Point Light System

the point light exposure system…

we lose em  because they aren’t used- often, because those who chatter in the photo-forums don’t understand their own gossip, mistaking it for information. So the point light systems are gone. Trashed because they no longer met purposes of practice. Even though this is the case of most darkrooms it was even more so with some of the specialized equipment that once was in every high quality professional darkroom.

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A general view.

A point light exposure system was important in the dye transfer printing process. It was also used in photomechanical systems, later being used by semiconductor, medical research labs. It provided an intensely focused light source which raised the sharpness of the recorded image. If you needed every bit held by the film, then a PL would pull it out, provided that you had the optics needed. Most current enlarger lenses will work as the optical portion of a point light system.(ex: El-nikkor, Rodagon, Componon-S)

A point light shows every spec of dust or surface mark on the film so careful attention is needed in processing and handling your films. All the grain is separated into readily seen groups.

With current optics, and digital lights making an updated Point Lamp exposure is worth the small effort. It should take only hours to assemble a basic system. (yep, I have plans that duplicate my system.)

Modification for an Omega D2 is easier than for a Beseler. In a follow-up post, I will go into additional depth on doing this.

Point Light Enlarger

Using-

  • insert negative
  • adjust image size and focus (use grain magnifier)
  • remove negative
  • ADJUST POINT LIGHT for UNIFORMITY on easel
    • adjust height of SOURCE LAMP HOUSING. NOT ENLARGER
    • minor adjustments of negative stage may be necessary. if so, then correct magnification (stage-easel distance)
    • if there are ‘fringes’ of color (blue/brown) adjust the lamp laterally (adjustment screws in housing)
  • replace the negative and expose
    • the lens must be wide open, therefore exposure is controlled by time or by adjusting the intensity of the lamp. This adjustment is much easier now with PWM controlled LEDs. The old PLs would change color with drastic changes in lamp voltage making variable contrast paper or color printing almost impossible. In those cases the enlargers were fitted with a shutter, like in a view camera. The lens was mounted into a ‘copal’ style shutter for exposure control.

Contrast of a Point Light is higher than a typical condenser enlarger by about 1/2 to a full paper grade; by more than full grade over a Zone VI cold-light head.

Oddly, contrast, for contact exposure using a Point Light is not higher, rather it is lower. Which is why it was used for contact separations and film intermediates in the better professional color labs, especially useful in the dye transfer process.

What a Point Light Enlarger is doing differently that a conventional condenser (or even a diffusion) enlarger is sketched out in this clip:

plsTheory_3523
point light contrasted with typical condenser enlarger

The left side sets of light rays are less concentrated than in the right, point light, system. The smaller lamp can be focused more intently than the larger, hence, more diffuse light source. If you are using a diffusion or cold-cathode enlarger, then the difference is more remarkable. This would be apparent in masks and separation sets; also in contrast and apparent separation in shadows.

Point Light Contact

A point light in contact printing maximizes sharpness of an image. This factor is what brought so many PLs into the print shop. The higher the dot count of the printing meant a need for higher sharpness in the intermediate production steps — Point Light Contact printers. Kodak published modifications to their Beehive darkroom lamp in so many litho publications it is hard to believe that more people didn’t know about them.

In addition to sharpness of a contact Point Light, you will see a lower contrast gain. Contrariness is the inner spirit of the PL. In an enlarger: higher in contrast. In contact: lower contrast, which works out fine. My current use of a Point Light Contact Lamp is for making prints on Chloride papers: Lodima and Lupex — both these papers lith very well. Probably not many who have even tried them, but the do give great greens and copper colors; if you can get the exposure time long enough. (4 mins with LED lamps)

Concluding:

The commercially made machines are hard to find, and will be difficult to get working if you aren’t an old style electrical tinkerer. Making a new one is much easier. The focus condensers can be found, but you will have to wait for months between searches since most of them were tossed when technical labs moved to digital. Even then, there weren’t many made. You may be lucky, finding a DM set called something else. A contact system is within ready reach.