SH2-284 is an HII star forming region of dust and gases, sculpted by the radiation and interstellar winds emanating from the young (3 to 4 million years) open star cluster Dolidze 35 located near its centre. Along the inner edge of the main ring structure are numerous dark dust pillars and Bok Globules, not unlike those of the Elephant’s Trunk nebula, of which the largest seems to resemble a hand with a large bony finger at the end pointing inwards (see cropped + rotated image below).
Despite its close resemblance to the Elephant’s Trunk and the nearby Rosette nebula, the emission nebula SH2-284 is by comparison somewhat overlooked. Being some x8 times further away it’s apparent size is a good deal smaller and much fainter in nature but still forms an excellent late winter image target.
IMAGING DETAILS
Object
SH2-284 or LBN 983
Constellation
Monoceros
Distance
18,000 light-years
Size
0.50o
Apparent Magnitude
Faint
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO ASI294MM CMOS sensor
FOV 2.87o x 1.96o Resolution 2.50”/pix Max. image size 4,144 x 2,822 pix
Centre = RA 06:45:20.506 DEC +00:18:12.758 Right = North Top = East
Exposures
Ha 53 x 300 sec, OIII 36 x 300 sec, SII 36 x 300sec = 11hr 30 min R 35 x 60 sec, G 35 x 35 sec, B 34 x 60 sec = 1hr 44min Total Integration Time: 13hr 14 min
@ 120 Gain 30 Offset @ -15oC
Calibration
5 x 300 sec & 20 x 60 sec Darks + 15 x LRGB & Ha, OIII, SII Flats & Flat Darks @ ADU 32,000
Location & Darkness
Fairvale Observatory – Redhill – Surrey – UK Typically Bortle 5-6
There’s a lot going on in and around the Auriga constellation and this winter I’ve been mainly imaging in this region, almost exclusively using the Samyang 135 widefield rig. Here with the whopping 7.50o x 5.67o field-of-view this set-up provides, it easily incorporates both emission nebulae IC405, AKA the Flaming Star Nebula and it’s nearby (visually) neighbour IC410, the Tadpoles Nebula, as well as much more.
Hydrogen gas ionized by the central AE Auriga star produces the dominant strong red colour, which combined with the rippling dust and gas lanes that run through the head of IC405 leads to a ‘flame affect’ and thus the nebula’s popular nickname.
The structures in IC410 are illuminated by radiation from the open star cluster NGC1893, located at the centre of the nebula. Hot, massive, young stars abound, especially around Simeis 129 & 130, the two tadpoles. These structures are ‘wriggling away’ from the centre of the nebula, because of the prevailing stellar winds and radiation pressure from the stars in NGC 1893.
This image is the cornerstone of a series of covering a wider area completed during January, which I intend to first present individually before, hopefully, bringing them together as an HOO mosaic later.
This image has been processed as two SHO versions of the Hubble Palette: (i) a basic mix above and (ii) using a dynamic mix ( main cropped image at top-of-the page). Once more I have been impressed by the ability of this small camera lens to produce exceptional detail and colours, but especially here with the starless Ha version of IC410, where the signature features or so-called tadpoles have been captured to great effect (see cropped starless Ha version of IC410 below).
IMAGING DETAILS
Object
IC 405 The Flaming Star Nebula + IC 410 The Tadpoles Nebula
Constellation
Auriga
Distance
1,500 & 12,000 light-years
Size
Approx. 37’ x 10’ & 40’ x 30’
Apparent Magnitude
+6.0 & +10
Scope / Lens
Samyang 135 @f2.8
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
Sky-Watcher EvoGuide 50ED
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO1600MM-Cool mono CMOS sensor
FOV 7.5o x 5.67o Resolution 5.81”/pix Max. Image Size 4,656 x 3,520 pix
Straddling the boundary of Taurus and Auriga, is the giant supernova remnant (SNR) Simeis-147 AKA SH2-240 or the Spaghetti Nebula. It is believed that the stellar explosion that created Simeis-147 occurred some 40,000 years ago, leaving behind a rapidly spinning neutron star or pulsar at the core of the now complex, expanding SNR; the nebulous area has an almost spherical shell consisting of numerous filamentary structures. With an apparent diameter of 3o the SNR spans some 160 light-years, making it a very large astrophotography target.
