Sporting a distinctive large aperture and deep light bucket, the Explore Scientific FirstLight 203mm f/6 Alt-Az Dobsonian Telescope gives users powerful performance at a reasonable price. Its large parabolic primary and smaller secondary mirrors are made from low-expansion glass to eliminate distortion across the entire field of view, especially at the edges, while allowing sharp resolution of star clusters and nebulae that smaller apertures cannot achieve.

The fast f/6 focal ratio and hexagonal rack-and-pinion focuser make this an ideal choice for imaging, by enabling shorter exposure times with the ability to achieve tack-sharp focusing with the strength to handle large imaging rigs and eyepieces. This 2.5" focuser is designed to eliminate vignetting when using large wide-field eyepieces when observing, and when using large imaging sensors for astrophotography. Reducer adapters are included allowing the use of both 1.25" and larger 2" eyepieces and accessories.

The heavy base provides a rock-steady platform with very low vibrations. This alt-az rocker mount features Teflon pads on the ground plate, and large altitude wheels for smooth and easy movement along both axes with little vibration. Dual mounting rings allow the OTA to be precisely balanced for even smoother movement, and the altitude wheels can be removed and replaced with a Losmandy-style dovetail plate so the OTA can be used with EQ and GoTo mounts mounted on large tripods or piers.

Large 203mm Aperture    1218mm Focal Length, f/6 Focal Ratio    Low-Expansion Glass Primary Mirror    Borosilicate Glass Secondary Mirror    2.5" Focuser with Reducer Adapters    1.25" 25mm Super Plossl Eyepiece    Wide-Field Red-Dot Finder    Large, Smooth-Movement Altitude Wheels    Floor-Based Manual Alt-Az Mount

• 203mm (8") aperture
• f/6 focal ratio
• 1218mm focal length
• Optical design: Dobsonian-variant of a Newtonian reflector
• Low-expansion H-PZ33 glass primary mirror
• 57mm low thermal-expansion Borosilicate glass secondary mirror resists expansion to limit aberrations
• Resolution: 0.6 arcsec

• Alt-az rocker design
• Large aluminum altitude wheels allow for smooth movement and tracking with reduced vibration
• Teflon pads on ground plate enable smooth 360° rotation
• Adjustable mounting rings enable precision balancing when using lighter or heavier accessories for smoother motion
• Mounting rings allow the altitude wheels to be removed and replaced with a Losmandy-style dovetail for attachment to an EQ, alt-az, or GoTo mount head for tripod/pier use

• Large 2.5" hexagonal rack-and-pinion design
• Provides strength and rigidity to handle heavy eyepieces and imaging rigs with little backlash, tilt, or shifting
• Large drawtube prevents vignetting with wide-field eyepieces during observation, or when using large imaging sensors for astrophotography
• Includes 2" and 1.25" eyepiece adapters to allow use of a variety of eyepieces and accessories

Super Plössl eyepiece:
• 1.25" diameter barrel
• 25mm yields 49x power

Finderscope:
• Red-dot finder
• Wide-field for fast subject acquisition and easy star hopping

Related Questions and Answers

Q: 1. What is needed to mount this telescope on a RRS series 4 tripod?

A: The Explore Scientific FirstLight 254mm f/5 Dobsonian Telescope is about 11 inches in diameter, 65 inches tall and weighs about 50 pounds. It cannot be used on a tripod.

Q: 2. Does "package weight" mean total optical tube weight with included diagonal and finder scope?

A: The " Package weight" for the Explore Scientific FirstLight 152mm f/12.5 Maksutov-Cassegrain Telescope includes the items listed " In the Box" the telescope's OTA, the Eyepiece, the Red-Dot Finder, the 2" 90° Star Diagonal with Reducer Adapter, the Universal Smartphone Digiscoping Adapter, and the Cradle Ring Assembly.

Q: 3. Can you recommend a compatible focal reducer for this scope?

A: Alpine Astronomical Alan Gee Mark II Telecompressor BH #ALAGII • MFR #AGII https://www.bhphotovideo.com/c/product/1403600-REG/alpine_astronomical_agii_alan_gee_mark_ii.html

Q: 4. What is the total weight with accessories?

A: 20 lbs.

Q: 5. Does the mirror come with a center dot?

A: Yes it does.

Q: 6. Can I change the focusor's position to the opposite side?

A: Unfortunately no, the focuser location cannot be changed.

Q: 7. I see the telescope comes with a 1.25" reducer adapter to accommodate 1.25" eyepieces. What is the diameter of the focuser?

A: The reducer that is part of the diagonal in this FirstLight 114mm F/4.3 Reflector Telescope is 1.25" diameter .

Q: 8. what's the mount size?

A: There is no mounting socket at the bottom of the base to mount it on any tripod.

Q: 9. what is its shipping box's packed weight ?

A: Unfortunately the question you're asking cannot be answered with our Q+A feature. Please contact our Sales directly for assistance.Email: Sales@bhphotovideo.com

Q: 10. The image from the telescope is upside down and backwards. How do I fix this?

A: You would just need to add a 90 Degree Star Diagonal. The Celestron 90° Star Diagonal (1.25") will work. Link: https://bhpho.to/3t4ZEMK