The Tamron 18-400 is an incredibly versatile lens crop sensor lens. In this video, I take it whale watching with San Juan Safaris in Friday Harbor and compare it against the Sigma 24-105 and the Sigma 100-400 telephoto lens.https://www.youtube.com/watch?v=uNZEVT0edkQ 

Tamron 18-400 Lens Specs

• APS-C Format
• 28.8-640mm (35mm Equivalent)
• Aperture Range: f/3.5 to f/40
• Three LD and Three Aspherical Elements
• HLD Autofocus Motor
• VC Image Stabilization
• Moisture-Resistant Construction
• Electromagnetic Diaphragm
• Rounded 7-Blade Diaphragm
• Compatible with TAP-in Console