I’ve long admired the spectacular SNR Simeis-147 AKA Spaghetti Nebula, which I first imaged with my standard William Optics GT81 scope in January 2022. The outcome (see image below) was pleasing but with the limited FOV it had to be just a nibble of this large object – something of an appetiser you might say. Therefore, ever since putting my Samyang rig together last summer I’ve had only one object in mind with this excellent widefield set-up, which had to be the full menu version of Simeis-147!
Apart from its size, Simeis-147 is very faint, making long exposure time essential, which is always difficult in the UK. However, a rare spell of cold, clear nights this January provided sufficient opportunity over five nights to obtain just over 20-hours integration and a complete image of this truly magnificent SNR.
Notwithstanding the favourable conditions and long-time achieved – a record for me at this location – the faint nature of this object made image processing difficult too. After experimenting, I eventually adopted a tone mapping technique: pre-processing each individual wavelength stack before removing the stars, stretching and processing each of the starless Ha and OIII images before combining using Pixel Math in the ratio: R – (Ha*1.70) + G – (OIII*0.80)+(Ha*0.20) + B- (OIII*0.80)+(Ha*0.20).
With further processing of the HOO starless combination I was able to obtain the desired result of marvellous SNR detail, together with pleasing Ha (red) and especially OIII (blue/green) colours, that altogether with the addition of the stars and some final tweaking produced a striking image with good depth. Moreover, I feel the widefield setting achieved using the Samyang 135 lens produces a striking setting for this fascinating object.
IMAGING DETAILS
Object
Simeis 147 / SH2-240 AKA Spaghetti Nebula
Constellation
Taurus
Distance
3,000 light-years
Size
Approx. 3.0o
Apparent Magnitude
Extremely faint
Scope / Lens
Samyang 135 @f2.8
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
Sky-Watcher EvoGuide 50ED
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO1600MM-Cool mono CMOS sensor
FOV 7.5o x 5.67o Resolution 5.81”/pix Max. Image Size 4,656 x 3,520 pix
Nestled within the western area of the Perseus Molecular Cloud, some 1,100 light-years from Earth is the colourful NGC 1333 complex, one of the closest and most active stars forming regions of the night-sky. I have long admired this exciting object but ruled it out for imaging as unsuitable for my equipment but eventually found its allure too compelling to avoid and just had to give it a try, with a surprisingly good result.
NGC 1333 shows details of dusty regions along with contrasting hints of red emissions from Herbig-Haro objects(1), jets and shocked glowing gases emanating from recently formed stars. In fact, the reflection nebula NGC 1333 contains hundreds of stars less than a million years old, mostly hidden from view by the prevailing dust.
Whilst NGC1333 is clearly the main act, numerous exciting objects abound throughout this complex region, including other reflection nebulae and Herbig-Haro stars, some of which which can be seen highlighted in the plate solving annotation above. However, I’m most pleased that for the first time at this Bortle 5 / 6 area I’ve been able to capture the extensive interstellar dust and gases, which really brings the entire image to life – every cloud has a silver lining. I am blown away by the outcome of this image, in the light of which I’ll need to reassess other hitherto neglected targets.
(1) Wikipedia: Herbig–Haro (HH) objects are bright patches of nebulosity associated with newborn stars. They are formed when narrow jets of partially ionised gas ejected by stars collide with nearby clouds of gas and dust at several hundred kilometres per second.
Final Word: as always, good quality data is the critical factor for all astrophotogaphy images but processing comes a close second in importance and is something I’m continually working on. This time I was able to use two new PixInsight features that were released shortly before Christmas and played an important role in completing the final image – thanks Santa.
Spectrophotometric Colour Calibration (SPCC) – based on results of the Gaia satellite’s work creating a three-dimensional map of our Galaxy, the Milky Way, SPCC usess the astrometric data (location) of all the stars and their related spectrometric data to accurately colour calibrate the image. This is an incredible piece of work that ensures that astrophotography objects, especially broadband wavelengths, can now be properly shown in their correct colours.
Blur XTerminator (BXT) – as astonishing as SPCC is, perhaps the real game changer is Russell Croman’s BXT, which literally does what it says on the tin, very, very well, and is causing something of a riot in the world of astrophotography. Like his other PixInsight tools NoiseXTerminator and StarXTerminator (also very popular), BXT is AI based with truly unbelievable results. The removal of blur, without damaging the image integrity at a pixel level, vastly improves the image quality – significantly improving the effective image resolution, which is like transforming your telescope to a more powerful, higher quality one!
