You don't say what sort of fertilizer, how much and/or how often you're applying it.

My thought is that the plants are "tired" because they've run out of root room, thus also nutrients & water. You have a lot of plant material in those rather smallish pots.

Maybe. Dirt is very good though(mostly compost). I fed them Medina Hasta Gro Plant liquid plant food(6-12-6)every other week. I kept them watered as needed.
I had the same problem with spring tomatoes that were in the ground, planted in my raised bed garden.
Since we had drought conditions early this year I was told that our tap water(very hard) had caused the problem.
Would like to solve the problem for next year. I wonder if it will solve itself if we simply have better growing conditions next year.

Could be late blight; it was a big problem in 2009. This video (link below) provides good information on diagnosis and management.

Here is a link that might be useful: eOrganic Late Blight webinar

Hi there mine look very similar. I am new to growing tomato's and wondered if anyone may have some advise. Our tomato plants are growing very high yet the leaves are beginning to die off quite quickly, turning a sort of yellow shade, curling and dying and I am picking them off however, tomato's are still growing. There also seems to be some sort of white fluffy flying bugs on my plants, I am finding small holes in the leaves and tomato's.