Geoff Lister

I measured the current consumption of my mounts. I have used a selection of 12V, 1.5A or 2A plug-top mains supplies with no problems. Geoff

This is what I use with my D3200 The adaptor is marketed by Celestron (same parent company as Skywatcher). I also have a mechanically-similar x2 Barlow, and you may need the Barlow lens to achieve focus.

As none of the experts has posted a reply; here is my take on it. The apo/achro/ED/doublet/triplet lens systems are designed to get a common focal point with the widest range of optical wavelengths. When you use a narrow-pass-band Ha or CaK filter, there is only one wavelength to consider. The CaK and Ha focus points will be different, but it does not matter, as you only use 1 filter at a time. A quick look at the SGL "Imaging -Solar" section, seems to advise a minimum f10 (even better, f15) refractor. A 90mm f10, stopped down to 60mm may work well. Geoff

I managed 70 degrees altitude with the 127's diagonal hitting the base, but by moving the OTA 25mm forwards I was able to get the full 90 degrees, with the rear of the diagonal just clear of the base. Doing a similar test with my Heritage 130P OTA, I managed 50 degrees at the balance point, and needed to move the OTA 50mm forwards to avoid the collimation locking screws touching the base. Geoff

I sometimes use my Skymax 127 Mak OTA on my Virtuoso mount. Yes, if the OTA is clamped at its balance point, the end of the diagonal will hit the azimuth clutch knob, if viewing high altitude targets. I move the OTA slightly forwards, but limit maximum slew rate to "4", to reduce possible strain on the motor-gearbox assemblies. The virtuoso mount will also take the OTA from my Heritage 130P; again, with the slight forward shift in the dovetail clamp. I, too, leave my diagonals in place, when storing my OTAs.

As well as GoTo, the Synscan system provides accurate tracking. At dusk, I can do a "Brightest star", (2-star, or, planet + 2-star) alignment; go inside for tea; and come out again when it is properly dark, and the last alignment star will still be in the field of view of a 25mm eyepiece, often close to the centre. The tracking makes it easy to change eyepieces, to select the optimum planet visual clarity/magnification compromise, without having to centre the target again. Geoff

Just spotted your posting, so sorry about the delay. Have you considered a monopod? I use one with my 15x70s. The monopod takes the weight, and small body movements help me to scan an area of sky. The monopod will also work well (held at an angle across your chest) for longer periods, when sitting in a reclining patio chair. A tripod, with only 1 leg extended, makes a good experimental monopod, to see if it works for you. Geoff

This is my setup with my Nikon D3200. The nose-piece of the adaptor has an internal thread for standard 1.25" filters. Geoff

I have the Skywatcher Skyliner 250PX with built-in Synscan. As Marv mentioned, above, the intelligence is in the handset, and the mount has the 2 motor and gearbox assemblies. These assemblies form an integral part of the support for the optical tube, and are not just an addition to a manual setup. This shows how the tube sits in the mount. The block, on the left side of the main tube, slides into a groove in the mount's altitude gearbox assembly, and is held in place by the large locking bolt on the top. I believe Skywatcher's solid-tube versions use a similar mounting. The photo, below, shows the azimuth gearbox. It may be easier to retro-fit to a manual base. Other manufacturers are likely to have different systems, but I would expect the ones with built-in GoTo would be cheaper than the combined cost of a manual mount + retro-fit kit. Geoff

These are a selection of my 12V supplies The battery packs, with springs for the negative terminals of each of the cells, tend to give a high internal resistance, unless they are very clean. The plug-top PSU was recycled from a scrap Ethernet switch, but similar devices are sold to power the LED lighting strips. I have also "borrowed" the supplies from older desk-top external hard drives. I measured the current consumption of my mounts The Skyprodigy handset has an RTC built-in, but, as mentioned above, does drift, and probably needs resetting about once a month. The Synscan handsets remember the last date when the mount was used, but reset the time to 8pm at each power-up. The CubePro and Solar Quest (no handset required) mounts have built-in GPS receivers, so always accurate for time and location. Geoff

