The 50 and 85 are for sure your best bets. If I were you, and this is just my opinion since you are a beginner, I would make sure I knew exactly how long the runway is. I say this because if you know your lenses, the angle of view for each, it will give you a great idea of where you need to stand in order to get the shots you want or need. Don't overlook this... hope you understood what I meant as I am outside, freezing, having a cig and my mind... well, may be frozen too. If you can use your flash you should be golden. Remember, shutter speeds of 1/250th and faster will freeze motion. Follow that rule and you will be fine. As for not being taken seriously... who cares? If you are serious about doing a good job, you will... no matter your equipment. Get the shots you need to get and don't be afraid to get creative... shots of the footwear when all the models come out at the end... that kind of thing. The models are going to rock... and you too my friend, will rock it as well.