IMAGING DETAILS
Object
NGC1333
Constellation
Perseus
Distance
1,100 light-years
Size
6’ x 3’
Apparent Magnitude
+5.6
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO ASI294MM CMOS sensor
FOV 2.87o x 1.96o Resolution 2.50”/pix Max. image size 4,144 x 2,822 pix
At this time of the year, I produce an astrophotography calendar for members of my family, which consists of my better images from the year just ended. In combination with the calendar, I also compile a video of the calendar images set to appropriate music, which we all watch together prior to seeing the actual calendar. It’s a great way to present the images, which look really stunning on today’s large Smart TV’s and is also fun to watch with the family.
2022 CALENDAR
Last year’s new Chroma filters, a new ZWO ASI294MM camera, further processing improvements, dark sky data from a remote Takahashi 106 telescope in New Mexico, USA (indicated by an asterisk *) and the addition of a new widefield rig built around the excellent Samyang 135 lens, contributed to a successful astrophotography year in 2022.
The said calendar video can be viewed on YouTube by clicking HERE and below is a brief overview of each image. More detailed background information and imaging details for those interested can be found in relevant blogs I posted on this website during the year. The background music is the track Leaps and Bounds from Nils Petter Molvaer’s album Re-Vision.
COVER
Pickering’s Triangle: A close-up, starless section of the Cygnus Loop SNR (Supernova Remnant).
JANUARY
M45 Pleiades Nebula: An open star cluster containing over 1,000 stars formed in the last 100 million years. Hot, blue stars are passing through an interstellar dust cloud, with the blue light from the brighter stars reflected off the interstellar dust.
FEBRUARY
Cone Nebula: Located 2,500 light-years from Earth, this rich star forming region is full of hydrogen gas, reflection, and dark nebulae. With nearly 14-hours exposure time this narrowband image shows the Christmas Tree open star cluster, Cone Nebula, and the Fox Fur Nebula to good effect.
MARCH
Barnard-22: Close to the aforesaid Pleiades, lies the dark region of the Taurus Molecular Cloud (TMC), which at 430 light-years is the nearest star-forming region to Earth. Consisting of hundreds of solar masses of primordial hydrogen and helium gas, as well as heavier elements, this vast area of dense stardust obscures almost all light from behind; Barnard-22 forms part of the TMC.
APRIL
Helix Nebula*: This iconic planetary nebula in the Aquarius constellation was formed by a star near the end of its life shedding its outer layers, which is expelling the resulting gases into space.
MAY
Thor’s Helmet*: An emission nebula, produced as a hot dying star, 20-times more massive than the Sun, emits a stream of particles expanding outwards, thus producing an interstellar bubble which here interacts with nearby molecular clouds and gives the nebula its form and glow.
JUNE
Lower’s Nebula: Located in the outer regions of the Orion constellation, between the Orion and Perseus arms of the Milky Way, the nebula mainly consists of ionized hydrogen, which is thought to be energised by a runaway star situated at its centre.
JULY
Sadr Region: This busy image uses a new widefield lens (8 x greater than my telescope’s field-of-view), framed to include some familiar objects across the very large Cygnus-X region, including the yellow-white supergiant Sadr star, Butterfly Nebula (top right) and the Crescent Nebula (centre).
AUGUST
Cygnus Loop / Western Veil Nebula: Located 1,500 light-years from Earth, this supernova is still expanding at 60 miles per second. The debris cloud has been sculpted by shock waves from the star’s explosion, with the colours arising from ionized hydrogen (red) and oxygen (blue) gases.
SEPTEMBER
Bodes & Cigar galaxies*: Located in the constellation of Ursas Major, Bodes spiral galaxy and the Cigar irregular galaxy are 11.8 million light-years distant. These galaxies have a gravitational lock on each other which has affected the shape and composition of each other.
OCTOBER
Clamshell, North America & Pelican Nebula: The Cygnus constellation is rich in targets and by using the new widefield lens, it was possible to capture all three nebulae in one narrowband image.
NOVEMBER
Horsehead & Flame Nebula: An old favourite located in the Orion constellation, here for the first time imagedin LRGB wavelengths to produce this colourful and exciting image.
