My first camera bag, and I think it makes a good basic beginner bag. Was £15 from Amazon.
This is a relatively small bag with a shoulder strap and a carrying handle on the body. A clip on the front holds down the top flap.
At the back are a couple strips, which could be used to thread a belt through and carry around the waist. Here you can also see the two part zip to get into the main compartment.
If you undo the front clip and lift up the flap, you find a zip under there. Opening that reveals the front storage area which is relatively small. Even now, I still sometimes reach for that area thinking it is the main area.
There are 3 pockets, which I found ideal for holding my spare battery and two spare CF cards in cases. There's enough room left for a filter in a large plastic case, or more with smaller plastic cases.
Back on the outside, to one side we see another strap with the hole orientated vertically. I have no idea what this is for.
On the other side is a pocket. It is quite tight in there but stretchy. You could stuff in more memory cards or maybe a small filter case.
Here is the main compartment inside the bag. There are two moveable bits of partitioning held in place by velcro. In this case, I put the camera with lens face down in the left side, keeping the right side for other accessories. Note there is another small mesh pocket on the left which I don't use.
Also on the left is stitched a piece of fabric. I move this over after the camera is in to protect the back of the camera. Alternatively it could be pushed down inside to further isolate the inner pocket.
In the lid of the main compartment is another little storage pocket. There are 4 small mesh pockets there. These are a bit small to hold a CF card in case, but ok without. I don't use these myself to maximise the space inside for the camera and lenses.
Finally, on the front bottom of the bag is yet another compartment. Opening it, the bag spills its guts.
Ok, it's actually a waterproof rain cover as the bag itself isn't waterproof. This is elasticated and covers the the whole front, top and bottom. The side and back are still exposed.
That covers the physical aspect. But what can you actually fit in it? Depending on the lens size, you can fit 2 or 3 lenses, of which one is left on the camera. Length is the limiting factor. Shorter lenses fit easily, with enough gaps left over for a lenspen and possibly a blower.
My maximum configuration would be the Sony A350, the 16-80 lens, a 50mm prime, and a 28-300 lens, with just enough room for a lenspen. In the front I'd typically have two spare CF cards, a spare battery and a polariser in its case. My Tamron 90mm is a bit physically long, so if I take that, I can only get a total of two lenses in the bag.