The most versatile smart telescope yet?
In just seven years, Chinese-based Dwarflab has grown from an optoelectronic start-up run by a group of young PhD entrepreneurs designing mobile phone microscopes and microscopic cameras to becoming one of the major players and innovators in the smart telescope market. Their latest product, the Dwarf III (hereafter called the D3), is the successor to the hugely popular Dwarf II (D2) that I reviewed in the June 2023 issue of Astronomy Now.
Since Dwarflab is now a successful venture with a high-volume manufacturing infrastructure, the company no longer needs the Kickstarter and Indiegogo-funded business model that worked well for the D2. The result of extensive research, development and user feedback, the D3 is typical of the current vogue for a highly portable and versatile smart telescope that’s equally at home capturing detailed images or video of daytime nature and sporting events, creating panoramic views of scenery, or imaging the denizens of deep space.
Hardware and cameras
Anyone familiar with its predecessor will immediately recognise the D3’s form factor. Indeed, other than a new satin silver–grey livery and slightly larger dimensions than the D2, the new and the old models are superficially very similar. On closer inspection there are some significant upgrades to the dual telephoto and wide-angle cameras, as well as hardware improvements including an internal rechargeable Li-ion battery rated at 10,000 mAh capable of powering it for several hours, and 128GB of internal eMMC storage for your images and movies.
Dwarflab’s proven and innovative periscope-style design is retained for the D3, a 162mm-long horizontal rotating cylinder with an axis of symmetry that forms both the telephoto camera’s optical and altitude axes in addition to housing the wide-angle optical system. Light enters the D3’s telephoto camera via a mirror inclined at 45 degrees, enabling parallel viewing with the wide-angle optical system. It’s a very smart design that combines extreme compactness with the stability of an unvarying centre of gravity wherever the instrument is pointed.
The six-element optics of the telephoto camera incorporate two ED (extra low-dispersion) glass lenses for improved colour fidelity by suppressing chromatic aberration. Its 35mm diameter objective has a focal length of 150mm, making it f/4.3. At its focus lies a Sony STARVIS 2 IMX678 sensor with two micron pixels in a 3,840 × 2,160 matrix, delivering a 2.93 × 1.65-degree field of view. The 8.3 megapixel IMX678 is one of the latest generation of CMOS devices that are extremely sensitive to faint light and capable of significantly suppressing electronic noise in long exposures.
The D3’s telephoto imaging system is equivalent to attaching a 435mm lens to a cropped APS-C format camera, or an impressive 700mm lens on a full-frame DSLR. The telephoto camera’s focal length of 150mm means its IMX678 sensor has a resolution of 2.75 arcseconds per pixel. However, a 35mm objective has a resolution of about 3.3 arcseconds at visual wavelengths, so the D3’s images are slightly oversampled in its highest-resolution mode, which makes good design sense from an imaging perspective.
The D3’s wide-angle optical system is also a notable upgrade from the D2, where it was largely used as an adjunct to the telephoto as a digital ‘finder’. Here the wide-angle camera is a fully-featured imaging system in its own right, capable of recording stills and movies in all the same shooting modes as the telephoto. The wide-angle camera’s 3.4mm objective has a focal length of 6.7mm (f/2) with a 2.1 megapixel Sony IMX307 CMOS sensor at its focus, featuring 2.9 micron pixels in a 1,920 × 1,080 matrix to deliver a 45 × 26-degree field of view at a resolution of 1.5 arcminutes per pixel.
Built-in filters
The D3’s telephoto camera has three software-configurable internal filters for capturing the most desirable wavelengths of light from a variety of deep-sky targets. The VIS(ual) filter is typically for daytime subjects to preserve terrestrial colour balance in the 430–650nm range, while the ‘astro’ filter extends into the infrared at 690nm, suitable for extended sources like galaxies. The dual-band filter is intended for capturing hydrogen-beta (486nm), oxygen III (500.7nm) and hydrogen-alpha (656.3nm) wavelengths of emission nebulae in moonlight, or under severely light-polluted skies.
