| Author | Message | ||
     David_nebenzahl Tinkerer Username: David_nebenzahl Post Number: 114 Registered: 12-2009 Rating: N/A |
I'm thinking of building myself a collimator. I'm getting tired of stepping outside during the day with a camera with a piece of ground glass held on the back by rubber bands, adjusting the focus at infinity. I'd basically like to "bring infinity indoors", as they say. So I looked at the article on building a collimator on our own Monopix's (Peter Robinson) site (it's here). Looks simple enough. My question is, how does this work? I know the reason for using a collimator--providing an image at virtual infinity to focus a test camera on. What I don't understand is how Peter's rig, basically a target inside the guts of an old camera with a diffuse light source behind it--can provide such parallel beams of light. Wouldn't one get the same effect by just focusing the test camera on anything? Obviously not, in practice. But I don't understand how Peter's target ends up located a virtual infinity. I'd like to understand how the process works, then build my own collimator, probably out of what's lying around in my parts boxes. So I looked around on the web for an explanation of collimation. There weren't very many Google hits, and most of them were astronomy-related. So if anyone knows of a good explanation out there of how this works, it would be appreciated. One of the pages on this site raises the issue of collimation, but provides no details. It does refer to an article by Mark Overton, who used to have an excellent page up explaining how to build a collimator (it was quite a bit more complex than Monopix's rig), but since Geocities shut down I can't find his stuff anywhere. |