I was fortunate enough to acquire a Celestron EdgeHD 8 telescope in early June this year. Before purchasing it, I was aware of the potential challenges of collimating it. However, once I began using the telescope, I encountered some difficulties in getting anything to focus properly.
My SCT imaging setup
- EDGE HD 8
- ZWO ASI AIR Plus
- Celestron OAG (133.34 of Back Focus)
- ZWO ASI AIR 533MC Pro
- ZWO ASI 220mm Mini Guide Camera
- ZWO EAF
- ZWO AM5
According to Astronomy Tools
- Celestron Edge HD 8, with a focal length of 2032mm, paired with ZWO ASI 533MSC Pro with a CCD Pixel size of 3.76µm, ok Seeing 2-4” and FWHM, Bin 2 – The ideal pixel size for OK Seeing (2-4″ FWHM) seeing is 0.67 – 2″ / pixel. The Resolution is 0.76 pixels
I sought help on various online forums to get assistance with setting up my OTA using the ZWO Ecosystem. In the past, I was able to achieve excellent imaging results with the RedCat 51. However, I’m now facing difficulties in obtaining proper OTA focus with the ZWO EAF after upgrading to the Celestron EDGE HD 8.
I extensively researched forums, attempted various recommendations, watched YouTube videos, and even purchased additional equipment such as the Hubble Optics 5 artificial star, Bob’s knobs, and a tri-bahtinov mask to assist with collimation. However, despite all my efforts, I was still unable to achieve proper focus.
These are the steps I took starting at F/10:
6-19-23 – 84° I was in Danville from 11:00 p.m. to 2:45 a.m. and the weather was great with a 5 mph wind. During that time, I focused and aligned my EDGE HD 8 telescope, which was a challenging task. However, I managed to achieve an initial focus and polar alignment. To get the best results, I used the maximum number of focus steps 0 – 65532 and made necessary adjustments to the secondary mirror with the help of Bob’s knobs.
Unfortunately, the session ended with severe focus issues and no successful collimation.
6-23-23 – 84° I observed Starlink using my EDGE HD 8 telescope at Bill’s in Chesterfield, MO from 8:00 p.m. to 10:45 p.m. The weather was good and I was able to see it clearly due to enough daylight. While looking at the power transmission lines, I spotted it at 9:48 p.m. Instead of using a polar alignment technique, I decided to focus on Vega and Polaris. However, even though I adjusted the focus to the maximum number of steps and used Bob’s knobs, I still need to do more research on the right focus steps for SCT.
I was unable to see the artificial star located 100 feet away due to being severely out of focus.
6-25-23 – 83° I spent the day researching the maximum steps EDGE HD 8 SCT can take. That night the weather was good with a wind speed of 7 mph. I discovered that EDGE HD 8 SCT can take up to 180-300k steps if the Native EAF max Step 65532 is adjusted for the Primary Mirror CW and CCW. Later in the day, I tried taking some pictures after sunset, but they turned out blurry due to the windy and dusty conditions. Even after adjusting the mirrors, it was difficult to capture clear images. I did not remove the imaging train, but I plan to try again using a diagonal and eyepiece instead.
Unfortunately, the session ended with severe focus issues and no successful collimation.
6-26-2023 – 81° I was at Broemmelsiek Astro Park in Missouri from 9:30 p.m. to 11:53 p.m. last night. During that time, I updated my ASCOM platform to version V220.127.116.1174 and my ZWO EAF to version 3.31.7. To improve the EAF’s performance, I used the APT Tools to adjust the Maximum Steps to 600K. However, I faced some issues with the EAF when focusing, especially when using BIN 2 and 4. I noticed that the Max steps would not exceed 52,498 and 95,755 values, which caused the EAF to click when it got stuck at those values.
It seems like there’s something amiss, and the focus is severely out of focus.
6-27-223 – No Imaging sessions, spent the day reading on CN Forum, suggestions:
* Move the primary mirror up/down.
* In the EAF use slow focus.
* On the SCT set Focuser to infinity focus by turning CCW.
* Adjust Step size 1500.
* Daytime Focus.
7-02-2023 – 86° At Broemmelsiek Astro Park in Missouri, I met with Grant Martin at 5:15 PM to test a daytime focus routine. We used a 5-star artificial star from Hubble Optics, and Grant chose three focus points.
- Hubble Optics 5-star (placed 100 feet away on a tripod)
- A conduit on a sign (1000ft away)
- Windmill and Astro Park sign (0.25 miles away)
We dedicated two hours, from 5:30 PM to 7:30 PM, to achieve focus at F10 with the ZWO EAF attached. Unfortunately, we faced some hurdles using the Preview, Live, and Focus modes on the ASI AIR Plus. To troubleshoot, we tried a different approach by replacing the ZWO EAF with the OEM Focus knob and switching to Video mode on the ASI AIR Plus. Then, we used the handheld controller to adjust the mount.
Finally, we were able to achieve a successful focus on the windmill, conduit, and Hubble artificial star using the methods mentioned above. After loosening the primary mirror, we proceeded to adjust the knobs on the secondary mirror, using BIN 2 for preview.
We have successfully collimated the secondary mirror and achieved focus on the primary. Now onto a real star.
7-04-2023 – 86° Between 7:15 pm and 11:45 pm at Broemmelsiek AP, MO, I manually adjusted my camera using BIN 2 and F10 to focus on objects such as trees and light poles that were over a mile away. I was able to achieve sharp focus in the Preview mode of the AA+. However, after astronomical twilight, I had difficulty getting Venus, Vega, Polaris, and the Moon into focus. I wondered if this was due to the FOV being larger than the minimum requirement of 0.2°. Interestingly, I was able to focus during the day on distant subjects, but the Polaris PA routine kept failing at night. I experimented with a range of gains from 360 to 0 and exposure times from 0.001 to 10 seconds.
