Likely you didn't harden them off enough before they got full sunlight.

If so individual spots won't enlarge, but more can develop.

Me too. I have spots on my leaves that look identical to those shown in your photos on essentially all of my tomato plants; varieties : TOV, Match, Bliss, Cheresita, and unknown Cherry, plus on two varieties of pepper plants. I know of one other greenhouse in the area that is experiencing the same necrotic spots, but to a very minor extent.
Some of the plants have been place for less than two weeks and others have been producing for over a year. All plants are in a small green house, in rock wool and during day light they are drip fed every 30 to 40 minutes and ~65 ml/feeding, depending on the time of year. Recently, the temperature ranges from 55 at night to 85 F during the day. The greenhouse is located in Tucson, so there is no lack of sunshine, but the plants are shaded with 50% white cloth.
The plants were either started from seed or cuttings or were excess stock from a hydroponics operation at a University. In general, the plants look healthy except for the spots.

Although I have had insect problems, the spots are not associated with attack by insects, unless the insects are invisible at 30X and greater.

This adnormality has not had an obvious--to me--effect on production, but I’m just entering my second year of attempting to grow crops hydroponically.

Note: I have photos, but I haven't figured out how insert them.

So, I am very curious as to what is causing these necrotic spots, and obviously I’m looking for a treatment. I'm looking for input.

dennyg

Just add a fertilizer like Fish Meal (usually 3-16-0) or else something like Jobe's Tomato Spikes (usually a 5-18-5 mix). The middle number of the three refers to the amount of soluable phosphorus in the mixture. To get the "elemental" phosphorus, multiple by .43 --- lots of phosphorus is needed (along with good wind--in order to polinate the crops-- and the right amount of water) to grow great tomatoes.