What's a 35mm DOF adapter?

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Created on Monday, 10 September 2007 04:42
Last Updated on Friday, 14 December 2012 20:15
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35mm DOF Adapter Z1U
Letus35FE 35mm DOF Adapter on a Z1U
A 35mm Depth of Field Adapter (also called a 35mm DOF Adapter) is a fairly new type of device offered by several companies around the world. DOF adapters allow one to place a 35mm cinema, or still photo, lens on the front of any camera - including still photography cameras, as well as minidv and HD cameras (even super8 and 16mm, if you so desire). The adapter sends the image thru the lens and projects it onto a ground glass, often called a GG, roughly the size of a 35mm negative. The image is then captured by the camera when it is zoomed in and focused on the image of the GG. Due to all of the glass it has to go thru, light is eaten by these adapters - often by as much as 1 to 2 stops or more! Lower light shooting is almost out of the question with normal lenses. These adapters make using a fast lens very important, especially for interiors or other low light situations. One big result is that the price of fast Lomo lenses, in decent condition, have gone up considerably and are now selling for around $400-$700 (US dollars) apiece on average.

A 35mm DOF adapter allows a cinematographer (or videographer) to capture footage with a very shallow depth of field - roughly the same DOF as one can get out of a 35mm cinema camera. But don't let this fool you into thinking that 35mm DOF adapters are great replacements for 35mm film, although they have been putting 16mm and Super8 on the sidelines more and more. The images are usually "grainy", but are much cleaner looking with rotating or vibrating GG models (although the moving glass often makes the picture look a little softer). The ground glass shows a noticeable grain due to the way that most ground glass is made; a moving GG will fool the eye into not noticing the grain as much.

A 1/3" CCD camera's DOF is quite deep, even with a wide open aperture, but coupled with a 35mm DOF adapter, it can record the same shallow DOF as 35mm. An adapter on the front of a 1/3" CCD HD or HDV camera will actually have near the same resolution as Super8 film (some may say more, some may say less), and, with the right GG, can seemingly give almost as much lattitude (although, realisitcally, this is not the case). These adapters have gained a lot of recognition, especially since they allow one to use superbly designed 35mm cinema lenses. They get the shallow Depth of Field (often called "that film look") that helps to seperate people from their background. They can record to almost any High Definition or Standard Definition video camera, and allow the footage to be placed in the editor's hands immediately after shooting.

Konvas 1M
Konvas 1M
Believe it or not, if you have the patience, you can build your own 35mm DOF adapter - but it's often easier to buy. Two of the more popular brand names, but definitely not the only ones, are P+S Techik and Redrock Micro. Other brands/adapters are the MOVIEtube, the Cinevate Brevis, the Letus35, the SGpro, the Indie35, the APEFOS, the Cine-One, and the Mighty Pico Image Converter (MPIC). There are several other companies/individuals that have decent designs and concepts, but have yet to release fully working production models, including the Cinemek G35, the El Da Vinci Digi35, the WDR35 (the Italian 35mm Adapter), the i-35HD, and the MagiCine Z-Box.

It must be said that the different 35mm DOF adapters range from inexpensive to moderately expensive (ranging from $350 to $15,000 approximately). Price does not always guarantee the highest quality image (although it does help), but usually acts as more of an indicator for professional build quality. Some 35mm DOF adapters may have vignetting, dark edges, barrel distortion, grain, and/or chromatic aberration. Image orientation is also an issue, because of the simple designs of several of these adapters. The lens creates a flipped image that can be harder to work with while shooting, as well as in post. A few of the adapters use a prism which converts the flipped image to "normal", but the prism usually eats up an additional 1/2 stop of light, or more, over standard GG designs.