Let's Photograph the Night Sky
...with Minimum Gear and Budget
From a Novice to Novices
This article is posted in the hope it will stimulate the fascination for the night sky which inherently resides in all of us. This article focuses on cost-efficiency and low budgets. It is a hobby which can not be enjoyed every day, because, besides availability of free time, it relies on the phases of the moon, weather and atmopsheric condition. Some say that people spending nights under the sky do not socialize. Try carpooling with friends and like-minded people and head out together for a dark sky site.
Hobby astrophotography with a telescope and a DSLR must not tribute lots of money and effort. Much of the required gear is available second hand, while no equipment on Earth can deliver Hubble Space Telescope images anyway. Do not get seduced to buy a telescope that is showcased next to a Hubble poster. Please do not screw your expectations up too high and start step by step with a low budget like walking in a mine field. Your first images won't be able to compete with the results of experts with years of experience, but you will cherish your first achievement. Astrophotography is one of the most difficult, unforgiving, but also most rewarding kind of imaging in return for patience and devotion.
Tracking Mount
The most important gear is a 'German Equatorial Mount' which follows the apparent motion of the sky as a result of Earth's rotation. You can keep the budget for a mount low by using a light-weight telescope. The price for a mount increases with sturdiness, payload capacity, tracking accuracy, as well as extras, such as GPS or WiFi. If you keep the payload low and choose short exposure times, say, under a minute, then accuracy is not a serious issue while you will get a sturdy mount under USD 1,000 new or find a second-hand deal for less.
The difference between tracking and guiding being is, the mount motors track the sky motion to keep an object within the eyepiece field of view, while additional guiding is performed by means of a computer controlled CMOS camera which follows a bright guide star in its view and regularly feeds its position to the mount in order to increase tracking accuracy for longer exposures. Guiding is not essential for the first steps.
Select a mount with sufficient payload capacity. Your OTA plus gear should not weigh more than half of that to have plenty of buffer for assuring tracking accuracy. As a rule of thumb, refractors up to 80mm aperture weigh up to 2.5kg, 80mm refractors weigh up to 3.5kg. A 5-inch (Ø130mm) Newtonian weighs about 3.5kg, a 6-inch (Ø150mm) brings about 6kg onto the scale.
The polar alignment of an equatorial mount requires an unobstructed line of sight towards a celestial pole, while modern electronic software algorithms are capable of performing alignment without pointing the scope at a pole. This requires a dedicated CMOS camera, such as a 'planetary camera' which is often employed as autoguide camera.
Another type of mount is the altitude-azimuth mount which compensates in one direction, then in the other. It is aligned to the horizon, not to the pole. This will generate blurred objects (field rotation). However, if you limit the exposure time to, say, 30 seconds and shoot tens of frames, then you might be happy with what you get. If you do not yet own a mount by all means pick a German Equatorial for photography.
Telescope
The more aperture a telescope has the more detail you can capture. The difference to smaller scopes is often like that of a $100 bottle of wine and a $4.99 bottle. Since a wide field and fast optics (provided by short focal lengths) are preferable for imaging deepsky objects, such as nebulae and star clusters, a refracting telescope or a reflecting Newtonian are the primary candidates. Fully multi-coated lenses or optically treated mirrors of good quality provided, small apertures starting from Ø60mm for lenses and Ø130mm for mirrors will be quite sufficient, also considering the capabilities of modern DSLRs and image processing software. Prices increase 'exponentially' with growing aperture and with optical quality as production becomes more demanding. Also, telescopes are not manufactured in lots of millions, not even in China, reflecting into sales prices. Telescopes often require the preparedness to compromise - in more ways than one. In December 2018, a Japanese astronomer discovered the faint comet C/2018 Y1 (Iwamoto) with only a Ø100mm lens.
EXAMPLE: Often, a good deal is a set such as the Advanced VX6" for USD 820 new (as of Feb 2019). A fast F5 Newtonian on a motorized GoTo
equatorial mount that has a maximum load capacity of 13.6kg.
