by Neil Martin, ASE member and owner of both scopes
There is a saying amongst astronomers that the “best telescope is the one you use”. It is also true that getting started in astronomy and astro-imaging can be challenging, resulting in many newcomers stumbling at the first hurdle, before even getting to the foot of the (potentially) steep and expensive learning curve.
The major equipment manufacturers have recognised this, and in recent times, have added technology to their products – even at entry level – to make life easier for the novice. In the last 5 years, however, a small number of new players have pushed the boundaries further, creating ‘smart telescopes’. This new category of device adds portability to the ease of use benefit – at a range of prices to suit most budgets.
This article presents a pragmatic comparison between two of the newest, and least expensive, smart telescopes available – the DWARFLAB DWARF II and the ZWO Seestar S50. The intention is to help the reader to make an informed choice as to which will best suit their needs – although it is entirely possible to conclude that the answer is, “both of them”. Be warned!
Another warning to heed, is that this is a dynamic marketplace – products and product capabilities are ever changing. It is wise to check the latest state of play before making any purchasing decisions!
Finally, it is important to recognise that these all-in-one devices are not intended to compete with the typical component-based setup employed by many amateur and professional astro-imagers. These setups involve careful selection of the hardware and software elements required, in order to create an optimum configuration.
We’ll begin with some basics about each device. Rather than going into technical detail about optics and sensors, we’ll focus on the principles and their impact on everyday usage.
DWARF II and Seestar are designed to work together with a mobile device – phone or tablet, iOS or Android – to view, but predominantly capture images of, the night sky. Neither includes an eyepiece to support visual observing. This is true of most other smart telescopes.
Both do, of course, capture light via a lens system which routes the light to the waiting image sensor. The DWARF II uses a periscope design, which enables the body of the telescope to be incredibly small. It is also very light, weighing in at approx 1kg. The Seestar uses a more typical refractor design, and whilst compact, it is physically bigger and heavier. That said, at 3 kg, it is still easily manageable.
Both DWARF II and Seestar make use of alt-azimuth mounts. This type of mount is subject to the effect of field rotation, so the devices limit the exposure length to 10-15 seconds to minimise the effect. However, the DWARF II can also be polar aligned, and mounted in equatorial mode, to avoid this. The Seestar is fixed in alt-az mode.
Returning to the optical capability, the DWARF II contains two lenses – a Wide Angle lens and a Telephoto lens. The Wide Angle lens is used for targeting only – all imaging is done using the Telephoto lens. More on this later. Meanwhile, the Seestar uses only a single lens. In both cases, the device can be targeted automatically (via goto methods) or manually (via the app joystick). The optical specifications give DWARF II a field of view of 3 degrees, whereas the Seestar has a smaller field of view of 1.3 degrees. Therefore, DWARF II is better suited to larger targets, and the reverse is true of the Seestar.
Turning to the use of filters – typically used to limit the light which reaches the telescope lens – there are again, similarities and differences. The DWARF II has an internal IR filter, controlled via the app, which either cuts out infra red light, or allows it to pass through – useful when shooting nebulae. In addition, the DWARF II supports the use of external filters, screw-mounted to the specifically designed filter holder accessory. This holder attaches magnetically to the DWARF II and is very easy to install and remove, even in the dark. DWARFLAB sells light pollution and solar filters as additional accessories. These are good quality and inexpensive. Other 1.25″ filters can also be attached, although the thread size should be checked, as these do vary. The Seestar also contains an internal, app-controlled duo-band light pollution filter, and uses an external solar filter. This filter is mounted on a plastic holder which is pushed into place. It is a little fiddly to install and remove, but at least this operation need only be performed in daylight!
In addition to the ‘official’ accessories, the creative juices of the astro-community are in full flow, and there is already a growing marketplace for various 3D-printed add-ons. These include shields, covers, focusing masks, brackets, alignment tools and more. The source files are freely shared for home printing and it is also possible to visit an ebay/etsy storefront to order from a hobbyist printer.
The software which drives these devices consists of two components – the device firmware and the user app. For both telescopes, the user app is available for both iOS and Android (via the associated App Store). The user apps also handle the device firmware updates, to ensure that app and firmware work together as expected. It is in these software components where most changes in functionality will be felt, and both vendors have already released multiple versions. As the user communities grow, and feedback is forthcoming, this is certain to continue for some time to come.
