Dobsonians for first users.

[creeksky]

Having decided on a Telescope and going for a Dobsonian,I now have one ( an 8 inch full tube).This is claimed to be an ideal beginners scope and the "best bang for buck,"which will let more light in, and allow you to see much further than Dept store bought scopes.

The learning curve has been steep and it keeps on curving, bringing new discoveries with it.
Yet, just like planning a rocket launch,I am yet to launch my new view of the universe and use it in the field.
-(cloud cover since purchase?)Apparently this is to be expected-4 days and counting!

I thought from my help deciding thread,it may be best to go from that, to actually having one- from a newbie perspective.
First, it is exciting just to have a decent Telescope, that will allow views of some DSO's (Deep space objects) far away tiny faint galaxies, planetary Nebulae, clusters and the solar system, they will be faint and not in colour,(Maybe larger planets will) it maybe even hard to dicern shapes.But you will be seeing further than you have ever before than with no Telescope.(light that has travelled years and centuries!)
First ,once you get a decent size light collecting telescope, they seem huge! But to others more experienced,it is tiny, A 12", 20 "or more must be amazing, but even a 60 inch will not see the colours we are spoiled with by Hubble images converted by many filters and reprocessing.
We all have to start somewhere...so start smaller and maybe later upgrade.

An 8 inch scope will fit laid across the back seat of a small car, with room for small cushions either end,as it splits in two- a rocker box-the wooden base ,I had to sit in the front passenger seat, strapped in with a black blanket covering it-The looks were priceless! As it resembeled someone covered in a Burqa.
The wooden base swivels, if this is stiff to move, adding a milk bottle washer will help greatly- thanks Iceman!
http://www.iceinspace.com.au/63-116-0-0-1-0.html making it buttery smooth:)

This allows you to track a star or object by nudging the base, so it again crosses your view FOV,through the scope,you may need to do this every 20 -30 seconds at high powers.(lower mm )eye pieces-EPs.eg:wide field of view=FOV (25 mm) =low power or a higher power =(10mm) EP or less.

So now to start, the questions you and I may have -Feel free to add your own.

-can the finder scope be focused? Or just a general point and go?

-Why does the dust cover have have 2 smaller caps, one a dummy and the other opens?

-Does this aid in someway to see things differently? Like planets?

-what is the best way to "Star hop" without altitude and azymuth markings, and time and decleration marked on the scope? Without smart phones and laptops.

Dobsonian scopes turn things upside down and reversed, how do you compensate?

[louie_the_fly]

Check out this thread on Astronomy Forum. It shows you how to focus the finder scope, assuming yours is the same.

http://www.astronomyforum.net/dobsonian-telescopes-forum/127903-apertura-ad12-first-light-report-4.html

[Solitarian]

To reduce the aperture, with the open hole fitted with a solar filter you can view the sun, the dummy is for holding the cap while doing so.

[creeksky]

Thank you Stewart, mine has a tiny silver knob which could be it, I did notice it today only by making a mount for a mobile phone. Will have to try it in daylight,no stars yet.
Can confirm SkyEye does not pickup a magnetic field, if mobile is mounted above the finder scope, have yet to confirm accuracy, in practice.If anywhere near main scope-magnetic field detected.
I aligned with the sun but not looking at it- seemed to be close.
Apparently an RACI (right angled correcting piece will help)for use without smart aids.
For use with star charts(credit Barx1963)

[creeksky]

Ok great to know Solitarian-Viewing the sun is extremely dangerous I was told by previous owner it helped with viewing the "jewellery box cluster? And planets, or moon.
-Will hold off on that,until I know more.

[creeksky]

Without a GoTo mount, do I need a laptop to calculate positions or just a star chart to pick out the brightest stars? Will a red light be enough to read star charts without disturbing others?

[creeksky]

Fact or false,?
collimating can be done simply by pointing at a distant tree branch, aligning with the finder scope if they match your scope is collimated? (This is from a retailer) I won't name.
Without a chessire coliminator or a laser can star coliminating be a good guide?
ie: can perfect concentric star circles confirm DSOs and other objects will be seen and in focus?
Near perfectly for your device?

