Any feedback about CEM70 ? Generic equipment discussions · Jérémie · ... · 168 · 9525 · 24

the_bluester 1.81
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I used to do that but I eventually decided that I was not really improving the nights results with all the effort involved. Now I am using Voyager, which sets the guiding exposure time internally anyway and is intended to be "Set and forget"

What you can do is set the driver for 1.5 seconds (And you should still get a good number of stars) and PHD2 to 3 seconds, it will guide on every second frame, then if you want to change to 1.5 seconds you can. I still didn't find any actual benefit in doing it though, personally I think if there is enough wind that increasing your guiding frequency seems advisable, you are probably going to get poor results anyway. The mount is going to respond in terms of maybe 0.5X sidereal rate and wind moving the scope is going to be many times that fast, and depending on the direction the mount is going to tend to spring back afterwards as well. I always found with shorter guide exposures that the star shape bounces around a lot more and I suspect that it just means you are chasing seeing as much as you are errors in the tracking.

I do wish they used a traditional guide cam type of driver that PHD could control, but only because it is one more thing to remember to do each night.
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Lasastard 3.10
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·  1 like
Hi,

so I am about to pull the trigger on the CEM70G as an upgrade to my aging NEQ6. I am however still a little unsure if this mount is actually "working well", or not.  I found a couple of comments, here and elsewhere, regarding DEC backlash, but most of the time it is an initial post compaining about it but not followed up by some kind of resolution. Is this a prevalent issue? Is this fixable by the user? Or more of a design flaw?

Otherwise, it sounds exactly like the mount I am looking for, but I'd hate to buy something that has a potential major flaw for imagers.

Cheers,
Marc
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GuillaumeGz 0.00
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·  2 likes
Hello Marc,
I have the CEM70 for 3 months.
First, don't use the LiteRoc tripod, it is too light. Buy the ioptron tri-pier for example.
I had a DEC backlash of 2500 ms (mesured on PhD guiding assistant).
The DEC belt was not well tensioned so I've slightly put a small plate between the motor and the support to add more space between them to tense the belt (the two toothed wheels are still perfectly aligned). It is easy.
Now I have a backlash of 150 ms and I am satisfied. Maybe now it is only the bashlash of the motor itself.
You can see my last picture after fixing this issue in my profile (my guiding was around 0.5 arcsec).
Cheers

Guillaume
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Lasastard 3.10
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·  1 like
Ah, thanks for the tip! I did some digging and found this: https://youtu.be/DOXOm4cDrVs?t=12
Basically, there is a bit of information out there on how to do this for the CEM60, which is probably similar enough to also apply to the CEM70. Basically, the motor is held in place by three hex screws - when lightly losened, these allow you to move  the motor in and out just a little bit, but enough to increase the belt tension. Well, in theory (since I don't have a CEM yet ;))
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GuillaumeGz 0.00
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·  1 like
Yes, but actually it is not a good idea to move the motor in or out. The wheels have to be aligned. Otherwise, the belt will be damaged after a while.
The plate solution works well but it is just an advice 
I am very happy with this mount now !
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Linwood 5.76
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·  4 likes
I had one for all of two nights out now, and like @GuillaumeGz lots of DEC backlash, but added tension in the motor.  I had a CEM40 and iOptron's recommendation was more like the youtube, they literally said put a flat screwdriver blade and pry the motor tight while tightening the screws.  A thin plate sounds good also, actually better, but my concern generally is the screw holes appear to not have enough room for adjustment to be really tight, I'm still showing 450ms backlash, which is way too high for a spring tensioned worm gear.   I may try a plate next, but worried I may have to further elongate the holes.

However, even at that, I guided around 0.5" for hours the second night out with a C11 at 2800mm and an OAG, so quite happy.  The cable management with the saddle ports is vastly improved over the CEM40, I now have no cables going up the axis (which is still available if needed) even with camera, focuser, filter wheel, guide camera and two dew heaters.

Coming from the CEM40 the base is also a significant improvement, as no need to loosen the mount bolts to adjust azimuth for polar align (which is good as they made the mount bolts almost inaccessible, which was stupid -- the hex wrench hits the altitude locks).  They also included a RA axis lock (shove the big included hex wrench in a hole in the axis) which makes me feel a lot more secure in moving the mount around on the tripod, that you won't hit the counterweight shaft and strip the RA gears.

Also, the saddle knobs for tightening are a vast improvement over the CEM40, large, easy to grab and turn in the dark.  Little thing, but really nice.

