Greg Marshall


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.


New Focus Control System (Finally) Available

I told you about PerfectStar B some time ago – it’s my new focus control system using bipolar motors instead of the traditional unipolar motors.  And I had intended to put it on my website and start accepting orders back in September, but ran into some software issues that delayed the release just enough to push it into the busiest time of year, so I didn’t get around to updating the website until now, even though I have already shipped a couple of these to existing customers. The “B” in the name refers to its use of/support for bipolar stepper […]


PerfectStar B Focus Motor

Along with the new PerfectStar B (PSB) Focus Controller, the PSB Focus Motor provides faster movement and additional features in comparison to the classic PerfectStar motor or other unipolar stepper motor.  The PSB Focus Motor attaches to many models of telescope in the same manner as the classic PerfectStar motor, using a 2-part coupler contained within a housing that attaches with thumb screws to your dual-speed focuser.  Other types of coupling, including SCT models, are available as custom orders. The PSB motor differs from the classic model in that the housing is metal, which makes it more rugged, reduces the […]


PerfectStar B Focus Controller

Building on the success of the classic PerfectStar Focus Controller, PerfectStar B (PSB) is the next generation controller, with enhanced speed, torque, and programmability. It is also a step up in production quality, featuring metal construction, engraved labeling, and better cables and connectors. But the essence of PSB is its support for biploar stepper motors. The classic PerfectStar, like most focus systems until now, uses unipolar stepper motors. Unipolar motors were probably originally chosen because they require less sophisticated electronics to drive them. But bipolar motors offer many technical advantages, and since they are now widely used in many areas, […]


2018 Calendar Now Available

The 2018 Calendar of Astro-Photography is now available!  For this edition the title is modified from the usual “Night Visions” to “Sky Visions: Night & Day” because a good portion of the photos included are of the Sun, including several from the Aug. 21, 2017 Total Solar Eclipse. As you can see from the cover, three other photographers have contributed to the calendar this year.  Bob Yoesle is a very skilled solar observer and photographer, and has provided images of the Sun captured with different filters.  Kay Wyatt and Michael McKeag are friends who both got better pictures of the […]


Early Christmas

For many years the AT111EDT has been my “workhorse” telescope, and it has been great, for the most part.  No longer in production, it is a widely regarded triplet refractor with an excellent optical design for its price point.  However, for the last few years I have been wanting to upgrade.  Specifically, I wanted the ‘scope pictured above (stock photo), the William Optics FLT-132.  Aside from having a significantly larger aperture, the FLT-132 uses a better grade of glass for the ED element, resulting in less chromatic aberration.  This has been a problem for me when capturing LRGB images with […]


LIGO Announces First GW Detection of Colliding Neutron Stars

You probably heard about this announcement from LIGO yesterday, but I thought I should add some details, and shift the emphasis of the story to where it really belongs: The previous detections of gravitational waves (GW) all originated from the merging of large black holes.  Such mergers can produce relatively strong, but very brief GWs – just a small fraction of a second.  And they produce nothing else – no light or other electromagnetic radiation.  Therefore, these observations could not be confirmed by optical telescopes or other detectors. In contrast, this event, dubbed “GW170817” because it was detected on Aug. […]


A Baby Elephant

There are, of course, a finite number of objects that an astrophotographer can shoot.  It’s a large number, but definitely finite, and when you add restrictions (and, trust me, there are a LOT of restrictions) it can seem like a pretty small number.  So it’s encouraging to see that the same object can be photographed and processed in many different ways.  As an example, I have now photographed the Elephant’s Trunk Nebula at 3 different focal lengths; 640, 350, and now 200mm.  A much longer focal length is often used on this target to capture just the “trunk” itself (the […]


Wider…Wider…

In my earlier attempt to capture the Spaghetti Nebula I found that the 200mm camera lens wasn’t quite wide enough.  And that a faster (lower focal ratio) lens would also be beneficial.  So I put an 85mm f/1.8 Nikkor lens (stopped down to f/2.8) on the QSI camera and tried again last night.  It didn’t work.  The moon was full last night, and even with a 3nm H-alpha filter, there was enough sky illumination to almost completely overpower the Spaghetti.  I’ll try it again when the Moon goes away, but I have to comment again on what this says about […]


Spaghetti (with Tomato Sauce)

This is a bi-color version of the Spaghetti Nebula.  I wasn’t able to put together a suitable rig for the wider angle lens, so just captured O-3 (oxygen) with the same 200mm setup.  Hydrogen is assigned to red and oxygen to blue and green.  In other photos of this nebula I found online very few bothered with the S-2 channel, as there is so little there.  Well, as I said before, even the hydrogen is very dim.  Oxygen is even dimmer:  You can see just a hint of it in blue/green near the top. I suspect that this is pushing […]


Mama Mia!

There are lots of things to be surprised about these days, starting with how long it has been since I posted anything here!  It has been very busy for several weeks here at Wa-chur-ed Observatory, including product development, order fulfillment, and my daughter’s wedding!  But it has not included any astro-photography – until last night. The Spaghetti Nebula, also known as Simeis 147 and Sh2-240, is a supernova remnant in Taurus.  It doesn’t have any spicy meatballs in it, but it is surprisingly dim – probably the dimmest target I have ever attempted.  It’s also very large at over 3 […]