Binnz7dw,
Something good that the 503HDV (latest version of the 503) has is an illuminated bubble level. This is very useful indoors, as there usually isn’t that much light faling on the tripod. I’ve tried holding a flashlight between my chin and shoulder while adjusting the level with one hand and tightening the leveling ball with the other hand. Having an illuminated bubble level would be pure luxury. Also, I’ve read posts from 503-owners that the 503 has smoother starts than the 501.
Ken Hull
