SVBONY SV109 M48 Variable Extension Tube (24–35 mm)

Product Overview

The SVBONY SV109 M48 is a variable-length extension tube with M48×0.75 male and female threads. Its length adjusts from 24 mm to 35 mm, so you can dial in the exact spacing a reducer or field flattener needs instead of stacking fixed spacers. It is anodized aluminium, internally designed to cut stray light, and weighs 28.3 g (1.00 oz).

Who It's For

This is a good match if you image through an M48 reducer or flattener and want to fine-tune backfocus, or if you need to adjust focus position or image scale in an M48 train.

Key Features & Design

• Adjustable 24–35 mm: an 11 mm range of continuous spacing.
• M48×0.75 male and female threads: fits standard M48 imaging trains.
• Stray-light control: internal design reduces reflections.
• Anodized aluminium: 28.3 g.

Recommended Uses

• Backfocus tuning behind M48 reducers and field flatteners, where corner star shape depends on the spacing.
• Focus reach and image scale adjustments in camera and eyepiece trains.

Compatibility and Accessory Notes

• Threads: M48×0.75 male and female, per SVBONY's key features. (The vendor's secondary feature list also mentions T2 threads; the M48 figure is the one in the product title and key features.)
• Spacing: add 24–35 mm to your camera's flange distance and any filter drawer to reach your corrector's backfocus. Send us your setup and we will work the figure out with you.

Good to Know Before You Order

• Mechanical spacer only: no glass.
• Minimum length 24 mm: for shorter gaps, fixed M48 spacers are the option.

Frequently Asked Questions

Is it difficult to set up?

No. Thread it into your train, set the length to the spacing you need, and lock it in place.

What is the adjustment range?

24 mm to 35 mm.

Is there an M42 version?

Yes, SVBONY makes the SV109 in an M42 (T2) version as a separate product.

Bottom Line

In short: a 28.3 g anodized aluminium M48×0.75 extension tube that adjusts from 24 to 35 mm for precise backfocus and focus spacing.