Darkroom

Durst Laborator 1000

by Maurizio Agelli

One of the many challenges in large format photography is enlargement. Unlike 35mm or medium format, making a print from a large format negative requires an enlarger of such size that its placement becomes problematic in darkrooms originally designed for smaller formats. While contact printing and scanning are possible alternatives, achieving a high-quality enlargement from a large format negative is an indescribable satisfaction.

The Laborator 1000 can be an interesting choice, as it is the “smallest” among the large format enlargers produced by Durst. It accepts negatives up to 4×5″ (10×12.5 cm) and can operate with different types of lighting, thanks to its interchangeable head.

The Laborator 1000 is as sturdy as a tank, quite bulky, and also quite heavy (45 kg with the CLS 450 color head).

With such weight, moving the head vertically using the traditional rack-and-pinion mechanism found in smaller format enlargers would be very difficult. The designers of the Laborator 1000 solved this issue with a lifting mechanism that utilizes the elastic energy stored in a spring positioned inside the sliding block. The spring acts as a counterweight, allowing the head to be moved with a simple friction mechanism operated by a crank with minimal effort.

This sliding block has two screws (see figure) for adjusting the friction mechanism. Tightening them increases the friction between a Teflon roller and the column, making it easier to raise the head along the column. It is important to avoid lubricating the column, as this would reduce friction and render the lifting mechanism ineffective.

The sliding block also features a knob that acts as a “parking brake” when the head is mounted or removed. If loosened by mistake when the head is not attached, the sliding block—no longer balanced by the head’s weight—will dangerously shoot upward due to the spring’s force until it hits the stop at the top of the column. Care must be taken to avoid this.

The sliding block allows the head to be positioned at two different heights.

The choice of position depends on the maximum print size desired on the baseboard, as well as the available vertical space, as shown in the following table:

Head Mounting Position Max Print Size (150mm focal length) Max Column Height
HIGH 48 x 60 cm 139 cm
LOW 35 x 44 cm 123 cm

Using a 135mm focal length will obviously result in a larger print area at the same head height.

The maximum height of the Laborator 1000 is relatively modest compared to its successor, the Laborator 1200, which reaches 166 cm.

The following image shows the head mounted in the upper position.

 

The head of the Durst Laborator 1000 consists of two parts. The lower section houses the negative holder, lens, and focusing mechanism. The upper section is interchangeable, with the following options available:

  • Condenser light head
  • Cold cathode head
  • CLS 450 diffuse color head

    Personally, since I prefer printing with diffuse light, I opted for the latter.

    The CLS 450 color head uses a 24V 250W lamp connected to an external power supply. A separate cable powers a cooling fan.

    The CLS 450 head can be opened via a hinge mechanism to remove and replace the diffusion box.

    For color printing, filtration can be adjusted using three dials corresponding to yellow, red, and blue. A small white switch on the left side of the head illuminates the filter scales. This filtration can also be used for variable contrast black and white printing as an alternative to under-the-lens filters.

    The diffusion box for the 4×5″ format is called Taunobox 450N and can also be used with smaller formats (though this results in some light output being wasted). The diffusion box is housed within a compartment called Taunodap 450, which is an integral part of the CLS 450 head. In the image on the right, the diffusion box has been removed. The Taunodap is the box labeled “Durst Color Laborator 1000.”

    The negative holder, called Tauneg, can accommodate:

    • Two glass plates
    • Two masks
    • One glass plate and one mask
    The glass can be positioned either at the top or bottom. The preferred solution is to place it in contact with the emulsion to prevent Newton rings. However, anti-Newton glass is also available.
    The masks (Otopfe) come in various formats (6×6, 6×9, 4×5″, etc.). The upper mask has pins that fit into the holes of the lower mask. When paired with glass, only the perforated mask is used, whether it is positioned at the top (if the glass is below) or at the bottom (if the glass is above).

    Several lens boards are available, depending on focal length and thread size:

    model type Lens Thread  compatible focal lengths
    Setopla 2825 recessed 25mm 50mm and 80mm
    Setopla 2339 recessed 39mm 135mm and 150mm
    Lapla 39 flat 39mm 135mm and 150mm
    Lapla 50 flat 50mm 135mm and 150mm
    The user manual for the Durst Laborator 1000 enlarger is available at the following links: