At least 200 would be recommended as this can help prevent the feathers from poking through the fabric.
The Swiss Dot Featherbed cover would help a person with a sore back the most. It provides two inches of comfortable padding and has an amazing 300 thread count cover for a "soft to the touch" feel.
Choosing which blend is best depends on your personal preference and what is within your budget. Classic featherbeds include 75% feathers and 25% down.
The best duvet based on thread count is the Grand Estate Verdi 400 thread count single ply duvet.
Featherbed covers can always be bought at Bed, Bath & Beyond or at your local mattress store. You can find featherbed covers anywhere that you can purchase a featherbed. Many shopping websites carry featherbed covers in a variety of sizes and prices.
Make sure that the duvet covering is of superior quality. A down-proof 100% cotton ticking with 230 threads per inch is best. Some cheaper ticking has a low thread count disguised by smoothly pressed sizing or filler which soon disappears with use. The down will escape through this porous cotton. Some very high-thread-count ticking is too fine and wears through quickly. http://www.oldeuropeduvet.com/choosing_your_down_duvet.htm
Martha Steward sheets are available in excess of 400 thread count, but it varies widely among retail stores.
Ordering featherbeds through direct-order warehouses is a good way to save money, as is buying online, though shipping may be costly.
175-200 excellent,and up 200 great
I really like the Cotton Sateen Count Duvet. It has a 500 thread count and looks nice too.
Sealy posturepedic is the best brand you can buy.
To ensure that your camera securely attaches to a tripod with a compatible thread size, it is best to check the thread size of both the camera and the tripod before purchasing. Make sure that the thread sizes match to ensure a secure fit.
You can store your clean featherbed in a waterproof blanket storage bag. You may even want to add some cedar chips or mothballs.