{"product_id":"takahashi-ortho-extender-4x","title":"Takahashi Ortho Extender 4X Barlow-Type Extender","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Ortho Extender 4X is Takahashi's high-power extender for lunar, planetary, and small-target imaging. It follows the same design goal as the 2x Ortho Extender — expanding focal length without adding aberration to an already well-corrected telescope. The unit threads onto the focuser drawtube with an M43 x 0.75 male fitting, measures 46 mm in diameter by 125 mm long, and has a published weight of 240 g.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you image the Moon, the solar corona during an eclipse, or small planetary nebulae and galaxies with a small-sensor camera, and want more reach from a telescope you already own. It also serves visual observers chasing high magnification with contrast intact.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eNominal 4x magnification:\u003c\/strong\u003e extends focal length roughly fourfold, with the realized factor set by the backfocus in the imaging or visual train.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM43 x 0.75 male mount:\u003c\/strong\u003e threads directly to a Takahashi drawtube or accessory with the matching female thread.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTwo extension tubes included:\u003c\/strong\u003e the Vari-tube S (20 mm) and Vari-tube L (40 mm), plus an M42-31.7AD adapter, to bring the achieved magnification toward 4x with a diagonal or ADC in the train.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompact aluminum barrel:\u003c\/strong\u003e 46 mm diameter, 125 mm length, 240 g.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eLike the 2x Ortho Extender, the 4x unit is built so an aberration-free telescope stays that way with the extender in place — it adds magnification rather than correcting anything. As a Barlow-type element, the realized magnification is a function of the spacing behind it: Takahashi's published diagram for the 2x model plots magnification against backfocus, and the same relationship governs the 4x unit, moving above or below the nominal 4x figure depending on whether a diagonal prism, T-mount, or direct eyepiece follows it. The two included Vari-tubes exist to bring that spacing back toward the point where the 4x figure holds.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eLunar close-ups, solar eclipse corona photography, and planetary imaging with small-format CMOS cameras are the stated use cases. For visual work it holds contrast at high power, useful for double-star splitting and fine lunar detail.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Ortho Extender 4X mounts to any Takahashi focuser or accessory presenting an M43 x 0.75 female thread — it is not built around one telescope model the way a matched flattener is. Because the achieved magnification depends on backfocus, a diagonal, T-mount, or ADC behind it shifts the effective factor slightly; the included Vari-tube S\/L extensions and M42-31.7AD adapter let you dial the spacing in. For how backfocus interacts with the rest of your imaging train, see the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eMagnification varies with spacing:\u003c\/strong\u003e the published 4x figure assumes a specific backfocus, and a diagonal or camera adapter behind it shifts the realized power — the included extension tubes are there to compensate.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eFraming narrows at 4x:\u003c\/strong\u003e the field of view is well suited to high-power lunar and planetary targets rather than wide-field deep-sky framing.\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 directly onto the drawtube's M43 x 0.75 thread. Getting the magnification close to the nominal 4x is a matter of choosing between the included Vari-tube S and L depending on what follows it in the train.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eHigh-power lunar, planetary, and solar-eclipse imaging, and high-magnification visual observing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it suit wide-field deep-sky imaging?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — at 4x the field narrows well past what wide-field framing needs; the 2x Ortho Extender or a dedicated reducer suits that work better.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat accessories come with it?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eThe Vari-tube S (20 mm) and Vari-tube L (40 mm) extension tubes and an M42-31.7AD adapter ship with the unit.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Ortho Extender 4X is a compact, aberration-neutral way to add roughly four times the focal length for lunar, planetary, and solar-eclipse work, mounting on the standard M43 x 0.75 thread and shipping with the extension tubes needed to fine-tune the magnification for your train.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047112527983,"sku":"TAK-TKA00831","price":426.14,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/tka00831-1_1.jpg?v=1786914045","url":"https:\/\/ontariotelescope.com\/products\/takahashi-ortho-extender-4x","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}