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Fiber Optic Scope Eye Piece Camera Problem.

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Hon1nbo

Sat Oct 17 2009, 04:24PM

Registered Member #902 Joined: Sun Jul 15 2007, 08:17PM
Location: Pacific Northwest USA
Posts: 1042

hello,
I recently acquired a Borescope off of ebay for $40 and I have found it very useful for certain types of work
however, I hope to use it in a little five minute movie for a school project in which the prrotagonist tries to see into a box through a small hole to know how to prepare a big surprise for later in the movie. I hoped to use the actual scope to get a realistic effect, and learn something about optics while I do.

The scope has a focusable Eye piece, and I want to be able to have the camera "see" through it. I figured a way to best mount the camera, but I am a little wary of lens adjustments and focusing. I can get a viewable image in focus easily, but it is too small in the camera view. I tried zooming, but it makes thing such as alignment much more critical and throws off the ability to focus easily. I am afraid to crack open the lens assembly on the scope because it is unlikely I can replace it easily.

Is there a way I can correct the image with basic optics? Or an optimal arrangement for the camera? - I thought about just letting the image be small in the camera view, then zooming in in Adobe because the resolution on the scope is low anyways, but image noise might be a problem when zooming in so much

any thoughts are appreciated

-Jimmy

klugesmith

Sun Oct 18 2009, 01:16AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

Search the internet for "afocal photography", even "afocal photography borescope".

That's where you focus an optical instrument (e.g. a telescope) while looking through it with your eye, then put a camera focused at infinity in place of the eye.
Orion Telescopes sells an accessory called SteadyPix which I found handy -- it clamps onto an eyepiece and holds a camera (via tripod screw) with enough degrees of freedom.
If the price is steep for you, I can post good pictures of mine (an older version than what's in Orion catalog) for DIY ideas.

What is the apparent field of view (in angular degrees) when you look into the borescope?
Camera field of view should match. Can you disable autofocus while playing with the zoom setting? (keep camera at infinity & do all focusing with borescope adjustment).

Then if you still have vignetting, there may be an incompatibility of "exit pupil" size.
I'm pretty rusty on that subject but there's plenty to read on the internet. Good luck!

Hon1nbo

Sun Oct 18 2009, 03:24PM

Registered Member #902 Joined: Sun Jul 15 2007, 08:17PM
Location: Pacific Northwest USA
Posts: 1042

Klugesmith wrote ...

Search the internet for "afocal photography", even "afocal photography borescope".

That's where you focus an optical instrument (e.g. a telescope) while looking through it with your eye, then put a camera focused at infinity in place of the eye.
Orion Telescopes sells an accessory called SteadyPix which I found handy -- it clamps onto an eyepiece and holds a camera (via tripod screw) with enough degrees of freedom.
If the price is steep for you, I can post good pictures of mine (an older version than what's in Orion catalog) for DIY ideas.

What is the apparent field of view (in angular degrees) when you look into the borescope?
Camera field of view should match. Can you disable autofocus while playing with the zoom setting? (keep camera at infinity & do all focusing with borescope adjustment).

Then if you still have vignetting, there may be an incompatibility of "exit pupil" size.
I'm pretty rusty on that subject but there's plenty to read on the internet. Good luck!

I can adjust the focus manually on both the camera and the scope, but I've found it best that the camera not be focused at infinity, but I might try some different placement configurations for the camera-scope distance and the scope focus and see how it works - I'll update this post with some initial pics once I upload my camera to my computer, which might take a while because I took slow motion video at a football game recently, and I have to back that up first

as for the angular field of view, if you mean what it looks like to look into the eye piece, it is fairly narrow - if you mean for what the scope is seeing in that view, then it is very wide

klugesmith

Wed Oct 21 2009, 05:18AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

DaJJHman wrote ...
as for the angular field of view, if you mean what it looks like to look into the eye piece, it is fairly narrow - if you mean for what the scope is seeing in that view, then it is very wide

The former: If it looks to your eye like 15 degrees wide, then camera should be zoomed to look at a 15 degree field. Experimenting with position, distance, and 2 focus knobs is much easier if you can contrive an adjustable mechanical support stiffer than your hands. Even sandbags on a tabletop can help!

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