Digital SLRs Galore!
Definitions And Explanations
Digital Single Lens Reflex
A DSLR is a digital camera with interchangeable lenses that allows you to view and compose your subject directly through the lens. DSLRs provide a through the lens view optically, using a mirror that covers the sensor until the shutter release is pressed and some sort of solid- or mirror-based prism that reflects light (the image formed by the lens) from the mirror into your eye. Without the prism, you’d see the image up-side-down and reversed left-to-right. The prism properly reflects light to provide an image that is right-side-up and correctly oriented left-to-right.
While I’m talking about how DSLRs produce a through-the-lens view of your subject, I need to mention the issue of viewfinder brightness. Different viewing technologies tend to produce different levels of viewfinder image brightness. For example, well made prisms usually produce brighter images; mirror-based viewfinders tend to product less bright images. This is not a hard and fast rule, though. You should check out the viewfinder of any DSLR you’re planning to buy to see if it works for you in dimmer light.
While we’re at it, consider diopter adjustments. If you wear glasses, it’s best not to wear them when taking pictures. You can adjust the viewfinder so you can see a sharp image in the finder (both your subject and the indicators in the finder) without your glasses. Most DSLRs allow you to adjust diopter settings between -3.0 and +1.0 diopter. The minus side corrects for nearsightedness; the plus side is for farsightedness. Some manufacturers make lenses you can add to the viewfinder to up the diopter adjustments in one or the other direction.