I currently use a Nikon D300 and D300s. I’m considering the purchase of a 1.4x ($510) or 1.7x ($540) teleconverter for sports photography. I have an 80-200mm f/2.8 lens and a 70-300mm f/4-5.6 lens. If I understand it correctly, a 1.4x magnifies both reach and aperture, which means: 80-200mm f/2.8 would be converted to 115-280mm f/4 70-300mm f/4-5.6 would be converted to 100-420mm f/5.6-8 Is that correct? Since I want to use it primarily for sports, I want to keep my shutter speed in mind. I like tripling my shutter:lens ratio (keeping it between 1/1000 and 1/1250 for day sports). My shutter speed would also have to be increased to compensate for the teleconverter, right? If I shoot the minimum at 200mm f/2.8 1/600, the new length would be 280mm f/4 and I’d have to increase the minimum shutter to 1/1000, right? The cost of a refurbished 300mm f/4 is about $1,300. Should I save my money and invest in the 300mm f/4, or cut the cost and get the $510 TC-14 teleconverter? Any suggestions would be greatly appreciated.