EFW 7*36-II

ZWO EFW 7x36mm Filter Wheel


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New ZWO EFW 7x36mm

The new 36mm EFW (Electronic Filter Wheel) was independently developed by ZWO for astronomical mono cameras. With the larger body and the newly-added screw holes on the covers, it will give a much easier and more fixable way to connect to ASI cameras.

There are 7 slots inside the EFW and we recommend you use the ZWO 36mm LRGB and SHO filter set with it.

The body is CNC milled from an aircraft-graded aluminum block. It is made with high quality and thin with a thickness of only 20mm. The heart of the EFW uses quality stepmotors produced by NPM, Japan, which can be very trustworthy. When photographing, you can rotate the EFW in both counterclockwise or clockwise directions for filter selection. The whole operation process is rather convenient and efficient.

Compared to the original 36mm EFW, you may find the new EFW has a bigger size. The screw holes on the front and back covers shall not only allow us directly connect the 36mm EFW to the camera and bring the filters closer to the camera sensor, also make the it possible to match it with M68 OAG.

There is no need for multiple cables to power this filter 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 CMOS’s USB hub.

All ZWO 36mm filters can be perfectly supported by this EFW. But if you use filters from third party, then please make sure the thickness of the filter should be between 1.5mm and 3.0mm (the thickness of the filter frame is 1.8mm).

What’s in the box?


Specifications for the darkening sets(4pcs):

External diameter: 88mm. Inner diameter: 55mm (2pcs) & 58mm (2pcs). Thickness: ≤0.2. 4pcs in total.
* The reason for including the darkening sets is to help solve the light leaking issue occurring in the gap of the filter wheel and camera.

How to install the darkening sets:

Mechanical diagram

The best solution of 55mm back focus length

The latest connection methods for the new 36mm EFW and ASI cameras can be found here: The best solution of 55mm back focus length

If you are using ASI2600, then directly head over to this instruction: [ASI2600 Guide] 4 Connection methods to get 55mm back focus length

ZWO EFWmini (5 x 1.25″or 5 x 31mm)

The smallest and most lightweight 1.25″ Electronic Filter Wheel in the world!

300g ONLY! Small than your hand!

The body is CNC machined from a full block of aircraft-grade aluminum.

Very thin design, 20mm ONLY

The step motor is the heart of the EFWmini, which is made by NPM from Japan. You can trust its quality and reliability.

Supports both 5*1.25″ filters or 5*31mm filters

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

Only one USB Cable is enough to power up the EFW, the max power consumption is around 120ma@5V, so you can connect it from the USB 2.0 hub of our cooled cameras.

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 filters won’t have vigentting 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. EFWmini 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

Mechanical drawing

How to use it?

you just need to plugin the EFW mini 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 for controlling 2 EFWmini in one software.

ZWO EFW 7x36mm Filter Wheel