[barx1963]

Pete
If that is the advice being given by a retailer they need to be named. Pm me with it uncomfortable doing it publicly.
Collimation has nothing to do with the finder, it is about aligning the mirrors within the scope to optimise the light gathering potential and minimise aberrations by ensuring the coma free portion of the image plane.
Star tests can be used to collimate a scope, a good explanation can be found here http://www.garyseronik.com/?q=node/238 and on the same website a bit of an explanation of collimation generally is here http://www.garyseronik.com/?q=node/169 , read the FAQS at the end as they make the purpose of collimation very clear. Also be aware that the no tools collimation can be a little hard to execute on a non driven dob (but not impossible) and usually needs good seeing. I usually use a star test to confirm my collimation.
Now for this question "can perfect concentric star circles confirm DSOs and other objects will be seen and in focus?". If collimation is not quite perfect, the scope will still be usable, it might not be optimal, but collimation is a game of diminishing returns. Your 8" f6 as a "slow" is quite tolerant of small collimation errors, so best advice is collimate it as best you can then get out and use the scope, rather than spending hours trying to get it perfect.

Malcolm

[barx1963]

More answers
Good to see the previous owner warned about the sun. The small removeable caps are used to "stop down" the aperture, in effect turning an 8" scope into more of a 2" (or whatever the size of the hole is. This can be useful for viewing bright objects like the Moon or even Jupiter when it is really bright, as the glare can sometimes obscure details.
DO NOT attempt to use this to observe the sun, MUST HAVE A PROPER SOLAR FILTER fitted (I know this has been said but you will wreck your eyes if you try and blindness is for ever!
Not sure why it would be used on NGC 4755 (the Jewell Box Cluster) as it is a nice object but not that bright! That is a very worthwhile cluster that is well worth checking out, if you have a look at the chart I have attached it sits next to Beta Crucis and is the yellow circle labelled 4755. Just wait till Crux is reasonably high and you will be rewarded!
Talking about finder scopes have you aligned yours?
A red light should be more than enough to read charts.
You should not need a laptop, unless you setup your scope with setting circles and then use the laptop to convert RA and Dec to Alt Az settings, but there are smartphone programs that do as good a job I believe.

Malcolm

[creeksky]

Ok I will PM the retailer, I was relayed from the prevous owner how he was told to align to a distant object (tree branch) and use finder scope confimation (I know there is alot more to it) I have found a vitiamin capsule lid that may fit instead of film canister.
Also some links I will post later for easier colilmation, ,but once I read some links makes it very easy to understand.
And don't let collimating put you off a dobsonian, it's easier than first thought.

[barx1963]

Just to clarify, it was not a retailer that told you, but it was the previous owner who was told, and he was telling you? Sounds like a serious case of Chinese whispers!! :D
Some retailer I wouldn't trust to give any advice (Aust Geographic stores for one!) but most specialist astro retailer in Oz give good advice.

Malcolm

[creeksky]

Well maybe he really didnt know, and just assumed a brand new scope was calibrated.
For the 5 times he used it, he had excellent views.
I wil check it as per your links and some I will add later, I'm just eager to have a clear night to be blown away! With no light polution, hoping for Jan21 new moon I think?

[inertia8]

you'll want as little moon as possible for viewing objects other than the moon and for viewing the moon itself you'll be best with it after new moon when the terminator makes viewing the craters near it show more detail.

[kens]

The "collimation" instructions you were given sound more like how to align the finder scope. You want the finder scope to point at the same point as your main scope. The silver button you mentioned on the finder scope sounds like one of the three adjusting screws you use to align it.

[geolindon]

Pete,
congrats on the 'scope n i think you will find it the right one; i know i sure did! great visual bang for buck n as u have said, portable. however . . . . beware aperture fever :)
i view the moon through the 50mm removable cap opening on the dust cover, it cuts down the brightness to what is for me a more comfortable level.
i am lookin to soonish upgrade my locating probably to skyEye n a tablet. so far and atm i am having lotsa fun juz using cheap n available online or magazines' sky charts along with skymap free on the iphone and some times stellarium on the laptop. i live in the bush so permanent dark sky site which i think makes it easier because i can see so much more naked eye. i find i can usually hop to the area then scan with finder 'scope then 25mm plossl. for the comets Comet Catcher put me onto http://cometchasing.skyhound.com/
after a while its a lot like using a street directory in an area ur familiar with - a check of the target's position against some familiar land marks, put the map away and go. tho some times mental gymnastics to get up n down left n right correct :)
i am impressed by nebulae, so early on got the filters.
i got the 8", plossls n barlow via the Mackay star gazers site, every thing else so far from IIS classifieds.
enjoy, regards Lindon

