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How to attach a 1.25” lens to a 58mm filter thread?

Started Jan 11, 2020 | Questions thread
RobinHsherwood
RobinHsherwood Senior Member • Posts: 1,173
Re: How to attach a 1.25” lens to a 58mm filter thread?

MacM545 wrote:

BTW, it’s a Bushnell 25mm Kellner. Let me get back to you with the thread parameters as long as they’re needed. BTW What magnification is that able to give on a 50-230mm telephoto on APS-C? With an objective it could be easy to find but the designation is different than that of telescope eyepieces, which are usually designated in millimeters which is dependent on telescope focal length.

Microscope oculars are designed to present the final virtual image at the human eye's closest distinct vision distance (nominally 250mm) therefore, if used as a microscope ocular, the 25mm focal length achromatic Kellner would be  250/25  or 10X.

The same ocular used with a telescope objective of 1200mm FL would be 1200/25 or 48X. Assuming that the zoom lens, at maximum zoom, functions as a 230mm telescope objective, the magnification would be 9.2X.

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Robin H

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