PlanetGazer

From someone who uses a GoTo dob, there will be a huge learning curve that will come with frustration. Once you get it sorted, it's amazing.

Note that you will need a proper AC power (a good battery, which is not cheap)

 Most alignment problem are from power. But it's all good when you get a good battery, until the motor gears slip 😢 then it gets messy. Not sure how common of a problem it's, but I got it after one year of use.

22 hours ago, Jm1973 said:

Thanks for the reply.

I've just bought an Ostara 2x Barlow and 6" EP for £40. Should be arriving tomorrow.

I am definitely keeping an eye out for a used 8" dob. I'm just trying to work out if I've got enough room for it.

Do you think keeping a telescope in a concservatory, that gets very hot on sunny days, will potentially be a problem for the optics?

Not sure exactly, I store it in my office, heat over here will ruin anything , yes it takes place in my office, but I would love to look at it everyday to remind myself to get it used. Not to mention that indoors reduces the amount of dust. 

You will figure the perfect spot for it once you buy it. You shouldn't be in a rush anyway. Enjoy whatever equipment you have at the moment, it's only a gate to the amazing heavens above

Clear Skies!

Hi JM

£20 well spent. It will serve good as a starter telescope, to test your eagerness of the hobby.

If you find yourself getting into the hobby, start by buying a 2x barlow and 5 mm EP which will serve you on the long run, the barlow with the 25mm you already have will give you 12.5mm, which would cover the 10mm range.

If the 25mm EP you have is the stock Skywatcher, I would keep it and rely on it, the 10mm stock ones are not that good.

I use the xCelx celestron 5mm, which give good planetary and lunar views. Not always though, the sky conditions have to be stable.

Edit: Consider buying a used 8 inch dob, the sweet spot

4 hours ago, Geoff Barnes said:

If your model is the same as mine this is the altitude cluch handle that you have to tighten by hand quite firmly, otherwise the goto motion will not work...

Oh that's the first time I see such a model. Which makes me think that such a handle should be there for all models. Mine doesn't have it, but the thread i showed in the earlier picture is on the same level, but from the other side. Your scope look 12 inches or more, right?

This is how my base looks, but I have a different handset model:

10 hours ago, Geoff Barnes said:

If you are using it in Goto mode and the clutches are tightened up fully then there is no way the scope can "slip" down on its own, you would have to physically push down on the front of the scope to do that. It sounds certain to me as the owner of a similar scope that yours has a fault that needs repairing, particularly as you say it is making strange sounds.

So how do you correctly tighten clutches in a goto dob system? I assume they are not easily accessible.

Initially I thought I would have to use a wrench to tighten this part in the altitude motor box, but wanted to ask here first.

2 hours ago, Peter Drew said:

Yes, balancing is most important.  I presumed, due to the fact that it was a driven Dobsonian, it would have been balanced being as it had been used.  If possible, disconnect the drive system and check that the optical tube assembly is balanced in the altitude axis.    🙂 

How do you check that? Do you mean leveling the OTA on the mount to the horizon before starting it up?

1 hour ago, Rusted said:

Far be it for me to intercede in this conversation, but are you sure about the balance point of the telescope tube?
I'm a martyr to changing balance of my OTAs. It's a constant uphill battle!
I think little people must sneak in and mess about in the middle of the night.

You're more than welcome to participate in the discussion!

If you mean balance point for equatorial mounts, then this does not apply in my case. My scope sit on a dobsonian mount which designed in such a way that it doesn't require balancing, unlike equatorial mounts. 

Here is a link showing a picture of my scope:

https://www.firstlightoptics.com/dobsonians/skywatcher-skyliner-250px-flextube-goto.html

Battery works very well, it was perfect the session before. The battery was fully charged for last session. 12.5 is max I usually get.

Regardless, battery issue doesn't explain why OTA slips before turing it on, it should hold it self without switching on the system

Long storey short :

the OTA slips dramtecly when vewing an object to 0 altitude.

Details:

So I bought the Skywatcher GoTo flextube 10 inch a year ago. It was nothing but great, until yesterday when I was just starting the session to level up the scope on the mount for alignment. I Went to get some equipment and when back noticed the scope has declined to a minus reading on the altitude! With no attachments on the OTA. 