I am struggling mightily at night. Unable to locate Polaris to complete the PA, even though I am pointed at a target, I can see it visually in the finder scope, Unable to get it in the FOV of the OTA.
7-09-2023 – 78° Broemmelsiek AP, MO 7:30 p.m. – 1:15 a.m. I aligned a street sign, which was 0.25 miles away, with the crosshairs of the finder scope by adjusting its two screws after pointing the OTA’s top at it. Then, I added a 0.7 focal reducer to the imaging train and removed the OAG and ASI533MC Pro. I used the diagonal and eyepiece to manually adjust the focus knob, and both the OTA and FS captured the street sign in focus. At 8:45 p.m., Venus became visible, so I slewed to it and was able to manually focus and align it with the OTA and FS. I waited for Polaris to make an appearance, and at 10:00 p.m., it was bright enough to be seen in the OTA and the FS.
Following a recommendation from my friend Alejandro, I made some changes to my equipment. I removed the diagonal and eyepiece and added the imaging train and EAF. To get a good indication of focus, I ran a 5-second preview on the AA+ using 100 gain and adjusted the focus step to 150. I was able to see Polaris in view with nice doughnut-shaped stars. Using the EAF focus routine, I achieved focus at 300 steps. However, I was unable to Polar Align in the AA+.
07-11-2023 – Last night, I headed out to my backyard at 83° Backyard StL Metro, MO, at 8:30 p.m. and stayed until 2:00 a.m. Two out of the three weather apps I use predicted clear skies. I took some suggestions from Alejandro and pointed my telescope to Vega, which is in the EAF. I set the fine to 100 steps and the coarse to 300 steps.
Initially, I assumed that the donut-shaped stars I saw were an indication of in-focus stars. However, I was mistaken. It turned out that the EAF had stopped at a zero position internally. When I removed the EAF, I discovered that the focus knob was not set to a zero position. So, I moved the knob to the CCW position to set the focus to a true zero position.
Next, I rotated the knob CW until I could get the stars in pinpoint focus. At this point, I reattached the EAF and ran the EAF AF in the AA+. After the process was completed, I had for the first time a true focus “AF succeeded step value 2698 in the EAF.” I then ran a quick Preview in the AA+ and Vega was tack sharp. I followed up with a PA, and that too went well.
As I have not yet figured out the OAG guiding for the guide cam, I limited myself to 10-EXP on the following M27, M13, NGC 6996. Despite this limitation, I spent the rest of the time hoping to see a few objects in my limited view of the sky.
Despite these challenges, I was determined to make the best use of the telescope, and with some additional experimentation, I was finally able to use it successfully for a night of astrophotography after almost six weeks. I learned a lot from the process, and I am now better equipped to deal with any issues that may arise in the future.
I present to you my first image captured with the EdgeHD 8.
M27 Dumbbell Nebula
Today, I processed the collection of images that I took on a particular night, and I am not satisfied with the outcome of the stars. I remember facing issues with guiding that night, and my total guiding error was 21.52. To get better results with longer focal lengths, I need to work on improving my guiding. I realized that I forgot to use a tri-bahtinov mask and the focus preview option in the AA+. Therefore, I am planning to revisit this object. However, this fall and winter, I will spend more time with the EdgeHD 8 to prepare myself to capture images of galaxies in 2024.
The Dumbbell Nebula (also known as the Apple Core Nebula, Messier 27, and NGC 6853) is a planetary nebula in the constellation Vulpecula, at a distance of about 1,360 light-years from Earth. It was the first such nebula to be discovered, by Charles Messier in 1764.
Planetary nebulae are formed when low-mass stars (like our Sun) reach the end of their lives and shed their outer layers of gas into space. The hot core of the star remains, and its ultraviolet radiation ionizes the surrounding gas, causing it to glow.
The Dumbbell Nebula is one of the brightest and most easily visible planetary nebulae in the night sky. It has an apparent magnitude of 7.5, which means that it can be seen with a small telescope or even binoculars.
In the telescope, the Dumbbell Nebula appears as a dumbbell-shaped object with two bright lobes and a fainter central region. The lobes are made up of ionized gas, and the central region contains the white dwarf star that created the nebula.
The Dumbbell Nebula is about 1.44 light-years in diameter and is expanding at a rate of about 26 kilometers per second. It is estimated to be about 9,807 years old.
Structure and Composition of the Dumbbell Nebula
The Dumbbell Nebula is composed of mostly hydrogen and helium, with smaller amounts of other elements such as oxygen, nitrogen, and sulfur. The nebula is also home to several dust knots, which are thought to be forming sites for new stars and planets.
The nebula’s dumbbell shape is thought to be due to the interaction of the white dwarf star’s magnetic field with the surrounding gas. The magnetic field creates a wind that pushes the gas outward, forming two lobes. The central region of the nebula is denser and less affected by the magnetic field, which is why it appears fainter.
Evolution of the Dumbbell Nebula
The Dumbbell Nebula is still in a relatively early stage of its evolution. Over time, the nebula will continue to expand and the dust knots will eventually disperse. The white dwarf star will eventually cool down and become a black dwarf.
Observing the Dumbbell Nebula
The Dumbbell Nebula is a popular target for amateur astronomers. It is best observed on a dark night with a small telescope or binoculars. To find the nebula, look for the constellation Vulpecula in the northern sky. The nebula is located just above the small constellation of Sagitta.
Significance of the Dumbbell Nebula
The Dumbbell Nebula is one of the most well-studied planetary nebulae. It is also one of the most beautiful and easily visible planetary nebulae in the night sky. The nebula provides astronomers with valuable insights into the final stages of stellar evolution.
Until the next adventure and Thank you for stopping by!
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