One of the more apparent differences between film and digital video is the way the cameras handle depth of field. Film cameras have allow for a shallow depth of field (resulting in only the subject area being is in focus), while video cameras offer a larger depth of field (resulting in everything being in focus). This article will go into the details on achieving a shallow depth of field with a digital video camcorder.
35mm Adapters - Benefits
Why is shallow depth of field good?
Having the ability to shoot with a shallow depth of field isn't really a good or bad thing. Think of it as an option when plotting a scene. Having a shallow depth of field helps keep your audience focused on what you want them to focus on. It also provides a feeling of depth to the viewer while a shot with a large depth of field is overall sharp and makes it difficult to focus on any single area.
Other benefits to 35mm adapters are the softness they provide to an image. This also aids in providing that "film look" we all desire from our footage.
There are three categories an adapter can fall in: Static, Vibrating, Spinning. The difference between the adapters all rely on movement of the ground glass the image is projected on.
There are pros and cons to each type:
Static adapters - The ground glass (focusing screen) has no movement.
Cons
- Grain can be visible and static in lower light conditions and/or when f-stop is set to a high number.
- Since the camera is focused on the ground glass, all imperfections and dirt will show up in your video.
- Depending on the type of ground glass you choose, cleaning the ground glass puts it at risk for damage.
Pros
- Ability to have a more compact housing.
- Cheaper and less time-consuming to make.
Vibrating Adapters - The ground glass vibrates.
Cons
- More expensive and time consuming to build.
- Requires battery power adding to weight.
Pros
- Imperfections and dust are blurred and rendered almost un-noticeable.
- Grain is blurred and aids in providing a soft feel to footage.
Spinning Adapters - The ground glass spins.
Cons
- Most expensive and time consuming to build.
- Requires battery power adding to weight.
- Poor alignment can cause an unwanted pumping effect blurring the focus in and out.- Larger and heavier.
Pros
- Imperfections and dust are blurred and rendered un-noticeable.
- Grain is blurred and aids in providing a soft feel to footage.
35mm Adapter - Basic Principle
The basic order for an adapter is camera > adapter > 35mm lens (see below)The main component inside and adapter is the ground glass (focusing screen). The ground glass is what the 35mm lens projects the image onto. The ground glass is also what the camera focus is set to. The distance of the ground glass to the camera (focal flange) is important to achieve the correct focus(varies by lens type). It is important to distance the ground glass far enough away from the camera so the camera can focus in on it.
How do I build my own 35mm adapter?
Basic parts overview
It varies between types and there are all sorts of tutorials and methods available on how to build an adapter. Although there are a lot of tutorials still be prepared for trial and error as there are a lot of variables that can affect your setup, from camera type to 35mm lens type. No matter which type you use the following will be common parts.
A macro tube.
These can vary, however many DIY adapters use inexpensive tubes found on eBay (see links to tubes below). These will provide the housing and/or distance needed in your adapter. Remember to choose the tube that fits you 35mm lens.
Step rings
Step rings will be needed to attach your camera to the extension tubes and/or filters utilized. There are couplers, step-up, and step-down rings. The sizes you need will depend on your camera's and filters thread sizes.
Circular Polarizing Filter (CPF)
Some adapters utilize a circular polarizing filter with the glass removed. This allows the tube to rotate to aid in aligning you ground glass (focusing screen)
Ground Glass (Focusing Screen)
You will need a focusing screen. They basically are diffused glass that the image from your 35mm lens is projected on. On static and vibrating adapters the Canon EE-S and EE-A are recommended by many DIY adapter builders. There are methods of making your own ground glass such as using wax or grinding the glass. For a spinning adapter a frosted blank CD is generally used. Note that no matter which one you choose, this is a crucial element in your adapter that will affect bokeh, light, quality, etc. So take time researching before you decide on any one method...again allow for trial and error.
Ground Glass holder
Unfortunately this is not a common part. There is only one place I know of that sell pre-made ground glass holders for both static and vibrating adapters (jetsetmodels.info). Although a bit costly, these do come highly recommended. You can also attempt making your own. There is a little information shared about creating your own holder.
35mm lens
In most cases you already own one. Especially if you have an old 35mm film camera that has been collecting dust since the age of digital photography came to be. The lens will have to be manual. A good place to start would be a 50mm lens. The larger the aperture can be open on the lends the better as this will allow more light through to illuminate your ground glass. I use 50mm the most, but it is fun to play with different lenses to achieve different results...experimenting and knowing your equipment is the key.
There are other parts such as 12mm vibrating pancake motors, achromats, battery holders, carbon fiber pins, etc. These parts relate to specific setups based on your adapter type and camera. You can find more details on these parts in the tutorials and link below.
Hey my image is upside down!
Flipping the image....
Yes, it is true the image projected onto the ground glass (focusing screen) is upside down and mirrored. This is an easy fix in any NLE video application, but the real issue arises when filming the video as it will be upside down in the LCD and viewfinder of your camera. There are many workarounds that range from utilizing a cheap mirror attached to the bottom of your LCD to a full on hack to your camera's LCD screen (risky if camera is under warranty). To me the best solution is to purchase a cheap field monitor and mount it upside down.
Does camera size matter?
Larger prosumer camcorders vs smaller consumer camcorders
Yes, size matters. The main differences will be the filter thread size and the distance needed from ground glass to camera. On larger cameras such as the Panasonic HVX200 the filter thread is larger (82mm on the HVX200). On smaller camcorders such as the HV30 the filter thread is smaller (43mm on the HV30). Also larger camera need a longer distance between the camera and the ground glass to allow them to focus in on the projected image. In the end this means that adapters for larger camera will tend to be longer and a tad more $$ needed for extra tubing and step rings.
Achieve Shallow Depth of Field Without an adapter
With some effort and planning you can achieve a shallow depth of field without the use of an adapter.
-First, Put your camcorder into manual setting (refer to your camera's manual)then open your iris (aperture, exposure)all the way.
-Second, You want your subject to be as far from the background in your shot and you want the camera as far away from the subject as possible (see image below).
-Third, zoom in on your subject as much as possible.
Too much exposure?
Try some of these tricks:
- Turn on your camera's ND filter (if equipped)
- Switch to a negative gain (try not to go below -6 dB)
- Try using ND filters
- Tweak the shutter speed to fine tune.35mm Adapters - Types Which type is the best?
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