IOptron CEM-25 Telescope Mount: Leveling and Zero Position

In this video I propose a method which seems to be a reasonable way to establish proper leveling of the mount.

[@aerofart]

In hindsight, and now that I understand a little more how a zero position relates to iOptron mount modeling, I don't think it is very critical what the absolute position of zero position is set to. In other words, ZERO POSITION does not need to coincide with plumb (vertical) or horizontal or level or any other physical reality. What IS important, however, is that once you set your zero position that you are able to return the mount to it precisely (by hand). This can only be done with accurate and repeatable markings.

[@ariebakx717]

Smart approach. But I would put the level on the other side of the head. To the fixed shoulder. If the adjustable clamp shoulder is not 100% parallel you introduce a small misalignment straight away.

[@aerofart]

Correct!

[@Mark-yn4vl]

Great video! You have your tripod spreader on upside down though. :) I liked "Fring Sweely", sounds like a long lost member of KISS!

[@aerofart]

LOL, thanks. Good point about the spreader! KISS brings back memories . . . KISS Freely . . . ;)

[@alexchong1979]

interesting ! hopefully can see how u setup everything for tracking at night sky shorting ! cus am going to buy this model later :D

[@southernexposure123]

Hi, Thank you for the video. I'm a complete noob. I have the iOptron 3200 model and I understand absolutely nothing about the zero position. My manual mentions the Set zero and the Go To zero buttons and I've pressed both during photo sessions. I assumed (and we know what that does) that zero position returns the scope to the polar alignment position, but mine doesn't do that. Also when I press the Set Zero Position all the numbers on the screen aren't the same as my home position. NOOB remember? ((-: I saw in your video that those numbers change while the motor moves. Someone in comments mentioned there could be an advantage / disadvantage to setting zero at 90 degrees or 270 degrees. This guider is my first ever motorized device for tracking sky objects. I never even used a beginner level EQ mount before. If it's not too much trouble can you please give me a few pointers to get me headed in the correct direction toward knowing more about setting the zero position. Thank you very much for your time and trouble.

[@aerofart]

Hi SouthernEx, and welcome to the head-scratching world of amateur astronomy. It’s been a while since I set up or used my ioptron mount, but to my best understanding, where the Zero Position is set is not critical, otherwise there would be no option to set it. What is important as I understand it with my fuzzy memory, is that once you establish an arbitrary position and set it, that you are able to return to it manually to that zero position. I believe this is required when a drive system doesn’t have absolute encoders. I know you must be excited to get your telescope up and running, but honestly you’d be better off in the long run spending some time (such as you are doing now) researching the topic of absolute vs relative (or non absolute) encoders. Absolute encoders are very expensive and found only on very high end mounts costing in the neighborhood of $10k plus. Those mounts know where they are pointing even when they are just powered up and require much less calibration. I think once you understand that concept the lightbulb in your head will light up and you’ll have a better understanding and appreciation for how the mount and astronomy in general works. Sorry I couldn’t help you more specifically, but for now just set an arbitrary zero position (I used gravity to set mine) and be sure to place a couple of pencil marks on the axis so that you can hit the mark again when the controller asks you to do that. Good luck and Clear Skies.

[@southernexposure123]

@@aerofart Thank you so much for the clarification. I used the mount to make some OK pictures and hoped I could get better ones if the zero position made much difference. I'll do as you suggest. After reading your reply I think maybe I'll get even more improvements by adding a Bahtinov Mask to the lens. Thanks again.

[@tempusfugit6820]

Would you please do a full review and maybe a set-up video for this mount? It sure is a nice mount and I a looking at it seriously as a future purchase. thank you

[@aerofart]

Sorry, I am selling it. I upgrade to and IEQ-45. It's a GREAT mount. Very smooth and precise when you keep the payload within limits. Good luck to you.

[@NomenNominandum]

What optical tube do you use? I intend to buy a CEM-25 for my Celestron 8. Do you think that is too much payload ? Choosing a IEQ-45 instead, means saying good bye to portability, doesn't it ?

