You have probably noticed chatter about the Unistellar eVscope.
I bought one of these telescopes because I am curious about new technologies. It is a small instrument, but computer controlled from smartphones and pad like the Google Nexus, allowing up to eight people to be part of an observing group. It cost $2500. It's about as user-friendly as a system like it could be. The autonomous finding gets almost any RA,Dec in about 40 seconds. Back last February a group of my friends observing from the edge of a brightly lit city parking lot saw tested it. The image from the telescope is visible in the eyepiece on the side of the tube as well as on the smartphone screen. We saw M42, the Horsehead Nebula, and a comet.
You can control the eVscope from an Apple or Android cellphone or form a pad like the Google Nexus, from a range of about 100 feet, so it can be used from inside a house with the eVscope outside.
They are busily marketing participatory citizen science. Below the photo are browser links from three recent emails. This email targets newbie amateur astronomers who are just starting and want to look at pretty sights:
This one is aimed at users with more background encouraging them to try a science observing run:
The eVscope can be programmed, but it's open-source at this time.
And this last one is for more serious observers, and probably an Citizen Science experiment by SETI:
They hope to collect data from up to 100 participants. Sales of the eVscope are about 2,500 afaik. SETI/Unistellar obviously put some time and effort into these campaigns, and I suspect they are fairly effective.
I have tested it for astrometry, and it's easy to get better than 1 arcsec results. Maximum single exposure time is 4 seconds. The minimum is a few microseconds. It stacks in real time. The image of M67 is overexposed for transforms, but the camera has potential to build a dithered 16-bit color (TR,TG,TB) image in a minute or so with the right software.
There's also a similar product called "Stellina" that has roughly comparable specs and price tag. The Stellina is probably more like how Apple would design a telescope: It's beautiful to look at, has an on/off switch and that's about it as a mechanical user interface, it is controlled by an app on your smart phone, you absolutely can't swap any of the components, but it's super easy to use.
The initial version of the app that controls the Stellina was so radically boxed-in that you could only pick targets from a list, You could not point the "telescope" at a random RA,Dec , e.g. a new SN, you would have to wait for the Stellina team to update the app and with it the target list (!!!). They did change this in an update to the app and now the Stellina can do any pointings you want.
I like the Citizen Science perspective of the eVscope. I'm still a bit torn, tho. It's easy to dismiss these products as a waste of money, and of course you can buy a much better telescope setup for the same amount of money. I am also a bit sceptical about doing filtered photometry with the eVscope, I think they don't block NIR from reaching the sensor (unlike what most one-shot-color cameras do), I guess in an attempt to make it easier to image faint nebula with the rather limited aperture. But NIR might leak into the TG and TB filters!
On the other hand: If I add all the time that I spend setting up my (mobile) telescope (assembling, connecting cables, starting software, alignments, focusing, ... and finally everything in reverse to bring it back into the house), the rough estimate is that I spend a whole day every year just fiddling around with the scope to make it work. What's the price tag on a day of your life every year?
I'm very curious to hear results from a test of the eVscope!
The system is completely turn-key, so you can be observing the night after it arrives. It is completely portable, and it is not necessary to polar align. Setup and operation are highly autonomous. These are appealing features for mny people. I don't know whether the sensor is IR blocked, but it gives reasonable color images of distant objects, so it probably is blocked.
Stellina appears to be complete different product aimed at a purely astrophotographer market, whereas the focus of the eVscope promotions is citizen science with the SETI, mainly asteroids and exoplanets.
I will be running more tests when our current rainy weather ends.
Would either the eVscope or stellina be useful to search for undiscovered asteroids? (Not occultations). Stellina has the ability to save fits files on a USB drive so it seems you could use a program like Astrometrica to process and blink images. It appears to record sufficiently faint magnitudes. Am I overlooking something? I am evaluating both scopes for purchase.
They are upgrading the software and have added the ability to shoot dark frames and the ability to run from pads like the Google Nexus. They say they will add software for running from computers, and I expect at that point we'll have FITS files. When they do a data run, the images are collected in real time on the phone, and transferred to SETI later.. Since the files are stored on the phone, they must be accesssible. If I were them, I would save some variation on FITS, but we will find out. I will be checking this next clear opportunity.