DECEMBER
Spaghetti Nebula: The beautiful complexity of this cosmic cataclysm is the product of a massive stellar explosion that took place some 40,000 years ago. Aptly named, the image concentrates on the southern lobe of this very large supernova remnant.
As our closest galactic neighbour, I’ve imaged M31 the Andromeda Galaxy five times since beginning my personal astrophotography journey in 2014, each time using my William Optics GT81 apo refractor – first with a DSLR, then a ASI1600mm-Cool and most recently ASI294MM cameras. Andromeda is perhaps the perfect object for my equipment, as it just fits the field-of-view of the aforesaid set-up, which produces something of an up-close-and-personal image of this alluring galaxy. But despite the success of these images, perhaps there’s an alternative view?
This year, I therefore deployed my Samyang 135 + ASI1600MM-Cool rig to capture 6 ½ hours of Andromeda, the result of which shows a whole new perspective of M31. The widefield format of this lens produces greater context than previous images, whilst still obtaining excellent details and colours of the galaxy itself. As a result, this final image (see above) better reveals the galaxy in its true glory deep in space, which in some ways I believe can be more powerful than the more popular close-up renditions of this impressive object (M31 with star reduction applied to the image below).
IMAGING DETAILS
Object
M31 Andromeda Galaxy
Constellation
Andromeda
Distance
2.5 million light-years
Size
3.2o x 1o or 220,000 light-years
Apparent Magnitude
+3.44
Scope / Lens
Samyang 135 @f2.8
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
Sky-Watcher EvoGuide 50ED
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO1600MM-Cool mono CMOS sensor
FOV 7.5o x 5.67o Resolution 5.81”/pix Max. Image Size 4,656 x 3,520 pix
The Cygnus constellation is rich in potential astrophotography targets and since the return of astronomical darkness I’ve bagged three objects from this area with my new widefield Samyang 135 rig: Cygnus Loop, Sadr Region & Crescent Nebula, and the Western Veil & Pickering’s Triangle. As the Cygnus season now draws to a close – in my case disappearing northwards behind my house – I was ready to snap one final Cygnus object using my main William Optics GT81 rig but then looked closer and realised using the Samyang 135 rig with careful framing there was another a more ambitious possibility.
The original object in question was SH2-119 AKA the Clamshell nebula, an emission nebula somewhat overlooked by photographers. Nevertheless, imaged in narrowband there’s plenty of structure to see throughout the nebulosity that makes up the two ‘shells’, whilst the bright magnitude +5 star 68 Cygni might be likened to the pearl at the centre, which would work well with the 81mm William Optics field-of-view. But deploying with care the much wider field-of-view of the Samyang 135 and it’s possible to include the North America and Pelican nebulae as well, just!
With some difficulty (weather) I finally managed to obtain 13-hours integration time over 6-nights, which has resulted in a pleasing SHO image (see main image at the top of the page – below is a dynamic version processed using PI PixelMath), once again demonstrating the capacity of this small but powerful lens. Personally, I find bringing all three objects together within a much larger field-of-view creates greater context, resulting in a more interesting image overall – in football parlance you might call it a hat-trick of nebulae!
IMAGING DETAILS
Objects
North America Nebula (NGC7000) + Pelican Nebula (IC5070 & IC5067) + Clamshell Nebula (SH2-119)
Constellation
Cygnus
Distance
approx. 2,600 light-years
Size
3.0o
Apparent Magnitude
approx. +4 to 8
Scope / Lens
Samyang 135 @f2.8
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
Sky-Watcher EvoGuide 50ED
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO1600MM-Cool mono CMOS sensor
FOV 7.5o x 5.67o Resolution 5.81”/pix Max. Image Size 4,656 x 3,520 pix
Following my routine summer break from astrophotography, I restarted in early August first using my new Samyang 135 + ZWO ASI1600MM-Cool rig, which immediately demonstrated its ability to produce excellent widefield images of very large objects, in this case the Cygnus Loop. However, also in late spring I had rejigged my William Optics GT81 telescope with the addition of a new ASI294MM camera, the successor to the ASI1600 which had been redeployed to the aforesaid Samyang rig. Having constructed, tested and briefly obtained First Light with this new combination, I then had to wait for the return of astronomical darkness and more suitable objects. Once again, I turned to the Cygnus Loop but this time concentrating on the western and central areas, generally known as the Western Veil and Pickering’s Triangle.