• Refractors (Achromatic)
Low cost, short focal length (fast) refractors typically sport a doublet lens (aka Fraunhofer achromat) which produce notable color and comatic aberration resulting in blue and red halos around bright objects and elongated stars in the edges of an image, respectively. Color fringes rob contrast and valuable detail that a large lens could theoretically provide. Refractors which correct or minimize such optical errors (ED doublet or triplet lens apochromats) easily cost 3-4 times more than an achromat. You can add a set of filters to a low cost achromat but possibly ending up spending a little fortune that could buy an ED doublet APO. Large Ø120-150mm aperture F5 achromats are designed for visual tasks. No optical correctors exist for such scopes as not ideal for imaging. An option is a long focal length refractor, say about 1000mm which is way less prone to aberration but trades this merit against extended exposure time, narrower field of view and need for more accurate tracking. As for aperture, Ø80-100mm should work just fine, otherwise the cost increase per inch of aperture quickly burdens your budget. Watch out inacceptable optical quality with ultra-cheap refractors; they are, sorry, scrap.
A few high quality products excepted, achromats are basically not recommended for astrophotography, but can help make you familiar with imaging without spending a fortune.
EXAMPLE: An achromatic refractor, Ø102mm FL600mm F5.9 for USD200 with tripod (as of Feb 2019).
• Refractors (Apochromatic)
Apochromatic refractors (APOs) use (two to four, sometimes five) extra low dispersion (ED) lenses with high permeability to minimize color aberration. There are basically three different types of apochromatic refractors in sequence of increasing optical performance: 1. Doublet with two lenses, 2. Triplet with three lenses and 3. Quadruplet with four lenses (typically a triplet with an integrated lens for flattening the field of view). While in most cases doublets and triplets require an optional 'flattener' when imaging with large image sensors, such as full frame and APS-C, a quadruplet eliminates need for this extra purchase. Depending of course on manufacturer and model it is often more economical than a doublet or a triplet with an optional flattener. Also, most flatteners are designed for a specific focal ratio and telescope model only.
APOs are designed with imaging in mind. They feature rigid 2" to 3" focusers achieving an image circle of Ø44mm which fully illuminates DSLR sensors. APOs priced under 1000 USD sport up to Ø80mm aperture (quadruplets up to Ø72mm) with 350mm to 480mm focal length (F5 to F7). Since high quality lens glasses are employed, this category is excellent for starting with astrophotography (otherwise they wouldn't build so many small APOs).
Ultra-portable APOs are available with Ø50mm or Ø60mm apertures with 250mm to 360mm focal length, resembling a telephoto lens and producing stunning wide field images. Because of their small aperture they can not provide high resolution, yet they do offer sharp images rich of contrast, especially when they employ quality lens glasses, such as 'FPL-53'. Their low weight and short focal lengths permit the use of portable tracking mounts (with autoguide control for imaging).
The waning moon captured in detail with a low-cost 1/3-inch CMOS camera through a Ø71mm APO.
EXAMPLE: A quadruplet apochromatic refractor, Ø71mm FL450mm F6.3 for USD 750 (as of Nov 2019).
EXAMPLE: An ED doublet apochromatic refractor, Ø60mm FL=360mm F6.0 for USD 425 (as of Nov 2019).
• Reflectors
The most common reflector achitecture is a Newtonian which is lower in cost compared with refractors of same aperture as it employs parabolic or spherical mirrors which are cheaper to produce since there is only one surface that needs to be ground and polished. It has a secondary mirror held by a 'spider' which obstructs the aperture by some 30% (10% by area) or so in that a Ø130mm to 150mm mirror should work well for imaging.
As a major advantage for photography, a Newtonian is free of color aberration because it is reflected light, not refracted. Reflectors are susceptible to coma at the edges of a view. For optimal results a fast Newtonian, say an F5, may require a 'coma corrector' in order to produce nicely rounded stars at image edges, especially on 'full frame' wide camera sensors. On 'cropped' sensors the worst of the coma will be off of the edges in that a corrector may not be worth while spending some USD 200, yet basically a reasonable investment in view of the lower prices of Newtonians. Newtonians produce diffraction spikes around bright stars which do not look astronomical but often very beautiful.
The back focus of a reflector is typically shorter than that of a refractor in that it is wise to make sure that your camera will reach focus preferably without barlows or extension tubes. Unlike refractors, the optical axis of a Newtonian tends to shift by usage time resulting in distorted images. Adjustment may require a tool known as 'laser collimator' or 'collimation eyepiece' which is an extra purchase. After all, Newtonians offer the best value per inch of aperture and are most satisfactory instruments for astrophotography. Absence of color aberration makes a Newtonian comparable with a quality apochromat refractor, but at a third of the cost. In plain English, "most bang for the buck".