Since I have had my eVscope, I have been trying to figure out how it works. You start with it pointed at the zenith. If you ask for a target (either by name or by (RA,Dec) coordinates, it moves away from the zenither, shoots a short exposure, plate solves it, moves to a second spot, place solves it, then moves to the vicinity of the object you want, shoots another, plate solves it, then centers the objects. This takes about 40 seconds.
The default exposure for plate solves is 200 ms, Once it's on a object, it usually goes to 3.95 second exposures and streams them live. You can center a bit to get the image you want, then begin the real-time stacking process. The stacked image improves rapidly. You see that image on your phone and through the eyepeice on the side of the telescope. The image you view is bright enough that you can see it in a bright parking lot, so at a star party, non-astro folks can see it easily without being deeply dark adapted. For star parties, it is fabulous. People really do say "Wow!" when looking at faint objects.
More on this scope as I learn more. My guess is they're doing 10-bit or 12-bit data from the SMOS sensor. For photometry, saturation might be an issue, but if you were to set the exposure and gain to avoid saturation, then stacking could avoid that with short 10-bit sub-exposures and summing to a 16-bit exposure. If the Bayer images are dithered, Bayer array sampling would not be an issue either. They are not giving out much in the way of technical details.
For what it's worth, I've added a photo of the sensor and its housing.
As for the sensor, their website says this:
Sensor Technology: Sony Exmor with NIR technology
Sensor Model: IMX224
(19k full well capacity, but 12 bit ADC)
So I would not be surprised at all if they use an IMX224 behind a clear glas, not a IR-blocking, window, exactly like the ZWO ASI 224
which is heavily leaking IR into TB and TG filters, see the transmission curve under that link. Heck...maybe there is acually a stripped down OEM version of the ZWO ASI 224 inside the evScope !
Retrofitting the sensor with a blocking filter could perhaps be possible for courageous folks, tho, if I see this right the sensor is at the front "spider".
The eVscope is the first instance of a new breed of telescope: autonomous, self contained, ready to use the day it arrives with no setup. It's a potential gateway into variable star observing for a class of observers who have the intellectual skils to be observers, but lack the mechanical and technical know-how to buy separate parts and assemble them into an effective data-grathering system. What you pay for with an eVscope is not the optics, but the control logic and software that allows the telescope to accept coordinates, find a field, make images, and return data to you via your cellphone.
They've promised to make the API available, so at some point in the not-too-distant future we'll have full computer access. As best I can tell, the cellphone issues a script to the telescope to execute an observtion, just as a far more powerful computer could. There's no reason that the right software could not reduce astronometry and photometry in real time. It's also worth rememebering that the same software that controls a 4-inch telewcope could, with little or no alteration, control a 12-inch telesope.
The other interesting aspect of Unistellar is they are science people, and a key focus of the eVscope is data collection:
In azny case, the Instrumentation and Equipment Section is devoted in new technology as well as existing and old technolgy, and that's what this prodcut is.
PS: This link assesses the science potential the small automatied telescope:
For a little less than the eVscope, you could buy a Celestron Nexstar 5se with Starsense and the ZWO ASI294MC-cooled camera.
Nexstar 5se: $700
That's roughly $2100 and for that price you'll get a telescope with the same field of view plus a sturdier mount (with a built-in equatorial wedge).
Or if you want to go cheaper, you can go with the Skywatcher Startravel 102 Az-Gti mount and scope combo ($500) with the ZWO ASI224MC ($250). The Startravel has a much shorter focal length than the Celestron 5SE (500 mm vs 1520 mm) so it can match the FOV of the eVscope with a smaller, cheaper camera.
Both options offer the same 1/2 degree field of view as the eVscope except the 102 Startravel set-up is over $2000 cheaper for similar capability and the Celeston 5SE offers an overall better system for one-third less in cost.
