prime35mmdiscontinued
SMC Pentax-M 400mm f/5.6
Pentax · 1977-1984
Ultra-long telephoto for serious wildlife work. Excellent reach.
Known for
- Wildlife
- Birding
- Sports
Considerations
- Very slow
- Requires tripod
Optical Characteristics
Sharpness (wide)4/5
Sharpness (stopped)5/5
Contrast4/5
Flare Resistance4/5
CA Control3/5
Vignetting Control3/5
Distortion Control4/5
Common Issues
- Check for fungus
- Inspect aperture blades
Buying Guide
Specifications
MountPentax K
Focal Length400mm
Max Aperturef/5.6
Min Aperturef/32
Aperture Blades8
Filter Size77mm
Weight990g
Optical Design
FormulaTelephoto
Elements7
Groups5
CoatingSMC (Pentax)
Pricing
£150 - £280
Typical used price
Mint: ~£380
Adapts To
Sony EFujifilm XCanon RFMicro Four Thirds
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Last verified: Jan 2026Report an error