William Optics 1.25" 90-deg Erecting Prism Diagonal with Helical Focusing # D-EP90-125
Contiguous US Customers:
All items we sell ship for free within the Contiguous US. Shipping will be via the cheapest shipping method which will vary depending on the items in your order. During checkout, you may also be shown other optional faster shipping choices.
US Customers in Hawaii and Alaska:
Free shipping applies to almost all products. A few large telescopes and mounts are excluded from this free shipping offer. For these items, please contact us to obtain a shipping quote before you check out using the online shopping cart.
International Customers:
Free shipping does not apply to international orders. During check-out, you will be presented with several shipping choices and costs. However, the export of some items may be restricted outside the US due to size or manufacturer restrictions.
Quick Overview
- 1.25” 90-deg erecting-prism diagonal with helical focuser gives right-side up images for terrestrial or celestial observing
- Works with any telescope with 1.25” focuser (except for Newtonians)
- Helical focuser gives 15 mm of travel for fine focusing adjustment
- Anti-reflection-coated prism gives bright, high-contrast images
- Made from black-anodized aluminum; includes end caps
Product Details
New from William Optics, this 1.25" 90-degree erecting-prism diagonal # D-EP90-125 gives correct right-side up images for terrestrial or celestial observing with any telescope (except Newtonian reflectors). The erecting prism in this diagonal is made of high quality BAK4 glass polished to a high surface accuracy and with anti-reflection coatings that give bright images and reduced ghosting.
The diagonal features a helical focusing mechanism for fine adjustment of up to 15 mm in the eyepiece holder. The inside of the erecting diagonal is matte blackened to reduce internal stray light reflection and keep image contrast high. Precision machined from aluminum and black anodized with a smooth finish, this diagonal is threaded for standard 1.25" filters and features a tapered barrel design.
Clear aperture = 20.6mm; Weight = 5.5oz; Includes two end caps.
