New Projection Lenses

We have always prided ourselves on the presentation standards at The Astor Theatre and are constantly looking for ways to improve what you see on the screen.

For some time we had been looking at upgrading our already-good projection lenses and, after exhaustive testing and evaluation, we decided on Isco-Optic's Ultra-Star HD Plus lenses (also known as the "Red Series").

The lenses were available with an f-ratio of 1.8 as well the more-common (and cheaper) 2.2 which meant they would pass at least 50% more light. Our choice was obvious!

There are minimum standards for the amount of light reflected from a cinema screen if the picture is to be acceptable to the audience. Many cinemas do not meet those standards - the picture is dim and the result can be eye-strain and even a headache.

The Astor has always met those standards but the minimum has never been enough because a brighter picture allows the eye to resolve more detail with better colour and contrast.

We had already reached what we considered to be the maximum amount of light and heat that could be passed safely through the 35mm frame so any further increase in projection-lamp power was really not an option.

The "faster" f1.8 lenses promised a relatively-painless way of getting more light onto the screen.

And that promise was fulfilled - so much so that we could also increase the size of the screen image and still have it brighter and sharper than before!

Both the 'scope (anamorphic) and 1.85:1 (so-called "wide-screen") ratios now use the full height of the screen and, to our delight, we were also able to increase the size of the 1.37:1 ("Academy standard") image.

This is particularly important because we show many "classic" films at The Astor and just about every film from the start of the sound era to the advent of CinemaScope in the mid-1950s was shot in the 1.37:1 ratio.

Many of those films - and particularly the older black-and-white prints - have very-dense emulsions. They need as much light as possible on the screen but they also absorb a lot of heat which places very-definite limits on projection-lamp power. The new lenses have resulted in a significantly larger and brighter image without any risk of damaging the film through excessive heat.

But we didn't stop there! New lamphouse mirrors were installed in both of the 35/70mm projectors and the light paths were laser aligned to ensure even illumination across the screen.

New, 5kW xenon-arc lamps were then fitted and the final step in the process was to align the magnetic field of both lamphouses to keep the xenon arc in the optimum position between the lamp's electrodes.

Magnetic-field alignment is vital for uniform illumination but it is an uncomfortable and potentially-dangerous operation because it has to be done with the lamphouse doors open. And those lamps operate at close to 700 degrees Celsius with an internal pressure of more than 40 atmospheres!

You will certainly notice the overall improvements to all the ratios but we won't be resting on our laurels because, at The Astor, we never stop trying to make sure that your cinema-going experience is the best in Melbourne.

The new lenses, mirrors and xenon lamps were supplied and
installed by Bruce Ker of Atlab Image and Sound Technology.