DPReview.com is closing April 10th - Find out more

What are the physics of an optical snoot & gobo?

Started May 22, 2021 | Questions thread
OP (unknown member) Forum Member • Posts: 70
Re: What are the physics of an optical snoot & gobo?

Thank you very much, I'm gonna experiment with all that and do some calculations.

Quick follow up questions:

For the image of the gobo to be projected at infinity, the lens should be focussed at infinity and the distance between the gobo and the lens should be exactly the same as the distance between the camera sensor and the lens.

If I'm understanding this correctly I should look up the flange distance of the specific lens mount I'm using and use that as the space between the lens and the gobo right?

The 55mm lens I'm using now is an M42 lens, but that means if I were to switch it to an EF lens or something else, I would have to change the spacing right?

  • You can find the infinity focus position for the gobo by trial and error using the far wall of a very large room (which will be near enough to infinity) to focus the image on.

Sounds simple enough to do, but just out of curiosity is there a formula to calculate that? What would be the variables that impact that value?

Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow