PerfectTemp Temperature Sensor

ps_temp Temperature compensation is a great feature of the PerfectStar focus controllers (excluding PerfectStarLite), but to perform to its full potential the sensor must read the temperature of the telescope accurately and not be influenced by the surrounding air, since they will change at very different rates.  That is, the sensor must be thermally coupled to the telescope tube and insulated from the air. This can be done with the standard sensor, but requires some planning and effort on the part of the user.  PerfectTemp makes it much easier:  Just place the sensor block face down on the telescope tube, secure it in place with the included hook-and-loop strap, and plug it into your PerfectStar Focus Motor.

The body of the PerfectTemp sensor is made of a plastic with good thermal insulation properties.  The electronic sensor is embedded in an aluminum cylinder that protrudes through the face of the sensor and is spring loaded to press firmly against the telescope.  The surface of the cylinder is polished to enhance thermal contact and for permanent or semi-permanent installations thermal grease can be applied to further improve heat transfer.  

In addition to the insulating properties of the body, the electrical connections to the ps_temp1sensor are made with very thin wires to reduce heat transfer through the wires.  The data cable (3 feet in length) is permanently attached to the sensor and plugs directly into the focus motor unit at the other end.

The included hook-and-loop strap passes through a slot in the top of the sensor body for easier handling.  Extra length of the strap allows securing additional insulation material if desired.



Precision: better than 0.1 degree C
Absolute accuracy: +/-0.5 degree C


PerfectTemp is based on the same integrated circuit as the standard temperature sensor and connects to the 1/8” stereo phone jack on PerfectStar and PerfectStar SCT motors.  Customers using the PerfectStar Focus Controller with motors from other manufacturers will need a custom-made cable to connect either temperature sensor.  PerfectStarLite does not support temperature sensors.



PerfectTemp Sensor: $40 (with strap for up to 9” diameter)
Additional strap length: $1 per foot
Custom cable: Please contact Wa-chur-ed Observatory for a quote


PerfectTemp is generally available from stock.

Buy It

Name (required)

Email (required)

Address (required)

Phone Number (required)

Telescope Tube Diameter (required)

Products to Include (required)

About Greg Marshall

I am a retired electronics engineer and after a few months of enjoying my leisure I began to miss doing product development. My astronomy hobby always needed new solutions to unique problems, so I decided that whenever I came up with a good solution I would try to make it available to others.

Leave a comment