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.

Looking Back

 in Blog  tagged IBM / nVidia / Orchid Technology / silicon valley / TurboPGA

Once again, it has been a ridiculously long time since I posted anything here, and I haven’t been doing much of anything directly related to astronomy or astrophotography, except my ongoing and time consuming work of manufacturing my products for astrophotography.  But I’ve been thinking about how I got here and decided to share some thoughts. My Power*Star design is, in several ways, the most sophisticated product that I can call my own design, and it was an amazing accomplishment to complete it with the short schedule and limited resources I had, but if you look at the amount of […]

A Wizard from New Mexico

 in Blog  tagged New Mexico / NGC 7380 / Santa Fe Stargazers / Wizard Nebula

  I haven’t posted anything here for a ridiculously long time (sorry!).  For most of the time since my last post I’ve been busy manufacturing stuff for my OEM customers, but for the last few weeks I’ve been on vacation in Santa Fe, New Mexico.  Although I brought a bunch of astronomy gear along, various things have conspired to keep me from doing much imaging.  The vacation is about over now, but recently I managed to get a fair amount of data on the Wizard Nebula (NGC 7380), an emission nebula in the constellation Cepheus.  I captured H-alpha frames first […]

The First (and hopefully, not last) Star Party of 2021

 in Blog  tagged Perseid meteor shower / SkyView Acres / star party

This past weekend (Friday through Monday night) I was at my favorite site for astrophotography, SkyView Acres, in Goldendale, WA in my first opportunity to attend a star party this year.  The first 2 nights were not expected to have good weather, and the forecast was largely correct, but this gave me some time to work out some ‘bugs’ that arose from new equipment and software – and from not having done any AP work for a full year! August 12(ish) is the peak of the Perseid meteor shower, so we were a bit early, but still saw plenty of […]

A Duet

 in Blog  tagged Ab Light / Adim Controller / dimmer / Flat calibration / PWM

Joining in a duet with the ‘Ab Light’ product that I announced recently, it’s now time to unveil the ‘Adim Controller’.  Adim (for the musically challenged, this is read as ‘A diminished’) is a dimmer for Ab Light.  It could also be used for other 12V devices that would respond well to a PWM power input, including fans and other types of lights.  Adim provides both manual and computer-based control, and can drive up to 1.5 amp loads. The PWM (pulse-width modulation) output operates at 2kHz, meaning that the on/off cycle repeats 2,000 times per second, or every 500 microseconds […]

Astrophotography Video

 in Blog  tagged astrophotogrphy / drone / SkyView Acres / video

My favorite site for astrophotography is Skyview Acres in Goldendale, WA.  Because of the pandemic we had only 2 star parties there last year.  Konstantin Mos was at one of these events and made a short video about his interest in the hobby, using footage from both a drone and the ground.  You won’t see me in the video, but you might recognize my AP setup – or my motorhome.  And one of the astrophotos he included is from me as well.  The video will give you some sense of what these star parties are like, so have a look: https://youtu.be/4fGQny29Wjk

The Music Series

 in Blog  tagged AbL / Flat calibration / flat light / lunar eclipse

In my last post I explained what flat calibration is and what is required to make it work. In this post I will introduce my solution to the problem, “Ab Light”: The name (in case it isn’t obvious) is a small pun based on my interest in music. “Ab” is read as “A flat”, and this is ‘a flat light’. Ab Light (abbreviated AbL) is based on LED technology, with a light pipe made of a special type of acrylic that is designed to provide even illumination when lit from the edges. I used the same material for the illumination […]

Flat Calibration Explained

 in Blog  tagged Flat calibration / flat frames / flat light source

To properly process an astrophoto the first step in most cases is ‘calibration’. The purpose of calibration is to compensate for various defects in the image sensor and the optical system. Essentially, we capture images that isolate the most common defects and mathematically apply the inverse of the error to each of the raw images we have captured. One part of this calibration is to remove unevenness in the brightness across the frame. This step is called ‘flat calibration’. Unevenness (lack of flatness) can be caused by vignetting of light by the optical system (the image is darker in the […]

Customized Power*Star

 in Blog  tagged custom / customization / enclosure / Intel / LattePanda / Lenovo / NUC / Power*Star / Raspberry Pi / SBC

One of the early customers for Power*Star is planning to use it with a single-board computer (SBC) at the telescope, and asked me to customize the enclosure to allow mounting the SBC on top of P*S.  It is more than worth noting here that where to locate the host computer is an important question.  Some competitive products to P*S have a built-in processor (ranging from small Raspberry Pi boards to full-blown Windows machines with high-end Intel processors), while others take the same approach as P*S, providing only the features specific to astrophotography.  While it is sometimes convenient to have everything […]