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Questions and Answers
What is the true field of view (TFoV) of a 25mm Plossl eyepiece in Hadley?
What is the approximate apparent field of view (AFoV) for a 25mm Plossl eyepiece?
Which eyepiece is considered the better option for budget high-power eyepieces?
What magnification does a 6mm eyepiece produce in Hadley?
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How much does a 32mm Plossl eyepiece typically cost?
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Which statement correctly describes the 9mm eyepiece?
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What is a significant disadvantage of using a 6mm eyepiece?
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Which eyepiece is recommended as a minimum-cost option?
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Which of the following eyepiece sizes does Hadley accept?
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What is the primary focal length of the mirror set recommended for the Hadley telescope?
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Which type of screws are specified for use in the Hadley telescope assembly?
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Which eyepiece focal length is recommended for producing low power magnification?
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What type of mirror is included in the recommended mirror set for Hadley telescopes?
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Which type of eyepiece should be avoided due to distortion at short focal lengths?
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How many #10-24, ½ inch long machine screws are recommended for assembly?
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What is the approximate cost of a 'd114/f900mm' mirror set?
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What is a notable feature of the 82 degree 16mm UWA eyepiece compared to a 25mm Plossl?
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Which characteristic makes the 82 degree 16mm UWA eyepiece a valuable investment for astronomy enthusiasts?
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What type of eyepiece design should be avoided due to poor focus and distortion?
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What is a common drawback of eyepiece kits?
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Why might someone consider deferring the purchase of the 82 degree 16mm UWA eyepiece?
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What is the recommended adhesive size when applying silicone to the secondary mirror holder?
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What should be done immediately after applying adhesive to the secondary mirror holder?
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How long should the adhesive be allowed to cure before mounting to the Upper Tube Assembly?
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Which of the following practices should be avoided when handling the mirrors?
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What type of screws are used to attach the spider and secondary mirror assembly to the Upper Tube Assembly?
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What must be done with the screws after they are seated in the primary collimation cell?
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Which component of the assembly ensures the smooth turning of the middle tube?
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What is the purpose of compressing the screws in the primary collimation cell?
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What should be verified during the fitting of the crescent bearings?
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What can be said about the ends of the bolts in relation to the nuts?
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What should be done first before assembling the primary knobs?
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Which action should be avoided during the tightening of screws in the primary collimation cell?
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What is indicated for the proper orientation of the crescent bearings during assembly?
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Study Notes
Field of View
- "Field of view" encompasses "true field" (TFoV) and "apparent field" (AFoV).
- True field (TFoV) represents the sky's arc size visible through the eyepiece, e.g., a 25mm Plossl offers a 1.4° TFoV in Hadley.
- Apparent field (AFoV) indicates how wide the view presentation is for the observer; a 25mm Plossl has an approximate AFoV of 50°.
Low-Power Eyepieces
- 25mm Plossl: Priced around $20 USD, recognized for sharpness and versatility.
- 23mm Aspheric: Available for $12 USD, softens images and has a tendency to misstate FoV around 50°.
- 32mm Plossl: Costs $25-30 USD, ideal for wider views to easily locate celestial objects.
High-Power Eyepieces
- Redline/Goldline series: Available in 6mm, 9mm, 15mm, and 20mm; the 6mm and 9mm are superior options.
- 9mm: Delivers 100x power with a 0.68° TFoV.
- 6mm: Provides 150x power with a 0.44° TFoV, favored for planetary and lunar observations while demanding more frequent adjustments due to a narrower field.
Advanced Eyepieces
- 82° 16mm UWA: Costs around $99 USD; provides an exceptionally wide AFoV and sharp images likened to high-end eyepieces.
- 82° 7mm UWA: About $99 USD, similar power to 6mm or 9mm eyepieces, allows for a larger field and easier planet finding.
Eyepieces to Avoid
- Short Focal Length Aspheric or Plossl Eyepieces: Poor focus and distortion due to their use of acrylic lenses.
- Eyepiece Kits: Often include poor-quality eyepieces and unnecessary extras, compromising overall viewing experience.
Telescope Assembly
- Mirror Requirements: A mirror pair (primary and secondary) is essential, with the Hadley telescope only accepting 1.25" eyepieces.
- Low-Power Options: A 25mm Plossl is superior for clarity, while a 23mm Aspheric is more affordable but less sharp.
- High-Power Options: Consider "66°/68° UWA" or "TMB Planetary" in 6mm or 9mm, avoiding short focal lengths that distort viewing.
Assembly Steps Overview
- Primary Knob Preparation: Standard nuts are used with screws in mirror cell assembly, ensuring easy adjustment.
- Middle Tube Assembly: Houses bearing wheels for smooth mount pivoting.
- Mirror Adhesive Application: Essential for securely attaching both primary and secondary mirrors, requiring caution to avoid touching reflective surfaces.
Final Steps
- Following mirror and optical tube assembly, mirror alignment and focus adjustments are crucial for effective telescope use.
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Description
Explore the key concepts of true field and apparent field as they relate to eyepieces in astronomy. This quiz covers important definitions and calculations for understanding how magnification affects views through telescopes. Perfect for students and enthusiasts looking to deepen their knowledge of telescopic observations.