Question about the JMI NGF-DX3 Focuser
Posted 27 January 2004 - 01:29 PM
Does anyone have a JMI NGF-DX3 focuser and/or have commentary on it? I am considering one for my 8" refractor. All responses welcome!
Posted 27 January 2004 - 06:13 PM
Posted 27 January 2004 - 06:26 PM
Posted 28 January 2004 - 12:53 AM
Posted 28 January 2004 - 05:38 PM
I found out that this is a focuser that is from a 18" starsplitter Dob. It was upgraded to a feathertouch!!! I'll pick it up tonight and make it fit on my Dob, since it has the flat base. Should be straight forward to make a wood block with a curve to fit my tube. I hope this will be the best bang-for-the buck upgrade for my scope in addition to putting it on a GEM.
Posted 28 January 2004 - 10:54 PM
Std focuer tube is 3" and that is what this one has I beleive.
I think you will need an extension to get your ep's to focus. These low profile focusers generally do not have enough travel to directly replace an R&P without an extension. While your R&P may have two or three inches of travel, it starts at about 3 to 4 inches above the tube. The top of the JMI is about 1.6” above the tube (when racked in) I believe. The JMI DX3 with a 3” tube gives you a maximum height of 3.41” (plus the height of whatever base you come up with). Not enough to bring your ep’s to focus. Probably a JMI 1.5” extension would work well.
Posted 29 January 2004 - 12:20 AM
This is a very nice focuser and I look forward to getting it on my scope and trying it out. I also got to admire his 18" Starsplitter Dob. What a beautiful scope! I hope I get to look through it one day.
Posted 29 January 2004 - 06:55 PM
You're right Stacy, need to get the 2" extender to match the R&P focuser I have now. You'll notice the curved base. It is designed for a 12.5" Dob (14"+ diameter) and it will definitely need to be shimmed or not used. I hope the holes are going to match but I'm not ready to put it on yet.
Posted 30 January 2004 - 12:58 AM
Posted 30 January 2004 - 10:55 PM
The unit is adjustable for collimation which is a nice thing to have. The Crayford mechanism has very precise motions. You can move the focuser in very small increments with no backlash.
For a moderate priced unit I would rate it very well.
Posted 31 January 2004 - 01:25 AM
Posted 31 January 2004 - 02:36 AM
My only peeve is that sometimes I bump the eyepiece, and as the thing is very smooth, it will push the focuser out of focus.