[@mauri740]

A great video! Why did you set the zero position on the hand controller, when the DEC axis was still horizontal? It would not be better to set the zero position when the DEC axis is positioned at 270°? If I have to recall the zero position, I would have the telescope that is oriented horizontally and not towards the NPC

[@Sutor1000]

Thanks. Very helpful and makes perfect sense. Would it work to mark ZERO for the RA Axis on the OTA side of the mount below the main board?

[@aerofart]

You can mark it any place where it won't move or be worn, wiped or smudged away and that you find convenient and cosmetically pleasing.

[@nandotenlohuis3903]

This mount looks (sounds?) pretty silent. Is that also when it's slewing to a star?

[@JohnS916]

It's the quietest mount I ever owned. I needed more payload, so I sold it.

[@aerofart]

Yes, it is extremely quiet!

[@nandotenlohuis3903]

John S Yes that’s why it’s not for me either.

[@gianniformica8235]

I dont have the set zero position option... I gotta be missing something.

[@aerofart]

Gianni Formica I no longer have this controller/mount set up, and I don’t remember exactly, but I think it’s part of the setup routine. Have you tried that?

[@jimngugk4741]

Hi what is the different between 25p and without p ? Thanks

[@aerofart]

If you are referring to video frame rate, the "p" after the number designates the frames as being PROGRESSIVE, versus frames that are render INTERLACED. A Progressive video frame is rendered all at once and represents the majority of video content viewable today. Interlaced video frame rendering is a legacy method that was used back in the days when cathode-ray televisions were widely in use. Interlaced video frames are render with only every other line, therefore it takes two cycles to render a full frame. In other words, you only get half as much video data as you would in a progressive video over the same amount of time.

[@hishama.h2178]

Thanks for the Video,i'l like to be sure before buying,can this mount stands the weight of Orion Sky quest 10 inch intelliscope plus the counterweights?the tube is approx.11 kilo,what do u think?

[@aerofart]

Hello Hisham. I don't know right off the top of my head, but you can look up the weight capacity of the mount online and the weight of the telescope OTA as well as the attachments (camera, mounting plates, finder scope, control devices, etc) to determine how much your total load will be. Keep in mind that you should never approach the maximum weight limit of the mount with your total load. Total load should be no more than around seventy percent (70%) of the total listed mount capacity for a steady and reliable configuration with no shaking or vibrations and to ensure that the slewing and tracking motors can handle the load comfortably and reliably. Manufacturers tend to overstate the load capacity of their mounts . . .

[@hishama.h2178]

@@aerofart Thank u for reply.

[@wilfredoz]

0:17, that's wat she said!

[@utilisateurinconnu7149]

Hi aerofart, I'm French and I bought this mount but the manual and all I can find about my ZEQ25 GT is in English, a technical english than I don't control but I saw on your controler you should set a zero point in the menu. this possibility is not listed in the mine. Do I have to update it ? I hope you'll answer me, tha,k you, David from France

[@aerofart]

David égoliate It is possible that the ZEQ does not employ this feature. The ZEQ and the CEM are two different mounts. In any case, you should always keep the firmware of your hand controller and your mount firmware updated to the latest revision. Please follow the manufacturer’s instructions carefully when updating your firmware to avoid causing irreversible damage to your electronics.

[@harveythommes2847]

I don’t have that feature too in my zen but notice it resets back to 0 when you turn the power off and back on. Hope this helps.

[@ratnamaravind]

Their Dec and RA clutches suck. So tight and sharp at the edges, my fingers hurt. Also setting zero position is not well documented.

[@aerofart]

You mean their DEC/RA clutch engage/release lever, the tiny disc-shaped knob with the thin sliver protruding out the middle of it that's supposed to be a finger handle. Yeah, that kinda sucks if you don't use it correctly. There's a specific procedure that you need to follow when engaging/releasing the RA/DEC axis from the motors. IF you follow that procedure, and you make sure to relieve any unbalanced load from the mount by hand so as to remove that load from the gears, then those tiny little knobs actually are not hard to operate. I think they were designed small intentionally so as to force the user to do things right and to prevent that user from using GORILLA FORCE and ruining his telescope mount. Of course, it should go without saying that your system should be balanced on both axes AT ALL times for best performance and to prevent the early demise of your otherwise GREAT little mount!