Canon teleconverters

[HoboSyke]

hi all.. Im using a canon 40D at the moment with the EF 400 f/5.6L and 1.4x TC. Am I correct in saying that this lens with that TC on a 40D body is an 800mm f/8 Equivelant focal length?

Also, can I put a 2x TC on this setup and acheive a 1600mm f/16 equivelant ?

 

[Battou]

No, for an 800mm setup you would need a 2X converter, I think the 1.4 TC on the 400mm is like 560mm or something like that. Never the less for 1600 you need two 2X TC's.

put the 2X on the 1.4x and you have 1120...as for your aperture I don't know.

 

[HoboSyke]

Canon 40D body has a 1.6x crop factor and a 1.4x TC = 2x magnification + 400mm = 800mm f/8 ????

 

[Battou]

Canon 40D body has a 1.6x crop factor and a 1.4x TC = 2x magnification + 400mm = 800mm f/8 ????

I did not know that I don't know anything about crop bodies, however I have to assume that math has to be applied to the second teleconverter as well.

 

[HoboSyke]

The 400mm with a 1.4 TC = 560mm and loses one stop of light, so it becomes a 560mm f/8. Then you have to factor in the 1.6x crop factor of the body, so 560 x 1.6 (crop factor) = 896mm.

 

[Battou]

400mm on 1.6 crop body is 640mm x 1.4 = 896 x 2 = 1792mm

I think, I am not good with math.

Additionally I am much more accustom to full frame.....