SVBONY M42x0.75 Extension Tube Kit (5, 10, 15, 20 mm)

Product Overview

The SVBONY F9160A is a set of four M42 x 0.75 extension tubes, 5 mm, 10 mm, 15 mm and 20 mm long. Each has a male and a female M42 x 0.75 thread, so they stack in any combination to add the spacing an imaging train needs, whether to set the backfocus behind a field flattener or reducer, or to adjust image scale. The tubes are all metal, anodized aluminium.

Who It's For

This is a good match if you image with an M42 (T2) camera train and need to fine-tune the distance between a corrector and your sensor, or to reach focus with a particular camera and adapter combination.

Key Features & Design

• Four lengths: 5, 10, 15 and 20 mm, used singly or combined (one, two or three at a time).
• M42 x 0.75 male and female threads: the T2 standard, so they fit any M42 x 0.75 camera adapter.
• Chainable: stack with other M42 x 0.75 parts to reach the length you need.
• All-metal, anodized aluminium: resists deformation and keeps the train rigid.

Mechanical Design

Flatteners and reducers are designed to sit a specific distance from the sensor, usually stated as a backfocus figure such as 55 mm. That total is made up of the camera's own flange depth plus every adapter, filter holder and spacer in between. With these four tubes you can make up any length from 5 mm to 50 mm in 5 mm steps, which covers most of the gap left once your camera and adapters are counted.

Recommended Uses

• Setting backfocus behind a field flattener, reducer or coma corrector.
• Reaching focus with cameras and adapters that sit too close to the focuser.
• Adjusting image scale where spacing changes magnification, such as behind a Barlow.

Compatibility and Accessory Notes

• Thread: M42 x 0.75 (T2) on both ends.
• Works with: any M42 x 0.75 camera adapter, T-ring, corrector or astronomy camera.

Send us your corrector and camera details and we will work out the spacer combination with you.

What's in the Box

SVBONY describes the kit as four extension tubes: 5 mm, 10 mm, 15 mm and 20 mm.

Good to Know Before You Order

• M42 x 0.75 only: for M48 trains, M48 spacers are needed.
• Weight: SVBONY does not publish a weight for this kit.

Frequently Asked Questions

Is it difficult to set up?

No. Add up your camera's flange depth and the adapters in your train, subtract from the corrector's backfocus figure, and thread in the tubes that make up the difference.

Can I use more than one tube at a time?

Yes. SVBONY designs them to be used singly or combined.

Do they fit T-rings?

Yes. They use the M42 x 0.75 (T2) thread used by T-rings.

Bottom Line

In short: four anodized-aluminium M42 x 0.75 spacers, 5 to 20 mm, that combine to set backfocus and focus position in a T2 imaging train.