Shallow depth-of-field on video (part 2)

Building a 35mm DOF adapter

The task of making a usable 35mm DOF adapter is simple yet contrived. The actual crafting offers little challenge, it is the design and the selection of appropriate components that makes it both interesting and complex.

After reading all I could find on this topic I realised that this is a type of device that has not matured enough yet to be offered to the consumer at an affordable price. It either is attainable at really high prices (several thousand USD) or at a lower price (sub 1000 USD) but built by enthusiasts; something which is by no means a bad thing.

Because of the state of the market for this type of product there are uncountable attempts by do-it-youself adventurers that will try just about anything to get a better picture from a device like this.

So I thought I would join the crowd.

Note. Joining a crowd is something that sends shivers down my vertebral column, so I must have been really curious about this.

The elements that I could isolate as being important when constructing a 35mm adapter for my camcorder were:

  • How to secure the adapter to the camcorder
  • How to secure the 35mm lens to the adapter
  • A screen to project the image from the lens which is diffusive enough so that objectscannot be seen past it, but transmissive enough to not lose much light. Also the material must have small enough grain so that it cannot be seen when the camcorder zooms in.
  • A lens system to condense the light from the screen to avoid vigneting (a darkening circle around the image, like in OLD movies)
  • A lens system that will allow my camcoder to zoom into and get the projected image in focus.

I solved quite a few of these issues by realising that basically I could modify a slide viewer for my purposes and then mount it on a base of some sort that would be attached to my camcorder via the tripod screw-in mount.

The black rectangular area on the left is the viewing area, it is covered by a large lens and is where one would look at a regular 35mm color slide. On the right side, I cut a circular hole such that I could fit a 35mm lens (as shown).

What was missing now was the screen.

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One Response to “ Shallow depth-of-field on video (part 2) ”

  1. what an interesting post! i’m attempting to do the same thing, in a messier ‘take-this-part-from-who-knows-where-and-fix-it-here’ kind of standpoint. it’s a great idea to use the slide viewer since it is already so compact, and you could place your gg or other focusing material in the slide slot.
    i’m curious though, is this the last post in your DOF-making endeavors? i can’t seem to find a part 3. great blog, anyway!

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