I re-leveled it to the horizon and it held itself, put on the nothing but stock attachments as usual. Switched on the GoTo and started aligning, when alignment is successful, I chose an object and notice the object is far off.  I check the battery voltage and it's 12.5 volts, which indicates it's not a battery issue.

I turn it off to re-align again, this time when I press the up arrow to align to an object I notice the GoTo gears struggle to move the OTA upwards, but eventually the speed increase to normal and manage to points upwards to the object. I pick a second object which happens to be near the zenith and the GoTo goes out of control straight to zenith and carrying on above 90+ degrees on the altitude bearing. I try to stop the scope with the handset before the base of telescope hits the wood in the base, only to notice the handset is not showing light or responding. I turn the GoTo off.

Start to align for the third time, this time aligns but still off target. I ignore and start viewing Jupiter which happens to be 40+ in altitude , after few minutes of viewing, the scope drops slowly to zero altitude with no hand or handset movement! Handset is still showing that the viewed object is still Jupiter!

Note: I did notice weird sounds of the gears when trying to increase altitude. Not the common sound.

Has anyone faced this issue and fixed it, should I return under guarantee? Is this a gear slippage? Or clutches not engaged? Your help will be much appreciated!

Hello Mr GuGuzai

Dobsonians are a great choice, usually size 8 , or 203mm with 1200mm focal lenght is the sweet spot. (https://www.opticaluniversescientificinstrument.com/products/gso-8-deluxe-dobsonian-telescope

or

https://www.opticaluniversescientificinstrument.com/products/duplicate---skywatcher-skyliner-300px-flextube-dobsonian-synscan-go-to-telescope-1-1-1

it depends on your budget at the end. all should do well for planets. I see planets fine in my 130mm and 250mm mirror telescopes. more detail in the latter.

Big mirrors does get affected by weather, change of temperature from warm to cold or vise versa (if telescope is stored inside then you bring it outside for example), it will require allowing the mirror to settle to surrounding temperature in the observing site. some use fans, but around 30 mins of waiting should be fine.

as for imaging, manual dobsonians and any manual Altazimuth mounts will make tracking obejcts hard, as you need long exposures to get good imaging. however some experienced astrophotographers manage to get ok images with dobs.

start with pointing an object on the ground during day, large tower chimney, can you see things fine ?

be ware of the sun, never go near it

On 16/02/2020 at 16:58, Neil H said:

get a good power pack like this it will power everything

https://www.firstlightoptics.com/batteries-powerpacks/celestron-lithium-lifepo4-powertank-pro.html

I second that

On 14/01/2020 at 20:49, Piero said:

With that focal ratio, I wouldn't get anything longer than 31mm focal length.

If money is a concern, I would go for a 24mm 82 deg (e.g. Explore Scientific).

Alternatively, 31mm TV Nagler, 26mm TV Nagler (second hand market), ES 30mm 82 deg), APM/Lunt 20mm HDC 100deg.

If you really don't mind the cost, you could consider a TV Ethos 20mm. Many people love it.

 

Personally, I'm very happy with the APM UFF 30mm.

Currently Looking at the ones you mentioned here,

also found these much cheaper ones:

https://www.365astronomy.com/32mm-SWA-Super-Wide-Angle-Eyepiece-70-degree-2-inch.html

definitely they would not match the quality of the above, but how much is the compromise?

On 11/01/2020 at 19:11, Philip R said:

Have you considered these by Explore Scientific?... https://www.firstlightoptics.com/explore-scientific-eyepieces/explore-scientific-82-degree-series-eyepieces.html

They are about half the price of a TeleVue Nagler... https://www.firstlightoptics.com/tele-vue-eyepieces/tele-vue-nagler-82-degree-eyepieces.html

I'm considering both, part of the list of comparision.

On 11/01/2020 at 19:11, Mark at Beaufort said:

Your scope has a focal length of 1200mm and with a 50mm EP you will have an exit pupil of 10.58. With an exit pupil of that range the sky will appear very grey. Young people  (don't know your age) have a pupil size of about 7 so anything above this is wasted light.