I have a TEC 140ED, Epsilon 130ED, TS 76/330 Quadruplet, Meade 8 " ACF, Takahashi FC100DL etc., many mounts like iOptron, G42 +, AZ GTi ..., cameras ASI224MM, ASI 071 Pro, Astrel 16200B, SBIG 4000XCM .... but there are a lot of cables, laptop (or tablet + ASIAIR), batteries, long settings etc. Otherwise, the eVscope is light, fast alignment (30-40 s), fully automatic system and EYEPIECE! Yes, you're right, the price is for standard newton is too high (probably a mirror from Orion Newton F4). I don't want to take astronomical images with this, I would just like to observe and share the observations with other people online as well.I think this system has some disadvantages, but I think there are many advantages. Also is interesting exoplanet research. https://tinyurl.com/y4g45pf3
I plan to buy a telescope eVscope and a DSO filter in my place (MSA 20.5) would be great!
I'm not even sure if it's possible to place a filter infront of the eVscope sensor (without invalidating the warranty and some serious DIY effort). The eVscope has the camera sensor bonded to the mirror-facing side of the spider vanes, it's not like you can easily take the camera out of the telescope, screw a filter on, and put the camera back. And even tho the aperture is quite small, there is no affordable filter that is big enough to put infront of the aperture I guess :-). On their website, there is a FAQ entry where it's mentioned that > 2 yrs ago they were looking into the possibility of adding filters, but looking at the actual specs now I'm pretty sure that never happened.
The Stellina product that competes in the same market segment claims to have a built-in light-pollution filter.
There is a small tube, where is the camera, diameter 20 mm, I think, and I plan put it CLS filter 1,25" on it.
Stellina is another category telescope, this is only for Astrophotography (has a low sensitivity) without an eyepiece and live view, but has a light pollution filter.
I wouldn't call it another category. The Stellna has a "live view" as well (on the sceen of your phone where the app runs), it lacks the display of the live view on an electronic eyepiece which after all is just a tiny additional OLED screen with a magnifying glass.in front of it. As looking thru that "eyepiece" runs the risk of touching the telescope and causing vibrations that will ruin any ongoing exposure, I suspect most eVscope users will prefer to look at the eVscope images building up in real-time in the app rather than using the "eyepiece"., which (as I understand) will also crop the image artifically to create a circular instead of the rectangular field of view of the sensor, just so it looks more like a real eyepiece view.
Both telescopes do astrophotography via live stacking, but have different marketing concepts perhaps: the eVscope tries to present itself as an evolutionary step from the old style visual telescopes, while the Stellina is marketed as something radically new altogether, even avoiding the term "telescope" as much as possible ("observation station").
I would prefer the eVscope over the Stellina (or their newest project, the "Vespera" which is a less expensive, shrunk Stellina, sort of) because of it's larger aperture and the Citizen Science aspect.
I didn't know that Stellina had a live preview, I only saw (in the web presentation) how the application shows the finished images.
Stellina has to take tens of minutes of exposure, but eVscope takes minutes for the same picture (20 min versus 2 min). I think, Stellina is for the general public, eVscope for amateur astronomers special in the future (asteroid occultation, exoplanets, comets), I can see different concept in this
Hmmm........a factor of ten, it is really that bad?? The Stellina has about half the aperture area of the eVscope (the ratio is a bit more favorable if you consider obstruction as well). Stellina's CLS filter could reduce or increase the time you need for equal SNR, depending on whether the object in question emitts mostly in the CLS filter's passband (e.g. emission nebulae ) or more in a continuum spectrum (e.g. galaxies I guess). But then again you want to use a CLS filter on the eVscope as well.
The sensors are both rather recent Sony CMOS sensors. So where would the Stellina lose another factor of 5 in exposure time for a given SNR (after allowing for the aperture area difference)?
Of course, it also depends on the processing software. ASI 224 has 1,5x bigger pixels, that mean picture of M13 take 79 000 pixels of ASI 178 and 30 000 pixels of ASI 224 and picture from ASI 178 has a worse S/N ratio. By the way, ASI 224 is has also better QE in Halpha.