In addition to their portability, smart telescopes are designed to be easy to use. Both the DWARF II and Seestar can be unboxed and configured in minutes, with each requiring only an app install, and possibly a device firmware update, to prepare the ground. Using a mobile device, a Bluetooth connection to the smart telescope is made. The telescope then responds by instantiating its WiFi access point, and inviting a connection back to the mobile device. The Seestar provides voice prompts to make this process even easier.
Once connected, the next steps are determined by the time of day/night and the intended target. During daylight hours, both telescopes support the capture of images and video of landscape/wildlife/scenery targets as well as a solar imaging mode. Remember to attach the solar filter(s) if the Sun is a target!
Both mobile apps provide a virtual joystick to allow the telescope to be rotated and the lens to be raised and lowered. The DWARF II can be moved manually in both directions, but the Seestar can only be moved using the joystick.
The DWARF II’s wide angle lens acts as a targeting aid – it has a wide field of view which makes finding targets in daylight particularly easy. Meanwhile, the Seestar has only a single lens, with a small field of view, making finding targets in daylight more challenging.
Having located and framed a target, both telescopes support auto and manual focus modes. Both devices’ autofocus function is very effective in daylight.
DWARF II and Seestar are equally comfortable shooting during daylight and darkness – when shooting the Sun (covered in more detail in the next section), it is IMPERATIVE that the correct solar filter is in place BEFORE pointing the device anywhere near the Sun. For daylight targets, each device provides appropriate shooting modes – Photo/Video in the case of the DWARF II and Scenery mode for the Seestar.
Seestar defines other specific modes for Solar and Lunar imaging, whereas the DWARF II relies on the Photo/Video mode (with object tracking). There is no discernible difference here.
Similarly, the Astro mode offered by DWARF II is described as Stargazing mode in the Seestar app. Again, these vary in name only. The method of capturing astro-images does vary – this is discussed later.
The DWARF II also provides a Timelapse mode, which enables the creation of moody and interesting videos, immediately available on the mobile device.
When comparing the solar imaging approach and capability of the devices, we again begin with a warning. Solar imaging of any kind MUST only be attempted when the appropriate solar filters are attached to the equipment. Solar filters are available for both devices – a single, plastic attachment for the Seestar (which pushes onto the device body) and a pair of ND threaded filters for the DWARF II (which screw into to the filter holder, allowing them to be attached magnetically to the device).
With the Seestar, entering Solar imaging mode causes the device to locate the Sun first of all. When centred (the Seestar asks for confirmation), the Sun will then be tracked. Single images and video images can then be captured.
The DWARF II does not provide a specific shooting mode – Photo/Video are used. The DWARF II also requires the Sun to be located manually. However, the ability to physically move the device, and the use of the wide-angle lens for targeting, make this a relatively easy task. Once located, the Sun can be positioned in the Telephoto lens, selected, and Tracking mode enabled. This keeps the Sun in the same location in the frame. Again, single images and video images can be captured. The Timelapse mode also allows interesting videos to be captured – clouds passing across the face of the Sun can be artistic as well as irritating!
Both devices allow images and video of our Moon to be captured – these are shot by following the Solar Imaging processes – a specific Lunar mode is provided by the Seestar, and the DWARF II uses Photo/Video mode as before. No filters are necessary in this shooting scenario.
The mode of operation of most interest to astro-imagers, is the DWARF II’s Astro mode, and the Seestar’s equivalent, labelled Stargazing. In this mode, both devices track the chosen object, capturing and automatically ‘stacking’ each image to provide a more detailed image, available immediately to review and share.
Although the basic function is similar, how it is achieved, and the level of control available varies between the devices.
First of all, each device must understand where it is, and orient itself, so that it can then determine how to ‘goto’ a selected object. Both telescopes use the Location Services provided by the connected mobile device to derive the location. The DWARF II requires a Calibration step to be initiated. This is best completed after first focusing on a bright star – although perfect focus isn’t necessary at this stage. The DWARF II will then take a series of images to align itself. Once calibrated, it is advisable to check both orientation and focus by navigating to a bright star, and adjusting focus manually – Vega as the target and a 3D-printed Bahtinov mask produced the best results. Although it is recommended that the DWARF II be level before starting this process, this was not necessary. On the other hand, the Seestar does require level positioning – and the app provides a mechanism to aid this. When the Seestar is level, everything else is automatic, including focus and calibration.
