Just beware that the more you zoom, the more your tremors will affect your photo.
There are several camera designs out there. SLR (Single Lens Reflect) is one of those designs. Basically, the light coming in through the lens is reflected upward to a prism, which then reflects the light out through the viewfinder. The sensor in an SLR camera, is sitting behind the mirror, so in order to record the light to the sensor, the mirror needs to flap up. This, logically, means that you won't see anything through the viewfinder as long as the shutter is open and letting light hit the sensor. This is the reason for the blackout you would see when taking photos with SLR cameras.
One of the benefits of this design, is that the shutter isn't sitting in the lens itself, but rather in the middle of the camera body. This makes it a lot easier to make lenses. Lenses are, however, pretty bulky and large (though "pancake lenses" are appearing on the market). Also, since the light coming through the lens is reflected (several times) and ends up in the viewfinder, what you see is what you get (95-100% of it anyway, there is some light falloff). This design, however, leads to a few problems, or challenges. One of them is that shake is more likely to happen. The mirror flaps pretty hard, and will invoke some degree of shaking on the body. This will affect your images to some extent, especially at slower shutter speeds (around 1/10th). Other challenges is that if you're using an ND filter, you're actually blocking the light, and so you won't see anything in the viewfinder while the filter is on, which means that you must compose and focus before putting the filter on. Putting the filter on MIGHT make the camera move, and then you're back to scratch.
Another camera design is "rangefinder cameras". Basically, the pros and cons with this design is the opposite of SLRs. Rangefinders were very popular earlier, with famous brands such as Leica, Olympus, Yashica, Voigtlander. The experience of using such a camera is completely different than using an SLR.
Ohh, you did state you wasn't completely aware of what SLRs was
