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Five 2-inch filters, changed automatically, in a lighter wheel
Why we like the ZWO EFW 5x2" (2025):
- Enough slots for most plans: five positions hold luminance, red, green and blue plus one narrowband filter, or hydrogen-alpha, OIII and SII with room for two more.
- One USB-C cable: it draws only 120mA at 5V, so it runs from the USB hub on a ZWO cooled camera with no separate power supply, and needs no driver.
- Tighter light sealing: the 2025 redesign adds a slot-fit chassis, light-blocking pads and a fully enclosed motor to keep stray light out of long narrowband frames.
- Worth knowing: if you want LRGB and SHO in the wheel at the same time, the 7-position EFW 7x2" saves you from swapping filters later.
The ZWO 5-Position Electronic Filter Wheel (EFW 5x2", 2025 model) holds five 2-inch mounted filters, or 50mm round unmounted filters, and turns them into place on command from your capture software. It's made for APS-C and full-frame mono cameras like the ZWO ASI2600MM Pro and ASI6200MM Pro. The CNC-machined aluminum body is 20mm thick and 167mm across, weighs 540g (1.2lb), and connects over USB-C to an ASIAIR, a computer running ASCOM software, or ZWO's ASIStudio.
Key specs: 5 positions for 2" mounted or 50mm unmounted filters · 20mm optical thickness · M54 × 0.75 threads on both sides · USB-C, 5V at 120mA · driver-free, works with ASIAIR, ASCOM and ASIStudio · anti light-leak sealing · 540g (1.2lb)
What you can image with it
- LRGB galaxies and clusters: luminance for detail plus red, green and blue for color on targets like the Andromeda, Whirlpool and Pinwheel Galaxies, with the fifth slot free for hydrogen-alpha to bring out star-forming regions.
- Narrowband nebulae from the city: hydrogen-alpha, OIII and SII filters for Hubble-palette images of the Eagle, Heart, Soul and Veil Nebulae from a light-polluted backyard.
- Mixed nights: shoot narrowband while the Moon is up and switch to broadband after it sets, all in one automated sequence.
How it works
Screw the wheel between your camera and the telescope's flattener or reducer using the included M54, M48 and M42 adapters, plug its USB-C cable into the camera's USB hub, and it shows up in your software. A high-precision stepper motor turns the 6061 aluminum carousel in either direction to the next filter, and the software refocuses and continues the sequence.
The wheel takes 20mm of the usual 55mm back focus. ZWO's example layout for an APS-C cooled camera is the camera (12.5mm), this wheel (20mm), a ZWO Large OAG (17.5mm) and a 5mm tilt adapter, which adds up to 55mm.
What to add for the best results
- Optolong LRGB filters, 2" (4 pieces): fills four slots for color imaging. For narrowband, add the Optolong SHO 7nm set or ZWO 7nm SHO set in 2".
- A mono camera: the ZWO ASI2600MM Pro (APS-C) or ASI6200MM Pro (full frame).
- ZWO Large OAG (12mm prism) with an ASI220MM Mini: guides through the main scope and completes the 55mm spacing.
- ASIAIR Plus: runs multi-filter sequences with autofocus on each filter change.
- ZWO EAFN electronic focuser: corrects small focus shifts between filters automatically.
EFW 5x2" vs. EFW 7x2"
| EFW 5x2" (2025) | EFW 7x2" (2025) | |
|---|---|---|
| Positions | 5 | 7 |
| Filters | 2" mounted or 50mm unmounted | 2" mounted or 50mm unmounted |
| Thickness | 20mm | 20mm |
| Wheel diameter | 167mm | About 199mm |
| Weight | 540g | 720g |
| Best for | LRGB plus one narrowband filter, or SHO plus extras, with less weight | LRGB plus SHO in one wheel |
See all filter wheels and drawers.
What's in the box
- EFW 5x2" filter wheel
- USB 2.0 Type-A to USB-C cables, 0.5m and 2m
- M54M-M48F, M54M-M42F and M54M-M48F-2 adapters
- Bag of 10 filter masks
- M2.5 × 6 screws (6) and M2 × 4 screws (26)
- 3 × 75mm Phillips screwdriver
Filters and the camera are sold separately.
ZWO EFW 5x2" FAQ
Do I need a filter wheel?
With a mono camera, yes, to shoot color. A filter wheel changes filters automatically during the night. With a color camera you usually don't; a single dual-band filter in a filter drawer is enough.
2-inch or 1.25-inch filters?
For APS-C and full-frame sensors, choose 2-inch (or 36mm for APS-C) to avoid dark corners. 1.25-inch filters suit smaller sensors like the ASI533MM; for those, see the EFW 5x1.25" or EFW 8x1.25".
5 or 7 positions?
Five is enough for LRGB plus one narrowband filter, or for SHO with luminance and one spare, and the wheel is lighter and smaller. Seven fits LRGB and SHO with no compromises.
Does it need its own power supply?
No. It runs on 5V USB power, typically from the hub on a ZWO cooled camera, so only one short cable goes to the wheel.
Will it work with my software?
Yes. It works with ASIAIR, ASIStudio and any ASCOM program such as N.I.N.A., and it's plug-and-play with no driver to install.
What's new in the 2025 model?
A USB-C port replaces the old USB Type-B, the chassis and motor are sealed against light leaks, and the body has a refined laser-engraved finish.
Specifications
| Filters | |
|---|---|
| Positions | 5 |
| Supported filters | 2" mounted (filter area ≤7mm thick) or Ø50mm unmounted (1.5–3.5mm thick) |
| Carousel | 6061 aluminum, 150.8mm diameter, M48 × 0.75 cells |
| Optical and mechanical | |
| Optical thickness | 20mm (30mm at the electronics housing) |
| Threads | M54 × 0.75 (adapters to M48 and M42 included) |
| Body | CNC-machined aluminum, 167mm wheel diameter, 177.5mm tall |
| Weight | 540g (1.2lb) |
| Electronics | |
| Connection | USB-C (USB 2.0) |
| Power | 5V, 120mA from USB |
| Software | ASIAIR, ASIStudio, ASCOM, ZWO SDK; no driver needed |
| Model / SKU | ZWO-EFW-5x2-25 |