Omg you are gonna have so much fun with that D850! Its basically a pro level monster lol. For a kids party and that $400 budget, you 100% need to get the Nikon AF-S NIKKOR 50mm f/1.8G. It is a total game changer and honestly the best bang for your buck ever!! Here is why you'll love it:

• The Bokeh: Thats the fancy word for the blurry background. It makes photos look super professional and hides all the messy clutter in the house!
• Speed: This lens is fantastic in low light. If the kids are blowing out candles or playing inside, you wont need a nasty flash and the shots stay sharp.
• Quality: Prime lenses are usually way sharper because they focus on one job. Your photos will look so crisp! Just pop it on and move your feet to zoom in and out. You're gonna take the best photos of your life at that party!

Jumping in because I am absolutely obsessed with the D850! It is such a powerful professional tool and you are gonna see amazing results once you get the hang of it. To give you the best advice though, I need to clarify one thing first... will this party be held in a large rented hall or just a standard sized living room? Space really matters with prime lenses because you cant zoom out if things get crowded. Primes are fantastic because they offer way better optical clarity than cheap zooms, which is vital for a high-res sensor like yours. Basically, the wider aperture (that f/1.8 number) lets in significantly more light. This allows you to keep your shutter speed fast enough to catch kids running around without getting motion blur! If the space is tight, a used Nikon AF-S NIKKOR 35mm f/1.8G ED might be a safer, more versatile bet than a 50mm. It is a legendary lens and super reliable for busy events!

Huh interesting. I had no idea. The more you know I guess 🤷

This thread is gold. Bookmarking for future reference 🔖

I totally agree with what everyone is saying about that camera! The D850 is a legendary beast and the reliability is just unmatched for pro-level work. Since you are just getting started with the technical stuff though, I think you should definitely do some independent research to see the results with your own eyes before you drop $400. Here is the most methodical way to find your answer:

• Search YouTube for Nikon D850 prime lens comparison. There are amazing videos that show side-by-side samples of the glass people are talking about.
• Check out the Reddit r/Nikon subreddit because they have massive threads specifically for F-mount lens recommendations.
• Visit the Nikon official site to look at their lens simulator which is fantastic for understanding focal lengths. Honestly, just google it and you will find exactly what you need in seconds. I saw a great video about this once that makes it way clearer than a forum post ever could, just look it up! Tbh it is way more reliable to see the glass in action before buying.