What does the whole plant look like? Early blight shows up on the lower leaves first and look a lot like your leaves. Removing the lower leaves and not planting in the same site if you have had problems before is the best control. Early blight usually shows up on younger plants. Starting on the bottom and eventually causing the whole plant to wilt and dry up. Late symptoms are usually from phythoptora which is harder to control. Getting plants that are disease resistant helps. If you have problems with blight it can take years before it goes away. So you have to rotate to different crops or location.
Tomatoes are susceptible to a variety of fungal and bacterial problems especially in humid wet conditions. Getting tomatoes with good disease resistence helps as well as good culture which includes good sanitation and spacing. Fungicides work better at prevention than as control. Take the lower leaves off the plant to prevent splashing and mulch. Try to keep the foliage dry.
It is hard to tell from dry leaves along if your plants have blight. If your tomatoes have small bad spots that grow into larger bad spots that soon destroy the tomato like cancer you have blight. Spray your plants with rust water and water your plants with rust water it will stop blight and they will recover in about 2 weeks if they are not already dead. It is easier to prevent blight than to stop blight water your plants with rust water all summer.
I put about 20 empty kitchen food cans in a fire to burn off the varnish then I put them is a 5 gallon bucket of water. A week later I had rusty water to spray on my tomatoes. It took 1 week to look like plants were not getting worse and another week for plants to start looking better. Now my plants are growing new leave and green tomatoes again.