The included guide scope is just next to worthless though.  I tried it with a 4" refractor and compared to a guide scope on the first night. Besides being too short, its sensitivity is low.  My little 60mm guide scope would see dozens of good guide stars and it might see one or two in a random location, this despite it having a wider field of view. And the focus adjustment on it is insanely difficult to adjust. You basically have to slide a screw (slide!  not turn) a fraction of a mm by hand to go completely in and out of focus for almost no visible motion.  It also requires separate management of exposure, e.g. PHD2 can't adjust its exposure as you adjust PHD2's rate, you need to do it on this stupid encoded dialog (e.g. -5 is 2.5 seconds or some such silliness). It works, I could guide, it was not completely awful, and you may be able to use it.  But it's really more appropriate for guiding something like a wide field camera lens than any telescope, and that's silly because a 70# mount is not likely to be purchased by people who want a DSLR with wide angle lens guided.

But the cable management and integrated USB (one plug for it, polar, saddle, etc.) in my mind is worth the additional cost.

Also, be aware if you get one, for reasons lost on me, you can connect to EITHER the guide scope OR the polar scope not both at once. This is not functionally limiting of course, but it is very easy to think something is broken if you leave one connected, or have a capture program that connects to everything at once run before you start polar align.  Why it's not just a USB hub in between I do not know; the saddle USB cables are hub connected and everything works independently (but from one feed).

Wifi: If you are imaging, I just don't get the attraction; it seems pointless.  If you are getting this for visual use maybe. But it's pointless for imaging since  you will have a USB cable connected anyway.   It also is limited to ad hoc mode, you cannot (as best I can tell) have the mount join a network (e.g. your home wifi in the back yard, which would allow you to have, say, an iPad connected to the internet at the same time as the mount).   But... it has wifi, cute little detachable antenna, seemed to work (at least I saw the SSID before disconnecting and putting the antenna away for good).

Bottom line: I wanted more stability and better guiding on my C11 than the CEM40 was giving me.  It is doing that, and doing it well. I recommend the "G" for cable management, but do not expect much from the "G"uide scope.
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Lasastard 3.10
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Thanks for taking the time to write such a detailed answer!

I think I am missing something about the nature of the backlash issue tho, since the whole "adding a plate" does not make sense to me yet.

I was under the impression that insufficient belt tension has to do with the distance the motor is from the axis, or rather the other gear that recieves the belt and the rotational movement. So if the gears are further apart, tension is increased, if they are closer to each other, tension decreases. And with low tension, it takes a tad longer for the gear movement at the motor to start moving the belt along.

Is this the basic issue with the DEC backlash? And if so, how/where does this plate go to address that? (it probably would help if I knew what the whole belt/motor assembly looks like in close-up...).
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Linwood 5.76
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·  3 likes
The plate would go between the mount of the motor and the motor, parallel to the motor and to the worm gear, pushing the motor a bit further from the worm gear than the mount naturally holds it, tightening the belt.

The mounts are made with loosely fitting screws to do that now.  I think contrary to the indication above, that iOptron thinks that's OK, just shift the motor and tighten the screws.  But for me, I can't get it tight enough like that, so I may try a metal plate if I can find one(s) the right thickness.  Though, to be far, even though my backlash is too high, it is not so high it doesn't work -- my guiding was very good last time out.

Both to the original aspect of the question: I think enough people have had to tighten their belt to say that there's a QC problem with these, they should be tensioned at the factory better.  Or... maybe the belt stretches over time when new.  But, check the belt tension (or measure the backlash) early when you get one, so as not to be frustrated if yours is loose.
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Lasastard 3.10
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·  1 like
Thanks, that clears things up! I also found this (http://www.ioptron.us/Support/CEM40_Belt_Tension_Adj.pdf) which gave me a better understanding of the engineering behind the motor/mounting. Really does seem that they need to revisit this part of the construction and come up with a more fool-proof solution, BUt as you say, might just be that the rubber used for the belt expands ever so slightly after being installed.
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the_bluester 1.81
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I am finding the guidescope fine for what it is (By that I mean fine for a 30mm F4 guider) Sensitivity wise I could plainly see nebulosity in PHD2 when imaging M42. My only gripe with it is that as it seems to be a "Video" camera the interface is clunky and it does not retain exposure and gain settings session to session. It guides to around 1" which is good enough for my current image scale (480mmFL refractor with a camera with 3.75um pixels) I would expect it to be a world of disappointment if I tried to guide my C925 with it.