The D3 rotates in azimuth about a base with a rubberised non-slip foot. While it’s possible to operate the instrument from any horizontal surface, you will need a tripod to get the most out of it. The D2 was supplied with a very basic tabletop tripod, but a miniature tripod with a pan-and-tilt head from Dwarflab’s website is a £68 optional extra for the D3. However, the foot of the instrument is equipped with a standard 1/4-20 photo tripod thread, but do source one with a pan and tilt, or ball head, to use the smart telescope’s more advanced features.
The D3 has a built-in neural network processing unit 2.5 times faster than its predecessor, giving it the ability to automatically recognise and track movement more effectively – although this will be of more use terrestrially for videoing birds and animals, or the antics of family and friends! (Curiously, although it’s equipped with a microphone and speaker, they are not yet enabled in software: all your videos are currently mute.)
First impressions
Supplied in a quality, soft DSLR-style carrying case with a shoulder strap and pockets, the D3 comes with magnetic solar filters in a soft pouch, a USB-C charging and data-transfer cable, cleaning cloth and a basic user manual. A finely crafted device that feels solid in the hand, everything about the fit and finish of the D3 lends it an air of quality, accentuated by the deep green anti-reflection coatings of the heated anti-dew optical window sealing the telephoto and wide-angle cameras.
The D3 can auto-focus on subjects from about 2.5 metres away to infinity, and sample daytime images obtained with the six-element telephoto camera on high-contrast subjects are very sharp with excellent colour fidelity and very little to no chromatic aberration. The instrument is capable of speedy dual-axis slewing up to 30 degrees per second over an azimuth range of 340 degrees (the 20-degree blind spot in azimuth prevents internal cable wrap) and can pitch in altitude up to 120 degrees either side of vertical. Its motors are quiet at all speeds too.
Operating D3 with the DWARFLAB app
Available in Android and iOS flavours, current versions of the DWARFLAB app are 3.1.1 for both platforms at the time of writing. The app will also prompt you if there is a firmware update for the D3 (presently v1.2.6), which it can download and install for you. I was very impressed with the modest hardware requirements for running the app – it was stable (albeit sluggish) on an elderly Lenovo tablet running Android 7, and was surprisingly sprightly on a nine-year-old iPhone 6S Plus running iOS 15.8.3. Anything newer will be fine.
The app initially establishes a connection with the instrument over NFC One-Touch (if your smart device supports it), or Bluetooth, then via a Wi-Fi hotspot generated by the D3. The instrument uses 5GHz Wi-Fi natively, but supports longer range (yet slower) 2.4Ghz communication too. You can also establish Station Mode connections between the D3 and a wireless router, permitting control of the smart telescope over your home’s network.
The app initialises to an opening screen with a prominent ‘Connect’ button, below which lie menu buttons labelled Home, Atlas, Album and Settings. Home is, somewhat intuitively, a link back to the opening screen. Atlas invokes a beautiful, customisable and searchable star atlas configured to your location, date and time that anyone who uses Stellarium will find very familiar.
From the atlas you can select and ‘GoTo’ an object of your choice, the D3 initialising a focus and alignment procedure (the latter is called ‘calibration’ by Dwarflab), if you haven’t already done so. Regarding alignment, the D3 is currently unique among smart telescopes inasmuch as it is designed to be used equatorially and has built-in polar alignment routines to eliminate field rotation in your images. It’s all elegantly thought out and implemented.
Next to Atlas at the bottom of the home screen is the Album tab where you can access folders of all of your images and movie captures and download them to your smartphone, tablet or PC with the USB-C cable, should you wish. Finally, Settings is the sub menu for configuring all aspects of your D3. This is where you can also create a Dwarflab online profile where one will presumably be able to find local users and share content in a future app update.
The D3’s list of shooting modes – Photo, Video, Burst, Astro, Time lapse, Auto-Capture and Pano(rama) – are available to both the telephoto and wide-angle cameras and a comprehensively illustrated pop-up help is available within the app for all of them. Indeed, the list of imaging options afforded by the DWARFLAB app is so extensive that it deserves its own review.