Cygnus Loop Morphology, ID & Approximate Image Location (Red Box)
Located 1,500 light-years from Earth within the plane of the Milky Way in the constellation of Cygnus, this large supernova remnant (SNR) occurred between 5,000 and 8,000 years ago. In its entirety the debris cloud has been sculpted by the shock wave from the star’s explosion, to form the Cygnus Loop object that we see today. The coloured light is created by the excitement of hydrogen (red) and oxygen(blue) gasses of the SNR, which is still expanding at about 100 km (60 miles) per second; image integration times for OIII & Ha wavelengths are in the ratio of 2:1 to enhance the weaker oxygen signal. More than twice the width of the full moon and spanning 35 light-years, this section of SNR only just fits into my field-of-view but with careful framing it works perfectly.
Western Veil (NGC 6960) Detail
Pickering’s Triangle Detail
The resulting image successfully brings out the exquisite nature of this exciting SNR, in particular highlighting the abundant waveforms that run throughout the entirety of this dynamic object. Furthermore, the combination of the new ASI294MM camera and 3nm Chroma filters, has produced a vibrant red-blue colour palette that further enhances the said structures. Altogether this diaphanous delectation convincingly demonstrates the power and beauty of the Universe whilst, moreover, pointing to a new level for my astrophotography.
Image Location & Orientation
IMAGING DETAILS
Object
Cygnus Loop Section: Western Veil Nebula (NGC 6960), Pickering’s Triangle, NGC 6979 & 6974
Constellation
Cygnus
Distance
1,500 light-years
Size
~2.9o total
Apparent Magnitude
+7.0
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO ASI294MM CMOS sensor
FOV 2.87o x 1.96o Resolution 2.50”/pix Max. image size 4,144 x 2,822 pix
EFW
ZWOx8 EFW & 31mm Chroma LRGB filters
Capture & Processing
Astro Photography Tool + PHD2 + Deep Sky Stacker, PixInsight v1.8.8-12, Photoshop CC v23.5.0
Image Location & Orientation
Centre = RA 20:48:47.0 DEC +31:00:54.7 Left = North
Exposures
Ha 41 x 300 sec (3hr 25m), OIII 82 x 300 sec (6hr 50m) Total Integration Time: 10hr 15 min
@ 120 Gain 30 Offset @ -15oC
Calibration
5 x 300 sec Darks 15 x LRGB Flats & Dark Flats @ ADU 32,000
Location & Darkness
Fairvale Observatory – Redhill – Surrey – UK Typically Bortle 5-6
Hitherto, most of my astrophotography has concentrated on a variety of specific objects that work within the 2.65o x 2.0o field-of-view provided by the combination of my William Optics GT81 refractor and ZWO ASI1600MM-Cool camera. After recently pairing the aforesaid ZWO mono camera with a Samyang 135 lens (often marketed elsewhere as the Rokinon 135) my astrophotography world has expanded dramatically to an enormous 7.50o x 5.67o, some x8 larger than before. As a result, this excellent lens that also captures great detail, provides new opportunities to image some of the very large features that abound throughout the Universe without having to resort to a mosaic imaging; this a great advantage when working in UK weather conditions which usually provides less imaging time than required.
Above, Cygnus-X Region & notable nearby objects: The red box appproximately outlines the image area, which in this plan is presented upside-down compared to the main image. The numerous red shapes define the location of the HII objects that make up the DWB catalogue (19 is the Crescent nebula). Just beyond to the left is the North America Nebula (NGC7000) and below the SNR Cygnus Loop, AKA the Veil Nebula (NGC 6960 & 6992).
In this case I chose to frame the image in such a way as to encompass some familiar objects, such as the Butterfly Nebula (IC1318) and the Crescent Nebula (NGC6888) anchored by Sadr, the yellow-white supergiant star that stands out from within the very large Cygnus-X region. Processed here in HOO, with 6-hours integration time and full calibration (darks, flats & flat darks), the final image provides a magnificent view of this large, interesting region that augurs well for future widefield imaging with this new rig. I’m particulalry intrigued by the bluish feature at about 8.0 o’clock of the Crescent Nebula, which I now believe to be associated with WR-134: a bubble-like structure some 50 light-years in diameter consisting of OIII rich light formed by an intense wind emanating from the Wolf-Rayet star at it’s centre. The breadth of view it provides can encompass myriad of objects in exceptional detail, thereby providing a wider context that is simply awe-inspiring to see – it’s just like shrinking the Universe!
