PHOTOGRAPHY- 24

 PHOTOGRAPHY- 24

SHUTTER –FLASH SYNCHRONY

In my previous account, I have mentioned of Colour-coded number specified by Camera manufacturer for use with FLASH LIGHT ,especially for SLR versions. Unlike their earlier cousins SLRs parade as prestegeous designs ,by their structural advantage for changing lens[es] halfway through a session of photo shoot. Such a design had its origin from some designers of Germany/ Italy. The former had an adamant adherence to robust equipment and the latter for condensing the overall size of the equipment to the least possible dimensions. These proved very attractive for travellers and wildlife photographers who carry a variety of equipment, lenses , filters, films  and heavy tripods to keep the equipment [on a solid footing]. While items like lenses , tripods are inevitably large, a heavy camera was an additional burden. Cashing in on this predicament of photographers hopping between continents, camera manufacturers sought to field compact or even ultra compact camera designs. Most such designers are Italians  who revamped camera design to attract global accolade. Two such SLR camera designs were –OLYMPUS –OM 1 and PETRI- MF1. While the former has a bayonet mount, the latter- a screw mount to hold lenses firm  in place.

Despite such structural revolutions in equipment design,  the shutter –flash synchrony has been a lasting problem in SLR Cameras, while their TLR cousins enjoyed complete synchrony between shutter speeds and peaking of flash. To understand the intricacy there in the basic difference in shutter design among TLRs and SLRs should be understood. SLR is a conceptual advancement over the earlier TLR versions. In all TLR cameras the Shutter and diaphragm are placed within the lens assembly; in SLR,the lens has its own diaphragm as a built in component and the shutter is shifted to an interior position within the camera; To be exact , the shutter is either a fabric screen or a thin light-proof metallic assembly just in front of the film. Since the light rays  are shone onto the film , the position is the place of focus or the Focal Plane and the shutter is FOCAL PLANE SHUTTER. Fabric shutters have horizontal travel L → R or R → L , WHILE METAL BLADE FOCAL PLANE SHUTTERS run vertically up from bottom to top. Among TLR lenses , shutters have only metal blades 3 or 5 in number, broad in front and narrow at the rear held on rivets that help moving from centre outwards and back to centre again. So, in TLR , Flash light exposure starts at centre and spreads outward. But, in SLR FLASH LIGHT registration begins at one end and proceeds to the other end. So,  in SLR  the shutter travel should be slow enough to permit exposure of the entire frame ; otherwise only partial exposure can occur from flashlight. So, the camera designers fix shutter speed 1/ 60 for flash synchrony  [horizontal travel focal plane] or shutter speed 1/125 for flash synchrony [vertical travel focal plane shutters]. In order that the issue is reminded, the shutter speed ideal for flash lit work is colour coded.

Always note cameras passively carry a number of coded information as everything cannot be in statements.Get yourself completely familiarised with such implied messages.

More to follow                                 K.Raman