[creeksky]

Thanks Lindon,
Halealuah!
The sky has cleared! Hooray!

http://i59.tinypic.com/2rhoh1g.jpg

http://i62.tinypic.com/34dkear.jpg

Was worried about having no red light, but found the charger of a USB with a 9V lipo battery has a tiny red light.
(The type used to charge RC copters)

WOW! To quote Jodie Forster in Contact" I had no idea! "
So many stars! used the 20mm mostly to the east, had about 25 minutes before clouds rolled in from the east, then the north west and they circled and closed,in until only at zenith could I see any stars
Then they were gone.
I saw Archturus, but no DSOs didn't get time to try the barlow and only 3 minutes with the 10mm.
Not sure if the eyepieces are too weak? Or just not in the right place.
It was not good placing the dob on a small square pallet larger than the base.
I ended moving the chair it just got in the way, nearly tripped over it!
Nor looking at skyeye and it was out, by a bit, even though aligned and on the scope.
Mossies had a feast.
It was fun, so much to see!

[geolindon]

Pete, great pics, looks like a slice of heaven right there. AND dark sky!

dunno about your ergonomics/physicals but i was fortunate to have a disused hot-water-system stand made of 20mm box steel and timber deck, its solid/stable and raises the scope to the right height for me (a tallie) to stand and view comfortably. i put the scope on the ground tho for shorties n wheelies.

note ur comments re skyEye n interested to see how you progress with that. there is a thread here where some members share good results.

also your eps are good 'powers'. after a while i read comments by others and now agree that wide apparent field of view eps make viewing easier with a push pull dob because the target stays in view longer between nudges. my 9mm 100 fov is my most used ep atm. but don't rush it my 25mm plossl still gets a lot of use. this link is an easy way to work out what eps do what in ur 'scope;
http://www.davidpaulgreen.com/tec.html

as molly said 'do yaself a favour n go out n . .' find comet Lovejoy (another discovery by Terry L an IIS member), its easy to find atm near the pleiades (see link in my last reply) 'cos its bright n fuzzy. the corona will nearly fill your 20mm's field of view. the tail is visible in finder scope n binoculars. its only in our skies for about two more weeks n its something yas won't see every night.

the mozzies etc don't compete with the BUG n i enjoy the balmy evenings. while in south africa in sept 2014 i went to Sutherland where Kambro Kind B & B and Middelfontein Farm have 12" scopes for tourists N IT WAS FREEZING at least for tropically adapted ppl!

clear skies (but not drought), Lindon

[geolindon]

Pete, great pics, looks like a slice of heaven right there. AND dark sky!

dunno about your ergonomics/physicals but i was fortunate to have a disused hot-water-system stand made of 20mm box steel and timber deck, its solid/stable and raises the scope to the right height for me (a tallie) to stand and view comfortably. i put the scope on the ground tho for shorties n wheelies.

note ur comments re skyEye n interested to see how you progress with that. there is a thread here where some members share good results.

also your eps are good 'powers'. after a while i read comments by others and now agree that wide apparent field of view eps make viewing easier with a push pull dob because the target stays in view longer between nudges. my 9mm 100 fov is my most used ep atm. but don't rush it my 25mm plossl still gets a lot of use. this link is an easy way to work out what eps do what in ur 'scope;
http://www.davidpaulgreen.com/tec.html

as molly said 'do yaself a favour n go out n . .' find comet Lovejoy (another discovery by Terry L an IIS member), its easy to find atm near the pleiades (see link in my last reply) 'cos its bright n fuzzy. the corona will nearly fill your 20mm's field of view. the tail is visible in finder scope n binoculars. its only in our skies for about two more weeks n its something yas won't see every night.

the mozzies etc don't compete with the BUG n i enjoy the balmy evenings. while in south africa in sept 2014 i went to Sutherland where Kambro Kind B & B and Middelfontein Farm have 12" scopes for tourists N IT WAS FREEZING at least for tropically adapted ppl!

