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CEM40 buyer's remorse?

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16 replies to this topic

#1 klaussius

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Posted 08 April 2021 - 03:37 PM

Hey guys.

 

I think I did thinks backwards.

 

I have been considering upgrading my mount (EQ5 non-goto) that I overload with my equipment nightly for a while now. My heaviest load includes the Explorer 150PDS (Newt) + Camera + CFW + Travelscope 70 guide scope, bordering 10kg total.

 

Problem I'm getting with the EQ5 is that it's not very precise and I don't get good guiding with it. In fact it's getting worse, I think it needs a tuneup.

 

So I did my research, and I was already decided on an EQ6-R Pro, when I was informed that SkyWatcher was super delayed (18 months IIRC). I saw an iOptron CEM40 that wasn't delayed, checked the specs, seemed close enough, checked some reviews from people that considered them both equivalent, and so I pulled the trigger.

 

Now I kept reading and I'm not so sure... all those "reviews" were from people doing visual. Oops.

 

So, I'm doing what I should have done before ordering it, asking here. What do you guys think? Can the CEM40 handle my eqiupment better than my EQ5? Should I wait 18 months for the EQ6-R instead?

 

I think I might still be on time to change my mind if I need to.

 

The CEM40 seems to be the higher-end model available here, so if I need something better I'll be in a tough position to find it. But better wait for something to be available than purchase something that won't do the trick I guess.


Edited by klaussius, 08 April 2021 - 03:38 PM.


#2 Jose_Salcedo

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Posted 08 April 2021 - 03:42 PM

I purchased a CEM40-EC mount with the 2” tripod from iOptron just 2 months ago for my smaller scope, a WO ZS81 APO loaded with stuff for AP (with a 260MM Pro camera). Total load is 9kg. I love the mount. I routinely do 10min guided exposures with rms errors below 0.5”. It is compact, reliable, solidly built and easy to carry. Get a very solid tripod, though.

You may also consider the CEM-70, one step up and quite possibly more appropriate to handle a 150mm refractor.

Clear skies.

Edited by Jose_Salcedo, 08 April 2021 - 03:45 PM.


#3 pyrasanth

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Posted 08 April 2021 - 03:48 PM

CEM40 is rated at 40 lbs max- go 30 lbs for AP and you will be fine- they are solid mounts when you get a good one. I have the CEM70G and its great for my long tubed RASA and I'm probably around 46 lbs total with 60 lbs of counter weights- no issues at all with guiding.


Edited by pyrasanth, 08 April 2021 - 03:48 PM.

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#4 wrnchhead

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Posted 08 April 2021 - 03:50 PM

I have used the EQ6R for a couple years now after an AVX. It's......better than the AVX, but it's not amazing. Out of the box, it could be considered bad honestly. I have had to twiddle with the gearing (the guiding got much worse after 3-6 months of use, it weighs a metric ton, both the USB ports (on-mount and on hand controller) have went out after only a few days use. 

 

So, I'm glad to have it, I didn't have 5k to spend so it filled my needs. If you are completely uncomfortable dialing things in, it would be awful. I would have had to send the mount itself in to get the USB port fixed and a couple months later again to have the gear mesh readjusted after break in. 

 

I wouldn't wait for one if you have the CEM option. I have no knowledge of those mounts, but I get the feeling they are pretty good. 


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#5 bobzeq25

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Posted 08 April 2021 - 03:56 PM

Hey guys.

 

I think I did thinks backwards.

 

I have been considering upgrading my mount (EQ5 non-goto) that I overload with my equipment nightly for a while now. My heaviest load includes the Explorer 150PDS (Newt) + Camera + CFW + Travelscope 70 guide scope, bordering 10kg total.

 

Problem I'm getting with the EQ5 is that it's not very precise and I don't get good guiding with it. In fact it's getting worse, I think it needs a tuneup.

 

So I did my research, and I was already decided on an EQ6-R Pro, when I was informed that SkyWatcher was super delayed (18 months IIRC). I saw an iOptron CEM40 that wasn't delayed, checked the specs, seemed close enough, checked some reviews from people that considered them both equivalent, and so I pulled the trigger.

 

Now I kept reading and I'm not so sure... all those "reviews" were from people doing visual. Oops.

 

So, I'm doing what I should have done before ordering it, asking here. What do you guys think? Can the CEM40 handle my eqiupment better than my EQ5? Should I wait 18 months for the EQ6-R instead?

 

I think I might still be on time to change my mind if I need to.

 

The CEM40 seems to be the higher-end model available here, so if I need something better I'll be in a tough position to find it. But better wait for something to be available than purchase something that won't do the trick I guess.

The CEM40 is very comparable to the EQ6-R, and much lighter.

 

I'd say sample to sample variability of each is larger than the difference between them.  A good X of either will beat a mediocre Y of either.

 

I think this person went from an HEQ5Pro to a CEM40, and is an imager.  You might PM him.

 

https://www.cloudyni...20011-randallk/


Edited by bobzeq25, 08 April 2021 - 04:04 PM.

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#6 cybermayberry

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Posted 08 April 2021 - 03:56 PM

For future reference Orion mounts are just rebranded sky watcher ones. Not sure of availability Buenos Aires how ever. I have heard very good things about iOptron CEM40 as well



#7 klaussius

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Posted 08 April 2021 - 04:08 PM

The CEM40 is very comparable to the EQ6-R, and much lighter.

 

I'd say sample to sample variability of each is larger than the difference between them.  A good X of either will beat a mediocre Y of either.

 

That's actually quite reassuring. I knew the EQ6-R had a bit of variability, but it's what's within my budget and am able to get my hands on, and at least lots of people have had great success with them. The dealer I'm used to dealing with does list the EQ8 and other bigger/better mounts, but they're way out of my price range for now.

