Tag Archives: Astrophotography

Informational

A step by step guide to Collimation

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If like me you own some sort of reflector telescope, whether this be a Newtonian, Dobsonian, Ritchey Chretien or as I have a Hyperboloid Astrograph then you’ll know that there is a very strong importance on collimation, the faster the optics the more critical collimation becomes, especially for imaging. After recently removing the rear mirror assembly for cleaning, as well as changing from the QHY183M to the QHY268C-PH amongst onther stuff in the imaging train, I wanted to share my experience and knowledge around collimation. Let’s start off with the details on what I use

Part 1 – Aligning the Secondary Mirror with the Focuser

Now on my SharpStar 15028HNT, they recommend you unscrew and remove the corrector from the focuser, however I have found no difference in collimation with or without the corrector in place and because it is part of the optical train I’d rather include it in the collimation, so the first step for me since my primary mirror was currently removed was to check the secondary alignment with the focuser, as well as the rotation of the secondary in relation to the focuser, in order to do this, I use the Teleskop-Service Concenter eyepiece, the eyepiece itself has a set of rings engraved into the plastic apperture like so

Teleskop-Express Concenter Eyepiece markings on lower end of barrel

I ensure that my focuser is at the most inward position and since my SharpStar has an M48 thread on the focuser, I used a 2″ extension tube that has an M48 thread on it, and placed the concenter eyepiece in there:

M48 threaded 2″ Extension tube with Teleskop-Express Concenter Eyepiece

This serves well to get the rotation and alignment of the secondary with the focuser by ensuring that the mirror appears as a perfect circle between the rings, now you can adjust your focuser position in order to get the edge of the mirror to appear on the lines, this is what the view looks like through the concenter eyepiece:

Here you can see the secondary mirror appears circular and in line with the concenter eyepiece markings showing a successful alignment with the focuser

The blue at the top right of the image is a piece of card I stuck behind the secondary in order to show the edge of the mirror better.

As you can see my secondary mirror is pretty much perfectly aligned with the focuser and square with the focuser also, if your mirror shows up as more eliptical, this means the mirror needs to be rotated, if the mirror does not fit in within the circle itself, for example if it is over to the left or right, you will need to move the mirror forward or backwards by means of loosening or tightening the central screw that holds the secondary.

You can see from the following image, I have a central screw which is used for moving the mirror up or down the tube away from or closer to the primary, as well as rotation of the mirror, but then there is also the three collimation screws that are used to adjust the mirror direction itself which we will talk about in the next section

Here you can see the central adjustment screw for adjusting the mirror rotation and centering the mirror with the focuser, the three outer scres are used for adjusting the tilt of the mirror to align with the primary

Part 2 – Aligning the Secondary Mirror with Primary Mirror

Now that we have our secondary mirror lined up and square with the focuser, the next step is to align the secondary with the primary, now for this I will use my FarPoint Astro Laser collimator, which itself has recently been collimated by FarPoint Astro, now you can re-use use the 2″ extension tube and place the laser into the tube, but for the SharpStar I will use the M48 to 1.25″ lockable adapter like so:

FarPoint Astro laser collmator in the SharpStar M48 to 1.25″ Adapter

Now the point of this part is to ensure that the laser hits the centre spot of the primary mirror, if it does not, then this is where you would adjust one or more of the three screws on the secondary, as you undo one, you should tighten the other two, as you can see from this image, I need not make any adjustments as the laser hits the centre of the primary perfectly:

Here you can see that the laser hits the primary mirror centre spot

Part 3 – Aligning the Primary Mirror

Now since I do not have to make any further adjustments to the secondary mirror, it is time to focus on the primary mirror, the trick here is to get the laser beam to return to the point of origin, here’s an example of the primary not being correctly aligned:

You can see two dots here, one is the laser aperture, the other is the reflection of the laser from the primary mirror, this reflection needs to meet the aperture

You can clearly see the red dot to the top left of the laser apperture, this means that the primary needs some adjustment by means of the three collimation screws which are situated on the rear of the primary mirror assembly:

Here you can see the primary mirror collimation screws, the larger push/pull the mirror, the smaller are locking screws to secure the mirror in place after successfully collimating.