I think a better eyepiece would be 30mm 82 degrees FOV - https://www.firstlightoptics.com/explore-scientific-eyepieces/explore-scientific-82-degree-series-eyepieces.html

My main EP for DSOs using an f/5 12" Dob is a 20mm 100 degree EP. This gives a darker sky and better contrast. I have a 30mm 70 degree EP which I rarely use.

 

 

Noted, thanks for the advice!

On 11/01/2020 at 19:26, John said:

I agree with Mark (above). 30mm will be a much more effective focal length and the Explore Scientific 30mm 82 degree eyepiece that Mark links to is an excellent choice for your 10 inch F/4.7 dobsonian.

A 20mm / 100 degree eyepiece is even better if you observe with some light pollution around.

 

 

you are tempting me more towards the 20mm, also thank you for the advice.

On 11/01/2020 at 20:32, LDW1 said:

With a low power ep you want as wide a TFOV as you can get, so some compromise may be required ! You can’t have everything just perfect to fit all the specs a bit of deviation from the perfect world is required to get not just good views but maybe awe inspiring views such as with the Double Cluster, Orion Neb., Andromeda Gal. etc. ! A little thinking of what you want in the end is required ! 

Thanks.

Sorry all for the late replies, I wanted to read all advice with a clear mind.

After reading all, I shifted my search to the right eye pieces, but i'm afraid I fell in a new rabbit hole, there are other options that came up, so still undecided, I will update with my final choices before I buy

Planning to add a 2" EP to my collection as I have a SW 250P (10 inch) and want something special for DSOs and would love to capture the range of Andromeda in a gaze, so angle would be important . I'm thinking of the range between 35mm to 50mm. Budget is not a limit, though I would prefer to have an EP reasonably priced if available.

I regularly use the 25mm standard plossl that came with the scope, which is doing more than ok. I have a 32mm and 16mm classical plossl, but don't use it much as it's hard to use with eyeglasses.

I was thinking of the Explore Scientific 52° 40mm, but then I realized it's only 52 degrees and other reviews say that the brand is planetary focused. I was also looking at the televues, but should I make the crazy jump? I wouldn't mind much cheaper EP that have a little less performance that I wouldn't notice anyway at my current level, or is it worth it now?

Thanks in advance!

Edit:typo

13 hours ago, John said:

My regular eyepieces are Tele Vue and Pentax but I've owned and used a few BST Starguiders and I think they are really pretty good eyepieces for their cost (£50 new, £30 or so on the used market).

 

Have you tried the Tele Vue Plossls by any chance?

a question that I have been wondering about lately, though, only looking for short exposure only, as I use my dob usually for visual. But would love to take a couple of short exposure pictures.

Wonder if the Canon EOS 4000D (NIS) is any good for astrophotography?

Also, Nikon COOLPIX B500, found it on sale

On 02/11/2019 at 21:07, Cosmic Geoff said:

You could buy a car jump starter instead of an astro power tank.

Something like this: https://www.halfords.com/workshop-tools/garage-equipment/battery-chargers-jump-starters/4-in-1-jump-starter

You just need to make sure it has a suitable +12v outlet.  There are lots of makes and models of these things and I'd be amazed if you can't find one locally.

That's a great price!

I did find similar car jump starters, but they are either small cheaply made lithium batteries, which is a safety concern for me;

or a lead acid battery that's over priced (equivalent to £ 100 after discount link). So maybe buying a proper safe lithium battery with double the life-span (theoretically), could be the best value.

17 minutes ago, DaveL59 said:

does seem pricey but may well do the job, has mains inverter output which is likely why, do you really need that?

so long as it doesn't auto-shutdown with a low-drain load it could work, tho using the AC outlet will reduce runtime quite a bit I expect. I have a LiPo car jump-start pack that's smaller but similar rated power and use the Cig socket adaptor to hook up to a Buck converter to deliver 12v out to the SynScan, seems to work just fine and cost around £65 all in. Just be sure you check the DC output  voltage before you hook up the scope as  they can be a lot more than you'd see off a regular 12v lead battery, mine showed 16v which is more than the 15v max for the goto, hence the buck converter.

I do need a power tank as most of my observing sessions are remote. I live in a flat with restricted outdoor space. the power tank is expensive, but the cheapest available power tank that can be shipped to my location.