 

So equivalence is a good thing, variance included.

 

 

You may also consider the CEM-70, one step up and quite possibly more appropriate to handle a 150mm refractor.

It's a newtonian, a bit lighter than a 150mm refractor, but still quite bulky and hard to balance.

 

I did consider the CEM-70 but it's unavailable at the moment.

 

 

For future reference Orion mounts are just rebranded sky watcher ones. Not sure of availability Buenos Aires how ever. I have heard very good things about iOptron CEM40 as well

 

I know an Orion dealer here in Buenos Aires, but it's way overpriced, and not as trustworthy as my skywatcher dealer. The price difference can be as much as 2x. Ouch.

 

 

So, I'm glad to have it, I didn't have 5k to spend so it filled my needs. If you are completely uncomfortable dialing things in, it would be awful. I would have had to send the mount itself in to get the USB port fixed and a couple months later again to have the gear mesh readjusted after break in. 

 

I wouldn't wait for one if you have the CEM option. I have no knowledge of those mounts, but I get the feeling they are pretty good. 

I wouldn't say I'm completely uncomfortable fiddling with mounts, but I'm no mechanic. I can tune worm gears or belts, but if it comes to in-depth maintenance like re-greasing and that kind of stuff, I'm way out of my comfort zone (and area of expertise).

 

In fact I will have to do that kind of maintenance to my EQ5, but I would prefer to have a backup before I do that. There's a high chance I might break something.

 

PS: Thanks for the replies guys :)


Edited by klaussius, 08 April 2021 - 04:11 PM.

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#8 imtl

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Posted 08 April 2021 - 04:28 PM

I think you will do fine with it. Maybe a bit of a balancing challenge with your imaging gear but once you got that dialed in it should run well. DO NOT turn on guiding and PEC together.


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#9 sbharrat

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Posted 08 April 2021 - 07:19 PM

...DO NOT turn on guiding and PEC together.

Is this something specific to the CEM-40? For the HEQ5/Sirius, I was following the EQMOD directions and am doing this....



#10 jonnybravo0311

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Posted 08 April 2021 - 08:28 PM

Definitely specific to the CEM40 (maybe other iOptron models as well). PEC + PHD = BAD :D.


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#11 bobzeq25

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Posted 08 April 2021 - 08:51 PM

Definitely specific to the CEM40 (maybe other iOptron models as well). PEC + PHD = BAD laugh.gif.

But there's a fine alternative.  The Predictive algorithm in PhD2 does periodic error correction "on the fly".  It's just as good, arguably better.


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#12 jonnybravo0311

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Posted 08 April 2021 - 09:17 PM

But there's a fine alternative.  The Predictive algorithm in PhD2 does periodic error correction "on the fly".  It's just as good, arguably better.

Totally agree, and it's what I use.


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#13 imtl

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Posted 09 April 2021 - 12:26 AM

Sorry I should have clarified. It's specific to Ioptron mounts. Actually, CEM40, CEM60 since that's all the experience with Ioptron mounts I have. But I think it is a driver issue with the Icommander. Anyways, PPEC in PHD2 is great as other suggested. With my old CEM60 and multi star guiding I used to get 0.4" rms regularely.



#14 limeyx

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Posted 09 April 2021 - 12:21 PM

Totally agree, and it's what I use.

Wondering if this would work better for me with my SkyGuider -- while I continue to wait for the CEM70

As far as I know, the same limitations are present on the CEM70 as the other listed mounts



#15 bemo47

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Posted 09 April 2021 - 01:01 PM

but regarding PEC on the mount + PHD or any guiding, when i talk about that, manytime the answer is :

- PEC on the mount is there for those who doesn't want to guide, its there as an improvement of the follow capability of the mount

- but if we want to guide, then we must disable PEC and do a guiding with any system like PHD or others...

 

what do u think about that ? could it be the right anwser ? PEC OR guiding and not PEC AND guiding....



#16 jonnybravo0311

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Posted 09 April 2021 - 01:09 PM

but regarding PEC on the mount + PHD or any guiding, when i talk about that, manytime the answer is :

- PEC on the mount is there for those who doesn't want to guide, its there as an improvement of the follow capability of the mount

- but if we want to guide, then we must disable PEC and do a guiding with any system like PHD or others...

 

what do u think about that ? could it be the right anwser ? PEC OR guiding and not PEC AND guiding....

Your first point is incorrect. PEC is not there for those who don't want to guide. It is there as a way for the mount to proactively correct itself for known and repeating periodic error. It typically works very well in conjunction with guiding.

 

PEC and guiding is great, unless your mount is iOptron. Then, it is PEC or guiding.


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#17 sbharrat

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Posted 09 April 2021 - 01:11 PM

but regarding PEC on the mount + PHD or any guiding, when i talk about that, manytime the answer is :

- PEC on the mount is there for those who doesn't want to guide, its there as an improvement of the follow capability of the mount

- but if we want to guide, then we must disable PEC and do a guiding with any system like PHD or others...

 

what do u think about that ? could it be the right anwser ? PEC OR guiding and not PEC AND guiding....

Well the PHD2 best practices https://openphdguidi...stPractices.pdf says to use PEC if your mount has it and you are using pulse guiding. And eqmod manual says to do this as well. The rationale given that I have read is that PEC is making the (periodic) corrections at a very fast frequency and PHD2 is making the additional (unpredictable) corrections at a much slower frequency (determined by exposure time).

 

My understanding of the comments in this thread is that for THIS mount, PEC by mount and pulse guiding don't play well together. 


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