My mount died last week, at least the DEC motor.. I had some fun for a few nights trying to manually locate galaxies at 2000mm on a 35mm sensor.. Using my smaller setup AZ GTI + a laser to help me find the target. But realistically, when capturing small objects, one need a goto mount and plate solving, so I ordered the CEM26. I would have take the GEM28 if it was available, for the small gain in payload.
Everything was well packaged and everything needed to use and guide the mount was included (e.g. USB cable, and the mount also has built-in wifi).
I had bad experience with ioptron commander and the skyguider pro (never got it to work) but the CEM26 was recognized on first attempt. I got the 1.5" tripod as the literoc wasn't available. First impression on the tripod: small and light package ! Not much more than a camera tripod but fortunately more robust. The whole system tripod + mount can be lifted with one hand without much effort. The RA & DEC clutch are nice to lock the setup and also to test balancing (really smooth compared to skywatcher mounts). An allen wrench is included, both to block the RA axis for transport, to attach the mount to the tripod and to adjust alt/azi for polar alignment. Same experience with ipolar. Install the soft from ioptron website, connect, worked out of the box. Require to take 1 black frame (really, 1 ?), adjust your exposure and start the adjustments. ipolar will show you where you should be pointing at vs where you are pointing at. Once you get closer to a good alignment, the reticle is zoomed for fine tuning. I didn't see any mention of the polar alignment error though. A bit disturbing, but I trusted the soft when it said I was polar aligned. A note about the DC adapter: 12V 5A; however the adapter is closer to the mount end rather than the plug end.. I was hoping to put the adapter in my weatherproof connection box.. but too short. I have a DC 12V extender, so next night I will probably use that.
Even though the mount feel robust, it's still quite small and portable (4.5kg / 10 lbs) and I was a bit uncomfortable, especially with the CEM design, to put on it my C8 edgehd (14 lbs) + D850 (2.2lbs) + guide setup (2lbs). Fortunately, the saddle seemed robust and with the clutch on, RA/DEC are indeed quite robust. In terms of balancing, the single weight provided was not enough, but I had several from my other mounts. To be clear, I needed the CEM26 CW (10lbs), 2x11lbs and 1x3 lbs to balance the setup. So for a payload of 20 lbs, you feel that you are starting to ask a lot. Even though it's working, I will probably try to find bigger counterweights instead of 4.
Once everything is setup, the overall impression is rather good. Albeit the weight of the setup, no noticeable backlash in either DEC or RA. To clarify, there is a micro backlash, but probably not more than 1mm, it's very moderate. From the guiding graph (see after), it doesn't seem to impact, but I will report later it if it does.
Well, new mount = bad sky. Axiom verified.
When the sky cleared up for 1h
First reaction: Yeah !
I have a wireless security camera on my rooftop to check my scopes; useful for meridian flips, to check the sky or just to reassure you your setup didn't crash in an horrifying way (e.g. we do have some high wind from time to time in the Bay area). Anyhow, I did the quick polar alignment mentioned above, adjust the focus on Capella - also playing with the auto focus aid of APT which now detect the best focus and backlash of your focuser - and started imaging the sunflower galaxy... while the moon was rising from the horizon and without filters. In other words: ideal conditions .
First impression: wow, this mount is silent and smooth ! I had some very noisy skywatcher mounts, this one is smooth and butter in comparison.
The guiding was surprisingly good for such a quick setup and with such bad sky conditions. To be clear, this is the best I got yesterday and there were peaks at 1.5", the average probably around 1.1":
I didn't fine tune PHD2 as this was a quick first light between the clouds, but I believe that even with that payload, I could achieve consistent guiding of 0.8" or 0.9". PS: using zwo290mm mini + zwo 280mm guide scope. I know about OAG but it can complicate the back focus when using the 0.7 reducer + I never actually had any issue guiding at 1500mm before, even with other scopes. One has to be careful of flexures and badly attached equipment of course. Overall the mount responded nicely to correction pulses, both in RA and DEC (not surprising considering they both have Φ88mm, 144 teeth aluminum).
I did 3mn exposure at ISO 400 (sweet spot for D850) for slightly less than an hour at f10. I saw some drifts so my polar alignment was not perfect, still each 3mn exposure at 2000mm was good with round stars. My focus isn't fantastic either, but the seeing between the clouds was not that good.
First (quick) light
Sunflower galaxy from the light polluted sky of San Francisco, no filter, with the moon rising and between the cloud - 1h exposure at f10 so obviously not enough for a good image, but sufficient to judge the tracking with that setup:
Conclusions & Perspectives
Overall, good/great impression. I am still impressed by how quiet and smooth the mount is. The whole setup was done without issue and except from the additional counterweights, the package contained everything needed. So far, I believe this is a better mount than skywatcher EQM35 (same weight) and HEQ5 pro (10kg) but not as robust as the tank EQ6r pro. And that makes sense, remember we are speaking of a 4.5kg mount instead of 17kg...
I am waiting for the next clear nights to:
- refine polar alignment and compare ipolar to phd2 drift align / sharpcap : my polar alignment was "good enough" but not perfect
- see if i can achieve a consistent 0.8" guiding
- if I observe backlash (there may be a few, hence peaks at 1.5" ?)
- didn't try PPEC yet
- also I would like to get an unguided graph to check the peak to peak PE
Edited by lpalbou, 04 March 2021 - 03:06 PM.