lastolite hotshoe ezybox 24" enough for this or need 30" ?

I planning to shoot friends horses and I'm thinking if 24" lastolite hotshoe ezybox I have will be enough for this kind of thing.

I'm also not sure if even new 30" is needed. For example here: http://www.horse-photographer.co.uk/horse-gallery-1.html

I can see rather beautydish so let's say it's 22" so maybe 24" sofbox will be enough?

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