Anyone using the JMI Motofocus?

[glend (Glen)]

To start with I have one of these and have mounted it, and subsequently removed it, from my 16" dob. I wanted to get some feedback from people using it on a regular basis, as I find it frustratingly slow. Is there some magic that can be done to speed it up in use?

As a visual observer, I find the Crayford 10:1 focuser on my dob very easy to use, but it can lead to loss of object if bumped slightly at high magnification (ie the scope moves), particularly when kids are trying to look through the scope and can't seem to look without touching; so I thought a Motofocus would allow more observation time through less chance of movement through having to touch the knob. It does work, it just seems to take forever to get anything in focus, and EP changes become slow compared to the manual process of just using the larger higher speed focus knob to goto focus quickly. There doesn't seem to be an easy way to dis-engage the Motofocus temporarily for an EP change and refocus, other than unlocking the focuser and moving the tube by hand to achieve near focus and using the Motofocus from there.

Any opinions on these things, are they just another junky accessory with little value in real world use?

[Stardrifter_WA]

I use JMI focuser's, and other JMI accessories on my scopes. I am a big fan of JMI products, as most of their products that I use are great, but some do have limitations, as they are a compromise.

I particularly like their focuser's and have had a few of them, although I use their top of the line Event Horizon focuser's. To me, the real advantage of the JMI focuser is the discreet motor that they have. .

As for the Motofocus that you attach to your current focuser. In this regard, I am inclined to agree that they are not really that great, as they are a compromise and have limitations, which is why I went for the full focuser, although these are not cheap, but they are fantastic, in my view. I use JMI Focuser as I am only a visual observer and don't need the computer control features of the Moonlite focusers.

On my Event Horizon focuser hand control, there is a slide switch that switches between slow speed and high speed, and I have always found the high speed to be more than adequate. See picture at http://www.jimsmobile.com/images/ev_2cm.jpg or here
http://www.jimsmobile.com/images/ev_2nm.jpg

I rarely have to disengage the motor to focus, however, I do use parfocal eyepieces anyway.

Cheers Pete

[deanm (Dean)]

I use JMI's Motofocus on an C11 - couldn't be happier!

Dean