{"id":33886,"date":"2025-11-15T13:50:07","date_gmt":"2025-11-15T12:50:07","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&p=33886"},"modified":"2026-03-04T17:00:00","modified_gmt":"2026-03-04T16:00:00","slug":"william-optics-zenithstar-81-559-apo-wifd-gold-ota","status":"publish","type":"product","link":"https:\/\/staging.telescoop.nl\/en\/william-optics-zenithstar-81-559-apo-wifd-goud-ota\/","title":{"rendered":"William Optics ZenithStar 81\/559 APO WIFD Gold OTA"},"content":{"rendered":"

William Optics AP 81\/559 81 - Powerful apo for sharp images<\/strong><\/h3>\n\n\n\n

The William Optics AP 81\/559 81<\/strong> is a compact, lightweight apochromatic refractor. It is ideal for astrophotography and wide-angle shooting. You easily set it up on a lightweight mount such as a Star Adventurer or Star Tracker. Within minutes you are ready to observe or take pictures.<\/p>\n\n\n\n

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\"William<\/figure>\n<\/figure>\n\n\n\n

Sharp images all the way to the edge<\/strong><\/h3>\n\n\n\n

The doublet lens with FPL-53 ED glass provides bright, color-corrected images. Together with an optional flattener, stars remain sharp all the way to the corners. This allows you to take impressive shots of star fields, nebulae and the Moon without distortion.<\/p>\n\n\n\n

Smart internal focusing system (WIFD)<\/strong><\/h3>\n\n\n\n

The Internal Focus Design (WIFD) lets you focus accurately without turning on the outside. You can use heavy, cooled cameras without vignetting. The integrated scale shows you exactly where the focus is. Compatible with the ZWO EAF for automatic focusing.<\/p>\n\n\n\n

\n
\"William<\/figure>\n<\/figure>\n\n\n\n

Compact, light and travel-friendly<\/strong><\/h3>\n\n\n\n

Despite the 81 mm aperture, the telescope is light and relatively short. You can easily take it with you as hand luggage. Aluminum tube and sturdy tube rings provide stability. Convenient accessories such as a Bahtinov mask and prism clamp make focusing and alignment easier.<\/p>\n\n\n\n

Versatile for observation and photography<\/strong><\/h3>\n\n\n\n

The ZS81 is perfect for astrophotography, planets and Moon. The extensive accessory system allows you to customize it optimally for your needs. You get excellent optics and ease of use at a fair price.<\/p>\n\n\n\n

Specifications<\/strong><\/h3>\n\n\n\n

Optics<\/strong><\/h4>\n\n\n\n
Feature<\/th>Description<\/th><\/tr><\/thead>
Type<\/td>Refractor<\/td><\/tr>
Design<\/td>Apochromat<\/td><\/tr>
Lens Design<\/td>Doublet<\/td><\/tr>
Aperture (mm)<\/td>81<\/td><\/tr>
Focal length (mm)<\/td>559<\/td><\/tr>
Aperture ratio (f\/)<\/td>6,9<\/td><\/tr>
Resolution<\/td>1,70\u2033<\/td><\/tr>
Limit value (mag)<\/td>11,3<\/td><\/tr>
Light output<\/td>130\u00d7<\/td><\/tr>
Max. useful magnification<\/td>162\u00d7<\/td><\/tr>
Corrected field of view (mm)<\/td>45<\/td><\/tr>
Tube length (mm)<\/td>607<\/td><\/tr>
Transport length (mm)<\/td>526<\/td><\/tr>
Tube weight (kg)<\/td>3,5<\/td><\/tr>
Glass material<\/td>OHARA FPL-53<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Focuser<\/strong><\/h4>\n\n\n\n
Feature<\/th>Description<\/th><\/tr><\/thead>
Design<\/td>Internal (WIFD)<\/td><\/tr>
Ocular connection<\/td>2\u2033<\/td><\/tr>
Reduction<\/td>1:10 finesse<\/td><\/tr>
Camera connection<\/td>M63<\/td><\/tr>
Free opening (mm)<\/td>64<\/td><\/tr>
Rotatable<\/td>Yes<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Mount<\/strong><\/h4>\n\n\n\n
Feature<\/th>Description<\/th><\/tr><\/thead>
Design<\/td>OTA<\/td><\/tr>
Type of mount<\/td>Without mount<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Included accessories<\/strong><\/h4>\n\n\n\n
Section<\/th>Description<\/th><\/tr><\/thead>
Handle<\/td>Yes<\/td><\/tr>
Transport bag<\/td>Yes<\/td><\/tr>
Tube Rings<\/td>Yes<\/td><\/tr>
Dovetail<\/td>Arca-Swiss & Vixen-Style<\/td><\/tr>
Dew cap<\/td>Yes<\/td><\/tr>
Focusing aid<\/td>Bahtinov Mask<\/td><\/tr>
Miscellaneous<\/td>Adapters M92\/M63<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

General<\/strong><\/h4>\n\n\n\n
Feature<\/th>Description<\/th><\/tr><\/thead>
Series<\/td>ZenithStar<\/td><\/tr>
Color<\/td>Gold<\/td><\/tr>
Application<\/td>Astrophotography, Moon & Planets, Nebulae & galaxies<\/td><\/tr>
Recommended for<\/td>Advanced<\/td><\/tr>
Observatory use<\/td>No<\/td><\/tr><\/tbody><\/table><\/figure>","protected":false},"excerpt":{"rendered":"

William Optics AP 81\/559 81 comes with a WIFD internal focuser, tube rings, Arca-Swiss & Vixen-style dovetail, handle, Bahtinov mask, adapters and a soft carrying case. \u00a0<\/p>","protected":false},"featured_media":97375,"comment_status":"open","ping_status":"closed","template":"","meta":{"_acf_changed":false},"product_brand":[643],"product_cat":[51,567],"product_tag":[],"class_list":["post-33886","product","type-product","status-publish","has-post-thumbnail","product_brand-william-optics","product_cat-telescopen","product_cat-refractors","first","instock","taxable","shipping-taxable","purchasable","product-type-simple"],"bundled_by":[],"bundle_stock_status":"instock","bundle_stock_quantity":null,"bundle_virtual":false,"bundle_layout":"","bundle_add_to_cart_form_location":"","bundle_editable_in_cart":false,"bundle_sold_individually_context":"","bundle_item_grouping":"","bundle_min_size":"","bundle_max_size":"","bundle_price":[],"bundled_items":[],"bundle_sell_ids":[],"acf":[],"jetpack_sharing_enabled":true,"jetpack-related-posts":[{"id":33894,"url":"https:\/\/staging.telescoop.nl\/en\/william-optics-zenithstar-81-559-apo-wifd-red-ota\/","url_meta":{"origin":33886,"position":0},"title":"William 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