On your Nikon APS-C bodies, both can work, but 50mm is generally the better choice for runway fashion.

A 35mm on APS-C gives a roughly “normal” field of view, while a 50mm behaves more like a short telephoto. For runway shots, that extra reach is usually more flattering for people and gives you more flexibility as the model walks toward you. It also helps avoid the wider-angle distortion you can get with 35mm when shooting closer.

Choose 35mm if you’re close to the runway or want more of the scene in frame. Choose 50mm if your priority is model-focused shots with a cleaner, more flattering look.

If you have enough distance, even longer focal lengths can work well for runway photography, but low light may become more of an issue, so be prepared to raise ISO or use flash if allowed.