Note how the following authors get it wrong.

MJA 2006; 184 (7): 338-341

Estimates of beneficial and harmful sun exposure times during
the year for major Australian population centres

By
Amanda J Samanek, Emma J Croager, Peter Gies, Elizabeth Milne,
Richard Prince, Anthony J McMichael, Robyn M Lucas and
Terry Slevin

Quote

Exposing the whole body to 1 MED produces serum vitamin D
concentrations
equivalent to an oral intake of between 10 000 and 25 000 IU.
Thus, exposing 15% of the body, for example the face, arms and hands,
to 1 MED would be equivalent to an oral dose of 1500 to 3750 IU of
vitamin D. For those aged 19 to 50 years, 200 to 600 IU per day of
vitamin D taken orally is recommended to prevent vitamin D
deficiency. The current Australian guidelines for recommended
vitamin D intake for different age groups are 200 IU/day
from birth to 50 years of age, 400 IU/day for people aged 51 to 70
years,
and 600 IU/day for those over 71 years. Therefore, 1/6 to 1/3 MED
would be sufficient to provide this amount.

Unquote
-----------------------------------------------------------
No matter that current Australian guidelines are grossly wrong.
Evidence is that a normal person that is replete in vitamin D
with uses about 3600 IUs a day of vitamin D3.

Of course, the Australian government gets it wrong also as
they've only approved the so-called vitamin D2 for use not the true
vitamin cholecalciferol as I recall. And the IU values of "vitamin D2"
in
comparison to vitamin D3 are also wrong. Vitamin D3 has a
4 times the biopotency over the longer term compared to D2.

Note that these authors fail to examine the serum blood
levels of 25 OH vitamin D which is the 'silver' standard for
determining
deficiency or insufficiency or adequacy or even excess of the vitamin.
Their conclusions are based on false assumptions and on no
immediate lab work on their part.

These authors should listen to the following
webcasts. The first is simple enough they might even
understand it. The second webcast is designed for those
who actually know the topic.

http://www.postgradmed.com/issues/2004/01_04/tan.htm

http://app2.capitalreach.com/esp1204/servlet/tc?cn=asbmr&c=10169&s=20343&e=6950&&

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I say get some sun on more than just the face, arms and hands and
also
take a couple thousand units of vitamin D3 perhaps
more during the darker months of the year. If you live in the tropics
expose more skin if only for 10 minutes (assuming you're white)  a
day
during the mid day sun. Do however avoid the sun if you are photo
sensitive due meds, mutation, or disease. If you're black you
may need 2 hours of the midday sun for an optimal dose of D.

And remember public health authorities and dermatologists through
their fear mongering about vitamin D3 and the sun are
the cause of much of the prostate cancers, breast cancers, multiple
sclerosis and
type 1 diabetes that afflicts the population of the world.
The vitamin prevents these diseases. Not a 100 percent but
as high as 80 percent of some of these diseases.