Conformation is all based on the difference in size between parts and the angles and length of parts...this is almost impossible to judge in a picture unless the horse is set up balanced and square on a flat surface...in person, you see the horse at many different angles, so you can compensate. In a picture, we only get one angle...so its got to be the best one possible.
There are lots of articles on the web that talk about shooting conformation photos for medical records, sales and marketing. Dig around and you'll find more hints than I've listed below.
If you are interested in learning more about conformation, The Horse Conformation Handbook is one of my favorites...very detailed.
• You need help with this. Either get someone to man the camera or hold the horse. If they are holding the horse, it needs to be someone with knowledge of horses and what you are trying to accomplish. A knowledgeable person should be able to set your horse up in the proper frame.
• Choose a flat area with an uncomplicated background to shoot on. Unless your stable is extremely well-lit and roomy, shoot outside.
• Shoot in the morning or late afternoon when the sun is at an angle (especially if your horse is dark bay or black). If you are more camera savy, you can also use a flash to fill in dark shadows. Oh, and don't shoot into the sun.
• Sometimes a partially overcast day is better for shooting than a sunny one. It will soften the shadows your horse throws.
• Sit in a chair or kneel to take the photograph: get on the same level with your horse's body.
• Size and Quality: you want to post a photo at least as big as the examples below...small photos, poorly lit photos, and blurry photos are very hard to judge.
Side View: Notice the hooves are completely level in both photos. Also, you want the horse looking ahead, not pointing his nose at the camera. The horse below is not really standing square, but its still a fine stance for judging conformation. More important that they are not leaning backwards or forwards.
The horse below is standing a little under herself in front, but still acceptable.
Front View: Chest, front legs, hooves. The horse should be square. The horse below isn't square in the back, but looks alright in the front.
Photo below is barely acceptable: the horse is nice and square, but the photo is very dark and hard to pick out details.
Rear View: Hindquarters, back legs, hooves. You may have to pull the tail out to the side for a clear shot. Again, horse stands square.