Using a 1.4 TC on a f/2.8 Lens

Using a 1.4 TC on a f/2.8 Lens
I've been asked on several occasions if I mind losing DOF (dept of field) when shooting sports with a 1.4 TC.  The short answer is no, not in the least.

What and when to use a 1.4 TC.
 I'll use a 1.4 TC on my 400mm f/2.8 for two field sports (Football and Soccer) and for gym sports when I'm also using strobes as well as on my 70-200mm f/2.8 for gym sports when I'm also using strobes.

Field Sports
When shooting Football and or Soccer longer focal lengths are necessary when trying to get as many keepers as you can from the game.  Using a 400mm with a 1.4 TC will get you a focal length of 560mm (not adjusting for your sensor size which is a totally different subject.)  For Football this will allow me to setup behind the end zone and will enable me to shoot across the filed to the opposing 10 yard line without a lot of cropping.  Below are a couple of examples:

Canon EOS-1D Mark IV, f/4 @ 560 mm, 1/1000, ISO 200

Canon EOS-1D Mark IV, f/4 @ 560 mm, 1/1250, ISO 200

 As the team moves from one end of the field to the other, I'll remove the 1.4 TC and shoot at 400mm.  A sample image is below:

Canon EOS-1D Mark IV, f/2.8 @ 400 mm, 1/1250, ISO 800

As a side note as the team continues down the filed I'll switch to another body with a 70-200, and when they are near the end zone I'm shooting at I'll switch to a third body with a 24-105 f/4 lens.

Gym Sports 

When shooting gym sports the only time I'll use a 1.4 TC is when I'm also lighting the gym with two or four Alien Bee's AB1600's.  When you use strobes to shoot gym sports your shutter speed will be limited to the fastest sync speed of your body.  With Canon 1D bodies that is 1/250, which by itself will give you motion blur.  So you have to use your strobes to freeze the action (again a totally different subject).  To do this you have to shoot at least two or three stops above the ambient light.  This will usually require stopping down to at least f/4 or f/5.  So adding a TC and losing one stop of light is not an issue.  So I'll add the TC to my 70-200 to give me a focal length of 280mm which allows me to shoot across the court.