Most telescopes have a push – pull method here, turning anti-clockwise will push the mirror further up the tube, whereas turning clockwise will pull the mirror towards the bottom of the tube, it is very important not to keep turning anti-clockwise because this could result in the screws becoming disconnected from the primary mirror. After an adjustment on a couple of the collimation screws, my primary is now aligned properly as the laser beam returns into the laser apperture:

Here you can see that there is no additional dot, the dot is centered right on the laser aperture indicating primary alignment is complete

Once the laser collimation has been completed, it is easy to verify this with the FarPoint Auto-Collimator, the eyepiece has a mirror inside which allows you to see where the centre spot of the mirror is and will form a slightly pale dot in the middle, if the dot appears in the middle then you have your collimation pretty much spot on after following the above, maybe a very slight adjustment on the primary collmation screws is all that is required, you can see here what the view looks like:

It is also normal on faster telescopes to see the mirror appearing offset as opposed to central to the OTA itself. Once completed, I would typically then perform a star field test and I prefer to use the Multi Star Collimation in CCD Inspector for this, you can of course use the de-focused star method.

I hope you found this useful, I just thought I would share my process in performing collmation to help others who may be on that journey also.

Equipment, Gear Reviews

SharpStar 15028HNT

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After months of trying to get my trusty Sky-Watcher Quattro F4 to work with the ASA 0.73x reducer I decided to go all in on an F2.8 astrograph. After doing some research I stumbled across the SharpStar 15028HNT F2.8 Hyperboloid Newtonian Reflector from my local supplier 365Astronomy.

After toying with the idea and speaking to my good friend Nick from Altair Astro and with the idea of going back to a refractor, I decided that I could not go back to slower than F4 and I wanted something that in essence would work with a bigger sensor than my QHY183M, and the Sharpstar looked like it could work for me, so I placed my order with Zoltan from 365Astronomy and collected it the following day.

Unboxing the scope, I was like a young child at christmas, the scope came with a very sturdy protective hard case and removing the scope out of the case you could immediately feel that a lot of time and effort had gone into producing the 15028HNT.

Aperture: 150mm
Focal Length: 420mm
Focal Ratio: F2.8
Weight: 6kg
Tube Material: Carbon Fiber

With the scope unboxed I started to fit my equipment onto the scope. In order to fit my Sesto Senso I had to rotate the focuser 90 degrees clockwise due to the telescope mounting rings, this is when I noticed an isue that one of the grub screws on the focuser would not tighten and I needed to stop the backlash, fortunately there’s another grub screw on the other side that tightened and stopped the backlash.

Before I attached my imaging equipment, I had to ensure that the telescope was collimated, so I stumbled across the collimation guide which after speaking with my good friend Terry Hancock over at Grand Mesa Observatory who was also evaluating the same scope, we both agreed that the colimation guide wasn’t very well written as it mentioned nothing about collimating the primary. One thing that it mentioned is to remove the corrector, Sharpstar include a tool for you to remove the mounting plate and corrector, but here is a word of advice……..remove this when the telescope is cold, take that advice from someone who tried to remove it whilst it was warm!

I performed a laser collimation with my Concenter Eyepiece to check the secondary, and then a laser to check the primary, now the collimation guide says to remove the corrector, I have done validation with both the corrector removed and the corrector in place, and it made no difference whatsoever, so my opinion is to leave the corrector in place.

With the scope closely collimated, I mounted my StarlightXpress Filterwheel and Camera which with the 15028HNT is an M48 thread for the gear to screw onto.

I will post some images as soon as I have completed some, the weather has been pretty poor (probably because I bought a new scope), but the frames I have got so far are very sharp, pinpoint and I can honestly say I have never seen images come directly off the camera so sharp.

My field of view with the QHY183M is around 1.21 Arcsec/Pixel which gives me a FOV or around 1.81°x1.2° and I love the difraction spikes being at 45 degrees compared to the 90 degrees on the skywatcher and I already have a pretty full target list for this scope ready to go this season.