The advantage of larger aperture: Moon craters taken with a low-cost 1/3-inch CMOS camera through a 150mm reflector and 3x barlow lens.
Composite of the Moon surface and planets to-scale taken with a low-cost 1/3-inch CMOS camera through a 150mm reflector and 2x barlow lens.
EXAMPLE: A Newtonian reflector, Ø150mm FL750mm F5 optical tube with dual-speed focuser for USD280 (as of Feb 2019).
EXAMPLE: A low-cost 1/3-inch CMOS camera produces exciting close-up images of the Moon and the Planets.
• Cassegrains
Catadioptric (or compound, combination of mirror and lens) Schmidt-Cassegrain (SCT) or Maksutov-Cassegrain (MCT) telescopes typically come with a mirror of long focal length, mostly 10 times the aperture in millimeters, which equals an F10 ratio, yet they are physically the shortest tubes. The resulting narrow field and longer exposure times disqualify this type for wide field deepsky imaging but are optimal for lunar and planetary work with astrocams. With precision tracking and guiding on sturdy mounts, SCTs with large aperture starting at 200mm (8 inches) are great for closeup imaging of deepsky objects, galaxies in particular. For instance a large 12 inch (305mm) F10 SCT has a focal length of 3050mm which results in a 0.44° field of view on a APS-C camera sensor which is a little less than the width of a full moon disk. Since focus is adjusted by moving the primary mirror the focal length slightly changes with focus position.
Like a Newtonian, a SCT eliminates chromatic aberration but has coma and field curvature. The image circle (over 60% equal light intensity) of an SCT is hardly Ø30mm wide, resulting in notable vignetting, calling for a focal reducer/flattener when using a DSLR, including APS-C format.
EXAMPLE: A Schmidt-Cassegrain, Ø150mm FL1500mm F10 optical tube seen for USD 400-600 (as of Feb 2019).
Advantage of 'Short' and 'Fast'
With short focal lengths errors in tracking and guiding are less noticeable than they would be through a scope with long focal length. The narrower the field of view is, the more precise focus and guiding have to be. For this reason, novices are best advised to use a short focal length for wide field photography. The shorter the focal length, the 'faster' the focal ratio of a scope with given lens or mirror aperture and the more light it collects within a given time hence requiring shorter exposure times which forgive tracking errors or a rough polar alignment. Note that optics faster than F5 are awkwark to focus and coma-prone.Optical Error Correction
The dark side of 'fast' short focal length telescopes is field curvature and aberration requiring corrections by means of lens units known as "field
flatteners" (for refractors) and "coma correctors" (for Newtonians) to compensate for optical imperfection. Long focal length scopes are
way less prone to aberration, eliminating need for correcting optics, however, as the worse light collectors they demand longer exposure times and higher
tracking accuracy because of the smaller field of view.
Why would your telescope need a correcting device? The simplest explanation is, both a lens and a mirror has a
curved shape, a lense is 'convex', a Newtonian mirror 'parabolic', while a camera sensor is flat. The parts correct the light path so that the image on the
sensor is flat and pin-point thus avoiding oval stars (comatic aberration) at the image edges. This correction is welcome for photography but less
significant for visual observation. Some correctors also reduce the focal length of the optical system it is attached to, however, this is no significant advantage for
anyway short focal length telescopes. A corrector may sacrifice a little contrast, is typically optimized for specific telescopes and focal ratios and is threaded for a camera T-ring.
It may not be usable on your next telescope.
