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Please Note

Orion has made the difficult decision to close our warehouse facility in the Netherlands. With the continuing supply chain/logistics challenges and slowness in the economy we have found that it is not economically feasible to maintain operations in the UK and Europe.

We have therefore stopped taking orders on this website. We apologize for any inconvenience.

We will continue to have Orion dealers in Europe to meet the needs of Orion consumers. We will also continue to honor the 30-Day product return period as well as honoring the Orion warranty for purchases made in the UK and Europe.

Our US-based Customer Service Representatives are here to help. Contact them via email at support@telescope.com or in the United Kingdom, via phone at 0-800-041-8146 (Monday-Friday between the hours of 1300 and 2400 GMT).

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Apparent Field vs.True Field
Apparent Field vs.True Field at US Store

An eyepiece's apparent field of view is the angular diameter, expressed in degrees (), of the circle of light that the eye sees. It is analogous to the screen of a television (not the picture seen through it). Eyepiece apparent fields range from narrow (25 - 30) to extra-wide angle (80 or more). The true field (or real field) of view is the angle of sky seen through the eyepiece when it's attached to the telescope. The true field can be approximated using the formula:

True Field = Apparent Field Magnification

For example, suppose you have an 8" Schmidt-Cassegrain telescope with a 2000mm focal length, and a 20mm eyepiece with a 50 apparent field. The magnification would be 2000mm 20mm = 100x. The true field would be 50 100, or 0.5 - about the same apparent diameter as the full Moon.

Date Taken: 03/15/2011
Author: Orion Staff
Category: Telescopes

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