Tuesday, July 21, 2009
DIY Depth-of-Field Adapter, Part 1
Recently I decided to get back into video stuff. I haven't touched video in about seven years, so I knew there would probably be quite a bit of catching up to do (the last video editing program I used was Adobe Premiere 6, with captured analog Hi8 footage, if that tells you anything). So I picked up the cheapest, lowest of the low-end Sony Handycam I could find, and started to try to learn exactly *why* video doesn't look like film. Well, a lot of it has to do with brightness, contrast, color saturation, etc, which can be adjusted in the video editing program. But another thing is depth-of-field. Here's where I began to kick myself for not taking photography in college. Depth-of-field? Aperture? What the heck is an f-stop? Anyway, you can google all that yourself, but basically I learned that cheapo consumer camcorders just don't have the same lens qualities that big film cameras have, but apparently, there's a way to fix that.
Enter the depth-of-field adapter: a rig that you put small camcorders on that allows you to attach nice lenses that you might find on any decent 35mm SLR camera. Unfortunately, these things can cost hundreds, if not thousands of dollars. No thank you - I don't have the money to spend on something like that, nor the rational to even save up for one (it's not like I'm doing professional video here). Which is where I discovered that apparently hacking together these things is a favorite DIY project of a lot of impoverished filmmakers. Well, in that case...
The Scates-O-Matic Depth-of-Field Adapter, ver. 1.0
Amazing what you can do with a little PVC pipe, huh? Basically, this rig consists of:
1. Sony Handycam
2. 25mm adapter ring
3. PVC pipe fittings
4. ground glass (focusing screen)
5. Crayola model magic
6. more PVC pipe fittings
7. used 20-year old 50mm Canon FD lens (from a 35mm SLR film camera)
8. scrap piece of aluminum
9. various screws, bolts, nuts, and washers
(I might also mention it's pretty handy to have a father who has access to a drill press and a lathe.) Anyway, the Canon lens is attached to a 2.5" electrical conduit male adapter (which we lathed out to house the lens, and it's held in place by set screws). The male adapter attaches to the female adapter which houses the focusing screen, which is the plano-convex lens extracted from a Nikon F4 focusing screen. The reasons for using the male and female adapters are several: First, I can open it up if I have to, because they just screw apart. Second, we can modify another male adapter to hold a different lens, such as a zoom lens. Third, I can move the male adapter, thereby adjusting the lens' focus on the focusing screen. (Hint: to achieve proper focus, I adjusted the lens' focus to 5 feet (the distance to my tv, but it could be any object), then adjusted the distance between the lens and focusing screen. That way, I knew that the focus should be correct.) Since taking the above photo, we modified the male adapter by shortening it by about 1/2" to help with focusing issues, and added additional set screws to the female adapter to hold the male adapter in place.
The focusing screen: I would have just used the focusing screen as-is, but it has that little circle viewfinder thing on it. Fortunately, I discovered that the focusing screen was two pieces of glass held together on the edge by clear tape, so I took them apart to get the clear plano-convex lens. I then got a larger piece of glass (from a cheap photo frame), put some 5 micron aluminum oxide grinding grit on it with a bit of water, and hand-ground the flat side of the plano-convex lens for about 15 minutes until it was nice and frosty. I then cut out a piece of clear plastic (from a package) to use as a frame, and then used Crayola Model Magic to hold the thing in place inside the female adapter.
The female adapter then attaches to the camera with another piece of lathed pipe fitting, which attaches to a 25mm lens adapter, which attaches to the camera itself.
The whole assembly is then mounted upon a scrap piece of aluminum with holes drilled in it. The female adapter has a mount to bolt onto the aluminum, and the camera itself is held by a bolt in its tripod mount.
Test Footage:
This is without any color or brightness correction, and it looks like YouTube stretched the footage a bit horizontally, but you get the idea. I need to clean the focusing screen off, for one thing, and adjust the focus from the lens to the screen, but it seems to be coming along. Still getting a bit of vignetting, and the plano-convex lens seems to help - but I do kinda dig the look, it's almost like a Holga camera or something.
But does it look like film?
Well, not quite, but it looks better than it did, haha.
Sources:
Of course, I couldn't have figured all this out without these websites...
J5 Studios
Jag35
35mm Adapter Resource
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Labels: film/tv/books/arts, geek stuff