Back Focus
A "back focus" of 55mm is a well established industry standard for DSLR T-rings. The height of T-rings is often matched to the back focus of the target DSLR-camera make to obtain the 55mm distance. Typically, a camera with a T-ring on has 55mm from the front of the T-ring to the sensor, namely the "back focus". For instance, a Nikon DSLR has a backfocus of 46.5mm on the camera house, plus T-ring height = 55mm. T-rings are Ø42mm or Ø48mm threaded to fit on an adapter that connects to a focuser sleeve. While Ø42mm are sufficient for fully illuminating APS-C sized sensors, Ø48mm are required for full frame sensors, while a telescope should provide a Ø44mm min. image circle to avoid vignetting. Focal reducers tend to reduce back focus, while barlow lenses tend to increase it. The Baader MPCC Mark III coma corrector does not alter the focal ratio of a Newtonian and is designed with a back focus of 55mm (+/-1mm) between its T-ring thread and the sensor. When, after removal of a ring, a Ø48mm T-ring is used, then the back focus increases to 57.5mm. If a DSLR with only a T-ring can be focused on a given Newtonian with focuser forward and backward travel remaining, then it will as well reach focus with the MPCC inserted in between on the same Newtonian.Light Collector
In combination with an eyepiece (ocular), a telescope magnifies a view but is primarily a light collector with ability to collect a lot more light than the human eye. The light gathering power of an aperture with 150mm compared to an adult pupil diameter being 7mm is given by (150/7)² = 460, while twice the aperture, 300mm, gathers about 1840 times more than a human eye. This is 4 times more than a 150mm aperture collects! A lens or mirror twice as large as another captures 4 times as much light.Likewise aperture dependent is the capability of splitting binary stars (resolution) which is determined as 138/aperture. Also called "resolving power", a 150mm aperture scope is theoretically be capable of splitting two stars 0.92 arc seconds apart, while a 300mm tube splits stars as close as 0.46 arc seconds apart. The multiple star Mira is currently 0.46 arc seconds away from its component in that the minimum aperture should be 138/0.46 = 300mm to resolve the pair. In reality, even the largest ground based telescopes cannot resolve finer than 0.5 arc seconds due to atmospheric turbulences.
Lens based refractor apertures typically end with 6 inches or 150mm, simply because of production cost and weight. Telescopes beyond six inches aperture are usually Newtonians and Cassegrains. The Hubble Space Telescope too has a mirror - 2.4 meters across.
Optical Architectures
Achromat Refractor
Newtonian Reflector
Schmidt-Cassegrain
Conclusion
Refractor or Newtonian, the choice of which depends on your budget, expectation and the preferences you have regarding manufacturer and type-inherent pros and cons. If your choice is a refractor, a small ED doublet or apochromat capable of minimizing color fringes would be preferable. If you find even little color fringes a nuisance and do not mind to periodically adjust the optical axis, then pick a Newtonian around Ø130mm, optionally with a coma corrector. Be sure that the Newtonian is optimized for imaging (focuser positioned closer to the primary mirror). If imaging is the main goal, even though aperture size theoretically matters, modern image processing software can perform miracles with image stacks taken through small aperture scopes.
If you can afford it, look for a telescope with a rigid dual-speed focuser that will help focus on faint objects less painfully. Also check bundled accessories, some of which make sense, others none. Very important for imaging, please confirm whether your DSLR (or CCD/CMOS) gets into focus. Online shops hardly unveil the back focus distance between the focuser exit and the telescopes's focal plane which varies by focal length (and tube length in case of refractors). Some telescopes require no extra parts except a T-ring for a DSLR while others require optional extension tubes. The lesser parts in between the telescope's focuser and camera (optical train) the better for compactness, stability and a straight optical axis.
A purchase of too cheap equipment often results in an upgrade purchase ending up in higher expenses, or loss of interest. On the other hand, if the goal is merely to practice imaging with a DSLR without being concerned about aberration, then a setup such as introduced further down this page is excellent entry level gear for the cost, weight and size without regret.
Camera
Most common are DSLRs which offer selectable exposure times up to 30 seconds and bulb exposure mode. Since astro-imaging merely requires manual camera mode and infinite focus, without need for electronic CPU control of lenses, a used or partly defect DSLR would do the job. Most common entry-level DSLRs sport an APS-C sensor chip which measures about 24x16mm with up to 6000x4000 pixels, which is more than sufficient for the hobby. Special features, such as noise reduction and in-camera image processing are dispensable as this can be done in image post processing using software, such as Photoshop, Paint Shop or GIMP. A vari-angle (tilt and swivel) LCD monitor would be great for comfortable working. A touch screen is a nice touch, though not essential for our goal, but the reduced mechanical wear on buttons and rotary switches, etc. can extend the camera's lifetime. Anyway, if you do not already own a DSLR, try and find a used camera body.
