every 1lb of unbalance will produce approx 10lb of pressure on the gear teeth). Low pressure reduces or even eliminates the static friction that occurs on the Dec worm, which helps reduce backlash and retrograde motion. This is especially important on spring loaded worms which are pushed into full mesh by the spring action. You want the Dec axis to respond quickly and accurately to reversal commands during guiding.

Unless you have a very long focus telescope, like a C14, with a small sensor camera, your standard pointing with good polar alignment will normally place the object somewhere in the field. From there, you can either do plate solve and center, or manually center and Recal. Both a quick and easy to do. Modeling with APPM comes into play for advanced setups where you want to automate your imaging sessions, or where you might want to go unguided. But doing so opens up another layer of complications because of the many options that start to exist for such setups.

KISS (Keep it simple ...)


-----Original Message-----
From: petetuson@...
Sent: Sun, Mar 27, 2022 8:23 am
Subject: [ap-gto] New to Mach 1, some newbie help appreciated

Hello all

On a whim yesterday I placed an order for a Mach1 CP3 being sold in the UK. I was looking for a new mount to replace my iOptron CEM40, I'm very excited to step in to the world of precision mounts. I hope it is okay to ask questions here even though I have not purchased the mount new from AP?

There's a huge amount to take in - for example you can't use PPEC on iOptron mounts if you guide, so that's new to me.

So really if there are some good resources I could be pointed to so I don't ask stupid or often asked questions I would sincerely appreciate it!

If you will allow me to indulge in just one question -

PEC with PEMPro, guiding with PHD2, APPM Point Modelling...! How do these play together, what overlap is there, are any 'must haves'? I have to set up and take down my gear most nights and also take it to dark sites, so is pointing model worth it?

I'm primarily interested in improving tracking in both axis as much as us reasonable.

Thank you

Roland Christen

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