Solar and lunar observing
With the magnetic, 100,000 ND (neutral density), solar filter ‘sunglasses’ clicked into place over the telephoto and wide-angle cameras, you can safely track and image the Sun. The telephoto camera’s 35mm lens can capture full-disc solar images showing prominent sunspots, or the progress of a solar eclipse in time lapse. By night you can track and capture whole-disc images or video of the Moon, or follow a lunar eclipse. Don’t expect super-fine resolution, but recording lunar features as small as seven kilometres across is feasible. Stacking a video in free, third-party apps like ASIStudio reveals much more detail.
An exciting new software development is the ability to create named lists of automated imaging tasks within the DWARFLAB app to run on your D3 without intervention during the night, even for future dates. You choose a deep-sky object by its popular name or catalogue number and the app tells you when it’s optimally placed to capture. You then select the start and end time of the imaging session on a timetable, setting the desired shutter speed and gain – the app even suggests a VIS(ual), astro or dual-band filter to suit the class of object! Once the schedule is synchronised with the D3, it will spend the night carrying out your tasks while you sleep, delivering a stack of images in the morning, provided you having ensured that the instrument had sufficient charge (or attached an external power pack) and internal storage space.
Noise reduction
The D3 uses a process of light accumulation, or image stacking, to produce images of faint objects. By capturing hundreds of short exposures (light frames) of several seconds duration and digitally superimposing them, a smart telescope dramatically improves the signal-to-noise ratio of the stack. This means that accumulated light from actual features in the subject gradually overwhelms electronically-generated noise that appears as randomly coloured pixels, and a clear picture starts to emerge.
Better results are obtained by digitally subtracting dark frames – images containing just the inherent electronic noise of the camera taken in total darkness and with the same exposure and gain as the light frames – to produce cleaner pre-processed light frames before we stack them. The DWARFLAB app enables you to create libraries of dark frames for different exposure, gain and temperature settings, a process that’s done automatically in about ten minutes once the D3 is placed in its zipped-up carry case away from any light source.
Using the latest (at the time of writing) v1.2.6 firmware, the D3 is also capable of automatically applying noise reduction to its final internally-generated stacked image, which it outputs in JPEG format. You can also save individual FITs files from the stack for processing on your PC, or the D3’s own internally stacked and processed images in FITs, TIF or PNG formats. The noise reduction works extremely well – a one-hour stack of the Andromeda Galaxy revealed magnitude +17 stars.
A 63-minute integration of the Rosette Nebula (NGC 2244) from the same location is all the more remarkable, since for the first twenty minutes I accidentally left an outside light on! I used the internal dual-band filter because the Rosette is predominantly an emission nebula shining at oxygen III and hydrogen-alpha wavelengths. Once again, the noise reduction applied to the image was entirely automatic and no processing was applied other than a simple levels adjustment. Viewing at 100 per cent scale on a computer monitor reveals astounding structural detail in the nebula for a 35mm instrument. Furthermore, I was very impressed that the internal filters don’t generate haloes around bright stars like some other budget smart telescopes.
Final thoughts
I have a great fondness for the predecessor of this instrument. My D2 has accompanied me to New Zealand for imaging the far southern sky, Iceland for aurorae and Canada for the total solar eclipse of 8 April 2024. Never once has it let me down, but I believe I’ve coaxed all that I can out of its 24mm aperture and IMX415 sensor. Many of you who also possess one will be wondering if the D3 offers enough to warrant upgrading, particularly with so many alternatives on the market.
Its 35mm aperture might not seem much of a step up, but the D3 gathers twice the light of its predecessor and the telephoto camera’s Sony STARVIS 2 IMX678 sensor is vastly superior, especially when one can stack two-minute exposures in equatorial mode. The complementary wide-angle camera is a substantial improvement for constellation, Milky Way and aurorae imaging too. Dwarflab’s latest app offers exciting new ways to find and image objects by using the atlas, while the ‘schedule’ function is a fantastic way to plan and automate your imaging sessions.
The D3 is an instrument that largely removes the need to carry a bulky DSLR around with you for creative daytime shooting. I think it’s the smart telescope that comes closest to being a product for all your imaging needs.
Ade Ashford has travelled the globe writing about astronomy and telescopes, serving on the staff of astronomy magazines on both sides of the Atlantic.
