I've been lugging gear around weddings for years now and honestly, heavy zooms are the fastest way to ruin your mood by hour six. If the Sigma Art feels too heavy in the store, itll feel like a literal anchor after ten hours on an a7 IV. Since you have a 1200 dollar budget, you have a few ways to play this that might be better than the two options you're stuck on.

• Tamron 28-75mm f/2.8 Di III VXD G2: This is probably your best bet for versatility vs weight. Its much lighter than the Sigma Art and the image quality is honestly 95 percent of the way there. It handles the crowded rooms way better than an 85mm would, but still lets you zoom in for those tighter headshots.
• Sony FE 35mm f/1.8: If you definitely want that 85mm prime, you need to pair it with something wider. You just cant shoot a whole wedding on a long lens... youll run out of space. This 35mm is cheap, light, and very fast. Primes give you that professional look, but zooms save your sanity when things get chaotic. If you go the zoom route, maybe spend the leftover cash on a Peak Design Slide Camera Strap to help distribute the weight. It really makes a massive difference for your wrists. Its a tough call but prioritize being able to move quickly over having the absolute perfect bokeh. Good luck with the big day tho, you'll nail it!

Honestly, grab the Sony FE 85mm f1.8 and dont look back! Its super light and the bokeh is amazing for creamy wedding portraits. I used it for a ten hour shoot recently and my wrists felt great... way better than lugging that heavy Sigma 24-70mm f2.8 DG DN Art around. The 85mm is just fantastic and saves you money too. Youre gonna crush it!!

Saw this thread this morning and had to jump in. Like someone mentioned, that Sony 85mm is a total beast for the weight! I remember shooting a ten-hour marathon in a hot garden last summer... my wrists would have snapped if I was using a heavy zoom. Honestly, if you have 1200 dollars, you really should look at the Sigma 85mm F1.4 DG DN Art. I did some side-by-side testing recently and the resolution numbers on this thing are insane, way sharper than the Sony f1.8. It weighs about 630g so its still way lighter than that 24-70mm brick. Plus the bokeh from those 11 rounded aperture blades is just creamy perfection! If you're really stressed about crowded spaces tho, check out the Tamron 28-75mm f2.8 Di III VXD G2. Its the lightweight king of zooms and the AF tracking is fantastic. Ngl, your wrists wont feel nearly as tired by the reception.