For me it's hard to see any detail in the flowers, but it is normal for the flower petals to drop off (after pollination), and the fruit begins to form. But I cant tell from the pictures. I was under the impression that with blossom drop the whole flower bud turns yellow and simply falls off the plant. Also there are a few reasons for blossom drop.

"Blossom drop:
Usually caused by dry soils, and drying winds, but may be caused by sudden cold spells, heavy rains, N overdose, or heavy infections by bacteria or fungi."

From
http://home.earthlink.net/~shelly.johnson/tomato.html

During the hot part of the day it gets up to 105 in the hoophouse even though I have shade cloth, exaust fan and 2 circulation fans on. I also have the plastic rolled up about 4 feet on each side and a chiller that maintains the nutrient temp around 78 to 80 degrees. I have wondered if the shade cloth is not giving them enough light... Thanks for the responses I am new and enjoying experiment.

Sometimes the first set of flowers won't produce fruit for me. Other times every one does. I'm not sure why, it seems to be hit or miss. Since you're at four weeks, those are probably your first flowers. Are you plants getting enough air movement or bug action for pollination?

Yes these are the first set of flowers. I have two circulation fans that move the plant leaves about 10 hours a day and I have each side of the hoophouse plastic rolled up about 4 feet. Could my shade cloth (50%) be too much?

Although I doubt that this is your problem, I've also read that excesses of ethylene gas can cause blossom drop. Unless your plants are real close (I mean super close) to running automobiles or an active compost pile this shouldn't be an issue. Another idea is a product called Blossom set Although I Haven't had really great results with it. I may be wrong but I still think it will correct Itself when the temps come down.
Good luck
Ken

Just from my experience, I think you should wait to see what happens with the next sets of flowers before doing anything drastic.

I have problem with heirloom tomatos. I have about 25 tomato plants growing 9 of which different varieties of heirloom. Only the heirloom have green flowers. All other are flowering normally.