I had similar azimuth-axis problems with my 10" Skyliner. The fault was a poor connection between one of the encoders and the az control printed-circuit board. The encoders are connected to the board, using ribbon cables, with a push-on cable connector, and matching pins on the underside of the board. I only spotted the partial disconnection when I unscrewed the board - it was not obvious with the board in place. The cables pass through ferrite rings; probably added, post design, to meet international EMC emissions and susceptibility requirements. This effectively shortens the cables, and makes the cable paths very tight, and thus prone to easy disconnection. I was able to re-seat the connector, (carefully) screw the board back in place, and replace the big black azimuth-axis assembly cover. That was several years ago, and I have not had problems since. Geoff

I'm glad to see that Skywatcher's more recent designs will work with a lower supply voltage. My Skymax and Skyliner mounts each have a V3 Synscan handset, which has a specified working range of 11 to 15V. The manual for my (again more recent) Virtuoso mounts, gives a range of 7.5 to 14V for an external supply; but I do not know if the bottom end of the voltage range applies when I use the mount with one of my V3 Synscan handsets. The manual for my Celestron Cosmos WiFi mount gives power requirements of (a) 8-off AA batteries, (b) 12V DC source with at least 1A capacity {no voltage range specified}, or (c) a Celestron PowerTank. Geoff

The rechargeable batteries have a nominal terminal voltage of 1.2V, whereas the alkaline batteries are 1.5V. Where the mount, or supplied pack, takes 8 cells, using rechargeables gives you 9.6V instead of 12V. The Synscan handset/mount interface needs a minimum of about 11V for reliable operation. The 6V packs give about 7.2v when freshly charged, and stay above 6v until they are close to being discharged. Sorry, No. The packs are wired in series. The photo shows a short loop, where the red wire from one connector is connected to the black wire of the other. The other wires are connected to the power jack (5.5mm dia. outer sleeve negative - to black wire, and internal 2.1mm dia. sleeve positive to red wire). The "spare" third connector is used to charge the combined batteries. The 3S LiPO pack gives 12.6V when freshly charged. I only use it as a backup. The cells should not be discharged to below 3V, but the mount alignment and tracking will drop out well before this point. The pack has a special 4-way connector, for use with a balancing charger, and I have a special plug-in voltmeter module that cycles through the cells and gives a "beep" if they are getting low (it also has 7-segment displays but these need to be masked to protect night-vision). Yes, it is possible to use a boost regulator to convert the +5V to +12V, but these packs already incorporate a regulator, to get a constant +5V from the internal battery as it discharges. The mAh values quoted for these packs tend to be for the cells at a nominal 3.7V, so give about half that at 5V and about a quarter at 12V. I hope that this answers your questions. Geoff

Welcome to SGL. My Skymax mount needs close-to 12V for reliable operation. I have various other mounts, and measured the current taken during start-up (before starting alignment - motors off), slewing, and object tracking. I would expect the Synscan WiFi mount to have similar current consumption to the Celestron Cosmos, above. These are some of my power sources:- Most of the time, when observing from my back garden, I use the 12V 2A plug-top supply; with the supply body plugged into a mains extension lead, in an old shoe box to protect the live bits from dew formation. I extended the 12V output lead, with some white, heavy-duty, bell-flex. This shows up better in the dark, so I am less likely to trip over it. For portable use, I tend to use the pair of 6V 2600mAh battery packs, "borrowed" from my radio-controlled model sailing yachts. These are fine for an evening's observing. They are equivalent to the 10-cell holder, but give a more-reliable electrical contact between cells. I have also used my 4-in-1 jump starter pack. These have, in theory, a 17Ah (17,000 mAh) capacity, but should not be discharged below 50% (except in an emergency), and then recharged immediately after use. One of these should give over 24 hours of mixed slewing and tracking. Geoff

I too found that the suggested 2nd star was behind house/fence/tree, so I spent some time with Stellarium and produced a table of the brightest stars visible from my back garden, at dusk and an hour before dawn, for the middle of each month of the year. I added compass direction and altitude for the best ones in each month, and try to select a pair with 90 degrees azimuth difference and about 30 degrees altitude difference. Polaris is also visible, but is not one of the brightest stars - it makes a good 2nd star for AzAlt. At the moment Jupiter is visible to the south, so I tend to do a planet + 2-star (it gives auto-slew to both stars, so faster than manual). Geoff