The next step required for DWARF II is to use the specific ‘Astro Darks’ mode to capture a series of ‘darks’ (calibration frames designed to remove a specific element of noise from the captured images). This process requires the lens to be covered to reduce/remove any light. Also, since darks are temperature sensitive, it is best to do this just before imaging – and to redo the process periodically as the ambient temperature changes. The Seestar does not have an equivalent process.
At this point, both telescopes are ready for imaging – they simply need to be pointed at a target. The DWARF II has a limited number of objects in its ‘object catalog’ – although it does allow manual entry of coordinates, in RA/Dec format. Beyond this, there is little assistance, so use of an additional sky atlas app can be helpful. The Seestar has a larger number of objects, an integrated sky atlas app, and a helpful ‘Tonight’s Best’ list of targets. Selecting a target provides some basic, but useful, information on the target, which helps to confirm its suitability before hitting ‘goto’.
Having centred the target in the view, the capturing process can begin. The DWARF II allows the basic shooting parameters – number of exposures and exposure duration – to be set, and allows a wide range of camera settings to be configured. Of these, gain is the most relevant. When the ‘shutter release’ button is pressed in the app, the DWARF II then captures the number of images chosen, using the selected duration. As it captures the images, the stacked image is displayed on the mobile device screen, along with the image capture and stacked counts. The ‘stop’ button can be pressed to stop the process at any time. The Seestar allows only the image contrast to be adjusted, and shooting works slightly differently. When the ‘shutter release’ button is pressed, the Seestar starts to capture images with a fixed duration of 10s. It continues to capture, stack and display the image – displaying the total duration captured – until the ‘stop’ button is pressed.
The process of sharing the stacked image captured also varies – on the DWARF II, the image must be saved to the mobile device first of all, whereas on the Seestar, the image is automatically saved to the mobile device. This seemingly trivial step is helpful – it is easy to forget to transfer the DWARF II images before shutting everything down!
Seestar has a useful feature, which attaches a footer to each image, detailing the target, the user and location, and the total duration of the exposure – this makes the rapid sharing of image content very easy.
Sharing and Community
The acts of sharing and promoting images, and connecting and interacting with other smart telescope users, are key selling points of both telescopes. Both benefit from active groups on social media platforms (primarily Facebook, Instagram and YouTube). The DWARFLAB team interacts directly with the user community regularly, on all channels.
Furthermore, both telescopes have been in the hands of experienced YouTube astro-imagers for several months now. with DWARF II appearing approximately 6 months earlier. These channel owners have created a number of reviews, unboxing, first-light, processing tutorial and comparison videos.
In terms of harnessing and connecting users, DWARFLAB have published user-produced content on their Help site. Meanwhile, the Seestar app has a built-in community where users can share and like the images produced and shared.
As noted earlier, whilst these telescopes are fixed in terms of optical performance and electronic hardware, the software elements of each system offers upgrade opportunities for DWARFLAB and ZWO. This applies to both firmware and appware.
The ZWO app is currently more complete and more polished.
DWARFLAB have a new app version under development. It has already been demonstrated and is scheduled for Beta release in November. It promises support for 1×1 binning, autofocus improvements, additions to the object catalog, and an overhaul of the user interface.
ZWO do not appear to be as engaged with their user base, but they have already added additional functionality – such as saving of individual images in the stack – with little in the way of fanfare.
There is no cast-iron answer to the question, “Is this the right telescope for me?”. Instead we return to the original premise – the best telescope is the one you use.
If visual astronomy is your aim, then these – and most other smart telescopes – are not for you.
However, if you are looking for a helping hand up the learning curve of astro-imaging, and the ability to do this from anywhere – inside and out – in minutes, using a simple-to-setup and compact unit, then both of these telescopes satisfy this criteria. Choosing between them is more difficult, as whilst they are different – inside and out – they also have many similarities. Therefore, if there can be only one, engage with the communities online, chat with users and view what they have created. Ask questions of them and use the answers to help make your final decision!