Leash and harness during dog photography
'Can I come to a photo shoot with a dog that has never been let loose in a public place and is on a leash?'
Sure, you can, this is not a problem. During the post-production of the photos, I can remove the leash, if necessary, so it won’t be distracting. As for a harness, I may not remove it due to its size, but this is not always necessary.

In many cases, it’s even beneficial if the dog is on a leash.
A leash is not only useful when your dog can’t be called back, but also in environments where there are potential sources of danger or distractions such as bicycles, runners or other dogs. If your dog gets scared, runs away or behaves unpredictably, accidents and injuries can be prevented if it’s on a leash.
So taking photos without a leash is only safe where there are no motorists/cyclists. You can let your dog run freely only if you can definitely call it back and it won't disturb others.
Another advantage of the leash is that you can use it to communicate with the dog and control it, for example if I want to photograph your dog while it’s jumping over a big branch of tree lying on the ground.
If we shoot, for example, in a field of daffodils, tulips or lavender, it is mandatory to use a leash in most of the cases. I also know a superb, dog-friendly lavender field near Budapest where you can let your furry friend run freely.