{"product_id":"takahashi-photo-tube-extension-dt","title":"Takahashi Photo Tube Extension DT","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Photo Tube Extension DT is Takahashi's Coupling (DT), an M55.9 x 0.75 ring built specifically for the \"DT\" photo\/visual train. Takahashi publishes its light path at 18 mm, and it comes with one notable restriction: it won't thread onto every M55.9 part in the lineup.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if your Takahashi system chart calls for the Coupling (DT) specifically, or you're assembling a camera train on the M55.9 accessory standard and need this exact spacing.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eM55.9 x 0.75 thread:\u003c\/strong\u003e Takahashi's drawtube-accessory standard shared across several refractors.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCoupling (DT) — Takahashi part TKP20006B:\u003c\/strong\u003e the manufacturer's own designation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e18 mm light path:\u003c\/strong\u003e a mid-length step in the M55.9 family, between the 10 mm Visual Coupling S and the 30 mm Extension Tube L30.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eUse it in an M55.9 camera train where the published system chart specifies the Coupling (DT) — typically to reach a flattener or reducer's stated backfocus.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eIt threads onto Takahashi's M55.9 x 0.75 accessory standard. Takahashi's own documentation notes that this coupling and the M55.9 Extension Tube L30 cannot be screwed onto the female thread of the Camera Angle Adjuster S — worth checking against your system chart before ordering. Its 18 mm light path is what it adds to the optical train, not a caliper measurement of the physical part. The \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e tabulates this figure alongside every Takahashi telescope's back focus target.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIt does not thread onto the Camera Angle Adjuster S's female thread.\u003c\/strong\u003e Takahashi documents this specifically — if your train includes the Camera Angle Adjuster S, send us your full setup and we'll confirm what does fit.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — it threads into the M55.9 chain directly, aside from the Camera Angle Adjuster S exception noted above.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eAdding a fixed 18 mm of spacing in an M55.9 photo\/visual train, per Takahashi's system chart.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs it a visual-only part or does it work for imaging too?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eTakahashi designates it \"DT\" for its photo\/visual train, and it carries no optics, so it works the same mechanically in either use.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eAn M55.9 coupling that adds a published 18 mm to the light path, built for Takahashi's DT photo\/visual train — with the one Camera Angle Adjuster S exception worth checking first.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047917965423,"sku":"TAK-TKP20006B","price":62.92,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/tkp20006b_3.jpg?v=1786936629","url":"https:\/\/ontariotelescope.com\/products\/takahashi-photo-tube-extension-dt","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}