bsmart - it's good you're body tolerates the high dosages of manmade D.
The idea of getting the real thing outside (Vitamin D/UVI) is NOT to tan at all. If in the sun, every square inch of your body will absorb the D as long as the good UVIs are out and they're the highest between 12-1 pm in most areas of the planet. The US NAVY has a chart you can check for Vit D and best window is between 12-1 daily. I only turn red in the sun - fair people (little melanin) burn but you only stay out a minute on each side or let the sun hit your legs/arms/whatever. The fairer you are the faster the D accumulates on top of the skin. Age/excess weight adds an extra minute or so. Best book is 'The Vitamin D Solution' by Michael F. Holick, Ph. D., M. D. If you notice you're turning red/any burning in sun you're overdoing it and need to stop. It's hard - you can't always tell after a minute. There are apps you can download to your cell to use for safe Vit D timing - they don't work that well but the timer is worth it not to end up lobster red/burned. You should only notice a very slight nuance of color (golden if white skinned after mos or pink my case) on your body, if that from sun exposure. It's scary.
The OTC bottled Vitamin D is the next best and pretty darn close to natural and good way to go. It does cause issues for some people.