Eyepiece and telescope pairing
Tele Vue 2.5mm Nagler Type 6 in the Celestron AstroMaster 114EQ: magnification and field
What the Tele Vue 2.5mm Nagler Type 6 does in the Celestron AstroMaster 114EQ, worked from the published focal lengths and apparent field.
Field of view
ring = 0.2 degrees true
dot = 0.3 mm exit pupil
- Magnification
- 400x1000 mm / 2.5 mm
- True field
- 0.2 degrees82 deg / 400x
- Exit pupil
- 0.3 mm114 mm / 400x
- Max useful mag
- 269xpublished
Computed optics
- Barrel match
- 1.25 in eyepiece in a 1.25 in focuser
Over-powered. At 400x this pair exceeds the published highest useful magnification of about 269x for the Celestron AstroMaster 114EQ, so the image dims and softens without showing more real detail. Use a longer eyepiece.
Magnification is the telescope focal length divided by the eyepiece focal length: 1000 mm divided by 2.5 mm is 400x. The true field of view is the eyepiece's 82 degree apparent field divided by that magnification, 0.2 degrees.
The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 114 mm over 400x, which is 0.3 mm. That makes this a high-power lunar, planetary and double-star setting.
The eyepiece to buy
Shop Tele Vue 2.5mm Nagler Type 6 on AmazonaffiliateFind Tele Vue 2.5mm Nagler Type 6 on eBayaffiliate