ZWO EFW 8 x 1.25″/31mm

Our latest EFW (Electronic Filter Wheel), larger than the previous but still low on weight. Only 400 grams (14 oz)!

The body is CNC milled from an aircraft graded aluminum block.
We decided to make it thinner, where it measures only 20 mm on the wheel body.

The heart of our EFW comes from NPM, Japan, whose the manufactor for the stepmotor and the quality is trustful and reliable. Guaranteed long life.

The Electronic Filter wheel can be rotated in both counter clockwise or clockwise direction for filter selection.

There are no need for multiple cables to power this wheel up, just one USB cable does the trick.The power consumption of this EFW is approximately 120mAh @ 5V, which can be operated from the Cooled CCD’s USB hub.

The distance between the filter and sensor is around 10mm when you connect it to ASI1600.

So 1.25″ filters won’t have vignetting up to F5 focal ratio scope and 31mm filter won’t have vignetting up to F2 lens.

Our new RGBL filters are recommended to work with ASI1600, it will offer nearly 1:1:1 RGB color balance.

What’s in the box?

1. 8*31mm EFW body
2. 1.25″ cover
3. T2 nosepiece
4. 1.25″ holder(with cover and 2 screws)
5. T2-T2 adapter(male)
6. A bag of filter masks
7. USB2.0 2m cable
8. Phillips screwdriver
9. A bag of M2 screws

How to install the filter?

1.25″ filters required to be: threaded  shorter than 3mm in length,  without threads less than 7mm in height

1. Take the back cover off
2. Lay the wheel down flat
3. Screw-in the filters up
4. Put the back cover on

Take the EFWmini for an example:

31mm and 36mm filter requires: a set of M2 screws and washers needed to fix the filters are included in the package .

1. Take the back cover off. Lay the wheel down flat
2. Hold the filter by the very edges and lay them in to the recess for each position
3. Attach the washers,put in the screws
4. Put the back cover on

Take the EFWmini for an example:

How to connect with the camera and telescope?

How to use it?

you just need to plugin the EFW with USB2.0 cable and install the   ASCOM driver

There are  ZWO Filter Wheel(1) and ZWO Filter Wheel(2) to select,  you can use either one of them

There are 2 ASCOM is for controling 2 EFW in one software.

Mechanical Diagram

Q & A

1. My EFW tries to move but gets stuck and cannot arrive at the right position.

1) Filter is too thick: Filters (not including the threads) must be less than 7mm in thickness and threadsmust be less than 3mm in thickness.

2) The M2 screw used to secure the filter is too long and causes the wheel to jam.

3) The M42 thread of the scope or the camera is too long and protrudes into the filter wheel, hitting the filter or wheel, causing it to jam.

2. My EFW spins but never stops, or stops at the wrong position.

ZWO EFW uses an infrared sensor to check wheel position.  If the sensor malfunctions, you can usually resolve by recalibrating the EFW in the ASCOM driver. Simply click “ReCalibrate” in ASCOM driver interface. It can take up to 60 seconds to perform this action.

3. I use 7-position EFW, normally I had slots 1, 2, 3, 4 filled and slots 5, 6, 7 empty, but then I got the error below and the EFW stopped working. I checked the carousel. It was not too tight or loose.

When using the filter wheel it is very important to keep its internal balance. The weight and distribution of the filters will affect balance. Thus we recommend you space the filters out and evenly distribute them. In this case, install them in slots 1, 3, 5 and 7, then the EFW will work again.