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iOptron CEM25P -- worth getting?


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Is this mount suitable for DSO AP with a short refractor?

I'm attracted by the guaranteed PE upper bound, included GPS, and portable design. 

 

I know the common wisdom is to get an HEQ5/Sirius but I've encountered manufacturing quality issues (see my post history).

 

My only concern with the iOptron is that the mount is relatively new to the market, so I'd feel to an extent like a guinea pig. 

 

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11 hours ago, bokchoy ninja said:

Is this mount suitable for DSO AP with a short refractor?

That's pretty much what it's designed for. I've been running on for the past year with only a few minor grumbles. I'm now using it with a 102mm/700mm triplet, guidescope, filterwheel etc which is pushing the payload a bit, but it's still delivering good subs most of the time, as long as you get it balanced well. 

I did run into an issue with declination backlash which was solved using this pdf, https://drive.google.com/file/d/1-uq7suUJw8osozk1aGyOzTlRVwXDEi5V/view  I would hope this is something they'd sort in the factory now. Ioptron's QC has improved a lot in the last couple of years. 

Overall it's a great little mount, but I'll probably be upgrading soon. 

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2 hours ago, JimothyC said:

That's pretty much what it's designed for. I've been running on for the past year with only a few minor grumbles. I'm now using it with a 102mm/700mm triplet, guidescope, filterwheel etc which is pushing the payload a bit, but it's still delivering good subs most of the time, as long as you get it balanced well. 

I did run into an issue with declination backlash which was solved using this pdf, https://drive.google.com/file/d/1-uq7suUJw8osozk1aGyOzTlRVwXDEi5V/view  I would hope this is something they'd sort in the factory now. Ioptron's QC has improved a lot in the last couple of years. 

Overall it's a great little mount, but I'll probably be upgrading soon. 

Hey cool, thanks for the reply. I just pulled the trigger on it!

Got any photos of or from your setup?

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I would add a yes to this, I've had mine for a year and have been using it with a William Optics Z73 to great effect. I think it is hard to beat in terms of performance vs. weight vs. cost, if you are looking for a portable or beginner mount, as I was. You can see images from the setup from the Astrobin link in my signature...most of the pictures are with the CEM25P. Autoguiding is a must, though, 45 seconds was the most I could bear unguided, although I've seen some people get amazing results with 2 minute subs.

Seems robust - used it in winter temperatures of -5C and also took it with me to Mauritius last year (I live in the UK). 

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16 minutes ago, eshy76 said:

I would add a yes to this, I've had mine for a year and have been using it with a William Optics Z73 to great effect. I think it is hard to beat in terms of performance vs. weight vs. cost, if you are looking for a portable or beginner mount, as I was. You can see images from the setup from the Astrobin link in my signature...most of the pictures are with the CEM25P. Autoguiding is a must, though, 45 seconds was the most I could bear unguided, although I've seen some people get amazing results with 2 minute subs.

Seems robust - used it in winter temperatures of -5C and also took it with me to Mauritius last year (I live in the UK). 

Nice set of images. I have the same scope/flattener and looking for a better portable mount rather than the Star Adventurer I use with it at the moment. Looks a good combination.

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2 hours ago, alexbb said:

For the owners, mind if I ask how does the typical guiding look like? arcsec P2P and RMS.

Polar aligning with a Polemaster and using an OAG, I average between 0.5"-1" (pixels right? The number in brackets on PHD2). 

I've seen better guiding than that but not often. This could also be due to having the wrong settings in PHD2...I've not been that scientific with it.

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49 minutes ago, eshy76 said:

Polar aligning with a Polemaster and using an OAG, I average between 0.5"-1" (pixels right? The number in brackets on PHD2). 

I've seen better guiding than that but not often. This could also be due to having the wrong settings in PHD2...I've not been that scientific with it.

" represents arcseconds which is the relevant measurement unit. It is also relevant only if you entered properly the guiding camera's pixels' size and the focal length.

0.5"-1" RMS is very good for such a small mount. You should aim for a RMS tracking figure about twice more precise than the desired imaging resolution.

