Tamron 2X MC7 C-AF1 BBAR teleconverter

catza.net photos: Tamron 2X MC7 C-AF1 BBAR

• a typical seven-element 2x EF teleconverter
• estimated retail price 200 EUR
• in my use for several years
• as my requirements on image quality got higher I no longer had use for a teleconverter

• an easy and cost-effective way to double focal lengths (I used this with Sigma 70-300mm f/4-5.6 APO Macro Super II to shoot the moon)
• doesn't stop the body from autofocusing since body is uninformed that there is a teleconverter present (in bright light this really helps)
• gives better results than the cheapest 4-element teleconverters
• very simple to use
• very easy to carry around

• causes visible loss of saturation, contrast and sharpness even with primes
• many buyers expect miracles but there are none
• some lenses that have a protruding rear element can crash with this and ruin both