Apart from the couple of product issues I have experienced (Grub screw on focuser and tube clamp thumbscrew being threaded) I am extremely happy with the scope, it is performing really well and here are a couple of work in progress images that I have started

Dark Shark Nebula Moscaic Panel 1 – 51x300S in Red, 25x300S in Green and Blue
Elephant’s Trunk – 51x300S in 6nm Ha
M45 – Mosaic Panel 1 – 12x150S in R, G and B

After a few weeks, the telescope has held collimation very well, I have not had to perform any re-collimation, I will re-evaluate this in the much colder months of winter.

I am so happy with the scope that I am actually considering a second one for an OSC Camera with a bigger sensor.

Gear Reviews

StarlightXpress Lodestar X2

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I was lucky enough that Terry from StarlightXpress sent me a Lodestar X2 for me to test to see how well it performed against my existing guider camera, so it only seemed fair that I provide my feedback via an equipment review. Many who know me know I have been using a QHY5L-II camera as a guide camera for a few years now but after seeing a few of my fellow astrophotographers using the Lodestar cameras it seemed silly not to try one out.

In comparison to the QHY5L-II the Lodestar X2 is a true CCD camera and not a CMOS camera, so immediately this would yield some higher sensitivity in what stars can be selected. One thing that is immediately noticable between the cameras is the Lodestar X2 is longer than the length of the QHY5L-II.

Just to add some more comparisons:

QHY5L-IILodestar X2
SensorAptima MT9M034Sony ICX829
Sensor TypeCMOSCCD
Sensor Size6.66mmx5.32mm6.47mmx4.81mm
Pixel Size3.75um8.2umx8.4um
MPX1.2mpx0.4mpx
QE74%77%
Length54mm85mm
Weight45g50g
Cost (27 Aug 2019)£175£378

The first time I used the Lodestar X2, I was shocked at how many stars were in the field of view, for the same 2 second exposure I usually guide at there was a lot of stars to choose from, far more than I could see with the QHY5L-II, there is probably a number of reasons for this, higher sensitivity of the CCD Sensor, slightly higher QE, but also the FOV, with the QHY5L-II on my 8″ Quattro with a 0.73x reducer it would yield a field of view of 0.47°x0.35°, the Lodestar X2 on the other hand would yield a field of view of around 0.6°x0.48°.

Since I use PHD2 for guiding one thing that was immediately apparent was the built in driver for StarlightXpress cameras, I asked Terry which would be the best to use, he said either, it makes no difference, so I tested this and he was right, the in built driver and ASCOM driver produced the exact same result, I remember specifically with the QHY5L-II that QHY recommend you do not use the in built driver and always use the ASCOM driver. When firing up the Lodestar X2 in PHD2 I built my dark frame library in order for me to see how good the ICX829 was for noise, so I compared the 2 second exposures and there was very little difference between using a dark frame library versus not using one, the QHY5L-II definitely requires a dark frame library in PHD2 that’s for sure!

My first night of guider testing seen a little bit of odd behavoiur with the Lodestar X2, since I am using the Pegasus Astro Ultimate USB Hub, I had everything connected in there, including the QHY183M which is a USB3.0 camera albeit connected to a USB 2.0 hub. When the camera was downloading the image the Lodestar would display an array of dots on the screen. Terry confirmed that it was an indication that it was dropping down to USB 1.0 speed. It turns out that when I did the same thing with the QHY5L-II as the guider camera, the QHY5L-II would actually go unresponsive according to PHD2, so I moved the imaging camera to a dedicated USB 3.0 port on the Intel NUC and never had a repeat of the issue on either camera.

PHD2 has no issues picking up and selecting a guide star, there’s plenty of stars to choose from

Conclusion
The Lodestar X2 is awesome as a guide camera, it works extremely well, very sensitive, the only drawback in my opinion is price, at over double the price of the QHY5L-II camera maybe a tad out of some folks price range.