Regarding voltage, the manufacturer states it has a " 4* 12V DC for car powered device under 60W" which I think means 4 outlets that you can connect to a cable with negative car socket adapter. The mains outlets are 2 and are 120V AC (300 Watt Surge)

9 hours ago, Cosmic Geoff said:

A more conventional choice would be a Celestron or Sky-watcher telescope power tank, or one of those car booster/12v cigar socket outlet devices from a car accessory shop. I have one of each, plus a 12v 7AH sealed lead-acid battery I wired up myself.

I tried buying the SW or Celestron power tanks from multiple sites, US and UK. but non would ship internationally. For safety reasons

On 24/10/2019 at 21:54, Dumbo said:

Total noob here first time post and need some friendly advice, 
I'm seriously thinking about getting into star gazing with telescopes and after looking around in various places it seems this is a good one to go for, I can see it's not that portable but still could be manageable with a bag and certainly doable with 2 people. 
I'm wondering what your thoughts are and if perhaps there are other options around this price range £200-300? 
As mentioned I'm a total noob with telescopes, all help and advise would be greatly appreciated.


 

Spot on, 8 inch is a good choice. And it's even doable with 1 person. 

What do you guys think of this power station. I would buy one for my current telescope or any other in the future.

Reason I'm thinking of this one, as it's the only site that'll ship internationally.

https://www.rockpals.com/collections/portable-power-station/products/250-watt-portable-generator-rechargeable-solar-generator-with-110v-ac-outlet

https://www.amazon.com/Rockpals-250-Watt-Generator-Rechargeable-Emergency/dp/B075SSMR6K

My favorite!

On 29/09/2019 at 17:20, Geoff Lister said:

I have the same Skyliner 250PX flextube Synscan GoTo. I bought it after enjoying the same GoTo system on my Skymax 127 Mak., but wanted more aperture. My experience is that the handset's indication of voltage is a few tenths of a volt lower than my DVM measurements at the power source. I usually use a 12V, 2.0A, plug-top mains PSU, with the 12V lead extended with about a metre of  heavy-duty, white, bell flex (shows up much better in the dark). I have measured supply currents for my powered mounts:-

The above are mean currents, and peaks will be slightly higher during acceleration. It is important to ensure that your 12V connectors are making good contact, and that any conductors have a decent diameter of copper.

At power-up, the "system" does not know where it is pointing, so it sets its electronic registers to zero (pointing to polar North and OTA level [alt = 0]). If the previous session ended with the "Park", "HOME" function, and the base has not moved, or has been put back exactly as before, then electronic and mechanical axes are aligned, and the handset should offer a reset from park position; avoiding the need for re-alignment (you still need to update time and date). Polar alignment is not required. The alignment process corrects for any errors in the starting position, and the cross-axis coupling if the base is not level, and the OTA is not sitting accurately in the Alt axis.

I have added a decent bubble level to the base, and use a wedge under one of the feet to get the base level. Turn the base so that the bubble points between 2 of the feet, and insert the wedge under the other one to centre the bubble. This ensures that the azimuth axis is as vertical as I can get it. This is not essential, but makes the alignment sums easier, and helps with the manual slew to the first alignment star.

I tend to use the "Brightest Star" alignment; often at dusk, when only the brightest stars are visible to the naked eye. Currently, I select Jupiter and, as the first slew is a manual one, the handset gives me the altitude, which I use to set the marker on the altitude scale, and then stand behind the OTA as it rotates, and stop when it is pointing roughly at Jupiter. Jupiter will then be in the finder, and I do the final centre with a 25mm EP and slew rate 4. Now the mount does a proper 2-star alignment, but with the advantage that it will do an automatic slew to the first star. Again, currently, Altair and Arcturus are visible from my garden, and make good alignment stars, clear of trees, fences and houses; and with good azimuth and altitude differences. I spent a few hours with the "Stellarium" program on my PC. I adjusted the date and dusk time for the middle of each month of the year, and selected 3, 4, or 5 bright stars, visible from my garden, and giving good azimuth and altitude separation. The table gives rough direction (N, NW, W etc.) and the altitude angle. I ended up with a table of 14 stars (+ Polaris, if stuck, makes a reasonable 2nd star), mostly the alphas of their respective constellations. I did the same for 1 hour before dawn, but this table has had little use.

