A picture’s worth a thousand words, so why not capture the emotions and feelings of a moment in a photo? SLR lens options like the Sigma 150-600mm F5-6.3 DG OS HSM Contemporary aren’t matched by mirrorless in terms of value, and you also have access to exotic glass like the AF-S Nikkor 800mm f/5.6E FL ED VR ($16,299.95), the likes of which simply isn’t available in a mirrorless format at this time.
The focal-plane shutter is primarily associated with the single lens reflex type of cameras, since covering the film rather than blocking light passing through the lens allows the photographer to view through the lens at all times except during the exposure itself.
For instance, if your PTZ Camera was set to a wide-angle guard position while someone was breaking into a car in your parking lot, the recorder will only have the footage from the angle that the camera was pointed at during the time of the occurrence.
With Digital PC-Based or Standalone DVR Recorders, adding extra stationary cameras is not difficult at all, as digital systems can generally be upgraded without major expense, so providing adequate coverage with stationary cameras is usually far less expensive even than installing a single PTZ Camera.
Light entered a lens mounted on a lens board which was separated from the plate by an extendible bellows.There were simple box cameras for glass plates but also single-lens reflex cameras with interchangeable lenses and even for color photography ( Autochrome Lumière ). Many of these cameras had controls to raise or lower the lens and to tilt it forwards or backwards to control perspective.