Camera Requirements
- Exposure time setting from 3 to 30 seconds, plus bulb mode
- ISO from 400 - 6400 to be included
- Shutter timer 2/5/10 seconds, or remote release cable
- JPEG and RAW image recording
- In-camera noise reduction for single frame tasks
- Intervalometer for timed exposures (over 30 seconds)
- Tilt and swivel monitor for convenience
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Camera SensorsSay, we have a telescope with a Ø44mm image circle, wide enough to fully illuminate a full frame DSLR sensor (36mm wide) without edge vignetting and a focal length of 750mm. This scope will also fully illuminate a smaller sensor, such as the more common APS-C (23.5mm wide). The 'crop factor' 36mm/23.5mm = 1.5 has the effect of extending the focal length to 750mm x 1.5 = 1125mm because the smaller sensor is like a smaller field of view. Equally, one can say that the smaller sensor yields a magnification of 1.5x.The field of view (fov) determined by a sensor dimension (sw) and focal length (fl) is: fov = 2 * atan(sw / (2 * fl)) Example APS-C: 2 * atan(23.5mm / (2 * 750mm)) = 1.8° Example Full Frame: 2 * atan(35.9mm / (2 * 750mm)) = 2.74° |
Starscape & Constellation Photography
Jupiter shining like a beacon in the the Milky Way.
Nikon D5300 with 28mm F2.8 lens. 13 exposurs 30 sec each at ISO 1600.
You can take beautiful photos of the constellations and the Milky Way with a standard camera lens and a tripod, without telescope and tracking. Note, that a lens does not need to support auto-focus and other control functions. As long as the iris can be changed and focus set to infinity, a used or partly defect lens will do. If you are living in a bright area, consider a light pollution filter for your lens. For wide field starscape and constellation photos a lens focal length between 24 and 50mm will be fine. The aperture should be at least 1:2.8 or wider. A 100-200mm telelens can capture large deepsky objects, such as the Andromeda galaxy and the Rosette, North America and Orion nebulae. However...
...for telelenses and exposure times exceeding, say, 25 seconds, a mobile tracker typically seated on tripods helps avoid star trailing with telelenses. The price of a mobile tracker depends on accuracy and can equal that of a good small aperture telescope.
EXAMPLE: The oldtimer Pentax *istD with an APS-C sized 6000 x 4000 pixel sensor has everything essentially needed for manual mode, except a vari-angle (tilt and swivel) monitor. The model is from 2003 and good for wide field imaging with fast telelenses.
EXAMPLE: The Nikon D5300 was launched in 2014. The body with an APS-C sized 6000 x 4000 pixel sensor weighs only 480 grams. It features long battery life and has all functions we need for imaging, plus alpha and a vari-angle (tilt and swivel) monitor.
EXAMPLE: A mobile tracker for cameras. Basic requirement includes the tracker body, a tripod, a ballhead and two AA batteries.
Accessories
You will need an adaptor which connects your camera to a telescope focuser sleeve. The part is a so-called T-Ring (Ø42mm or 48mm) which threads to the telescope on one side, the other side being a bayonet lock for your camera model, Canon, Nikon, Pentax, Sony, Fujifilm, you name them. Depending on the type and make of the telescope you may need an extension tube and/or converters to reach focus and/or match sizes. Alternatively, the camera can be inserted into the focuser in place of an eyepiece by means of a nose piece that fits the T-ring thread diameter. A nose piece is typically threaded for 1.25" eyepiece filters. Use the least possible number of adapters.
Startup Kit
Coatings
A blue, green, or purplish tint is a sign of optical coating. Simplified definitions are:
- Coated: at least one optical surface has a single layer coating.
- Fully Coated: all surfaces have a single layer coatings.
- Multi-coated: at least one surface has a multi-layer coating.
- Fully Multi-coated: all surfaces have multi-layer coatings.
As a result of scattering and reflection, every uncoated air-to-glass interface equals to about 8% loss of light transmission for each tier. For instance, a doublet refractor with four air-to-glass transmissions including a very simple eyepiece looses 100% - ((((100%*.92)*.92)*.92)*.92) = 28.4%. Optical coatings with continously improving efficiency significantly help maximise permeability by reducing scattering and reflection.
Omission of coating information is either idleness or for a reason. Just like bundled eyepiece types are often not specified except focal length and resulting magnification. Whether it is a Huygen, Kellner, Plössl, or other is written in the stars.
