{"product_id":"shelyak-el0110","title":"Shelyak 0.63x SCT F\/6.3 Focal Reducer","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e0.63x Focal Reduction Factor\u003c\/li\u003e\n\u003cli\u003eTransforms f\/10 Systems to f\/6.3\u003c\/li\u003e\n\u003cli\u003eApochromatic Triplet Optical Design\u003c\/li\u003e\n\u003cli\u003eStandard 2-inch (50.8 mm) SCT Thread\u003c\/li\u003e\n\u003cli\u003eOptimized for Low-Resolution Spectroscopy\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\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\u003eShelyak 0.63x SCT F\/6.3 Focal Reducer\u003c\/h2\u003e\n\u003cp\u003eThe Shelyak 0.63x SCT F\/6.3 Focal Reducer converts a standard f\/10 Schmidt-Cassegrain telescope into a faster f\/6.3 instrument, specifically for spectroscopy. This 0.63x reduction is achieved with a high-contrast apochromatic triplet optical system. It attaches via a standard 2-inch (50.8 mm) rear cell thread, making it compatible with most Meade and Celestron SCTs.\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\u003eAn Apochromatic Triplet for F\/6.3 Spectroscopy\u003c\/h3\u003e\n\u003cp\u003eTransforming your telescope from f\/10 to f\/6.3 is critical for efficient spectroscopy. The faster focal ratio concentrates the star's light more intensely onto the narrow slit of a spectrograph like the Alpy 600 or UVEX, dramatically improving signal-to-noise ratio and reducing exposure times on faint targets.\u003c\/p\u003e\n\u003cp\u003eUnlike standard reducers designed for visual use or general imaging, this unit employs an apochromatic triplet design. This ensures that different wavelengths of light are brought to a single, sharp focal point before entering the spectrograph, preventing chromatic aberration from contaminating your spectral data and ensuring maximum accuracy in your measurements.\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\u003e2-inch SCT Threads for Meade and Celestron Telescopes\u003c\/h3\u003e\n\u003cp\u003eThis reducer is engineered for seamless integration into the most common catadioptric setups. It features the standard 2-inch (50.8 mm) female thread found on the rear cell of virtually all modern Schmidt-Cassegrain telescopes from Celestron and Meade.\u003c\/p\u003e\n\u003cp\u003eThe output side of the reducer is threaded to accept accessories like the Shelyak variable T-adapter (BA0027), allowing you to achieve precise back focus for your specific instrument. This direct-thread system creates a rigid, flexure-free connection between your telescope and spectrograph, which is essential for maintaining alignment throughout a long observation session.\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\u003eShelyak 0.63x vs. Celestron f\/6.3: A Spectroscopist's Choice\u003c\/h3\u003e\n\u003cp\u003eWhile both reducers offer a similar focal length, they are designed for different tasks. The choice depends entirely on your primary application.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eCelestron f\/6.3 Reducer\/Corrector:\u003c\/strong\u003e Its primary advantage is wide-field correction. It's a 4-element design engineered to correct for the coma inherent in SCTs, delivering sharp stars across a large imaging sensor. It is the superior choice for deep-sky astrophotography.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eShelyak 0.63x Reducer:\u003c\/strong\u003e This reducer's strength is color fidelity at the focal point. The apochromatic triplet is optimized for axial color correction, not off-axis coma. For spectroscopy, where all the light from a single star passes through a tiny slit, this superior color correction is far more important than wide-field sharpness.\u003c\/li\u003e\n\u003c\/ul\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\"\u003eWhy do I need the Shelyak 0.63x reducer for spectroscopy with my SCT?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA standard f\/10 SCT produces a small, dim image at the focal plane. The \u003cstrong\u003eShelyak 0.63x reducer\u003c\/strong\u003e converts this to f\/6.3, creating a brighter, more concentrated beam of light. This allows more photons to pass through the narrow slit of your spectrograph per unit of time, significantly boosting your signal and allowing you to capture spectra of fainter objects.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat makes this Shelyak reducer different from a standard Celestron or Meade f\/6.3 reducer?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe key difference is the optical design and purpose. Standard reducers are also correctors, designed with 4-element lenses to flatten the field and reduce coma for wide-field imaging. The Shelyak reducer uses an \u003cstrong\u003eapochromatic triplet\u003c\/strong\u003e design optimized for on-axis color correction, which is more critical for preventing wavelength shifts and ensuring the scientific accuracy of your spectral data.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill this 0.63x reducer work with my 8\" Celestron SCT and an Alpy 600 spectroscope?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, this is an ideal combination. The reducer will thread directly onto the 2-inch rear cell of your 8\" SCT. The resulting f\/6.3 focal ratio is perfectly matched to the input requirements of the Alpy 600, ensuring optimal illumination of its slit for low-resolution spectroscopy.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDoes the Shelyak 0.63x reducer correct for coma or field curvature?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, this is a dedicated focal reducer, not a corrector. Its primary design goal is focal reduction and high-fidelity color correction at the center of the field, where the spectrograph slit is placed. It is not designed to correct for off-axis aberrations like coma or field curvature, making it less suitable for wide-field deep-sky imaging than a dedicated reducer\/corrector.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I attach the Shelyak 0.63x reducer to my telescope and spectrograph?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe reducer has female 2-inch SCT threads. You simply unthread your existing visual back or camera adapter from your telescope's rear cell and thread the reducer on in its place. The output side of the reducer has male threads that connect to other accessories, such as the Shelyak variable T-adapter (BA0027), which then connects to your spectrograph.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use this reducer for deep-sky imaging of the Orion Nebula (M42) instead of spectroscopy?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile you can, it's not its intended purpose. The reducer will successfully shorten your exposure times by converting your scope to f\/6.3. However, because it does not correct for coma, you will likely notice that stars away from the center of the field appear elongated or misshapen, an effect that would be noticeable across a large target like the Orion Nebula (M42).\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\u003eReduction Factor\u003c\/td\u003e\n\u003ctd\u003e0.63x\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eResulting Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/6.3 (from f\/10)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical Design\u003c\/td\u003e\n\u003ctd\u003eApochromatic Triplet\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eAnti-reflective\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTelescope Connection\u003c\/td\u003e\n\u003ctd\u003e2-inch (50.8 mm) SCT Female Thread\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompatibility\u003c\/td\u003e\n\u003ctd\u003eMost Meade \u0026amp; Celestron SCTs\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\"\u003e0.63x SCT F\/6.3 Focal Reducer\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\u003ca href=\"https:\/\/davidastro.com\/pages\/shelyak-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eShelyak 1-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Shelyak","offers":[{"title":"Default Title","offer_id":52943029240093,"sku":"SHK-EL0110","price":233.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Shelyak-0-63x-SCT-F-6-3-focal-reducer-1_d9c47f69-7c31-4b68-a351-498ceb173434.jpg?v=1789615875","url":"https:\/\/davidastro.com\/fr-us\/products\/shelyak-el0110","provider":"David Astro","version":"1.0","type":"link"}