What lens do I need for full body portrait/dogs

[Andy Stringer]

For a full body portrait of a person, say 1.8m tall, using a full frame camera, you would need the following focal lengths:

Subject Distance	2m	3m
Landscape focal length	26mm	40mm
Portrait focal length	40mm	60mm

For its versatility, I support Rick's suggestion of the 24-70mm f/2.8L USM. It also suits your current kit very well.

I would not recommend a 24mm prime lens for portraits. You have to get quite close to people and this can make their noses look big. Apart from that, you might struggle to get a well lit subject from an on-camera flash at such short range (but that's another topic and I'm not an expert on lighting. I just know that I would want the flash off camera and/or shoot from further away). Another reason to avoid a short focal length is bokeh. At 24mm, f/1.4, the depth of field will be around 40cm in front and 50cm behind a subject 3m away. It's easier to blur the background with longer focal lengths. Maybe you have a plain background and that won't matter so much.

I have no experience with the original 24mm f/1.4L USM, but I have read of one professional landscape photographer who thinks that it does not resolve enough detail for the 5D Mark II's sensor. The current 24mm f/1.4L II USM is a much better choice for the latest full frame DSLRs if you are choosing between the two versions, especially if you will be making large prints. I'm very pleased with mine, but I don't use it for portraits.