Skip to content
Collimation woes! | Hyperion Astronomy

Collimation woes!

Collimation, oh collimation !

 

Hamza
Just another amateur

    After getting the big OOUK AG16 installed with all its accessories, camera, filterwhel, etc..we thought playtime was around the corner and we were going to image our hearts put. WRONG! the Collmation ( optical alignment) did not survive the trip to the observatory and we had to do something about it. Typically, a laser suffices to align a newtonian but not this time, the AG16 operates at F/3.6 with the provided 0.95x coma corrector/reducer which makes things very tricky. 

    One of the issues you run into is the secondary mirror offset and all it entails to figure out and collimate the scope properly. After exhaustive research, we reached a point where only the best tools need to be purchased. To that end, we reached out to Jim Fly from CATSEYE who provided us with ample information about why his product should be used and how. He provides ample information of his very detailed website linked above from graphs, images, animated GIFs, Youtube videos and so on. We ordered the tools and now awaiting some measurements Jim requires to obtain the best collimation possible.

COllimation Assessment

    On of the best tools available in PRISM Pro and Advanced is its great scripting language that allows extensive capabilities. Alain Maury ( www.spaceobs.com) has written a great script that allows the user to take a series of images in sequence which allows PRISM to calculate the actual tilt in your system, the script is available here. The concept here is to perform autofocus runs ( V-curves) on 500 stars in your images one at a time. In theory and if your system is "flat" and exhibits now tilt at all, all the stars should come to focus at the same point As you can see for the image below, they do not which means, in this instance, there is tilt( other aberrations might be present as well but we suspect tilt is the culprit here). This scope is very fast coming in at a native ration of F/3.8 which makes tilt like this extremely noticeable. The image shows the output of the tip/tilt measurement tool in PRISM, all the numbers displayed on the image are the relative distances from the main focus point.

Tilt Measurement Tool in PRISM v10: This is the output of the tool which measures the relative focus distance in MM.

As you can see from the image below (NGC6946 - The Fireworks Galaxy), there are a few issues across the image. If you pan through the image, you will realize that the corners exhibits different behavior and we believe this is due to the secondary offset being incorrect as well as tilt in the focuser itself since it has a tip/tilt plate.

It exists yet another tool that allows us to quickly check the center of the image as well we all the corners, you can find this under  Analysis > Four Corner Reduction: Quick Collimation Checks. This is a quick way to quantify what is happening in your images instead of zooming in and panning across.

This saga will continue as we unravel what is going on with this beautiful system and hopefully, we get performing at its best soon.

 

Previous article How-To: Find a Suitable Star For Autofocus
Next article The Hunter: Perfect for Asteroid/Comet/SuperNova Discovery

Leave a comment

Comments must be approved before appearing

* Required fields

★ Judge.me Reviews

Let customers speak for us

18 reviews
83%
(15)
17%
(3)
0%
(0)
0%
(0)
0%
(0)
Imaging Made Easy

Prism is my GoTo program for observatory control and imaging. Prism's many features make imaging taking a breeze.

I was concerned about giving Prism a try , especially as its quite expensive. So far Im very impressed and glad of my decision.
Im a beginner at all this so haven't tried other more recommended software, Prism appealed as it seems to do everything instead of using several programs 👍🏻

Great lightweight guide scope

This guide scope replaces a 400/80 that was waaay too heavy for what it did. The smaller 60mm scope does a great job guiding and I can RA balance with just one counter weight now - much better - and it looks like something Ferrari designed

Still learning Prism using Wireless links...

I have much of your software working at this time... I have it parked on my main computer, and a notebook... My main computer is a OverClock computer with 32 Gigs of RAM Clocking presently at 4400MHz with software parked on SSD drives... The rotation dome by NexDome is still not working... Most problems like this have to do with ASCOM Drivers... There is not very much detail information on how to use this software... I have to feel my way to a total operational staus... Second issue... The rain in the San Francisco Bay Area this year has limited my access to my larger telescope (12 inch SCT)... This rain has been so significant, I was force to weatherize my observatory... My goal here is,,, I am trying to remotely control my observatory totally. I have used Netgear Powerline 2000 to handle camera images and discover controlling rules to do that... High speed is vital for images with cameras over 3 Megs... I have both 12 Mega sensors and 24 Mega sensors... I am also using Netgear Nighthawk router and its mating extender to increase control signals to my observatory that is about 100 feet on the side of hill... I am also using Virtual Here software on a Raspberry Pi inside the observatory to solve the USB interface requirements... I started out using Model B and B+ on level 3 raspberry Pi's... I have moved to Level 4 Raspberry Pi to gain access to USB 3.0 technology... Big difference! I hope by early spring to have everything working... Bob Ritter MicTechS

A great program, even for beginners!

I have to admit, I was hesitant to invest in an “all in one” astrophotography program. Being a beginner, I thought the learning curve would be way too steep, but after talking with several friends I decided to give it a try. The first thing I noticed was the logical layout of the main screen. It was very intuitive and easy to navigate. Everything you could need for astrophotography is in this program! Setup of my equipment was quick and easy with no glitches or errors. Everything runs smoothly from capture to the final process. You will surely have questions and this brings me to the next point. Prism’s customer service is second to none! With on line tutorials, a Facebook group and email you will have instant access to knowledgeable users worldwide. My first question was answered directly by the US distributor within a matter of minuets! Take the next step and invest in your future in astrophotography! You’ll never look back!

Greg Hemmings