Astrometry image plan
IMAGING DETAILS
Object
Sadr Region
Constellation
Cygnus
Distance
+5,000 light-years
Size
Full FOV – see below
Apparent Magnitude
+/- 7.0
Scope / Lens
Samyang 135 @f2.8
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
Sky-Watcher EvoGuide 50ED
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO1600MM-Cool mono CMOS sensor
FOV 7.5o x 5.67o Resolution 5.81”/pix Max. Image Size 4,656 x 3,520 pix
It’s been nearly two years since acquiring my Samyang 135 lens but since then it’s unfortunately only had limited use in combination with my modded 550D DSLR. Whilst impressed with the results from this set-up, my main objective has always been to combine it with my ASI1600 mono camera for some serious widefield astrophotography but as that was being used with my William Optics refractor it just didn’t happen, until now. After upgrading to a ASI294MM Pro camera in May, at last I was finally able spend the early part of this summer working on a new Samyang 135 + ASI1600 rig and now that astronomical darkness is (just) back I recently managed to catch a few photons with this new set-up of the large SNR Cygnus Loop.
I originally purchased a x2-ring Astrokraken 3D-printed clamping system for the lens + DSLR combination from Philippe in France but since then he’s tweaked the design. In particular x3 built-in M4 nuts have been incorporated on either side of each of the two main lens clamping rings, for the purpose of attaching ancillary equipment, which for me has been a game changer. I therefore bought a new x3-ring Astrokraken bracket, with the said bolt holes, around which to build my new rig:
The two main clamping rings that hold the lens have a shoe immediately above the lens, to which I’ve fitted a Sky-Watcher EvoGuide 50ED guidescope (not yet working), with the rear third ring holding the ASI1600 mono camera & EFW.
I swapped the Canon lens bayonet adapter for a bespoke M42 screw adapter, in order to ensure a more secure attachment, thus reducing any potential lens-camera movement at this critical point of the image train.
I’m continuing to use the excellent Astrokraken micro-focuser, which consists of a ring that clamps onto to the lens’ focus ring, with two small bolts above that make contact with either side of the guidescope shoe, so that when turned the focus ring can be adjusted either way to obtain focus, which is then locked when completed. So far I’ve found the micro-focuser to work very well with this lens, assisted by the addition of an Astrokraken Bahtinov mask which is inserted into the front of the lens casing.
Using this lens with the ZWO ASI1600MM-Cool camera and EFW, the backfocus guideline is 44mm, which I was able to achieve by adding an Altair T2 variable locking extension ring set to 17.5mm = 44mm minus 26.5 (camera + EFW).
With my Chroma filters now being used with the new ASI294MM Pro camera, I purchased another ZWO 31mm x8 EFW and brought my ZWO 31mm filters out of retirement.
Finally, using the new M4 nut holes I’ve added a Baader SkysurferIII RDF on the left-hand side of the Astrokraken bracket system to help with sky navigation and framing.
After bolting the Astrokraken with the lens, camera and said components to a Losmandy plate it makes a very nice compact rig, that is easy to handle and store. Notwithstanding, as they say – the proof of the pudding is in the eating: SEE top-of-the page for original image & below for 50% crop.
Whilst the recent heatwave produced clear skies, it was far from ideal here for astronomy and was further hampered by a full moon. However, with only just over two hours integration time and a few Dark calibration files, I’m still impressed with the outcome of this quite amazing lens. It is very pleasing to capture the entire Cygnus Loop comfortably sitting within the lens’ FOV – for information on this FOV and comparisons go to this previous WTSM blog HERE. For me context is important with astrophotography and in this regard the astronomical perspective this lens produces is outstanding, no wonder it is so popular. I just love working with this FOV and can’t wait for better conditions for greater integration time and more widefield targets to point this wicked little lens at.
IMAGING DETAILS
Object
Cygnus Loop
Constellation
Cygnus
Distance
2,400 light-years
Size
3.0o
Apparent Magnitude
+7.0
Scope / Lens
Samyang 135 @f2.8
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding – Not Used
Sky-Watcher EvoGuide 50ED
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO1600MM-Cool mono CMOS sensor
FOV 7.5o x 5.67o Resolution 5.81”/pix Max. Image Size 4,656 x 3,520 pix
WATCH THIS SPACE(MAN) 