Building on the earlier suggestion, I've gotta say the 50mm is a solid choice, but I actually found myself much more satisfied with a slightly longer reach for graduation shots. I picked up the Nikon AF-S NIKKOR 85mm f/1.8G a couple years back for my niece's ceremony and honestly, the background compression is way better than what you get with a 50. It gives you that creamy, professional blur that makes people look amazing. On your D7500, it'll feel like a 127mm lens, which means you'll be standing a bit further back, but the sharpness is just incredible. I have used mine for countless shoots and have no complaints about the low light performance—it handles dim auditoriums like a champ. It might push the 400 dollar budget if you buy brand new, but I grabbed mine used and it has been the best investment I ever made for my kit.

Honestly, its kinda frustrating how expensive glass has gotten lately. I had high hopes for some of the newer lenses but the price tags are just ridiculous now, and unfortunately, the cheaper entry-level primes can feel a bit like plastic toys. If youre sticking to that 400 dollar limit, you really gotta look at the used market or you might end up disappointed with what you get brand new. I actually had issues with a lens recently where the autofocus kept hunting in dim rooms... total nightmare. For your D7500, I would look for a used Nikon AF-S NIKKOR 50mm f/1.4G. Its better in low light than the f/1.8 and feels much more substantial. You can usually find them for under 300 bucks if you look around. If thats still too much, the Nikon AF-S DX NIKKOR 35mm f/1.8G is a solid budget choice for tighter shots. Just test it first. Youll do great at the graduation tho!

The Nikon AF-S NIKKOR 50mm f/1.8G is your safest bet. It's sharp and fits the budget.

• consistent focus
• decent low light It just works.