Basically it allowed me to get the USB3 and better integration with input USB port only, while spreading the costs out as this is a second rig and I didn't have to buy a second OAG and guide camera at the same time. I probably will buy one later when supply of astro stuff loosens up a bit again.

My only current gripe is that the software is a bit flaky. I though the current commander version had resolved it (I was running for a couple of months on the previous) but it tends to loose settings for the user defined park position and degrees past the meridian. The first results in a weird but safe park position but I have to check each night as the second would cause a meridian flip failure during an imaging run.
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bemo 0.00
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Hello,
i just post in order to follow this topic.
I have ordered a CEM70G to replace an EQ6R and i use a Newton 200x800 carbon with an ASI533MC plus a ASI224MC as guide camera. That one will not be need if iGuider is enough for my guiding.
Thanks for these valuable infos.
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BrianSweeney 2.61
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How do you get the wifi to work?

If I try to check the wifi status on the hand controller, the screen says:
"Wi-Fi module is initializing.... Press BACK to return"

Selecting the "WiFi on/off" also says the same thing.

No matter how long I wait, it is never initialized.

I have tried the "Restart" and "Reset to Factory" under the WiFi menu tree.
I have tried "Reset all settings" under the main settings menu tree.

I tried updating the firmware, but it was already on the latest version
Mainboard: 200115
RA: 200116
DEC: 200116
Hand Controller: 200303
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Linwood 5.76
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Mine says that for longer than I would expect, but after a while the status appears.   Does yours ever show up as an available SSID (e.g. if you look on a phone or laptop for available wifi)?

If it never comes back I'd say it is broken.  I do not think there is any magic other than what you are doing.
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battleriverobservatory 6.06
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·  3 likes
While people are talking about the cem70 I should mention this. There are 2 set screws at the front lower side of the mount, they lock the azimuth so it cannot rotate. This seems the be set a certain tension at the factory but I found when they are left as is, my mounts rocks on this axis. forward and back. At first I thought this was the tripod until I took it off and confirmed it was the base plate of the mount. This would be severely detrimental with a big scope and any slight breeze as it was for me 2 nights ago.
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BrianSweeney 2.61
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While people are talking about the cem70 I should mention this. There are 2 set screws at the front lower side of the mount, they lock the azimuth so it cannot rotate. This seems the be set a certain tension at the factory but I found when they are left as is, my mounts rocks on this axis. forward and back. At first I thought this was the tripod until I took it off and confirmed it was the base plate of the mount. This would be severely detrimental with a big scope and any slight breeze as it was for me 2 nights ago.

Can you share of photo of which screws you are talking about? my polar alignment seems to change depending on where I am looking so I am wondering if I need to tighten them too
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battleriverobservatory 6.06
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·  2 likes
Brian Sweeney:
While people are talking about the cem70 I should mention this. There are 2 set screws at the front lower side of the mount, they lock the azimuth so it cannot rotate. This seems the be set a certain tension at the factory but I found when they are left as is, my mounts rocks on this axis. forward and back. At first I thought this was the tripod until I took it off and confirmed it was the base plate of the mount. This would be severely detrimental with a big scope and any slight breeze as it was for me 2 nights ago.

Can you share of photo of which screws you are talking about? my polar alignment seems to change depending on where I am looking so I am wondering if I need to tighten them too

Its the 2 set screws on the left and right.

https://drive.google.com/file/d/1_xKYrl64gWSOx_5OOp-96i7Nl-J7D5Md/view?usp=sharing
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Linwood 5.76
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That image is not accessible.
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bemo 0.00
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While people are talking about the cem70 I should mention this. There are 2 set screws at the front lower side of the mount, they lock the azimuth so it cannot rotate. This seems the be set a certain tension at the factory but I found when they are left as is, my mounts rocks on this axis. forward and back. At first I thought this was the tripod until I took it off and confirmed it was the base plate of the mount. This would be severely detrimental with a big scope and any slight breeze as it was for me 2 nights ago.

Thanks for the picture, so dou u mean that u just block these two screws and now its ok ? no more rocking of the base ?
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battleriverobservatory 6.06
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While people are talking about the cem70 I should mention this. There are 2 set screws at the front lower side of the mount, they lock the azimuth so it cannot rotate. This seems the be set a certain tension at the factory but I found when they are left as is, my mounts rocks on this axis. forward and back. At first I thought this was the tripod until I took it off and confirmed it was the base plate of the mount. This would be severely detrimental with a big scope and any slight breeze as it was for me 2 nights ago.