Events

Knowledge – The sky is not the limit

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A while back I was approached by my local primary school and asked if I would be happy to go in an present an assembly on astrophotography for the children (and the staff were keen too) as part of their Space Education curriculum and STEM, anyone who knows me knows I love to present to a crowd as I do this every day, but this time would be different, this time I would be presenting to children as young as 6 so I had to put some real thought into the content in order to keep their attention.

We started off by talking about what astrophotography is, many of the children had a good idea of what it is, most of the children had told me what things they had seen in pictures from space such as the Moon, Planets such as Jupiter and Saturn as well as images of the milky way, we also talked about how astrophotography images are taken and we talked about different telescopes, especially the Hubble Space Telescope (HST) and how much it cost when it was first launched in 1990, we looked at some of the images produced by Hubble and then looked at some of the images I have produced and the children thought mine were better because my telescope cost far less.

After looking at some images, I shown them some photos of the equipment I use for imaging and I asked them if they knew what each part was, I was pleasantly surprised at some of the reactions and answers to my questions, clearly the staff at the school had done an outstanding job of teaching them about space. I got many questions from the children about my hobby and about space in general and the enthusiasm and thirst for knowledge about what lies beyond our planet was amazing. We finished up with a video of my images which was met with oooh’s and wow’s from the children, a link to the video can be found at the bottom of this post.

I wish to thank Miss Reeve at Northland Wood Primary Academy for inviting me to come in and talk to the children and I hope I inspired some budding astronomers in the audience (as well as the staff).

Equipment, Gear Reviews

The source to the halo around bright stars

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When I moved to the Sky-Watcher Quattro telescope I noticed some bizzare halo’s around bright stars in my images, this was evident in both my Atik 383L+ CCD Camera as well as my QHY183M ColdMOS Camera when using the Quattro 8-CF at F4, if you browse my galleries you will see what I mean, and it was more noticable in my Narrowband images. Below is one of my recent images where you can see the halo around Magnitude 3.9 star 15 Mon in the Christmas Tree Cluster / NGC2264.

I contacted Baader back in February 2019 since all of my filters were Baader, and I noticed that the Halo was present in all of my filters but significantly less in Red, but more prevalent in Narrowband filters, so the logical cause would be the filters. Baader immediately dismissed this to be the fault of their filters and suggested that my Coma Corrector be the root cause.

Not convinced that the Coma Corrector was causing the issue, I did some research online and came across a brilliant page on the Astronomik website where they claim to have resolved the majority of the Halo issue, and after reading the following line from the page I was convinced the filters were my issue:

In recent years very fast optical systems have become popular for imaging. The energy in a filter induced halo grows exponentially as the f-ratio decreases. Additional to this, the smaller the FWHM band pass of the filter, the stronger the halo.

The above line described my issue perfectly so I mentioned this to Baader who again dismissed the possibility of it being their filters and again put the blame firmly to my optical train. Again not happy, I contacted Astronomik and Eric emailed me back very promptly and offered to send me out one of their 6nm Ha filters to test. A few days ago the filter arrived and I was able to perform some testing against the Baader filter also for comparison on the same star.

Since the star in my image above was of magnitude 3.9, I wanted to find something similar, so I found star Alhaud VI and proceeded to obtain 15x300S Exposures for each filter, and here are the results:

Astronomik 6nm HA filter, 15x300S with Darks and Flats applied
Baader 7nm Ha filter, 15x300S with Darks and Flats applied

So as you can see the Baader filter shows a high amount of Halo around the bright star and the Astronomik filter does not, now if this was something to do with the rest of the optical train there would be evidence in the Astronomik filter also.

Now I agree there will be some reflection in the optical train, all that glass in the coma corrector, the glass on the camera etc, so I thought I would have a look at both images in a bit more detail, zoomed in on the stars there is what appears to be a slight halo in the same place on both images:

Astronomik 6nm Ha Filter
Baader 7nm Ha Filter

So both filters show the Inner Halo which in my opinion would not be visible in an image, but again clearly the Baader filter has some reflection issues happening as you can clearly see two additional Halos. The interesting thing about all three Halos is that the central one visible in both filters has no relationship to the distances between the other two in the Baader, however the two outer Halos on the baader are the same distance apart as the middle halo is from the star, so clearly this is some sort of reflection.

