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Extension Tubes

Threaded Output Adapters

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What is an Extension Tube?

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Focuser Adapters Plus...

 
Flat Backup Plate
Add Support When Mounting JMI 1.25" or 2" Focusers to Cardboard or Wood Optical Tubes



ADPTBUPF
$25

Buy Now
Curved Backup Plate
Add Support When Mounting JMI 1.25" or 2" Focusers to Cardboard or Wood Optical Tubes



ADPTBUPC
$
25
Buy Now

Backup Plate

For adding support when mounting JMI EV, NGF (1.25" and 2") or RCF focusers on Sonotube (cardboard) or wooden optical tubes.  (Will not work with the EV-75 Upgrade.)  The 0.075" thick aluminum plate can be easily curved or flattened as needed.

 

 
1.25" Eyepiece Adapter
For Inserting 1.25" Eyepieces in a 2" Diameter Drawtube



ADPT2-1.25
$49
Buy Now

1.25" Eyepiece Adapter

Adapter for inserting 1.25" accessories in a 2" drawtube.  The adapter uses a compression ring to secure inserted equipment.  It includes a slot on the 2" outside surface for securing the adapter in a drawtube with a compression ring.  It also includes standard 48mm filter threads.  (This adapter is a standard accessory with EV-1n, EV-2n and Ev-3n focusers.)  See the Adapter Comparison Chart.

Our 1.25" Eyepiece Adapter (shown), T-thread Adapter and Enhanced Extension Tubes include a compression ring for holding eyepieces and accessories without scratching the equipment.  The adjusting screw presses against the ring which tightens around the eyepiece or accessory.
 
Combination 1.25" Eyepiece and T-thread Adapter
Holds Either Eyepieces or Other Equipment with "T" Threads



ADPT2-1.25T
$55
Buy Now

Combination 1.25" Eyepiece and T-Thread Adapter

Adapter for mounting a CCD or other camera, with a standard T-thread, into a 2" drawtube.  It also doubles as a 1.25" adapter.  A T-adapter holds a CCD camera more securely than a standard 1.25" adapter.  The adapter uses a compression ring to secure inserted equipment.  It includes standard 48mm filter threads.  See the Adapter Comparison Chart.

 
2" Eyepiece Adapter
For Inserting 2" Eyepieces in a 3" Diameter Drawtube



ADPT3-2
$75
Buy Now

2" Eyepiece Adapter

Adapter for inserting 2" accessories in a 3" drawtube.  The adapter uses a compression ring to secure inserted equipment.  (This adapter is a standard accessory with NGF-XT focusers.)  See the Adapter Comparison Chart.

 
Enhanced
Extension Tube
2" Diameter
2.13" Height



ADPT2X2.1E
$75
Buy Now
Enhanced
Extension Tube
2" Diameter
2.63" Height



ADPT2X2.6E
$79
Buy Now
Enhanced
Extension Tube
2" Diameter
3.13" Height



ADPT2X3.1E
$79
Buy Now
Standard
Extension Tube
1.25" Diameter
1.6" Height



ADPT1EXT
$45
Buy Now
Standard
Extension Tube
2" Diameter
1.5" Height



ADPT2EXT
$49
Buy Now
Standard
Extension Tube
2" Diameter
2.5" Height



ADPT2EXTL
$59
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Extension Tubes

Enhanced extension tubes include a compression ring and 48mm filter threads.  See the Adapter Comparison Chart.

2" diameter x 2.13" height
2" diameter x 2.63" height
2" diameter x 3.13" height

Standard extension tubes do not include a compression ring or filter threads.  See the Adapter Comparison Chart.

1.25" diameter x 1.6" height
2" diameter x 1.5" height
2" diameter x 2.5" height

NOTE Since JMI focusers are low profile, you may need extension tubes to reach focus after converting from a high profile focuser (longer drawtubes are also available) or to alternate between visual and photographic positions.

Enhanced Extension Tubes come in three sizes.  All three are for 2" drawtubes and include a compression ring (see below) and filter threads.  The extension lengths are 2.13", 2.63" and 3.13".

Standard Extension tubes come in three sizes.  Two for 2" diameter drawtubes and one for 1.25" drawtubes.
The Enhanced Extension Tubes include a compression ring (just like the EV drawtube shown at left) for holding eyepieces and accessories without scratching the equipment.  The adjusting screw presses against the ring which tightens around the eyepiece or accessory.

 

 
SCT Threaded Output Adapter
2"
2" Threaded Output
2" Diameter Input



ADPT2THREAD
$49
Buy Now

SCT Threaded Output Adapteró2"

Standard SCT threaded output for inserting into a 2" drawtube.  This adapter duplicates the standard 2"-24 threads found on a small SCT allowing standard SCT accessories to be attached to the output of any 2" focuser.  An indentation on the side (in combination with a compression ring) makes it resistant to falling out when using heaving equipment.  It also includes 48mm inside filter threads.  (This adapter is a standard accessory with EV-1c, EV-2c and EV-3c focusers).  See the Adapter Comparison Chart and the Refractor Diagram.

These adapters give output of standard SCT threads.   The first fits into a 2" drawtube and the second fits into a 1.25" drawtube.  This adapter allows attachment of standard SCT accessories on the output side of a focuser.  With this adapter you could even mount a JMI focuser on the back of a refractor.
 
