Looks just like my fusarium, doesn't mean it is.

What are you using for fertilizer? Are these container grown plants? If so, are you using a store bought potting mix for soil?
At first glance, it looks like an iron deficiency sometimes seen with plants that are at the same time producing heavy amounts of fruit. I have noticed this when using commercially prepared or home prepared peat based mixes as the plant's nutrient requirements suddenly change from foliage nutrient requirements to fruiting requirements.

I always found it best in any case to use a complete fertilizer especially designed for tomatoes that contains all of the necessary trace elements such as copper, sulphur, iron etc. The organic types seem to have a greater effect with less stress or shock or abrupt changes in soil structure that may be ideal otherwise.

Ironite- a mineral supplement found at most garden centers contains all of the tomato dependent minerals such as, soluble iron, boron, copper, manganese, sulfur, molybdenum,calcium and zinc. Many potting mixes or soils that are amended in which to mimic the properties of peat based potting mixes, usually lack one or more of these essential minerals and is especially apparent on new soil establishments. While great for house plants, these soils are rarely adequate for vegetable growth without some fine tuning and establishment of micronutrient balance for the high demands of fast maturing and heavy fruiting plants.

I should add that the use of ironite has become somewhat controversial(news to me)due to suspected additions of arsenic and lead.At any rate, it is best to have your soil tested initially. Many of the organics or a mixture of organics such as tomato-tone and garden-tone will typically have all of the trace minerals.