First Attempts
When your gear is set up and firmly seating on a tracking mount and if the season is good for the constellation of Orion, the most rewarding object for a first attempt is without failure the Great Orion Nebula (Messier 42). Other first choice objects are the Andromeda Galaxy (Messier 31), as well as the Trifid (Messier 20) and Lagoon (Messier 8) nebulae in Sagittarius. Likewise easy targets are open star clusters, not only the famous Pleiades, but also Messier 35 in Gemini and by all means the Double Cluster in Perseus (Caldwell 14). Later, depending on the season, try the North America nebula (NGC 7000) in Cygnus, the Rosette Nebula (NGC 2244) in Monoceros and the Flame Nebula (NGC 2024) in Orion next to the bright star Alnitak and the Horsehead Dark Nebula.
The Orion Nebula processed from a stack of 40 frames, 10 seconds exposures each at ISO 3200 through an Ø150mm FL 750mm F5 Newtonian.
Single exposures of, say, 30 seconds at ISO 3200 look nice on the camera's small LCD but coarse and noisy on a PC monitor. In order to minimize noise and to bring out detail, you need to take at least 20 exposures, better 50, and use software to 'stack' them, such as the popular "Deepsky Stacker". A so stacked image will then need to be further processed in image processing software which will tweak the most out of your image stack if used with experience. In many cases, images of star clusters look good enough in a single exposure merely requiring simple steps to reduce the background skyglow, a job which PC-bundled software can easily perform to satisfaction.
Courtesy: Pixelbay.com
Where to Photograph
Obviously, the best location is a place under a darkest possible sky. Sadly, this is a luxury in our not only 'light-polluted' planet for which many have to move tens, sometimes hundreds of miles. Imaging under light pollution is still possible and rewarding provided you add filters and shoot as many as possible exposure frames. Experienced astro-photographers have come up with brilliant images taken in their 'light flooded' backyards followed by extensive image processing on the PC. As long as you are not tied to the middle of a city, it is manageable, indeed, and becoming easier the more routine you will gain. Astrophotography is an open end learning experience.
Please, do not dispair should your images look like washed out. You will be taking image frames exposed for several tens of seconds. Within this time atmospheric turbulences and poor seeing can ruin your images in spite of pin-point focus and accurate tracking. Since the light of target objects at low altitude travels a longer way through the atmosphere you should wait until it reaches maximum elevation as the object crosses the meridian. If all odds are against you, try again when conditions improve. Oh yes, and please stay away from roads, not only because of bright head lights.
Constellation Leo with interfering clouds. Single frame
25 sec at ISO 1600 with mobile tracker.
In addition, you may be bothered by wind and vibrations on the setup. When clouds are frequently passing through your exposure imaging of objects will be time consuming, considering that you may be taking some 50 frames 30 seconds each. That is a total minimum time of 25 minutes during which no interference whatsoever can be tolerated. If clouds frequently threaten to cross your exposures you will need to program more than 50, perhaps a 100 exposures and spend about an hour to make sure to obtain at least 50 clear of clouds at the end of your session. In such unfortunate nights, be prepared to image only one or two objects. Experienced people often go out for imaging just one specific target object during the night.
Double Cluster Caldwell 14 in Perseus with a Ø80mm/FL910mm achromat.
Equipment Summary
Telescope Imaging
- Tracking mount (preferably German Equatorial)
- Telescope (Ø60-80mm refractor or Ø130-150mm newtonian)
- Camera (entry-level DSLR)
- Adapters (T-ring and nose piece/extention tube)
- PC or laptop with stacking and image processing software
Camera Lens Imaging
- Tripod (mobile tracker for extended exposures and telelenses)
- Camera (entry-level DSLR)
- Lens (focal ratio 1:2.8 and less, 24-50mm, if telelens up to 200mm)
- Light Pollution Filter (for bright locations)
Please feel free to use this website's field of view simulator to verify how much of sky you can photograph with a given DSLR and focal length of a lens or telescope.
Anyway, do not rush because it is clear and new moon but carefully explore all options. A dealer partner you can trust is worth gold. Astronomy clubs, star parties, telescope dealer shops and exhibitions are good opportunities to try and clarify details before you buy. In particular star parties are fantastic for collecting unbiased information and -- for socializing.
www.astropical.space
Printed on 2024-12-21
No liability whatsoever assumed.
Work in progress, please stay tuned. Feedback regarding experience with low-cost equipment alongside 'real-life' images is most welcome.
