High Precision Pentaprisms for Optical Systems & Cameras | Custom Solutions by Bote

What Is a Pentaprism? – Pentaprism Meaning

A pentaprism is a five-sided optical prism that reflects light at a fixed 90° angle using two reflections. Unlike ordinary mirrors, pentaprisms preserve image orientation and are critical in optical instruments where precise beam deviation and stability are required.

Key Feature: It reflects light through two internal surfaces, maintaining the same image orientation while deviating the beam path by exactly 90 degrees.

At Bote (www.bote.com.sg), we design and produce custom pentaprisms with tight angular tolerances, various coatings, and precise alignment suited for camera viewfinders, surveying systems, and metrology applications.

Pentaprism in Cameras – How Does It Work?

In DSLR cameras, the pentaprism sits just above the mirror box. It redirects the image from the camera lens to the optical viewfinder, allowing photographers to see exactly what the lens sees—right-side-up and laterally correct.

Function of Pentaprism in Camera

Redirects light 90° vertically
Preserves image orientation
Allows real-time optical viewing

Pentaprism vs Pentamirror

Feature	Pentaprism	Pentamirror
Material	Solid optical glass	Multiple mirrors in plastic housing
Image Brightness	High	Lower
Durability	Strong and stable	Lightweight, less rugged
Cost	Higher	More economical

Pentaprisms are preferred in professional DSLR systems due to their brightness and durability, while pentamirrors are often used in entry-level cameras.

Does a Mirrorless Camera Have a Pentaprism?

No. Mirrorless cameras do not use pentaprisms or mirrors. Instead, they rely on electronic viewfinders (EVFs) or LCD screens to display the image directly from the sensor.

✅ Pentaprisms are unique to DSLR designs.

Pentaprism Angles & Design

A standard pentaprism reflects light through two internal surfaces at 45° and 45°, producing a total beam deviation of 90° regardless of the prism’s rotation. The remaining surfaces are often coated to reduce losses.

Typical Specifications

Parameter	Value
Beam Deviation	90° ± 30 arc seconds
Surface Flatness	λ/4 or better
Coating	Enhanced Aluminum, BBAR, or custom
Material	BK7, Fused Silica, or Optical Glass

We also offer custom roof pentaprisms, which add a roof edge for image inversion, widely used in binoculars and surveying scopes.

Types of Pentaprisms We Offer

Standard Pentaprisms – 90° deviation, image-preserving
Half Pentaprisms – Compact size for tight spaces
Roof Pentaprisms – Adds inversion for binoculars and rangefinders
Customized Coated Pentaprisms – For cameras, laser alignment, or lab optics

Applications of Pentaprisms

📷 Pentaprism Viewfinder: In DSLR cameras
📡 Metrology & Laser Systems: For accurate beam redirection
🧭 Surveying Instruments: For angle measurement
🔬 Microscopy: Beam control in imaging paths
🛰️ Aerospace & Defense: Ruggedized, coated optics

Pentaprism in Photography

Pentaprisms play a vital role in optical viewfinders, giving photographers:

Accurate framing
Bright real-time viewing
Minimal latency compared to electronic displays

Professional photographers still prefer optical pentaprism viewfinders for outdoor, sports, and wildlife photography where speed and visibility matter.

Why Choose Bote’s Pentaprisms?

🔧 Custom Fabrication Services
We offer fully customizable pentaprisms including:

Dimensions: from 5mm to 75mm aperture
Angular accuracy: down to ±10 arc seconds
Coatings: BBAR, mirror, or IR-compatible

🌐 Global Manufacturing & Delivery
With a full-scale optical workshop in Nanjing and a QA/assembly center in Singapore, Bote provides efficient, cost-effective solutions globally.

💡 Design Support
Need Zemax optical simulation? Our engineers help evaluate tolerances, angles, and coatings based on your system’s needs.

Images You Can Include (Recommended Alt Text)

Pentaprism in DSLR Camera Cutaway
Alt: Cutaway diagram of DSLR showing pentaprism above mirror box
Standard vs Roof Pentaprism
Alt: Diagram showing shape difference and image paths
Bote Custom Pentaprism Product Photo
Alt: High-precision coated pentaprism from Bote Singapore
Pentaprism Beam Deviation Illustration
Alt: Light entering and exiting a pentaprism with 90° deviation

FAQs – Quick Answers for Search Users

❓ What is the difference between a pentaprism and a mirror?

A mirror simply reflects light, often inverting the image. A pentaprism redirects light while preserving orientation, which is essential in camera viewfinders.