Depth Of Field and Teleconverters

[DickVH]

If I use my 300mm f2.8 lens w/ a 2x tc, do I get the DOF from the table on 300mm or 600mm?

Dick

[mdurisseau]

I would suspect that you end up with the DOF based on the focal length you end up with. Maybe someone has a more detailed answer...

[KdLaneJr]

While I can't point you in the exact right direction, Here is a link to the online DOF calculator, which contains this statement; "Use the actual focal length of the lens for depth of field calculations. The calculator will automatically adjust for any "focal length multiplier" or "field of view crop" for the selected camera."

Since his table adjusts for field of view crop, then I would suspect that you need to take the 2x TC into account when using the calculator also.

I know when I put the 1.4x TC on my 300, LR tells me I shot with 420mm lens and in () tells me 300mm +1.4x.

[billbunton]

Surprisingly, I recall Bjørn Rørslett did some testing and found that the TC doesn't affect the DOF. (I think it was some posts on Nikon Cafe).

[DickVH]

Bill,

That is not all that surprising to me. I have suspected that the DOF stayed the same when you put the TC in place. It seems to me that the TC just takes whatever image the lens creates and spreads it out, but I've been hoping to find out from an expert.

Dick

[jonnydonut]

here's what I'm thinking... increase in focal length decreases DOF, however a teleconverter will raise up your f/stop thus increasing DOF. I bet they cancel each other out pretty evenly. ..but i'm not an expert on tele converters.