Rodenstock Enlarger Lens

Rodenstock Enlarger Lens

An enlarger lens is designed to project a flat piece of film onto a flat surface, with little curvilinear distortion. Simple and straightforward with few aperture blades, they are usually standard 50mm or 80mm lenses without any internal focusing mechanism.

The majority of enlarger lenses have a 39mm screw thread and are focused using a bellows , moving back and forward. Rodenstock is the main manufacturer of enlarger lenses.

Types of enlarger lens

A condenser enlarger comprises a light source, a condensing lens, a negative holder and a projecting lens. The condenser ensures illumination is even on the negative that sits below. They produce a higher contrast that diffuser enlargers as light is scattered by the negative's image silver, known as the 'Callier Effect'. However, it will also emphasise any defects in the negative, including scratches, dirt and graining.

A diffuser enlarger diffuses light using translucent glass or plastic for even illumination. The image has the same contrast as the contact print from the negative.

Dedicated colour enlargers usually contain an adjustable filter mechanism, known as the colour head, between the light source and the negative so that the user can adjust the amount of red, green and blue light reaching the negative, and controlling the colour balance.

How it works

The image from the transparency or negative is projected through a lens that is fitted with an adjustable iris aperture onto a flat sensitised photographic paper. Various enlargements can be gained by adjusting the distance ratio from the lens to the film, to the lens to paper. The enlargement is made by focusing the image with the lens at maximum aperture, with the aid of a focus finder. Enlarger lenses have an optimum aperture range and the shutter mechanism is controlled by an electronic timer, or the operator.

Features

Rodenstock enlarger lenses comprise of 3, 4, 6 and 8 elements, some of which are apochromatically corrected. The Rodagon-WA lenses are for shorter focal lengths with a larger image angle. The APO-RODAGON-D is a specialist ultra lens for use in slide duplication and making internegatives.

Enlarger lenses are suitable for film formats up to 35mm, 6x6cm and 6x7cm roll film with an illuminated aperture scale and click stops, and a standard focal length of 50mm. A range of the lenses have a pre-set aperture feature, with focal lengths of up to 135mm and are ideal for macro lenses on SLR cameras.