{"product_id":"svbony-sv197-cheshire-collimating-eyepiece-125in","title":"SVBONY SV197 Cheshire Collimating Eyepiece - 1.25\"","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003ePrecise Collimation Tool for Newtonian Telescopes\u003c\/li\u003e\n\u003cli\u003eFits Standard 1.25\" Focusers\u003c\/li\u003e\n\u003cli\u003eDurable Steel Crosshairs\u003c\/li\u003e\n\u003cli\u003eCNC-Machined Aluminum Body\u003c\/li\u003e\n\u003cli\u003eNet Weight: 156g (5.51oz)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eSVBONY SV197 1.25\" Cheshire Collimating Eyepiece for Newtonian\u003c\/h2\u003e\n\u003cp\u003eThe SVBONY SV197 1.25\" Cheshire Collimating Eyepiece provides a direct, accurate method for aligning Newtonian reflectors to achieve the sharpest possible views. Its CNC-machined aluminum body weighs a solid 156g and houses durable steel crosshairs, creating a stable and reliable reference point for adjusting your primary and secondary mirrors.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003ePrecise Newtonian Alignment with a 1.25\" Cheshire Eyepiece\u003c\/h3\u003e\n\u003cp\u003ePoor collimation is the single most common reason for soft, low-contrast images in a Newtonian telescope. The SV197 Cheshire eyepiece is a simple, effective tool that gives you a clear view of your mirror alignment, allowing you to make precise adjustments. By fitting directly into any standard 1.25\" focuser, it ensures your optical axis is perfectly aligned for optimal image clarity.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e156g CNC-Machined Aluminum Body with Steel Crosshairs\u003c\/h3\u003e\n\u003cp\u003eBuilt for repeatability and durability, the SV197 features a single-piece aluminum body that is CNC-machined for a precise fit. At 141mm long, it sits securely in the focuser without wobble. Unlike tools with fine wire, the SV197 uses robust steel crosshairs that will not sag, shift, or break, ensuring your alignment reference remains true every time you use it.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eCollimation at f\/5 and Slower: A Centered View for Alignment\u003c\/h3\u003e\n\u003cp\u003eThis tool is designed to be intuitive, especially for telescopes with focal ratios of f\/5 and slower, where the reflections appear centered and straightforward to align. For faster telescopes below f\/5, the view through the eyepiece will show a slight, expected offset due to the wider light cone—this is a normal characteristic of Cheshire alignment in fast optics. The goal remains the same: adjust the primary and secondary mirror screws until the reflections are concentric.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the SVBONY SV197 help collimate my Newtonian telescope?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003eSVBONY SV197\u003c\/strong\u003e provides a set of crosshairs and a reflective surface that you look through from the focuser. This allows you to see the reflections of your primary and secondary mirrors simultaneously. You then adjust the mirror tilt screws until all the reflections are perfectly centered, ensuring the telescope's optical path is correctly aligned for sharp images.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the SVBONY SV197 Cheshire eyepiece hard to use for a beginner?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, it's considered one of the more straightforward collimation tools. Unlike a laser collimator that can itself go out of alignment, a Cheshire is a passive tool that is always accurate. The process involves simple visual checks and adjustments, making it an excellent tool for learning how to properly collimate a Newtonian telescope.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the SV197 work with my 8-inch f\/6 Dobsonian?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, absolutely. An 8-inch f\/6 Dobsonian is an ideal telescope for the \u003cstrong\u003eSVBONY SV197\u003c\/strong\u003e. At f\/6, the reflections you see through the Cheshire will be well-centered and easy to align, allowing for a very quick and accurate collimation process.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy do the reflections look off-center in my f\/4 imaging Newtonian with the SV197?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis is normal for \"fast\" telescopes (typically below f\/5). The steep light cone of an f\/4 optical system requires a slight offset in the secondary mirror's position relative to the primary. The view through the \u003cstrong\u003eSVBONY SV197\u003c\/strong\u003e will reflect this, appearing slightly off-center even when perfectly collimated. The tool is still effective, but you must account for this known offset.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the SVBONY SV197 made of?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe main body of the SV197 is made from \u003cstrong\u003eCNC-machined aluminum\u003c\/strong\u003e for a precise fit and durability. The internal crosshairs are made of \u003cstrong\u003esteel\u003c\/strong\u003e, which prevents sagging or breaking over time, ensuring a consistent and reliable alignment reference.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the SV197 Cheshire eyepiece with a Schmidt-Cassegrain or refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, the \u003cstrong\u003eSVBONY SV197\u003c\/strong\u003e is designed specifically for collimating \u003cstrong\u003eNewtonian reflector\u003c\/strong\u003e telescopes. Refractors and Schmidt-Cassegrains do not have the same user-adjustable secondary and primary mirror configuration and require different tools and procedures for alignment.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eBarrel Size\u003c\/td\u003e\n\u003ctd\u003e1.25\" (31.75mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBody Material\u003c\/td\u003e\n\u003ctd\u003eAluminum, CNC Machined\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCrosshair Material\u003c\/td\u003e\n\u003ctd\u003eSteel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDimensions\u003c\/td\u003e\n\u003ctd\u003e141mm x 41mm x 32mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet Weight\u003c\/td\u003e\n\u003ctd\u003e156g \/ 5.51oz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eSVBONY SV197 1.25\" Cheshire Collimating Eyepiece\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/svbony-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eSVBONY Warranty Policy\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"SVBONY","offers":[{"title":"Default Title","offer_id":52861238313245,"sku":"SV-W9154A","price":23.97,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/SVBONY-SV197-1-25-Cheshire-Collimating-Eyepiece-for-Newtonian-1_5f3305ad-b007-422a-be1f-42b8c53f74f0.jpg?v=1788660452","url":"https:\/\/davidastro.com\/fr-us\/products\/svbony-sv197-cheshire-collimating-eyepiece-125in","provider":"David Astro","version":"1.0","type":"link"}