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Greg Marshall's Blog (15)

Welcome Back, Neal

It was great to see Neal Heacock "back in the saddle" - and for 4 straight nights! Watching him at work it seemed like he hadn't been away at all.

The skies were not great on any of the 4 nights, but most of us were shooting things barely above the southern horizon because around here this is the only chance we get to shoot them. Well, this year July should be good also.

There were 7 people (all imagers) and most stayed all 4 nights. Skill levels ranged from "master" (Neal) to…


Added by Greg Marshall on June 16, 2015 at 9:10pm — No Comments

Focus Motor for SCT

I got an 8" EdgeHD scope a while ago and have just finished development of a focus motor for it. I am now offering the "PerfectStar SCT" along with the PerfectStar Focus Controller. The PS SCT motor was developed specifically for the EdgeHD series and will be available more or less off-the-shelf for 8", 11", and 14" scopes from that family. Most SCTs use the same kind of mechanism, so the design is easily customized to other models, but specific dimensions vary, so I am concentrating on the…


Added by Greg Marshall on December 26, 2013 at 12:57pm — No Comments

2014 Calendar of Astro-Photos

As in previous years, I have produced a calendar of my best recent astro-photos. This year the calendar is a little bigger (12 x 9 inches) and has more information about each object, including a sky chart on the back cover that shows where each object is located. That makes it an even better gift for people who are not familiar with astronomy. And the price is still just $15! To order, send me an e-mail through my web site:…


Added by Greg Marshall on November 6, 2013 at 12:13am — No Comments

PerfectStar Focus Controller and Motor

I've just released an all new version of the PerfectStar Focus Controller firmware and driver. The new version adds several new functions and enhancements, including greater robustness. At the same time, I am announcing a new PerfectStar Focus Motor that fully encloses both the motor and the focuser coupling. I am now using Hurst motors, the premier manufacturer of stepper motors. For details, see…


Added by Greg Marshall on April 21, 2013 at 10:20pm — No Comments

Join the Online Discussion on Night Sky Photography

April 16 at 1PM (Central Time) Minnesota Public Radio will be hosting an online discussion on Night Sky Photography. I and 2 other photographers will be answering questions from the public. Since I only do "deep space" imaging I don't know how many questions will come my way, but the other 2 people are experienced in (and good at) night sky photography. There's a link to the event on my web site:

Added by Greg Marshall on April 15, 2013 at 3:47pm — No Comments

New Product Announcement: "Mister T" T Mount Adapter

Wa-chur-ed Observatory (that's me) is proud to announce our newest addition to the product family, MRT (Mister T).

MRT (Mister T) adapter for Canon DSLR astro-photography. With rock-solid mounting and easy camera rotation adjustment, I pity the fool that doesn’t use this adapter!

Click here for more information:…


Added by Greg Marshall on March 5, 2013 at 3:54pm — 7 Comments

2013 Calendar of Astro-Photos

Forgive the shameless commercial pitch, but I've just printed 100 copies of a calendar and need to get the word out if I'm going to sell enough to cover the cost. For more information see:




Added by Greg Marshall on November 8, 2012 at 4:18pm — 3 Comments

Recommendations for OAG?

I've always used a separate guide scope and like the simplicity that it offers, but I now have pretty clear evidence of differential flexure despite doing everything imaginable to make a solid connection between the 2 scopes. So I want to try an off-axis guider and am looking for recommendations. I think it should be very adjustable (both rotation and prism position) to be able to find a good guide star. My current setup uses 2" SCT threads to connect the reducer/flattener to the scope. This…


Added by Greg Marshall on August 21, 2012 at 10:55am — 7 Comments

"PerfectStar" Focus Controller

Astro photographers all know that perfect focusing is both essential and difficult. A motorized focuser is a big help because it allows finer control while avoiding the vibrations typically induced by turning a focus knob by hand. However, simple DC motor systems cannot provide enough precision and absolute positioning systems using stepper or servo motors are usually very…


Added by Greg Marshall on May 28, 2012 at 11:16am — No Comments

ELF Panel Tests

As promised, here are the results of testing my ELF panel, an electroluminescent panel designed specifically for making "lens cap" type flats. That is, by placing the panel directly in front of the telescope. This technique does not provide the highest possible accuracy, but when done properly it works quite well and has the distinct advantage that you can do it in the middle of a shooting session without bothering anyone. ELF is designed to fit snugly around the end of your scope so that…


Added by Greg Marshall on April 26, 2012 at 11:51am — 1 Comment

New Astronomy Products from Wa'chur'ed Observatory

Since I retired from a career in designing electronic products (mostly related to imaging), I've often had to rely on the skills learned over the years (and learn some new ones) to solve problems that came up in astronomy. Thinking that my friends in astronomy and astrophotography might benefit from the solutions I developed (and having little else to do), I decided to make some of these solutions available as real products. My intent is not to make a big business from this and it's not…


Added by Greg Marshall on April 5, 2012 at 5:52pm — 1 Comment

Update on Differential Flexure

Not satisfied with the results of my previous testing, I decided to try again. This time I used a technique that is directly applicable to imaging rather than a theoretical measurement of worst-case flexure. What I did was to simply capture 30 images at 2 minute intervals while guiding, then measure the position of a star in each frame to see how it varies in RA and DEC over the hour. Obviously, there is some "noise" in the measurements and I didn't bother trying to filter that out (such as… Continue

Added by Greg Marshall on June 16, 2011 at 12:25pm — No Comments

Full Time Astronomy?

Got laid off today! It was only part time work and the lay off was expected - not a big deal. So now I can spend all (well, most) of my time on astronomy.

Coincidentally, my previous employer, Xerox, announced today that they are outsourcing most engineering to India. It has been my opinion for some time now that the company was run by fools. This is proof positive.

Added by Greg Marshall on June 8, 2011 at 8:00pm — 3 Comments

Flexure and Field Flatness Tests

Neil gave me the idea of testing to see how much differential flexure I have in my side-by-side setup and I got around to doing that last night when we had partly cloudy skies such that I didn't want to try real imaging, not knowing how long it would last. My AT111EDT (with QSI 583 camera) and Orion ST80 (with Meade DSI camera) are mounted on a 3/8" aluminum plate, about 8" apart. Recently I also added an aluminum bar across the tops of the rings to couple the 2 scopes there in addition to the… Continue

Added by Greg Marshall on June 5, 2011 at 10:00pm — 1 Comment



I've just joined AstroGab on the recommendation of a friend. Here's some details on my interests and techniques.

Photography has been my primary hobby for the last 20 years. I got interested in astro-photography somewhere along the line and did some experiments with a film camera on a barndoor tracker, but didn't start seriously pursuing it until 6 years ago. Although I like science in general and astronomy in particular, it has always been the aesthetics of deep-sky… Continue

Added by Greg Marshall on May 14, 2011 at 12:12pm — 3 Comments

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