Takahashi FC-100D F 50.8 AD Adapter M64

Product Overview

The F 50.8 AD Adapter converts the rear thread of the FC-100DL and FC-100DF onto a male M64 x 0.75 thread, so these telescopes can accept accessories built for Takahashi's older M64 accessory system. Takahashi publishes a 15 mm light path for it — the amount it contributes to your optical train, not its physical length end to end.

Who It's For

This is a good match if you own an FC-100DL or FC-100DF and want to run an M64 reducer or another legacy M64 accessory on it.

Key Features & Design

• Rear-thread to M64 conversion: bridges the FC-100DL/DF's native thread to Takahashi's older M64 system.
• 15 mm published light path: a known, fixed contribution to your back focus total.
• Solid aluminum, black anodized: keeps thread alignment consistent across mounts and removals.

Recommended Uses

Running an M64 reducer or another older M64-thread accessory on an FC-100DL or FC-100DF, for either visual or imaging use.

Compatibility and Accessory Notes

Built for the FC-100DL and FC-100DF. The 15 mm light path is worth adding to your full back-focus total alongside the M64 accessory you are pairing it with — the Takahashi Back Focus Guide tabulates every Takahashi adapter's light path alongside each telescope's back focus target.

Good to Know Before You Order

It is specific to the M64 accessory generation: it exists to bridge to older M64 gear, so it has no role in a train built entirely from Takahashi's current thread standards. Send us your accessory list and we will confirm whether you need it.

Frequently Asked Questions

Is it difficult to set up?

No — it threads onto the rear of the FC-100DL or FC-100DF and presents a male M64 thread on the other side, with nothing to adjust.

What is it used for?

Letting an FC-100DL or FC-100DF accept a reducer or other accessory built for Takahashi's older M64 thread standard.

Does it work for visual use as well as imaging?

Yes — it is a mechanical thread adapter, so it carries through a visual or imaging train equally.

Bottom Line

A 15 mm light-path adapter that puts an M64 male thread on the back of an FC-100DL or FC-100DF, for running older M64-system accessories.