In 35mm adapters, the ground glass often moves in order to simulate a film grain look, and to minimize the presence of the ground glass texture in your image.
People are always chasing the illusive film look with video cameras, looking for ways to mimic the look and feel of film. When 24p video popped onto the market a decade ago, it was a big deal, and brought the video world a bit closer to mimicking the look of film on a small budget. Besides the 24 frame per second movement, film also has a much shallower depth of field than video. In film, having this kind of control over focus is often used to draw the viewer's attention to certain parts of the frame and away from others. A major pitfall of video has always been sensor sizes, which are physically much smaller than a frame of 35mm, resulting in a huge depth of field and just about everything always being somewhat in focus. Yet, another weakness in the prosumer video market is that most camera models often have a fixed zoom lens, forcing the user to work within the constraints of the manufacturer's lens. A solution to both these problems is to add a 35mm adapter to your camera.
Does the 35mm Adapter Move?
In a 35mm adapter, there is a piece of ground glass that resides between the mount of the adapter and the lens of your camera. This ground glass becomes the focus point for your camera. The lens you place on the adapter projects an image onto this glass as if it were a frame of 35mm film. With the adapter connected, you are filming a projected image off the ground glass. The area of the ground glass is much larger than the size of the sensor in your video camera, so the image on the glass has much less depth of field, giving you more control and bringing you a lot closer to the film look.
In 35mm adapters the ground glass often moves in order to simulate a film grain look and to minimize the presence of the ground glass texture in your image. There are four types of movement, static, vibrating, spinning and off-center spinning. In static adapters the ground glass doesn't move, making it easier to film at higher shutter speeds but increasing the likelihood that you will see the texture of the glass in your image.
In vibrating adapters, the ground glass moves quickly back and forth to soften the appearance of the ground glass texture and simulate grain. While this technique works well, technically there would be a fraction of time each second that your image is out of focus due to the shifting of the plane, but you would be hard pressed to actually see it. Sometimes this can make shooting at higher shutter speeds difficult.
In spinning adapters, the glass remains on the same plane so it doesn't phase out of focus at a point like in a vibrating system. The circular plane spins to soften the glass texture and give the hint of a film grain. An off-center spinning glass works in the same way, but reduces the glass texture even more and more importantly promotes even light transmission.
If you hold up a bare lens near your eye and look through, you'll notice that the image is upside down. That upside down image is what is going to be projected onto the ground glass of your adapter, meaning that in some cases you will be seeing an upside down image in your camera. Most adapters offer an accessory to flip the image right side up. Basically, a prism goes between the ground glass and the camera to right the image. Letus and P + S Technik sell their adapters as one piece with the image correction built in. Redrock, Cinevate, and Shoot35 offer an additional accessory to correct this. If you find yourself lacking this accessory, some cameras have the option of flipping an upside down image for previewing it correctly. Other times you would have to set up an external monitor, mounted upside down to assist in framing. Always remember, that if you record an upside down image you will have to spend time flipping all your footage during editing.
Each manufacturer offers a variety of lens type mounts for their adapters. Most companies include your choice of one lens type mount at purchase and the additional types available at an additional cost. The type of mount on the adapter is easily changed by the user. Almost all of the adapter providers charge an additional fee for professional lens mounts such as PL, BNCR, OCT19 and B4.
JAG35 makes the least expensive adapters on the market, starting at a surprisingly low $99 for the JAG35ST, which features a static interchangeable ground glass element, and boasts 1/2 stop of light loss. The JAG35E adds a vibrating ground glass at $199 and at $299, the JAG35Pro adds an achromat to the mix. JAG35 models are available with Canon FD, Nikon and M42 mounts. All JAG35 models invert the image, making it upside down, but are available at a killer price.
Cinevate's Brevis35 features a vibrating interchangeable ground glass element, and starts at $850 and an optional image flip attachment (which corrects the image to display right side up) is available for a total of $1100. Cinevate makes 6 different ground glass pieces for the Brevis 35, each provide a different level of diffusion and light transmission. The Brevis 35 has 1/2 stop of light loss and is available with Nikon, Canon EOS, Canon FD, Minolta MD, Pentax M42, Pentax K, PL and OCT19 mounts. Cinevate also makes their own support system for the Brevis35.
