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Re: Crosshairs On Monocular

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Posted by Robert May on February 7, 2000 18:08:07 UTC

By a monocular, I assume that you're talking about a finder scope of some kind although the principle is applicable on all optics. Pull the eye lens set from the scope and find it's focal point. The EP of most scopes have a diaphram at some point to define the field of view. Looking into just the EP will show a bright field with a sharp edge. When you look at the other end, you will see the diaphram and this is the sharp edge that you are seeing. You can place a pen point up into the area and it will be in focus. This plane is where your crosshairs go. Before you start with the delicate part of putting crosshairs on, make sure that you can move the diaphram if necessary to focus the crosshairs properly. If you can't move it for some reason, then you have to be careful in putting them in so that you have the crosshairs in focus when you're looking through the EP with your eye relaxed to whereever it focuses to. This part is important because the objective will also focus at this plane and the easiest focus for the eye is when the eye is relaxed. Many types of materials can be used for the crosshairs including ultra fine wire, spider silk and glass plates with fine lines on them.

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