This photo shows the similarity between the Celestron and Skywatcher mounts. The Sky Prodigy has a built-in 640x480 web-cam and Starsense software, and a battery-backed real-time clock; so alignment is one button-press away, if you are observing from the same site. Geoff

The extra 28mm on the diameter gives you about 60% more photons. I would be tempted to wait for the "Slow Boat from China" and go for the 130mm version. Geoff

Hello Joe. I have the Skywatcher Skyliner 250px Dobsonian with Synscan GOTO. The mount's interface with the optical tube is very different from the equivalent "manual" setup. It's not just a simple matter of adding motor drives and an intelligent handset. Geoff

Hello Gary, and welcome (back) to SGL. I am a big fan of the Synscan GOTO system. As a beginner, I made the "mistake" of buying the Celestron Astromaster 130EQ-MD. The optical tube is similar to the 130p that you mention, and is a good compromise of size, weight, focal-length, and light capture, but I found the equatorial mount counter-intuitive, and difficult to use. About 6-months later, I bought the Skywatcher Skymax 127 with the Synscan handset. The mount is the same as the Explorer, but with a Maksutov optical tube. The 130p optical tube is a good all-rounder, and makes it easier to see wider star groups than the 127mm Mak. (I still sometimes use the Astromaster 130's optical tube on the Skymax mount - see below.) Andy has suggested a gti-wifi mount. I have a Celestron "Cosmos" wifi mount, similar to the Skywatcher one, and using my tablet in place of the Synscan handset. I have found it much easier to use a handset, with "real" buttons, rather than virtual buttons on the tablet's touchscreen, particularly whilst looking through the eyepiece. Synscan's initial alignment process is accurate and, after doing some homework, I found it quick to use. I use the "Brightest Star" alignment, and, using the (free) Stellarium program on my PC, produced a table of 14 bright stars, visible from my observing position, and, for dusk in the middle of each month of the year, identified 3, 4 or 5 of these stars, with good azimuth and altitude separation, to make the GOTO accurate. I can now be observing in under 5 minutes. The Synscan GOTO system is no substitute for (slowly) learning the night sky, and how it changes over a year, but it makes it easier to find fainter objects; and the associated tracking keeps the objects centred as you observe, and change eyepieces to find the optimum magnification (or go indoors for a call of nature or make a hot drink). There is no "ideal" amateur telescope system, but I would suggest that your Explorer 130p is a good place to start. Geoff

I too have failed to get my Virtuoso mount to go into EQ mode, using the "5" button power-up. However, I made a crude wooden wedge for my 51.4 degree latitude and changed the mount's location latitude to 90 degrees (pretending to be at the North Pole). This gave me tracking movement in the azimuth axis only, so effectively an EQ mount. The mount works well in Az/Alt mode with the Az/Alt V3 Synscan handset "borrowed" from my Skyliner 250PX. Geoff

My 10" Skywatcher Skyliner 250PX truss-tube Dobsonian will definitely not fit in my Mazda MX5 2-seater; all of my other systems will. I bought the Skyliner before I retired, and am glad that I did not go any larger, as I can envisage a time when I will not be able to carry the base and optical tube, the 10 yards (through a limited-width doorway, and down a small step) from my garage to my patio. Geoff

Me too. Having realised that my Astromaster 130EQ-MD was a pain to set up and use, I went for the Skymax 127 GoTo with Synscan handset. This was a vast improvement; and, shortly afterwards, I bought a second one to take to my holiday home in France. The 127mm Mak works well for planets (including Uranus and, just about, Neptune - they look like stars, but with a bit more "body", and definitely need a tracking/GoTo mount to find them, and hold the view steady whilst you change eyepieces). This is my grab-and-go setup Works well for me too. Geoff

There is a nice site with PDFs for printing, and cutting details, at http://www.deepskywatch.com/Articles/make-bahtinov-mask.html Wikipedia has a description of the mask's operation, and a link to "Pavel Bahtinov", but if you follow that link it brings up an "empty" page. Clearly, honours are overdue.

The image in mine remains rock steady as I rotate the focuser. Geoff

With my GPCAM & x0.5 focal reducer, I keep the 90 degree star diagonal, remove the eyepiece, insert the camera, and adjust the focus. Geoff