Looks like you could thin them out a bit. Leave only one apple per cluster. Don't worry the remaining apple will be bigger and this will cause more flowers to be set for next season. Next time you could thin them out a bit earlier, like late June/ early July.

I think I'd be tempted to leave two in each cluster - but definitely remove the smaller ones to give the others more space and light to grow bigger.

I agree with the other comments (particularly the one that it is a bit late). However it also depends on the variety. This is not necessarily a heavy crop for some varieties (e.g. Falstaff, which this looks a bit like). There is plenty of shoot growth and leaves, so it can carry a good crop.

Thanks guys, as usual I appreciate your advice. I'll be on it tomorrow a.m.