Camping, Sleeping Bags, and Temperature Ratings
One of the most important considerations when choosing a sleeping bag for camping is the temperature rating of the sleeping bag. Most sleeping bag manufacturers offer a suggested temperature range that they expect the bag to perform capably within. Generally, these ratings specify a temperature and suggest that the bag is suitable for use at any temperature down to the rated temperature. A +30 Fahrenheit sleeping bag won't keep you as warm as a -10 Fahrenheit rated bag. These are only guidelines, not absolute standards. You must consider your own needs when sleeping when choosing a bag.
These ratings are somewhat subjective. For example, you could purchase what by most accounts is a good 0 Fahrenheit bag from a reputable dealer, and freeze your buns off, even though the temperature goes no lower than 30 Fahrenheit. For better or worse, camping is one of those areas where you get what you pay for. If you try to get a bag on the cheap, you might find that it doesn't.
Unless you are an advanced camper, you won't be out in the wilderness in winter, you'll be out there in warmer months. You can safely choose an inexpensive bag filled with synthetic material and it will satisfy most of your needs. If you are too warm in your sleeping bag, you can open the zipper and ventilate it. If you are too cold, you can add a blanket. Even if you are backpacking, a fleece blanked can be very light in weight.
If you start camping in cooler weather, you will want some additional features. For example, you may want a hood, a collar, drawstrings, and insulated zipper flaps. You may also want a mummy shaped bag. These will keep you toasty warm, by trapping body heat. However, they may not be comfortable for you if you are a side sleeper or if you tend to toss and turn when you sleep.
Like any choice of gear, your sleeping bag should reflect both the season and type of camping you would be doing. For the more dedicated, hardcore campers, survival camping is the way to go. It can involve setting off into the wilderness with very little beyond their hiking boots. At the other end of the spectrum, recreational vehicle campers typically travel inside their own mobile hotel room. These recreational vehicles (RVs) come fully equipped with just about every possible amenity: their own electricity, heat, and patio furniture, and in some cases, satellite TV. RV campers may find they don't even need a sleeping bag, as many RVs have built in beds. They can rely on blankets.
What level of experience do you have as a camper? Your sleeping bag choice--and price--should reflect this. Campers come in all ages, abilities, and degrees of ruggedness. No matter whether you are in an RV or a tent, there are a variety of facilities available to you. The bottom line is that if you are truly interested in camping, you must find the level of the pastime that suits you, and likewise, your sleeping bag.