PHOTOGRAPHY -7
TLR CAVED IN , SLR MOVED IN
The caption summarises the change in fortune of the 2
camera versions-The TLR and The SLR.
Twin lens reflex systems have 2 lenses for viewing and
registering the image as two segregated functions ; the SLR was a revolution in
design in that both viewing and registering of image was handled by a single
lens—hence Single Lens Reflex. Other than reducing the number of lenses, has
there been any advantage? To consider
the question in all criticality it is sensible to assess the limitations of TLR
design, so as to recognize the need or relevance for SLR as a concept.
TLRs are served by two independent lenses one each for
viewing and ‘image registering’. The two operations left to the care of 2
different optical outfits was a limitation in determining the critical pictue
quality in terms of composition.
‘Composition’ is the term used to refer to ‘placement’
of objects in a picture to give the effet of harmony among picture elements.
This demands a high degree of ‘exactitude’ between the view ‘seen’ and the
image ‘registered’. The final picture should be what is preferred by the
photographer and not inclusion of views or objects that tend to disrupt harmony
in the picture. To recognize the suggestion made, try the following study,
using your ‘vision’ in studying image composition.
Sit steady in a place and watch the scene before you,
without changing place or position; do not move the eyeball. Now, close one of
the eyes and see the objects –using the ‘unclosed Eye’. Retain in memory the
objects noticed and their positions in the ‘frame’. After a few seconds , open
the ‘closed eye’ and close the other eye. Repeat the exercise a few times;
there is difference in the two views –as the two eyes are separated by a small
distance. This is the ‘drawback ‘ in using two lenses –one for viewing and the
other for ‘picture taking’. Thus, some difference between the viewed image and
the one registered necessarily creeps in. This is termed error of parallax or
parallax error.
Camera designers resolved the issue by opting to use a
lens common for viewing and ‘taking’. A snag had to be overcome to permit light
rays on to film without their being diverted to the viewfinder. For this,
designs were made to provide a high quality mirror that would guide light rays
on to the viewfinder but move out of light path to help the light reaching the film.
Earlier designs had a mini crank to reset the mirror for picture taking.
However, soon ‘instant-return mirror-designs’ were mandatory on SLR Cameras.
With the advent of single lens designs, rapid
application of optical types-Tele/WA caught up with photographers –professionals
or amateurs. All these design –oriented alterations threw up the prospects of
employing 35 mm film format for making a larger number of images [36] on a roll,
with the innate advantage of using all lenses on a single film to suit any
requirement. It was quite a time lag for Indian enthusiasts to catch up with
the West, largely due to financial constraints. All these design shifts resulted
in an over whelming desire to make colour photos , as automated colour
laboratories that sprang up [1983 on]could deliver good products at moderate
cost. That in brief was the broad survey of photo industry in my late thirties
when I was too involved in colour-processing strategies at the user level.
To Continue..
K. Raman
In TLR we use both eyes closing and opening (one at a time) . What will be the effect if the person’s eye is defective?
ReplyDeleteVery interesting articles on photography. I remember using your Yashika TLR few times to capture my family events. It was a great experience. I appreciate your wholehearted support and encouragement. What surprised me was that you took risk for allowing me to handle a costly equipment by a novice at that time.
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