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timthelder

JMI EV-1cM motorized focuser

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Hi all.

Purchased one of these fairly recently and thought that I would give my humble opinion on it's performance.

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JMI focusers

After using a GSO dual-speed crayford-style focuser for several years, I was finally able to afford an electronic motorized focuser. I chose the JMI event horizon EV-1cM motorized focuser for Schmidt-Cassegrains.

This is a finely crafted focuser, I could immediately tell that the tolerances were much tighter than on my cheaper crayford.

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It's operation is smooth as silk and I cannot detect any significant amount of play in the focuser at all.

For planetary imaging it's fantastic. I used to look like I was doing 'palettes' exercises while staying on top of focus, but no more. I can happily sit and adjust focus by simply pushing a button on the hand control.

The hand control besides having back-focus and in-focus, also has a couple of focusing speeds, or if you simply hold down on one of the buttons for about 2 seconds it will automatically advance in the faster speed.

With a few more accessories available from JMI, it is controllable via a PC or laptop.

MOIO-focus control

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It can still however be operated manually with the simple turn of a thumbscrew which will engage/disengage the motorized gear that is controlled via the hand control unit, which is powered by a 9v battery.

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Overall, as you can read I am extremely pleased with the quality and performance of my new focuser.

Cheers, Tim.

(I do not endorse nor receive any gratuities from JMI products in any way...)

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As Captain Bristow would say "Damn fine machinery" I have drooled over JMI stuff for years, but condemned to the OPJ* brands.

I modified an Orion single speed focuser motor to a GSO Focuser. That works very satisfactorily, likewise a 9v battery lasts for a very long time.

* Other people's junk!

Cheers Dave.

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I have one of these exact focuser's Tim. It came with my C14. I've been very happy with it to date. I made up an extension cable so that the controller sits at my desk in the observatory, however I'm going to have a gander on their website and see what I need to control it with MaximDL. I've been out of the loop and didn't realise I could set it up with PC Control.

Ray

(I to, do not receive any money, bribes, favours, massages from JMI in anyway, however I'd like to:cool:).

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Looks neat Tim, as shown it looks like it fits a 1.25" nose on a camera or eyepiece for planetary photography. How does it adapt to using the f6.3 focal reducer and a larger t thread or 2" for deep sky images?

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Looks neat Tim, as shown it looks like it fits a 1.25" nose on a camera or eyepiece for planetary photography. How does it adapt to using the f6.3 focal reducer and a larger t thread or 2" for deep sky images?

Hey Tony, It is a 2" focuser. it comes with a 2" to 1.25" adapter. So it will easily accomodate a 2" barrel.

What I am starting to 'not like',in most all adapters, is compression ring tightening on AP instruments. There is a minimal amount of flop in compression ring tightening that one doesn't get with the old fashioned thumb screws.

BUT, As you know...Having experienced trying to focus manually for planetary AP, (with the scope shaking all around) A motorized focuser is absolutely 'Da'bomb!' (You just look at the screen and focus by pressing a button!)

Tim

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Have you got the focuser being adjusted through the computer yet? And because I'm "outta da loop" at the moment, is there software that can focus during an avi?

Ray

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I used to have a JMI Microfocus 2-speed knob that installed over the factory knob of my CPC-1100. It was a bit easy to knock out of alignment so I sold it and replaced it with a Starlight Feather-touch. It can be seen in this photo.

20140517_192031.jpg

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Sweet bit of kit Chris.

I purchased the motorized focuser primarily for planetary imaging. As the mirror adjusts to the temp changes during a session, constant focus check is imperative. The motorized focuser sure helps with the jitters being I no longer have to touch my scope, (except for flipping the filter wheel.) A motorized wheel is on my 'toy' wish list. The JMI's tolerances are also a lot tighter than my old GSO two speed focuser. Of course that's $150 vs. $500. The GSO wasn't bad for the money.

Now I just use the focusing knob on the scope for a rough focus. Although I still manually focus using the JMI focuser when using the DSLR 'live-view'.

Tim.

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How does that work' date=' Poppa Chris? What is it attached to, and what does it push against?[/quote']

Not sure what you are questioning there Aratus, but if it is the focuser knob, it completely replaces the factory Celestron knob. It then gives you two-speed capability, normal speed just like the original knob and a 1:10 low speed that allows for very fine focus adjustments. When NASA chose a C9.25 SCT to send to the ISS they used this same after market focuser. Needless to say I am very pleased with it. It only took about 10 minutes to change out the focuser knobs with a small Phillips screwdriver and a small crescent wrench (adjustable spanner). Wasn't too cheap though. About $250 USD if I remember correctly.

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Sweet bit of kit Chris.

Tim.

I have to second that Tim. First time I've seen one of those. Looks really well laid out.

Ray

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