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I routinely see sub 1” when guiding. And that’s with a 102mm. 

Heres my setup in action. I had to get hold of a extension for the counterweight bar to help it balance.  

Also attached a pic of the soul nebula I’m H alpha . Which i think were 640s exposures  

 

 

405BB12C-E749-4B21-87F4-8FDBAD211136.jpeg

5A33189E-21CE-44FA-928E-F1A92710B53B.jpeg

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3 minutes ago, JimothyC said:

I routinely see sub 1” when guiding. And that’s with a 102mm. 

Heres my setup in action. I had to get hold of a extension for the counterweight bar to help it balance.  

Also attached a pic of the soul nebula I’m H alpha . Which i think were 640s exposures  

Awesome rig! What scope is that? How close are you to the weight limit?

Edited by bokchoy ninja
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Thanks. It’s an Altair Astro 102/700 Super triplet. So I thInk made in the same factory as the TS and Williams Optics stuff. Not weighed the whole setup yet, but I must be well over the recommended 1/2 payload for imagining. 

She guides ok but can take a while to settle after dithering.  

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1 hour ago, alexbb said:

" represents arcseconds which is the relevant measurement unit. It is also relevant only if you entered properly the guiding camera's pixels' size and the focal length.

0.5"-1" RMS is very good for such a small mount. You should aim for a RMS tracking figure about twice more precise than the desired imaging resolution.

Thanks for the clarification - when I said I wasn't scientific in PHD2, I mean I still tweaked the more "obvious" settings...but I haven't spent an evening fine-tuning all the settings to perfection for example!

Here is a picture of my rig:

20190224_171520-1814x2419.thumb.jpg.570356509ba992dd92a387d99cc4a25a.jpg

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8 minutes ago, eshy76 said:

Thanks for the clarification - when I said I wasn't scientific in PHD2, I mean I still tweaked the more "obvious" settings...but I haven't spent an evening fine-tuning all the settings to perfection for example!

Here is a picture of my rig:

 

Sweet! What are those black containers on top, batteries?

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2 hours ago, bokchoy ninja said:

Sweet! What are those black containers on top, batteries?

From left to right - 1. Minix mini-PC - this runs all my imaging and guiding. I remote into it using an iPad via the little white travel router on top 2. Bottom - yes a lithium ion battery for the dew heater 3. On top of the battery is a Lacerta dew heater controller which measures the ambient temperature to regulate my dew heater.

I velcro all this to a dovetail which is bolted onto the scope rings...I've since moved to a lighter dovetail, as the one in the picture was unnecessarily heavy. Next stop is to shorten as many of the cables as I can....

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I'm getting around 0.8" on a good night, 1.2" on an OK night. I'm using a Stellarvue SV70t-IS, effective focal length of 336mm. That's with an Orion 50mm guidescope on a finder shoe, which is hardly ideal. As for what you can shoot with a CEM25P -- oooh, an excuse to post my Horsehead again? 

combo_stacked_composite-denoise smaller.jpeg

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4 hours ago, rickwayne said:

I'm using a Stellarvue SV70t-IS, effective focal length of 336mm.

Yes, very nice image of the horse and flame ?

Can you confirm pixel scale or imaging camera for this please. Also sub exposure durations.

I'm looking at the CEM25P for a lightweight travel mount and so very interested in real world performance.

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Oh, sure. I was using an ASI 183MM Pro, about 1.4" per pixel. Combination of 300s and 600s exposures, all the tech deets you can eat at Astrobin.

I got mine with the 2" tripod, haven't used it with the 1.5" but was cautioned to steer clear of that one. I've never recorded periodic error correction for the mount.

I also got some results unguided with the thing, including a not-APOD-but-recognizable M33 with a 1000mm scope and my Pentax DSLR. Image scale on that is more like 1" per pixel, and I was doing 4' 27" exposures. Pretty much an acid test for a duffer like me.

I was going to urge you to consider iOptron's Powerweight counterweight battery but I see they've discontinued it. Clever idea to save overall weight, I thought. Of course one could build one's own.

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