digicam vs dSLR

The dSLR actually debuted in 1986, in the form of a prototype analog electronic still SLR camera from Nikon. Kodak took the concept a step further, and in 1991, released the first commercially viable dSRL built from a modified Nikon body, rebuilt drive unit, and a storage unit that was connected by a cable to the rest of the body. It had 1.3 megapixels and cost …$30,000.

Since then, the race has been on for companies and design teams to both streamline and bulk up these ‘next generation cameras’. For people that are less familiar with photography, this concept of a $30,000 camera seems a little ridiculous. Time to look at the guts of these things and show the difference between a digital point-and-shoot camera (digicam) and a full-sized digital Single Lens Reflex camera (dSLR).

For a digicam, the viewfinder is just this extra lens on top of the camera. It’s good for framing or composing an image, but it can be as much as an inch away from the lens – and the lens is what will be taking the picture. The best way to make absolutely sure that you are seeing what picture will be taken, is to use the LCD screen on the back of the digicam. This screen takes its reading directly from the lens itself, so there is no offset. When you snap the picture, you can be looking at either the screen, or through the viewfinder, and the camera will take the shot, exposing the ‘film’ (actually a sensor, in the case of digital cameras), and storing the image all without interrupting your sight.

For a SLR, well. It’s a long process for the light to get to that sensor.

The light passes through the lens assembly, is reflected into the pentaprism by the reflex mirror (which must be at an exact 45 degree angle), and is projected on the matte focusing screen. A condensing lens, and internal reflections in the roof pentaprism, projects the image through the eyepiece to the photographer's eye. When an image is photographed, the mirror swings upwards (suddenly making the viewfinder useless for a split second), the focal-plane shutter opens, and the image is projected and captured on the sensor, after which actions, the shutter closes, the mirror returns to a critical 45 degree angle (making the viewfinder functional again), and the diaphragm reopens and the built-in drive mechanism retensions the shutter for the next exposure.

Whew.

Did you catch the key differences? Through a series of mirrors and lenses, you are looking into the viewfinder, but out the lens. When you press the button, mirrors and lenses realign for a split second to allow the sensor to see what you were looking at, and then switch back again.

This key difference is how photographers make certain they have the right view of their subjects’ eyes. A tiny variation, where the person may be looking too high, or past the photographer, may not seem a big deal – but the human eye would recognize it in the resulting image, and can make for some amusing looking people with crossed eyes. The SLR format also allows for extremely close-up imagery, called macro photography, that would be much more difficult with a camera that required you to use a viewfinder a full inch away from the lens. You’re going to miss that ladybug by a mile if you think you’re looking right at it, but the lens is pointing beside it at the leaf.

A bit of a joke, there.

The camera shoots, leaves, and you missed it.

…Okay, that was a stretch. Promise I’ll work on it.