Takahashi CA-125 Multi-Flattener CA Ring

Product Overview

The CA-125 is the spacer ring that sets correct back focus for the Takahashi FC/FS Multi-Flattener 1.04x on the FC-100DL, FS-102 and FC-125. The flattener is a common optic across the FC and FS doublet line; the CA ring is what makes the spacing correct for your specific tube. Fitted with the CA-125, the pair sets a 69.2 mm metal back distance, the figure Takahashi publishes for this telescope group.

Who It's For

This is what you need if you own an FC-100DL, FS-102 or FC-125 and are fitting the FC/FS Multi-Flattener 1.04x for imaging. It has no function on its own — it is bought alongside the flattener, not instead of it.

Key Features & Design

• Telescope-specific spacing: sets the 69.2 mm metal back distance Takahashi publishes for the FC-100DL, FS-102 and FC-125 with this flattener.
• Threads directly onto the Multi-Flattener: the ring's accessory side mates with the flattener's M56 x 0.75 telescope-side thread.
• Compact and light: a single machined ring, adding minimal length ahead of the flattener.

Recommended Uses

• Imaging setup on the FC-100DL, FS-102 or FC-125: fitted between telescope and flattener whenever this model group is used for astrophotography.
• Switching the Multi-Flattener between tubes: if you own more than one FC or FS telescope, the CA ring is what changes when you move the flattener across them.

Compatibility and Accessory Notes

The CA-125 is one of seven CA rings Takahashi publishes for the Multi-Flattener 1.04x, each matched to a different telescope group:

Full spacing figures for the FC and FS line are in the Takahashi Back Focus Guide.

Good to Know Before You Order

• It does not work alone. The CA-125 only sets spacing for the Multi-Flattener 1.04x — the flattener itself is a separate purchase.

Frequently Asked Questions

Is it difficult to set up?

No — it threads between the telescope and the flattener, setting the 69.2 mm back focus without any adjustment on your part.

Do I need this if I already own the Multi-Flattener?

Yes, if your telescope is an FC-100DL, FS-102 or FC-125. The flattener ships without a ring; the ring is what makes it fit your tube.

Will the CA-125 fit a different FC or FS model?

No — each CA ring is matched to a specific telescope group and back focus figure. Send us your model and we will confirm the right ring.

Bottom Line

In short: the spacer ring that fits the FC/FS Multi-Flattener 1.04x to the FC-100DL, FS-102 and FC-125, setting the 69.2 mm back focus Takahashi publishes for this group.