Lens Adapter

Definition

An adapter (lens adapter) is a mechanical or electro-mechanical intermediate piece that allows the mounting of lenses onto cameras with different bayonet systems. Depending on the flange distance difference, an adapter can be purely mechanical or contain optical elements.

Principle of Operation

Flange Distance

The distance between the lens mount and the sensor plane is crucial:

Lens Flange Distance > Camera Flange Distance
→ Simple Adapter (mechanical only)

Lens Flange Distance < Camera Flange Distance
→ Adapter with optics or not possible

Example Flange Distances

Adapter Types

Mechanical Adapters (Dumb Adapters)

• Mechanical connection only
• No electronic communication
• Manual aperture required
• Affordable, reliable

Electronic Adapters (Smart Adapters)

• Transmits aperture values
• Autofocus (partial)
• EXIF data
• More expensive, software updates needed

Optical Adapters

Speed Booster / Focal Reducer

• Reduces crop factor
• Increases light sensitivity (approx. +1 stop)
• Contains a converging lens

Teleconverters

• Extends focal length
• Reduces light sensitivity
• For telephoto applications

Popular Combinations

For Cinema Cameras

For Vintage Lenses

• M42 → E-Mount (very common)
• Nikon F → E-Mount
• Canon FD → MFT

Quality Features

What to look for?

1. Planparallelism: No tilting
2. Material Quality: Aluminum, no cheap plastic
3. Fit Accuracy: No play
4. Aperture Mechanism: For adapters with an aperture ring

Premium Manufacturers

• Metabones
• Wooden Camera
• MTF Services
• Fotodiox Pro
• Viltrox (Budget)

Limitations

• Infinity Focus: Not achievable with incorrect calculation
• Vignetting: With extreme combinations
• Autofocus: Often slower or unavailable
• Stabilization: Check IBIS compatibility

See also

• Speed Booster – Focal Reducer
• PL Mount – Cinema Standard
• Flange Distance – Register Distance