I had to add a weight at the primary end of the OTA, as the clutch tended to slip if I was using a binoviewer, DSLR or my 2" 56mm EP. I also tightened, slightly, the altitude axis nut; but still leaving enough slack for manual adjustments.

Geoff

 

 

lots of good tips and advise in this post, which helped me. Thank you!

On 29/09/2019 at 21:19, masjstovel said:

I'm sorry, I didnt read Your post well enough, just got caught up in the power-supply-thingy:)

No problems at all

On 29/09/2019 at 21:49, Owmuchonomy said:

It is highly likely the problem lies with your power supply. I had exactly the same problem with my 12 inch Synscan Dob. I solved the problem by using a 12V 4 amp mains power supply.  My Powertank was supposed to be 17 Ah but it would not power the Dob for more than 30 minutes.

3 Amps for mains power seems fine so far,  4 Amps could be next on my list, though mobile batteries are my priority now

On 29/09/2019 at 22:08, Marvin Jenkins said:

I lost three valuable nights astronomy due to major alignment inaccuracies. My large power supply said perfect but plugged into the mains all problems disappeared. A day later the battery said it needed charging! Eliminate the obvious.

Battery packs are great but the light systems on the front to test charge are not very accurate.

Marvin

Trust me I have lost more, and kept my patience in many xD but glad that I gained knowledge in a new area (power and electricity)

On 29/09/2019 at 22:11, James said:

A lead acid battery giving 11.7v is effectively dead for use with the scope. Connecting it to another battery (or any charger) for a few  minutes will result in the voltage going up, but it won’t last, check again in half an hour and it will probably be back down at 11.7. 
 

You really need to get a proper charger for it (I suspect you’ll need a new battery, lead acids don’t like being emptied all the way). If you use AC power then things will probably improve but if your are away from an easy source of power then you’ll need a new, fully charged battery

This was also helpful, I've never went back to the battery and decided to try a working car battery first, before buying a dedicated one. Thank you!

On 29/09/2019 at 22:40, teoria_del_big_bang said:

 

As above I would get a new battery and charger and make sure it is always fully charged before a session, do not fully discharge and recharge after every session. I would also be tempted to get a bit bigger capacity battery then 7Ah.

Steve

I'm considering a 17 Ah or larger. Can't find a shop that will ship to me, due to safety regulations. Though I may just end up buying a separate car battery

On 30/09/2019 at 17:12, Ships and Stars said:

I use a Yuasa 70Ah deep cycle leisure/marine battery and fully charge it before each use. Heavy, but lots and lots of reserve power. £62. Both this battery and my 105Ah deep cycle in my camper read between 12.7 and 12.8V when fully charged, quickly dropping to 12.4-6 once in use and peaking around 13.8-14V when charging. I have a double cig lighter cable for my GOTO. Sometime I'll pop in the voltmeter and see what it drops to when slewing on Rate 9 etc. 

Impressive battery!

I've bought a value voltmeter for the long run. I will start to learn how to use it.

On 01/10/2019 at 10:59, JOC said:

I have been where the OP is with mine and understand the frustration.  I have a 17 Ah Car jumpstart box that seems to work well, but for the avoidance of doubt it is also possible to invest in a mains plug for the system at reasonable cost.  Even it means running an extension lead testing the telescope with a mains supply in the back yard it would remove doubt in the power supply until the issue is solved.  I find the mains lead is a really good investment and only use my power box if I'm too far from the house for the extension lead.

FWIW I have never dismantled my Dob and removed said plastic ring and I've never adjusted the clutches - I wouldn't know what these are or what to do with them - I think with synscan Dobs they are a non-issue and in this case, probably, a red-herring.  What I have taken to doing is in terms of finding North I've started finding the Pole star and lowering the telescope to horizontal at that position and using that as North - at that point I switch on the synscan.

