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TeleVue - 21mm Ethos Eyepiece


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Manufactured by: TeleVue

TeleVue - 21mm Ethos Eyepiece


TeleVue 21mm Ethos Eyepiece 

The Ethos 21mm eyepiece completes the logical set of 21mm / 13mm / 8mm and nicely juxtaposes the 17mm / 10mm / 6mm combination. Each step within these two sets approaches a 3x field area gain. The 21mm's effective field stop diameter is 36.2mm, bringing its true field close to the 35mm Panoptic (38.7mm Field Stop diameter). Its true field is also larger than the 26mm Nagler with its 35mm effective field stop diameter. In an f/4 Dobsonian, the exit pupil is just 5.25mm using the 21mm Ethos instead of 8.75mm with a 35mm Panoptic, or 6.5mm with a 26mm Nagler.

Additional Information

Name TeleVue - 21mm Ethos Eyepiece
Manufacturer TeleVue
Model ETH-21.0
Manufacturer Part No ETH-21.0
Apparent Field of View 100°
Eye Relief 15mm
Eyepiece Barrel Size 2"
Field Stop Diameter 36.2mm
Focal Length 21mm