One of the main tools of the cinematographer’s art for controlling image properties is depth of field (DOF). Briefly stated, the depth of field is the area in the frame that is in acceptably sharp focus. Knowing how to manipulate this field helps the cinematographer call attention to certain aspects of the image. For example, if your subject is in front of a crowded parking lot, you may want to arrange the depth of field so that she is in sharp focus and the cars behind her are blurry, so the eye won’t be distracted by the busy background and will naturally be drawn to the subject.
You control depth of field by the manipulation of a few factors: the size of the lens aperture (the larger the hole, the smaller the DOF); the length of the lens (the longer the lens, the smaller the DOF); and the size of the CCD/CMOS chips themselves (the larger the sensor, the smaller the DOF).
This last point is where 35mm adaptors such as Redrock’s M2 come into play. The image sensors in most camcorders are very small compared to the 35mm frames of film cameras. Because of this, the depth of field of video cameras is very large compared to that of film. This can be a good thing, by making focusing less critical. If you’re a little off in the focus, you’re still going to be in the acceptable range. But if you’re trying to achieve a shallow DOF, for specific composition reasons, or you’re trying for a shot-on-film look, this is a limitation that you need to overcome.
The imagers in your camcorder are a constant; you can’t just slap a 35mm lens on the front. In order to create a larger image plane so that you get a shallower DOF with the same small imagers from your camcorder, you have to create a secondary image plane and use the camera to focus on that. That’s what 35mm adaptors do: create a new image through a 35mm lens on a piece of ground glass that your camcorder focuses on.
Redrock Micro M2
Redrock has long been a name associated with 35mm adaptors, and their M2 adaptor is a very popular model. The unit we tested came with the adaptor, rods, follow focus control, MicroX flip accessory, quick-release system and adaptor rings. I like that you can purchase these items in a bundle or as separate pieces, depending on how you want to customize your setup.
The first question you want to ask yourself is this: What kind of 35mm lens am I going to use? You can order the M2 with mounts for Nikon, Canon, Minolta, Olympus, Pentax and PL lenses. In this case, older lenses developed before the advent of all these new-fangled SLR autofocus and auto-exposure drives are better, because they offer the full manual controls that you will need to use the adaptor effectively. There’s quite a thriving market now for older SLR lenses, so you should be able to easily find one that meets your needs.
One caveat about using 35mm lens adaptors is that, in most cases, due to the way the optics are arranged, the image coming to the camcorder is upside down. This is fairly easy to fix in post by just flipping the image, but it is very distracting during shooting, especially when you are trying to tilt and pan backwards. If you’re lucky enough to have a camcorder that can flip the image in the viewfinder, then you’ll be fine. If you don’t, a common technique is to simply attach the camera to an external monitor, and turn the monitor upside down on set. Included in our package was Redrock’s MicroX accessory that fixes this problem by attaching to the adaptor and flipping the image to the correct orientation before it gets to the camcorder.
The M2 contains Cinescreen II, a new ground-glass element that improves light transmission, sharpness and contrast over the previous model. One difference between the M2 and some other 35mm lens adaptors is that Redrock incorporates a rotating image element that minimizes dust particles and grain from the ground glass in your picture, unlike adaptors that have a static image element. This does mean, however, that you have to turn the adaptor to On, and it’s powered by one 9-volt battery.
Setting up and using the M2 is a pretty simple process, once you’ve attached the adaptor to your lens and assembled the supporting rods. The unit with lens is far too heavy to use handheld, and it puts enormous strain on your camcorder’s built-in lens if you don’t support it. Redrock recommends that, once you have attached the M2, you point the rig at a bright light and open your camcorder’s aperture wide open. Then reduce the aperture of your 35mm lens until you can easily see the screen. Zoom in so the image takes up the whole frame, then set the focus until the screen’s grain comes in nice and sharp, and then lock the focus down on the camcorder. From now on, you will use the focus control on the 35mm lens to control the focus of the scene. To get optimal sharpness, set the 35mm lens aperture between f4 and f5.6, and open and close the iris on your camcorder to set exposure. Only if it’s too far out of range should you go to your 35mm lens and adjust the aperture there.
In the field, you simply turn the unit on and use the focus controller on the M2 to focus your image, rather than using your camcorder’s controls. It sounds easy when you describe it like that, but there’s a reason why there’s a focus-puller position on feature films. You will definitely need to practice a little before using this adaptor on a shoot. Because the depth of field is much shallower than you’re used to, getting exact focus is much more critical, and doubly so if you’re shooting in HD.
Redrock has helpfully designed its focus control with a white area where you can make focus marks, allowing you to find different focus points visually. The most reliable method is still the lowest-tech method. Using a tape measure run from the adaptor to your subject, dial that length in on your 35mm lens. You will almost definitely need some kind of monitoring solution on set as well, since adjusting fine focus is extremely difficult using the small LCD panels and viewfinders on your camcorder.
If this sounds like a lot of hassle, it is. But the results do speak for themselves when you see the footage. The M2 allows the cinematographer much more creative freedom in composing the shot, and the shallower depth of field does make your video look a lot more like a feature film, adding quite a bit of production value to the finished piece.
Lens Mounts Supported: Nikon, Canon, Olympus, Pentax, Minolta, PL
Image Plane: Rotating ground glass
Power: 9-volt battery
Weight: 1lb, 15oz
- Great-looking shallow DOF
- Film-like images
- Complicates shooting process
If you’re going for the “Film Look,” the first place to stop is the Redrock Micro M2.
John Burkhart is Videomaker‘s Editor in Chief.
PO Box 271395
Flower Mound, TX 75027
$1,745 (as tested, lens and camcorder not included)