Quote (Csabi @ Aug 25 2013 10:59pm)
but there is enough light, i always shoot at 800-1250 iso, f4-5.6, just need a lil more light

so dunno
That light is really nice inside the first one. You shouldn't have any worries with lighting. Don't be afraid to run 1600. Just make sure your exposure is right or a little over. Last thing you want is to push shadows at high ISO.
Is 4-5.6 the fastest lens you have? That's a bummer because at 2.8 you could probably shoot at 800 iso.