Conclusion:
Astronomik have done a fantastic job at eliminating Halo artifacts around bright stars, clearly the Baader filters are causing major Halo artifacts because if this was the optical train then it would be evident in the Astronimik filters also, I suspect that the Baader filters are not optimised for faster focal ratio imaging systems. I have provided this information to Baader and await a response from them.

Good job Astronomik Filters

ColdMOS Images

M101 / NGC 5457 – Pinwheel Galaxy in RGB

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M101 / NGC5457 or most commonly known as the Pinwheel Galaxy is a face on spiral galaxy in Ursa Major and has a distance of around 21 million light years from Earth.

The QHY183M picks up quite a lot of the Ha detail in this galaxy without me having to image separate Ha Filter data

Image Details:
101x150S in R
101x150S in G
101x150S in B

Total Capture time: 12.6 Hours

Acquisition Dates: Feb. 27, 2019, March 29, 2019, March 30, 2019, April 1, 2019, April 11, 2019, April 12, 2019, April 14, 2019

All frames had 101 Darks and Flats applied

Equipment Details:
Imaging Camera: Qhyccd 183M Mono ColdMOS Camera at -20C
Imaging Scope: Sky-Watcher Quattro 8″ F4 Imaging Newtonian
Guide Camera: Qhyccd QHY5L-II
Guide Scope: Sky-Watcher Finder Scope
Mount: Sky-Watcher EQ8 Pro
Focuser: Primalucelab ROBO Focuser
FIlterwheel: Starlight Xpress Ltd 7x36mm EFW
Filters: Baader Planetarium RGB
Power and USB Control: Pegasus Astro USB Ultimate Hub Pro
Acquisition Software: Main-Sequence Software Inc. Sequence Generator Pro
Processing Software: PixInsight 1.8.6

ColdMOS Images

NGC4565 – Needle Galaxy in RGB

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The Needle Galaxy is located int he constellation of Coma Berencies and is an edge on spiral galaxy at a distance of 30-50 million light years from earth

Image Details:
101x150S in R
101x150S in G
101x150S in B

Total Capture time: 12.6 Hours

Acquisition Dates: Jan. 28, 2019, Feb. 3, 2019, Feb. 25, 2019, Feb. 26, 2019, Feb. 27, 2019, March 26, 2019, March 29, 2019, March 30, 2019, April 1, 2019

Equipment Details:
Imaging Camera: Qhyccd 183M Mono ColdMOS Camera at -20C
Imaging Scope: Sky-Watcher Quattro 8″ F4 Imaging Newtonian
Guide Camera: Qhyccd QHY5L-II
Guide Scope: Sky-Watcher Finder Scope
Mount: Sky-Watcher EQ8 Pro
Focuser: Primalucelab ROBO Focuser
FIlterwheel: Starlight Xpress Ltd 7x36mm EFW
Filters: Baader Planetarium RGB
Power and USB Control: Pegasus Astro USB Ultimate Hub Pro
Acquisition Software: Main-Sequence Software Inc. Sequence Generator Pro
Processing Software: PixInsight 1.8.6

ColdMOS Images

NGC 2264 – Cone Nebula and Christmas Tree Cluster in HaRGB

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Located in the constellation of Moneceros, this image shows both the Cone Nebula and the Christmas Tree Cluster, located around 2600 light years from earth the Cone Nebula being an emmision Nebula

Image Details:

101x150S in R
101x150S in G
101x150S in B
101x300S in Ha

Total capture time: 21 Hours

Acquisition Dates: Jan. 9, 2019, Jan. 31, 2019, Feb. 3, 2019, Feb. 14, 2019, Feb. 15, 2019, Feb. 23, 2019, Feb. 24, 2019, Feb. 25, 2019, Feb. 26, 2019, Feb. 27, 2019, Feb. 28, 2019, March 24, 2019, March 25, 2019, March 26, 2019, March 28, 2019, March 29, 2019

