The Canon EOS 5D Mark IV is a top-of-the-line DSLR camera that offers professional-grade features and performance. It was first released in 2016 and has since been widely used by photographers and videographers of all skill levels. If you're in the market for a second-hand 5D Mark IV, there are a few things you should consider before making your purchase.

Another important factor to consider is the camera's shutter count. The shutter count is the number of times the camera's shutter has been activated. A higher shutter count generally indicates that the camera has been used more and may have a shorter lifespan. However, it's important to note that the 5D Mark IV has a high-durability shutter rated for 150,000 actuations, so even if the camera you're looking at has a high shutter count, it may still have a lot of life left in it.
You'll also want to check the camera's firmware version and make sure it's up to date. Canon releases firmware updates for its cameras to address bugs and add new features, so you'll want to make sure the camera you're buying has the latest firmware installed. You can check the firmware version by turning on the camera and going to the “Menu” settings.
When it comes to lens and accessories, it's worth asking the seller what comes with the camera and what condition these items are in. Buying a second-hand camera body only can save you some money, but it's worth considering if you want to purchase the camera with the lens and other accessories.
Finally, make sure you're buying from a reputable seller. Look for reviews and ask for references if possible. It's always best to buy from a reputable retailer or a private seller with a good reputation.
In conclusion, buying a second-hand Canon EOS 5D Mark IV can be a great way to get a professional-grade camera at a lower price. However, it's important to do your research and make sure you're getting a camera that's in good working condition. Be sure to check the camera's condition, shutter count, firmware version and make sure you're buying from a reputable seller. As long as you take the time to do your research, you'll be able to find a great second-hand 5D Mark IV that will serve you well for years to come.