SVBony SV226 M54 Filter Drawer — image 1
SVBony

SVBony SV226 M54 Filter Drawer

M54 filter drawer · 2 inch filters · 20 mm optical length · W9184C

Lets you change filters without taking the camera off the telescope. A small aluminium box that sits in the imaging train and accepts a filter on a slide-out tray.

80/ 100
Polaris Score
The sensible middle ground between one filter and a motorised wheel
From$68.99
Where to buy
Affiliate link — we earn a commission, you pay the same. We rank on fit, not payout.
What problem does this solve?

Changing a filter should not mean rebuilding your imaging train.

A filter in a one-shot-colour setup usually threads into the nosepiece or sits in the camera's own filter slot. Changing it means unscrewing the camera, handling glass in the dark, screwing everything back and hoping you have not rotated the camera or shifted the spacing. Do that at two in the morning with cold hands and you will eventually drop something.

A filter drawer is a fixed part of the train with a tray that slides out sideways. The camera never moves, the spacing never changes, and the filter lives on a cartridge you can swap in about five seconds. It is a small mechanical convenience that changes how willing you are to use filters at all.

You need one if
You need one as soon as you own more than one filter and have started leaving the wrong one in because changing it is a nuisance.
You can skip it if
Skip it if you own exactly one filter and never change it, or if your imaging train has no back focus to spare, because 20 millimetres is a lot to find.
How it actually works

What the setup looks like.

The drawer is a passive spacer with a hole in the side. Fitting it is an exercise in arithmetic before it is an exercise in assembly:

The drawer is a passive spacer with a hole in the side. Fitting it is an exercise in arithmetic before it is an exercise in assembly:

1
Work out your back focus budget first
The body is 20 millimetres thick without the adapter ring. Your flattener specifies a fixed distance to the sensor, usually 55 millimetres, and this eats a large share of it. Do this sum before you order.
2
Thread it into the train
M54 on the telescope side and M54 on the camera side, with an M54 to M48 adapter included for a 2 inch train.
3
Mount filters on the cartridges
Each cartridge takes one 2 inch filter on an M48 thread. Buy a cartridge per filter and you never unscrew glass in the field again.
4
Slide and shoot
Two pairs of magnets pull the tray to a repeatable stop, so the filter returns to the same place every time.

The tray is unidirectional. It only goes in one way round, which is deliberate: it means the filter always sits at the same distance from the sensor and your spacing does not change between filters.

01Will it fit my setup

Compatibility.

What this accessory works with — check the fit before you check the price.

What this accessory works with — check the fit before you check the price.

M54 imaging trains, which is most modern flatteners and reducers2 inch filters on an M48 threadSensors up to full frameAny camera with an M54 or M48 connection
Note✕Costs 20 millimetres of back focus before the adapter ring✕Takes 2 inch filters only, so 1.25 inch filters need a step ring✕Manual, so you are at the telescope for every filter change✕Competes directly with an off-axis guider for the same millimetres
02The numbers

What These Numbers Mean

5 numbers in plain English · full specifications

5 numbers in plain English · full specifications

Optical thicknessThe whole decision
20 mm
This is the number that decides whether you can fit one. Every imaging train has a fixed distance from the flattener to the sensor, commonly 55 millimetres, and everything between competes for it. Twenty millimetres is over a third of that budget. Add an off-axis guider at 12.5 millimetres and a camera at 17.5 and you have already overrun.
ThreadsModern standard
M54 both sides
M54 is the thread on most current flatteners and larger reducers, and it is wide enough not to vignette a full frame sensor. The included M54 to M48 adapter covers the older 2 inch standard, so this drops into either generation of imaging train without a machinist.
Filter sizeFull frame capable
2 inch (M48)
Filter size has to exceed the light cone at the point the filter sits, or the corners of your image darken. Two inch glass clears a full frame sensor in a normal train, which is why the drawer takes this size and not 1.25 inch. It also means your filters are the expensive kind.
PositioningRepeatable
2 magnet pairs, unidirectional
The thing that matters about a filter drawer is not that it holds a filter but that it holds it in the same place every time. Magnets pulling to a hard stop, with a tray that only fits one way round, mean the filter returns to an identical distance from the sensor, so focus does not shift between filters.
OperationYou are there
Manual
A drawer is not a filter wheel. Changing filters means walking to the telescope and pulling a tray, which is fine for a one-shot-colour imager swapping between a dual-band and clear glass, and impractical for an automated mono sequence that cycles three filters through the night.
Optical path
Thickness20 mm without adapter ring
Telescope threadM54 x 0.75
Camera threadM54 x 0.75
Filter threadM48 x 0.75
Sensor supportUp to full frame
Build
MaterialCNC aluminium
Magnet pairs2
Filter size2 inch
Adapter includedM54 male to M48 female, 2 mm
03Before you buy

Good to know.

The honest caveats — the things that save you a return, a bad first night, or a second purchase you didn't need.

The honest caveats — the things that save you a return, a bad first night, or a second purchase you didn't need.

Budget the back focus before you buy anything else.
This is the most common reason a filter drawer ends up unused. Add the drawer, your camera's sensor depth and any off-axis guider, then check the total against what your flattener specifies. If it does not fit, nothing about the drawer can be adjusted to make it.
Buy a cartridge for every filter you own.
The point of a drawer is that glass stays mounted. If you have one cartridge you are still unscrewing filters in the dark, just in a different place.
It competes with an off-axis guider.
Both live in the same few millimetres. If you image at long focal length and need an off-axis guider, work out whether both fit before assuming you can have them.
This is the M54 version.
SVBONY also sells an M42 drawer. M54 is the one to choose for a modern flattener and a larger sensor, and it is the version that will not vignette full frame.
Editor’s Take

Filter drawers are one of the few accessories that change behaviour rather than image quality. Nothing about your photographs improves because the filter is on a tray. What improves is that you actually use the right filter, instead of leaving the dual-band in on a moonless night because swapping it means dismantling the camera. The only real question is the twenty millimetres, and that question has a definite answer you can work out on paper before you spend anything.

— The Skynocular verdict
80/ 100
SVBony SV226 M54 Filter Drawer
M54 filter drawer · 2 inch filters · 20 mm optical length · W9184C · $68.99

Lets you change filters without taking the camera off the telescope. A small aluminium box that sits in the imaging train and accepts a filter on a slide-out tray.