-
Starlight Instruments 3.5" Base Curved w/ Leveling Screws
To achieve a mechanically perfect installation of a 3.5" Feather Touch Focuser, the Starlight Instruments 3.5" Curved Base is custom-machined to match your telescope tube's exact diameter. This base uses a 5.25" center-to-center mounting pattern and connects via M138x1 threads to the required A35-503TMB adapter ring, forming a single, rigid unit with the focuser.
Custom Machining for a Perfect 3.5" Focuser Seat
A large-aperture focuser is only as stable as its mounting point. This base is custom-machined to the specific radius or diameter of your optical tube, ensuring a flush, no-slip fit that eliminates flexure before it starts. This perfect mechanical mate is critical for supporting heavy imaging trains on large Newtonian and Dobsonian telescopes.
To complete the connection, this base is designed to thread into the Starlight Instruments A35-503TMB tube adapter ring (sold separately). This ring, with its M138x1 threads, then accepts the 3.5" Feather Touch focuser, creating an integrated, rotatable focusing system.
Precision Alignment with a 5.25" Mounting Pattern
Achieving perfect alignment of the focuser's optical axis is non-negotiable for critical imaging. This base includes integrated leveling screws, allowing you to make fine adjustments to square the focuser to your telescope's optical path, correcting for any minor imperfections in the tube surface. The base secures to your OTA using a 5.25" center-to-center mounting hole pattern and comes complete with all necessary mounting hardware for a straightforward installation.
-
What information must I provide when ordering the Starlight Instruments 3.5" Curved Base?
You must specify the exact outer diameter or radius of your telescope tube in the order notes. Starlight Instruments will then custom-machine the base to match this dimension for a perfect fit.
Is the A35-503TMB tube adapter ring included with this 3.5" base?
No. The A35-503TMB tube adapter ring must be purchased separately. This base threads into the adapter ring, and the adapter ring accepts the 3.5" Feather Touch Focuser.
What is the purpose of the leveling screws on the Starlight Instruments 3.5" Curved Base?
The leveling screws allow you to make minute adjustments to the tilt of the entire focuser assembly. This is crucial for squaring the focuser's optical axis precisely with your telescope's primary mirror or optical train, which is essential for achieving sharp, coma-free stars across the entire imaging field.
Will this base fit my 16" f/4 Newtonian telescope?
Yes, this base can be made to fit virtually any curved tube. As long as you provide the correct outer diameter of your 16" Newtonian's tube when you order, the base will be custom-machined for a perfect mate.
Does the Starlight Instruments 3.5" Curved Base include the bolts to attach it to my telescope?
Yes, the base comes complete with all mounting hardware required to attach it to your telescope tube. You will not need to source your own bolts or screws.
How do I connect my 3.5" Feather Touch focuser to this base?
The connection requires an intermediate part. The process is:
- Bolt the Curved Base to your telescope tube.
- Thread the A35-503TMB Tube Adapter Ring (sold separately) into the base.
- Insert the 3.5" Feather Touch Focuser into the adapter ring.
-
Starlight Instruments 2-Year Warranty
