Rotators allow imagers to frame objects at the most suitable angle. Unless it’s a remote setup, rotation can be done manually, but that involves loosening screws and estimating how much to rotate the camera by hand, which is not the most accurate way and can be time consuming.
Pegasus Astro offers one of the slimmest motorized computer-controlled camera rotators. At $626, it is also one of the most cost-effective. Here I share my experiences with the Falcon and discuss some of its advantages and disadvantages.
The Falcon is well packaged in a lightweight, CNC machined aluminum body. It weighs only 700 grams (1.5lbs), so it won’t add much additional stress to lower-capacity focusers or mounts.
Slim Form Factor
Another plus for the Falcon is that it requires only 19 millimeters of back focus; most imagers will find it fits in their imaging trains.
Falcon profile and dimensions (mm). Credit. Pegasus AstroMounting and Connections
The 19mm thickness includes both the M54 female threads on either side, so you will need adapters on both sides in most cases. The Pegasus comes with a 2-inch nosepiece and a male M54 to male M48 adapter, with more adapters are available, but keep in mind these use up a few millimeters of additional back focus.
While mounting shouldn’t be an issue in most cases, the motor housing is rather bulky and may interfere with the telescope or focuser, as it protrudes a fair amount (about 40 millimeters (1.5 inches)).
Furthermore, connections use threads rather than dovetails and setscrews, which means the user can’t adjust the orientation of the rotator once it’s screwed onto the focuser threads. This won’t be an issue if you are using the nosepiece, but I generally recommend threaded connections.
Pegasus Astro rates the Falcon at 6Kg (13.2lbs) payload capacity, however I noticed my 2.1Kg (4.6lb) imaging train would flex when I applied a bit of force with my fingers. I suspect the focuser will remain flex-free with light cameras and filter wheels up to APS-C format.
But I wasn’t confident enough with it for use with my larger full frame setup, large filter wheel and off-axis guider. Also, very fast telescopes below f/4.0 may be affected more by the minute tilt that may be introduced here.
The Falcon has a rotational resolution of 86.6 steps per degree of rotation, and takes about 31,000 steps to complete a full rotation. It has a mechanism to ensure cables don’t get wrapped and damaged with a partial rotation in one direction, reversing in the other direction for the other half of a full rotation.
Opening the cover reveals a geared stepper motor and a belt drive. There is the slightest indication of backlash, but it is almost negligible due to the nature of gears. There is a small adjustable cam pulley to adjust the tension of the belt should, if needed.
The standalone software is very straight forward and easy to use. It displays the current angle, and you can set the rotation either by increments or by entering the required angle.
An ASCOM-compatible driver allows it to work very well with other imaging software. I had no issues downloading, installing, or operating any of the software.
Pegasus Astro has added a feature that calculates the rotation needed for it to counteract the frame rotation in alt-az imaging systems, effectively making it a field derotator. I was unable to test this feature since my mount is a German equatorial.
The Falcon is a simple and low-cost rotator with decent clear aperture. Its standard M54 threads make it easy to incorporate in most setups, and the low profile means it will be optically compatible with many imaging trains.
As a lightweight rotator, I found its stiffness inadequate for my demanding imaging needs. Having contacted Pegasus Astro about my concerns, they did send a replacement, but that too had similar performance.
Overall, the Falcon should suffice for the average imager with small- to moderate-sized imaging trains, but I would advise a more heavy-duty unit for those with large, heavy, or long imaging trains, especially with very fast optical systems.