The NBRGB Script in PixInsight was used to blend the Ha into the RGB Image

101 Darks, Flats and Flat Darks were used in the frame calibration

Equipment Details:
Imaging Camera: Qhyccd 183M Mono ColdMOS Camera at -20C
Imaging Scope: Sky-Watcher Quattro 8″ F4 Imaging Newtonian
Guide Camera: Qhyccd QHY5L-II
Guide Scope: Sky-Watcher Finder Scope
Mount: Sky-Watcher EQ8 Pro
Focuser: Primalucelab ROBO Focuser
Filterwheel: Starlight Xpress Ltd 7x36mm EFW
Filters: Baader Planetarium RGB and Ha
Power and USB Control: Pegasus Astro USB Ultimate Hub Pro
Acquisition Software: Main-Sequence Software Inc. Sequence Generator Pro
Processing Software: PixInsight 1.8.6

ColdMOS Images

M78 / NGC 2068 in RGB

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This is the first time I have ever imaged this object, I will re-visit next year when I will image at F2.8 with a wider field of view using a keller reducer.

Since this object is in the southern area of sky, I am limited by trees and the house on the data I can capture in a single night

Image Details:
101x150S – Red
101x150S – Green
101x150S – Blue

101 Darks, Flats and Dark Flats

Image Acquisition Dates: Jan. 1, 2019, Jan. 2, 2019, Jan. 8, 2019, Jan. 9, 2019, Jan. 27, 2019, Jan. 28, 2019, Jan. 30, 2019, Feb. 10, 2019, Feb. 20, 2019, Feb. 23, 2019, Feb. 24, 2019, Feb. 25, 2019

Equipment Used:
Imaging Camera: Qhyccd 183M Mono ColdMOS Camera at -20C
Imaging Scope: Sky-Watcher Quattro 8″ F4 Imaging Newtonian
Guide Camera: Qhyccd QHY5L-II
Guide Scope: Sky-Watcher Finder Scope
Mount: Sky-Watcher EQ8 Pro
Focuser: Primalucelab ROBO Focuser
FIlterwheel: Starlight Xpress Ltd 7x36mm EFW
Filters: Baader Planetarium RGB and Ha
Power and USB Control: Pegasus Astro USB Ultimate Hub Pro
Acquisition Software: Main-Sequence Software Inc. Sequence Generator Pro
Processing Software: PixInsight 1.8.6

ColdMOS Images

IC36 Y Cas Nebula in SHO

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Located in the constellation of Cassiopeia this rather feint nebula is illuminated by a very bright Magnitude 2.15 star Navi

Image Details:
101x300S in SII – Red Channel
101x300S in Ha – Green Channel
101x300S in OIII – Blue Channel

Total integration time: 25.2 Hours

101 Darks, Flats and Dark Flats applied

Acquisition Dates: Oct. 27, 2018, Dec. 13, 2018, Dec. 27, 2018, Jan. 1, 2019, Jan. 2, 2019, Jan. 4, 2019, Jan. 8, 2019, Jan. 9, 2019, Jan. 11, 2019, Jan. 18, 2019, Jan. 20, 2019, Jan. 23, 2019, Jan. 27, 2019, Jan. 28, 2019, Jan. 30, 2019

Equipment Details:
Imaging Camera: Qhyccd 183M Mono ColdMOS Camera at -20C
Imaging Scope: Sky-Watcher Quattro 8″ F4 Imaging Newtonian
Guide Camera: Qhyccd QHY5L-II
Guide Scope: Sky-Watcher Finder Scope
Mount: Sky-Watcher EQ8 Pro
Focuser: Primalucelab ROBO Focuser
FIlterwheel: Starlight Xpress Ltd 7x36mm EFW
Filters: Baader Planetarium Ha, SII and OIII
Power and USB Control: Pegasus Astro USB Ultimate Hub Pro
Acquisition Software: Main-Sequence Software Inc. Sequence Generator Pro
Processing Software: PixInsight 1.8.6