Horse shows can be tricky depending on if it is indoors or outdoors but the 70-200 range is basically the standard for that kind of thing. Since you have a $2000 limit, you wont be able to grab the big f2.8 GM II brand new, but dont sweat it because the Sony FE 70-200mm f/4 G OSS II is an incredible piece of glass that fits your budget perfectly. This lens focuses fast which is exactly what you need to keep up with the a1 sensor. Quick tip tho, if its an indoor arena and lighting is garbage, you might want to look at the Tamron 70-180mm f/2.8 Di III VC VXD G2. That lens gives you that extra light for way less money, even tho you lose the crazy high burst speeds native lenses get. Honestly, for horses, 15fps is usually plenty. Youll do fine!

Totally agree. Be careful with third-party specs tho:

• Sony firmware caps non-native lenses at 15fps.
• I once missed a jump using the Tamron 70-180mm f/2.8 Di III VXD because of it.

tbh its a bit disappointing that the a1 is such a powerhouse but the best lenses for it are so expensive. You basically bought a Ferrari but only have enough left for mid-range tires... dont worry tho, we can definitely make it work. Before I give you a final list, quick question: is the horse show indoors or outdoors? Lighting makes or breaks these recommendations. Since we're sticking to a $2000 budget, check these out:

• Tamron 70-180mm f/2.8 Di III VC VXD G2 is a solid alternative. It keeps up with the a1's fast tracking for way less cash than the GM versions.
• Sony FE 70-200mm f/4 G OSS II is technically great and super sharp, but f/4 might be a struggle in a dark arena.
• Sony FE 200-600mm f/5.6-6.3 G OSS if the show is outside and you need serious reach. Let me know about the lighting situation!