Large Format SCT Visual Back Adapter
for NGF-XTc
3.25"
Non-vignetting Adapter for Mounting NGF-XTc on 10" to 14" SCTs



ADPT3XT
$65
Buy Now
Large Format SCT Visual Back Adapter
for NGF-XTc
4"

Non-vignetting Adapter for Mounting NGF-XTc on 16" SCTs



ADPT4XT
$129
Buy Now
Large Format SCT Visual Back Adapters for NGF-XTc

Non-vignetting adapters for mounting an NGF-XTc focuser on a 10" to 14" SCT with 3.25" diameter threads or 16" SCT with 4" diameter threads.  (The 3.25" adapter is a standard accessory with an NGF-XTc focuser)  See the Adapter Comparison Chart.

3.25" diameter threads
4" diameter threads

 
Astro-Tech RC
Visual Back Adapter
for NGF-XTc
M117x1
Non-vignetting Adapter for Mounting NGF-XTc on M117x1 Threads



ADPT117XT
$169
Buy Now

Astro-Tech RC Visual Back Adapters for NGF-XTc

A non-vignetting adapter for mounting an NGF-XTc focuser on an Astro-Tech 10" or 12" RC Astrograph with M117x1 threads.  See the Adapter Comparison Chart.


Focuser Motors

 
Motor
for EV Focusers
Event Horizon Focusers
(Includes Hand Unit and Cable)



EV-MTR
$170
See
EV Individual Parts

Motor for JMI EV Focusers

JMI EV-1, EV-2, EV-3, EV-B, NGF-XTc / -XTn (after late 2006)

NOTE

The EV focuser's modular design means that you will NOT need to return the focuser for an upgrade.

 
Motor
for NGF Focusers
Next Generation Focusers



MFNGF...
$249
Buy Now*

Motors for JMI NGF Focusers

JMI NGF-1 / -2 / -3 / -4, NGF-55D / -55S, NGF-C, NGF-DX1 / -DX2 / -DX3 / -DX4, NGF-SE, NGF-XTc / -XTn (before late 2006), NGF-mini1 / -mini2 / -mini3 / -mini4, NGF-miniC

This is an aftermarket motor for upgrading a manual NGF focuser to a motorized focuser.  It includes the motor and any necessary mounting hardware as well as a hand control unit.

* In some cases, you will need to return the focuser to the factory for modifications.  Additional charges may apply for parts and/or labor.  (For more specific information, please review the notes below.)  For all NGF focusers we need to have certain information in order to supply the correct parts.  When ordering, please place a note in the shopping cart Comments area identifying the specific focuser model and purchase date.  A digital picture is "worth a thousand words" in describing the specific model.  If you email a picture, please give us your Order ID along with your Name.  If we need more information, we will contact you.

NGF-XTc / -XTn manufactured after late 2006,  Part Number EV-MTR ABOVE
NGF-XTc / -XTn manufactured before late 2006,  Part Number MFNGFXT
NGF-C, NGF-55D manufactured after 2003, Part Number MFNGFC
NGF-SE, NGF-55S, NGF-55D manufactured before 2004, Part Number MFNGFS
NGF-DX1 / -DX2, Part Number MFNGFDX1
NGF-DX3 / -DX4, Part Number MFNGF
NGF-1 / -2 / -3 / -4, Part Number MFNGFO
NGF-mini1 / -mini2 / -mini3 / -mini4, Part Number MFNGFMIN

NOTE

In most cases you do not need to return the focuser for the upgrade.  If you have an original focuser (see DRONGFO list above), an NGF-SE focuser or a focuser manufactured before 1998, we recommend that the focuser be returned to JMI for the motor upgrade.  (All NGF-1 focusers must be returned for modifications to the base.)  With some focusers (generally those manufactured before 1998) we may not be able to provide the right parts without examining the focuser and there may be an extra charge for specialized parts and/or labor.  Normal labor charge for an upgrade is $20.

If you place an order without returning the old focuser, we will need to know approximately when it was manufactured.  Damage done during installation by anyone other than factory trained technicians will void the warranty.  Please see our document titled JMI Return Policy for additional information.

Please note:  The hand unit in the picture is an old version.

ngf_mfupgrade.jpg (51501 bytes) This picture shows a Motor Upgrade has been installed on an old NGF-1 focuser.

 

 

 
Motor
for RCF Focusers
Reverse Crayford Focusers



MFRCF
$189
Buy Now

Motor for JMI RCF Focusers

JMI RCF-1, RCF-mini1

This is an aftermarket motor for upgrading a manual RCF focuser to a motorized focuser.  It includes the motor and any necessary mounting hardware as well as a hand control unit.

Please note:  The hand unit in the picture is an old version.


What is an Extension Tube?

Extension tubes are placed in the end of a drawtube to extend the length of the drawtube.  If you have replaced a high-profile focuser with a low-profile model, an extension tube may be necessary to reach focus.  A longer drawtube is another option to consider.  Extension tubes can also be useful for alternating between visual and photographic positions.

JMI sells standard and enhanced extension tubes.  The enhanced version includes a compression ring for holding equipment without scratching the surface.  The adjusting screw presses against the ring which tightens around the eyepiece or accessory.  Filter threads are also included in the bottom of the extension tube for holding 48mm filters.


Customer Comments

"... THAT is excellent service !!!  JMI, I will be one of your customers in the future and I will recommend your company to one and all !!!!."  (B. H.)

"... I LOVE the quality of your equipment."  (J. L.)

"The whole amateur community owes companies like yours a very great deal; uncompromising quality at the cutting edge is what has driven this hobby forward so amazingly in the last twenty years and where our entire future lies."  (J. K.)


Frequently Asked Questions (FAQ)


Q. Questions?
A. No FAQs at this time.  Let us know if you have any suggestions.