Shoot35 produces the SGBlade, an extremely customizable adapter system. The SGBlade features interchangeable spinning ground glass elements that range in 1/2 stop to a full stop of light loss. Pricing for SGBlade packages range from $999 to $1650. An optional flip attachment is available to right the image, as well as a plethora of lens mounts, and a Shoot35 made rod support system.
Cinemek's G35 boasts itself as a low cost solid-state adapter, with an ultra thin ground glass and is available starting at $1199. The G35 differs from most other adapters in how it attaches to the camera as well. Its uniquely designed CS mounts are crafted with specific camera models in mind. This gives the mount a perfect custom fit that not only securely attaches the adapter to the camera but also covers camera focus controls, preventing any accidental bumps to the focus settings. This type of mounting system is a huge plus, and not available on any other adapter in this price range. The G35 has a static thin ground glass in a sealed tube, and unlike other adapters requires no power, as it has no moving parts. On the downside Cinemek's site states the G35 has whopping 1.4 stops of light loss, meaning it will need more light than almost any other adapter on the market.
Redrock Micro recently released the M2 Encore as the successor to its M2 adapter. Despite its deceiving similar looks, the Encore is not just an upgrade to the M2 but a complete redesign. Among the improvements are better light transmission losing only 1/2 stop of light, improved edge sharpness, a rechargeable battery and a collimating lens mount. Redrock offers a microX Encore flip accessory to correct the image orientation. The M2 Encore has a spinning ground glass and is available with Nikon, Canon FD, Canon EOS, Minolta, Olympus, Pentax K, and Pentax S mounts. Redrock recently started shipping its new Live Lens active lens mount for Canon EF lenses. The Live Lens mount allows users to electronically control their Canon EF lenses. The M2 Encore can be used with virtually any camera up to 1/2 inch chip size. Redrock Micro was the first company to bring an affordable 35mm adapter solution to the market. They also manufacturer their own support system, follow focus, mattebox and a variety of other affordable and well made cinema accessories. The M2 Encore starts at $995 on its own and is available in a variety of packaged configurations.
Letus35 makes a variety of adapter models, with varying features and price range. The Letus35 Mini features a vibrating ground glass and is geared towards consumer cameras with filter sizes smaller than 43mm, like the Canon HV30. The Mini model starts at $1099. The next step up is the Extreme, which is Letus35's entry-level model for larger prosumer cameras. It also features a vibrating ground glass and starts at $1199. The Letus35 Elite is similar to the Extreme, but adds a back focus ring and an optimized achromat, for $1899. Letus35's premiere model is the Ultimate, which adds a controllable variable speed off-center spinning ground glass, LED readout and flash memory. All of this and more at a whopping $4499, making it the most expensive model of all its US competitors. All models feature 1/2 stop of light loss, standard right side up image orientation and are available in most any standard lens mount.
Perhaps the oldest adapter company on the market is Germany based P + S Technik. P + S Technik makes a line of Pro and Mini 35 adapters that are built with quality that we've all come to associate with German engineering. In quality they are the Mercedes of adapters and come with the price tag to match. The Pro35 2/3" chip adapter model starts at $22,000 and a Pro35 model made specifically for the Sony EX3 is available for $17,000. The Mini35 400 is geared towards 1/3" prosumer cameras like the Panasonic HVX200 and starts at $5500, making it expensive but not much more than the Letus35 Ultimate. Like the Cinemek G35 the P + S Technik MINI35 400 has specific hard mounts made for each camera model that prevent the accidental changing of focus. P + S also makes the MINI35 Compact which is designed for small cameras like the canon XL H1 and it is also priced at $6500. All P + S models, with the exception of the MINI35 Compact, display the image right side up, and all models feature a variable speed off-center spinning ground glass. Light loss ranges from an impressive 1/3 stop to a monstrous 1 2/3 stops, making it much more light hungry than any of its lower cost competitors.
There are numerous things to consider when buying a 35mm adapter, cost, type of ground glass movement, amount of light loss, lens mounts, and image orientation to name a few. They will increase the size and weight of your camera; sometimes to a point making it extremely difficult to handle. If you can get your hands on one before you buy it'll give you a better idea of what you're dealing with. Demo footage is available on just about every company's website, showing samples of the types of images obtainable with their equipment. Before purchasing an adapter, make sure that the model you choose offers a lens mount compatible with the lenses you intend on using and also that they make a camera mounting solution that is compatible with your camera.
Nathan Beaman is an Apple Certified Final Cut and Motion Graphics Trainer.