SKU: 27103169127

Explore Scientific 99% Reflective 3" Diagonal

Sale price$265.50 Regular price$295.00
Save 10%

Pay in installments of $73.75 with ShopPay, AfterPay and Klarna

Shipping Estimate
USA
  • USA
  • CAN

Ships within 48 hours · Estimated delivery Sep 1 - Sep 6

Promo Codes Available:

For Your Every Summer RSVP, with Code: SUMMER15

Description

Explore Scientific 99% Reflective 3" DiagonalA 3 inch dielectric coated star diagonal that reflects 99% of incoming light through a full 3 inch optical path designed for telescopes with 3 inch focusers where a standard 2 inch diagonal would vignette the light cone and clip the edges of wide field views. The first surface dielectric coating reflects virtually all incoming light, delivering the brightest and highest contrast image your telescope can produce. This is particularly important at the 3

A 3-inch dielectric-coated star diagonal that reflects 99% of incoming light through a full 3-inch optical path — designed for telescopes with 3-inch focusers where a standard 2-inch diagonal would vignette the light cone and clip the edges of wide-field views.

The first-surface dielectric coating reflects virtually all incoming light, delivering the brightest and highest-contrast image your telescope can produce. This is particularly important at the 3-inch aperture class, where the telescopes paired with this diagonal are typically fast, large-aperture refractors — instruments where every fraction of a percent of light transmission matters for deep-sky performance.

The double-taper insert barrel slides smoothly into 3-inch focusers and the wider taper section prevents the diagonal from accidentally falling free. A compression ring lock secures eyepieces without set screw marks. Includes a 2-inch adapter so you can use your existing 2-inch eyepiece collection, and dust covers to keep optics clean in storage.


Key Features
  • 99% first-surface dielectric coating for maximum brightness
  • Full 3" optical path — eliminates vignetting on large-format focusers
  • Double-taper insert barrel for secure, smooth fit
  • Compression ring eyepiece lock — no set screw marks
  • 2" adapter and dust covers included
  • Weight: 2.0 lbs (0.90 kg)

Ideal For
  • Large refractor owners — the ES ED152, FPL53-series, and other 3"-focuser telescopes need a 3" diagonal to avoid vignetting
  • Deep-sky visual observers — the full 3" light path paired with 99% dielectric reflectivity delivers the brightest possible wide-field views
  • 2" eyepiece users — included adapter means your existing eyepieces work immediately

Good to Know
  • 1.25" eyepiece adapter is sold separately
  • Designed for telescopes with a 3" focuser — will not fit standard 2" focuser drawtube
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 27103169127

Discover Niche Categories That Outsell

Top-Converting Item to Boost Your Average Order

4.1 ★★★★★
Based on 14 reviews
Sort
Highest Rating
Newest First
Oldest First
Product Reviews
C
Chloe
Phoenix, US
★★★★★ 3
Its alright
Color: Black, Size: 5X-Large
True to size per the size chart. The fabric is soft but it it feels cheap to me. It attracts lint but you can brush it off easily so its not the cheapest material I've dealt with. Also, it is opaque (not see through). There is no front/ back indicator either which is indicative of a cheap shirt in my opinion. Would be friendly for tag sensitive people (to stay positive).
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 14, 2026
A
Verified Purchase
Amazon Customer
Houston, US
★★★★★ 5
Fit and colors are perfect
Color: Black, White, Apricot, Size: Large
They fit very well, I got them for my husband and he was very excited for the style & fit i am actually going to buy him another pack
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on October 7, 2025
C
Verified Purchase
ChilledOut
Waukegan, US
★★★★★ 1
Fuzzballs get wearing once
Color: Black, Size: X-Large
Very smart to wear, but the quality is terrible so after one wash the collar start fraying and fuzzballs start forming. Very disappointing.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on June 2, 2026
C
Verified Purchase
Charles S. Fulton
Bozeman, US
★★★★★ 5
Cool shirt
Size: X-Large, Color: Black
Very comfortable and light weight. The material is like a moisture wicking material and feels cool on my skin. The shirt stretches and moves with you and is nonbinding in the areas of your arms and neck.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 26, 2026
R
Verified Purchase
Rt
Natrona Heights, US
★★★★★ 5
Worth it
Size: 3X-Large, Color: Black
This shirt is light weight , comfortable, great quality and I would definitely get more
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on June 1, 2026

recommand products