Expectated peak to peak periodic error with AM5 past february 2023

Fredvallee

Hi, I ordered an AM5 a few days ago. In the mean time I looked at a lot of posts on this forum regarding guiding strategy, especially higher rate (1 per sec or less) of smaller pulses in duration rather than slow rate (1 every 2 or 3 sec) of longer pulses. I have a question for ZWO team. I noticed in the AM5 presentation that "the PE duration changed from 432s to 288 starting feb 2023".
My question is, did the max peak to peak PE changed in the same proportion (design change consequence)? if yes the drift speed will remain approximately the same and the guiding challenge in terms of compensating 0.x arcsec / sec will be the same. If no, the guiding challenge will be more difficult as the slope of the periodic error is now steeper by the ratio 1.5 (432/288). Does anybody having bought AM5 past february 2023 had some high peak to peak like 40 arcsec? or 30 arcsec? or more difficulty to achieve a reasonable guiding performance (0.6 0.8 arcsec with no spikes)
Thanks for your reply, CS Frédéric

Kevin_A

Fredvallee from what I have seen so far is when they changed from 432 to 288 all the max PE numbers were much lower similar to the AM3 mounts. I have been seeing lots of numbers in the 9/4 range and some lower but at the same time the charts have become more erratic looking and less sinusoidal. From others user experiences this erratic PE chart has not been detrimental to their guiding and most have been below 0.7rms average.

Fredvallee

Kevin_A Hi Kevin, thank you for the information. Zwo will hardly recognized why they changed, improvement? cost reduction with more prodution of a single product? difficulty to master the production of the 432s period stain wave? Nevertheless, as far as I understand reading through a lot of post (including the very instructive one of w7ay :-)), the key parameter is the PE rate in arcsec / sec, ie the slope of the PE curve. Assuming 14 arcsec peak to peak smooth pe curve it would mean 0.15 arcsec/sec max slope, let's take the double or even the triple for erratic PE curve you get 0.45arcsec/sec that you can compensate with a 61ms pulse every sec at 50% sidereal guiding. And that is achievable with PHD2 with 1sec. Following the same analysis, I changed everything on a small NEQ5 goto and I improved guiding significantly by increasing the guiding rate to 2 times / sec 0.5s exposures but OAG becomes difficult as there is not enough light for short exposures.
CS Frédéric

Kevin_A

Fredvallee i would not run an OAG with my AM5 mount personally using asiair… maybe with phd2. My mount is fair at 0.16 arcsec/sec and it really only runs well with a big guide scope with great star centroids. Asiair seems to need perfect stars and a good SNR so gain would have to be bumped up but not many scopes have great stars with oags so it comes down to how your mount runs. Some of the AM3 mounts have really low numbers but their charts are so ugly and scary, but they seem to run ok so I am told.