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Stargazing June 15th ✦ 6pm-10pm
Stargazing June 15th ✦ 6pm-10pm

ZWO 7-Position Electronic Filter Wheel for 2-Inch Filters

by ZWO

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The filter wheel body is CNC milled from an aircraft graded aluminum block.

Excellent craftsmanship, very thin and light with only 20mm thickness.

The core part of our EFW is the stepper motor which has reliable performance and quality that comes from NPM, Japan.

We have two specifications for EFW2”:

  2″ Thread-In Filters or

50.4mm ±0.5mm Unmounted Filters can be used 

The 2” Electronic Filter Wheel can be rotated in both counter clockwise and clockwise direction for filter selection.


Requirements for 2inch filter from third party

Filters (not including the threads) must be less than 7.5mm in thickness and less than 50.8mm in diameter. Threads must be less than 2.7mm in thickness.


What’s in the box?

1. EFW2*5 or FW2*7 body
2. USB2.0 – 2m cable
3. A bag of M2.5*6 screws (6pcs/ bag)
4. A bag of filter masks for 50mm filters (7pcs/ bag)
5. Phillips screwdriver
6. A bag of M2*4 flat screws (23pcs/ bag)
7. M54M-M48F adapter
8. M54M-M42F adapter


6200-55mm-backfocus-solution-5 (2)

*5mm sensor tilt adapter is REMOVED from the camera.

This is the very first and also the most recommended connection solution. The combination of the mono full-frame camera and 2”filter wheel can create many possibilities on your astrophotos. The use of OAG will also help simplify your imaging setup by replacing the guide scope. It’s very suitable for the middle and high-level astrophotographers.

The installation of the M68 OAG, 2” EFW and ASI6200 camera is not very complex, but considering you need to remove the sensor tilt adapter of the camera first, so we’d like here teach the detailed connection steps to help you quickly complete installation without making mistakes.


The detailed guide of the fifth connection solution:

1) Disassemble the 5mm sensor tilt adapter on the main camera with the help of a screwdriver:

connect ASI6200 with 2inch EFW-1

2) Remove the back cover of EFW:

connect ASI6200 with 2inch EFW-2

3) Disassemble the filter wheel carousel (Note: Please do not disassemble or move the central screw of this carousel, otherwise the EFW will be damaged):

connect ASI6200 with 2inch EFW-3

4) Align the four screw holes of EFW with these in the four corners of the camera chip as shown below:

NO.5 对准EFW与主相机接口位置

5) Tighten the screws at the interface between the EFW and the main camera:

connect ASI6200 with 2inch EFW-5

6) Install the filter wheel carousel:

connect ASI6200 with 2inch EFW-6

7) Fix the M68 OAG to the back cover of EFW

Note: You may reposition the prism to make sure it would not block the sensor.

The M2.5*8 screws used here can be found in the package of M68 OAG.

connect ASI6200 with 2inch EFW-7

8) Fix the 5mm sensor tilt adapter to this M68 OAG. If the thread of the telescope side is M42 or M48, then you should use the M54 sensor tilt adapter just removed from the camera. While if the thread of the telescope side is M68, then you should use the new M68 sensor tilt adapter.

connect ASI6200 with 2inch EFW-8

9) Attach the back cover of EFW to the front cover:

connect ASI6200 with 2inch EFW-9

10) Installation completed.

connect ASI6200 with 2inch EFW-10



*In all solutions, the producing motor side of the EFW(the side where the ZWO logo lies in) attaches to the camera.

*Please make sure the prism does not block the sensor or your telescope.

*Adjust the focal length of a guide camera by using the guide knob.

*It would be better if you finish the above steps during daytime, as it is very difficult to adjust it accurately at night.