Thanks for the picture, so dou u mean that u just block these two screws and now its ok ? no more rocking of the base ?

Yup it locks in the azimuth so you can’t rotate. I should have taken pictures when I had it apart. It’s a wedge system but it’s a bad design. If your set screws are too tight you can’t rotate but if they’re too loose you have too much play. Best case is to loosen and tighten them each time you have to set it up. Worst case find exactly where you need to be tight so you still rotate the base. Which leads to metal wear IMO. For those in a permanent setup I recommend locking them in place. I literally could grab the counterweight rod and rock the mount up and down on this base before. It got worse the more I setup and took down my mount.
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uriabraham 0.00
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·  1 like
Hi gain guys,

Although my scope is not suitable for the iGuider I was still curious to see how the iGuider works.
Firstly I found that focusing the iguider is uneasy as it required a super gentle movement of a focusing knob which doesnt move smoothly and  it is super hard to adjust, in addition I always get vertical bands covering the whole FOV so hard to visually see any stars.

Has anyone had similar experience ?

Thanks
Uri
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Linwood 5.76
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·  2 likes
Yes. Focusing it is an exercise in frustration, and the image you get is poor.  Even with relatively long exposures I also got few stars I could see and have PHD2 track with (I did not try but I can't imagine metaguide can get anything for video speeds).

I did get it working, I did guide, it was not awful considering the short focal length.  But it is a lot more work than it is worth.

And by the way -- you can't access iPolar and it at the same time. Who knows why, they just won't both work together. Not like you NEED to, but often I only close iPolar down once everything else is up and sync'd and working, in case I kick the tripod or it settles or something.  You must release iPolar before connecting to iGuide.  Weird -- you would think they are just two video devices on the USB bus, but it's more complicated apparently.
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the_bluester 1.81
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·  2 likes
Are you setting the gain and exposure in the camera settings tab (Next to the PHD2 "Brain") as that was exactly how mine behaved until I did, noisy vertical lines and no stars. I set to gain 256 and exposure -6 (1.5 seconds) but with PHD2 set to 3 seconds so it is using every second frame (3 seconds, or -3 in the camera settings tab leaves me with lots of saturated stars)

With the gain and exposure set, I get a field full of stars, when I was imaging M42 you could actually see quite a bit of the nebulosity in the guider images. And yes, it is fiddly to focus, but I did that in about ten minutes on the first night and have not touched it since.

Guiding wise I am now getting about 0.9" RMS, not bad for a 120mm focal length guider and perfectly adequate for my imaging setup. I will go back to an OAG eventually but there is no rush for me to spend the money IMO, it is working perfectly well as it is.

I did have a few issues with the driver dropping settings (Degrees past the meridian and custom parking position) but i found recently that if I start the mount driver before connecting to it with my imaging program, it retains settings as it should. I just need to check if it "Finds" the mount if it is started up before you connect the USB, if so I will set Windows up to start the driver on boot so it is always running when called by the imaging platform.
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BrianSweeney 2.61
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·  1 like
As a followup about my wifi problem in case somebody else has the same problem.

iOptron provided the following instructions for fixing it
1. Remove the two screws on the plate where all the connections are.
2. Pull out the circuit board.
3. Press firmly on the wifi module.
4. Put everything back.

This worked for me. Seems the wifi module became loose in transit to my house.
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uriabraham 0.00
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Hi Paul,
Thanks very much for your reply, I initially adjusted the camera setting according to iOptron instructions (exposure -7)  and  did try to adjust the gain with no better results, however I haven't tried to go to 3 seconds in PHD. I will try your suggestion., thanks.

Guiding last night was horrible with the iGuider comparing to previous night i suspect due to bad seeing

Uri
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battleriverobservatory 6.06
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·  2 likes
2 months in I now have a problem with mine. It is no longer tracking properly. One night it ran flawless and I got my most recent image, the next night same setup I go out to get more data it no longer tracks proper and because of that it can't guide. I spent 2 nights and about 11 hours disassembling and reassembling every single component using different computers new firmware etc. My RA is constantly driving but it seems to be too much because the stars run off the image in a few minutes of sitting there watching it live. Moves faster than guide can correct and you hear a battle of wills back and forth. This had nothing to do with guide rate as tracking rate is dictated by the SIDEREAL which is the mode it is in. I will be sending this mount back to iOptron but will probably sell it and never buy another iOptron
My 2 Skywatcher mounts, never had a problem.
If I could go back I would keep my EQ6-R which guided my 37lb scope at .4" average and 2-3x better than this mount ever could dream of.
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