Interchangeable Lenses for the Canon HG10 High Definition Video Camera

I'm a shutterbug and an owner of a Canon Rebel XTi Digital SLR camera. What distinguishes a DSLR from its counterpart point and shoot camera are the interchangeable lenses. A DSLR with the right lens can take certain kinds of shots that are entirely impossible with a point and shoot. Shots taken with a fast lens (i.e. high aperture) creates a shallower depth of field and the opportunity to selectively focus on subjects while blurring out the background. Lenses with different focal lengths allow one to vary the angle of view from one that is narrow to one of extreme width.

So when I acquired by Canon HG10 (a high definition AVCHD video camera with a Hard Disk Drive) I longed for the ability to interchange lenses to create different and unique shots. The Canon HG10, much like a point and shoot camera, isn't designed to have interchangeable lenses. Only a high end camera like the Canon XL H1 comes with this option. Unfortunately, I didn't have the conviction to unload $8,000 for this kind of flexibility.

The most basic additional lens one can buy for a consumer camera would be a telephoto and a wide angle lens. The Canon HG10 has a 43mm filter thread where you can attach these kinds of lenses. I purchased a Merkury Optics 0.45x 58mm wide angle lens (see photo on the left) for $25. The Merkury lens includes also a macro lens (you'll need a 43mm to 58mm Step Up ring to attach this to the HG10). This is certainly a cheap way to add variety to your videos. The wide angle lens would be something you don't want to leave behind when you travel. It has the potential of creating for you those breath taking panoramic shots that you see on channels like National Geographic HD.

My Digital SLR has spoiled me, I craved for more variety. So I embarked on building myself what is called a Depth of Field (DOF) adapter. A DOF adapter allows one to attach a 35mm SLR lens onto a video camera. The resulting effect is claimed to be one that would emulate the look and feel that you find in movies (The HG10 can capture at 24 frames per second, emulating the capture rate of film). There is possibly little difference in the capabilities in the sensors (outside of noise sensitivity) in a consumer high definition camera and a commercial industry grade one.

Being able to attach, arbitrary 35mm SLR lenses to a consumer camera makes commercial quality accessible to the masses. The dream is that we can all capture our own lives with the same magical movie quality (some scenes in the movie Borne Supremacy were in fact captured with cameras adapted with 35mm lenses). It is no surprise that people only watch their home made videos once or never at all. The quality is has simply been unbearable.

In my research, I was surprised that an entire cottage industry has sprung up around providing this contraption to consumers. Companies like Cinevate, Movietube, Redrock Micro and Letus are peddling their 35mm DOF adapters. It's entertaining to visit their respective website to see the complex rigs that enthusiasts have cobbled together. Acquiring one of these adapters will set you back a minimum of $1,000. I figured that I had no ambitions becoming an independent film maker, so I took the cheap DIY route. My adapter may not be of the same quality, but I think it's just good enough for my needs.

I don't have access to a CNC machine nor do I have any skill in operating them. The key to building one cheaply is to find some reusable components that are already out there. The DOF adapter works by projecting the 35mm lens image on a focusing screen. The video camera then is set to focus and record the screen.

If the 35mm lens were directed instead directly at the camera's sensor, the sensor size would be too small to achieve the shallow DOF look that's required. The HG10's sensor size is 1/2.7" which is equivalent to 6.592mm diagonally). This is about the same as what you would find on a point and shoot camera. By contrast the Rebel XTi with an APS-C sensor is 30.1mm diagonally and a full frame 35mm sensor is 43.3mm diagonally. So to get the same kind of effect from an SLR lens (see: "How sensor size affects your photography"), you have to project the full frame on to the smaller HG10 sensor or equivalently have the HG10 focus on a 35mm focusing screen. The differences in length of the various commercial DOF adapters account for different lenses that focus on the focusing screen. A longer lens would presumably be able to capture more of the full frame focusing screen.

My Do It Yourself (DIY) DOF adapter consists of the following components:

• EOS Macro Extension Tube - Includes the an EOS compatible adapter.
• Nikon D Focusing Screen - The screen where the images from the lenses are projected on to.
• JetsetModels Focusing Screen holder - An enclosure for holding the Focusing Screen.
• Merkury Optics 58mm Macro Lens - lens for focusing the camera on to the focusing screen.
• 43mm to 58mm Step Up Ring - adapter to attach the macro lens to the camera.

That's really all there is to it. The only tricky part is positioning the Focusing screen in the EOS tube. It has to be the lens registration distance of the kind of lenses you want to use. I happen to have a couple of older Super Takumar Pentax lenses. So my registration distance is about 45.5mm. To use these lenses, I used by M42 to EOS adapter that I had already owned. The photo on the left shows the adapter hooked up to the legendary F1.4 Super Multi-Coated Takumar lens. You don't have to stick to fast prime lenses. My adapter also takes Canon EF and EF-S lenses, thus giving me with a lot of reusability. I've attached a 70-200mm F4 lens and it works quite well. Finally, I have a video camera with some serious zoom capability.

I still need to tweak my design a bit. It needs a more robust tube connector, maybe the use of an achromat and possibly some rod support. The above design cost me around $200. My adapter is the static kind, thus it's very susceptible to dust particles on the focusing screen. A vibrating focusing screen would reduce the effect of dust particles, alternatively, I would have to vacuum seal the adapter. The adapter also doesn't flip the image, so you have to record video with the camera upside down. It's a bit of an inconvenience, but with practice it's a workable situation.

I'm a bit out of time, but I promise to post here the shots (or videos) I've taken so you can see for yourself if this kind of contraption is worth it.