It might be worth checking the daylight savings time settings.  If you have a mobile downloading an application called Synscan init 2.0 and turning on the phone GPS will give the OP every setting correct and in the correct format that they need to put into the device, one thing I tripped over was don't forget to add in any leading zeros esp. in the position settings those leading zeros are really important if they are there - it does sound like you are in the East, but if you are in the west then a minus sign might be needed.  If you use the app. then enter everything exactly as it is presented - from what the OP writes it sounds like they are getting most things right, but the app. just give that extra confidence and I still use it each time.

Other things I found was that mine was highly sensitive to weight.  I don't know what the OP is using, but when you do the set-up try it with EXACTLY what the scope was sent with and nothing else.  No added finders, no big chunky EP's, no dew shields or heaters, no hefty battery packs etc.  Strip it down to just what it was sent with  and just use the little light Plossl EP's that probably came with the scope and the provided finder - nothing else - mine still calibrates best when I use only these with the telescope.   Also, don't fill the holders up with stuff or sit things on the edge of the base - do nothing to upset the balance or twisting motion and see if that helps.   It can also help if you use something like the mobile phone version of Stellarium to make sure you know which star the unit is driving to so that when it says centre star in the eyepiece you are certain in your own mind of which one to be getting into the middle of the EP.  I don't know my stars well and it does help to be certain you know where the scope is driving to and therefore what to centre on when it stops as part of the calibration.  It is also best if you select stars that are a longer distance apart in the sky so try to pick one that is almost behind you from North maybe. 

Also check that the cables are not getting wound around the scope as these can upset things.  Oh, yes and I can practically guarantee that the day you finally get it functional you will get that excited that you will forget the cables and after 10 minutes they will get that tied up that they pull themselves out and you have to start all over again!!

 

I have used the default accessories for the initial trials until I got it aligned and then used different accessories but were similar weight and did not find any major problems.  regarding set up options, all were correct, I double checked with the amazing Synscan init 2.0 app as well.

and yes I was excited!  I found that the scope takes the longer angle to rotate sometimes, and the the cables get extended to the limit. to remedy that, I locate the object on the sky map, manually rotate the scope to the direction of the object  (with the handset directional buttons) then use the GoTo to locate the object, this will make the scope not turn more than 180 degrees and will contribute to saving power.

On 01/10/2019 at 14:22, barkis said:

These headaches can spoil the enjoyment no end.
Ron.

They have, but I'm much happier now xD Thanks for the help Ron

On 01/10/2019 at 18:09, Ceramus said:

One simple thing that perhaps has been mentioned before but of great importance is the precise centering of alignment stars in the eyepiece. I use a high-ish power illuminated reticle eyepice and make sure the last adjustments are UP and RIGHT.

This is good advise. the use of up and right as final steps to align, do contribute to the accuracy of the allignment

Update :

I would like to thank everyone for their contribution in this topic. I have finally managed to sort it out. As many have suggested, power was the issue, and I have managed to solve it. Sorry for the late reply, but finding the right time for an observing session + weather + debugging the issue, all contributed for the late reply.

I have planned to test 2 methods:

1- Use mains power 2- try car socket battery power. Which meant I had to find some power supply cable and an extinction cord for the cigarette socket to position the scope an appropriate distance away from the car, to keep all sides visible.

1- I found 2 power supplies with 2 Amp 12 V (Mains power),  tried them and both didn't align the scope correctly . I managed to find a power supply with 3 Amp 12 V and with multiple tries on different nights I finally managed to get the stars aligned with acceptable accuracy. As long as the target is anywhere in the 25mm EP view, I'm pleased. Boy was I happy when I managed to view Uranus for the first time! Not an easy target

2- So after I managed to align successfully using mains power, I had to insure that my scope works well when using batteries, since I ,mostly, stargaze outside my home. I tried using a working car battery via an interior cigarette socket, using the original cable that came with the scope, connected to an extension cord I bought. I manged to get an alignment that was one nudge away from target ( I might have been able to align more accurately if I tried again), though this was good enough for me to start the session and this time I went for Neptune! very small even in a 5mm EP, which was pushing the limit of my skies at that night. I have also enjoyed the views of a couple of DSOs.

My next mission now is finding the ideal battery for my use!

I would like to thank this community for helping me solve my problem and for keeping this hobby live and enjoyable!