clear skies (but not drought), Lindon

[creeksky]

Thanks Lindon for the link and tips.
Yep slice of heaven, why do I need a scope? All those suns, DSOs lighting up my dark skies at night, keeping me awake at night.I'm too used to the dark,even street lights annoy me:lol:
So I'm exploring what and where they are.:lol:
Placing the dob on a larger base helped to make it higher so I could stand and sit better but still not ideal, as I had to try and read skyeye on top of the dob finder scope instead of on an angle facing me so was too awkward.Also my back ached.
I didn't need push pull too much as I mainly used the 25mm EP. But 5 minutes with the 10mm I could see how you would need too.
All a learning experience, fun and makes me appreciate what you all do with such dedication.
-I am in process of creating a trolley for TARs, out of an old golf cart, which seems ideal in theory, it even has EP holders already and the handle adjusts down to horizontal to make a mini table, for star maps or a tablet.
(I went into town looking for a trolley or a pram, and lo and behold there at the tip recycling was an ideal old golf cart, free and with 3x EP holders....? Spooky.)

[creeksky]

"Now if we are all ready" On the dark side of the moon ?
"I don't think we could have asked for a more wonderful sky!"-CE3K
Just went out to check, thought it was a total white out! But no, total clear skies-Yeeha!
20.oo pm.

http://i61.tinypic.com/643xcp.jpg

http://i58.tinypic.com/2q04tpu.jpg

Temp TARs Trolley:eyepop:
With table for star maps, red 3 layer celophane torch and pen with Mars rock I found in the creek;
May sell on Ebay to afford a 12 inch lol!

[creeksky]

Skies have cleared, rain has gone.
The stars are near ready to fairly blaze upon the valley!
T.A.R.S has been positioned on the launch trolley....:thumbsup:

http://i57.tinypic.com/30hrh5k.jpg

:D look out U.F.Os and D.S.Os

[creeksky]

Had some great views of the cresent moon using 25mm +2x barlow and the 10mm
Brilliant! crystal clear.
Clouds started coming from the west and had a look a Sirius wow! It was like a supanova!
Then Jupiter rose and it was brillant too, could make out 2 brownish bands and 3 moons.
Questions:
What is the silver screw for in the centre of the crayford focuser?

Sometimes changing EPs I would push the focuser out of focus, and was hard to re-adjust?

How can I adjust the finder scope, there doesn't seem to be enough free play to move it?

Also I still cannot seem to find a way to focus the finder scope?

I think I need a beekeepers suit for the mossies:lol:

[inertia8]

If it's like the gso one there should be a screw to lock the focuser and another adjusts the tension of the mechanism. Ie if that is very loose and you put a heavy eyepiece in the focuser will drop all the way in with the weight.

[raymo]

I assume that your Saxon has the same finder as all other Skywatcher Newts. This being so, you will see that the rear end of the objective lens holder is knurled. Hold the lens holder and slacken off the knurled section, which is a separate ring. Turn the lens holder to focus the finder, and tighten the knurled ring while holding the lens holder.
The silver screw on the bottom of the focuser is a lock screw to keep
the focuser locked in focus whilst imaging, or sometimes if you have a very heavy eyepiece in the focuser. The screw should therefore be slack when adjusting focus.
You must have a different finder, because most have two adjusting
screws and a spring loaded third one located equally spaced around the rear end of the part of the mount that the finder slides into.
Hope this helped.
raymo

[Suzy]

Hi Pete,

For the mozzies, I found the best results were by taking my box fan outside and blowing them away. I have a really really long extension lead. :lol: I find even when I use RID, they still buzz around my head trying to bite my ears and nose and bits :mad2: and the sound of bzzzz bzzzzz around my head all night is really annoying and distracting to observing :mad2:.

As for the finder. I have a Saxon dob. I no longer use the finder that came with it as I have a Stellaview finder now, but wow, I didn't know it could be focussed. All the time I had it, I was doing the glasses on/glasses off dance for the finder. Thanks for that info Raymo.

[raymo]

No problems Suzy. I don't know about when the scopes are sold as Saxons, but when sold as SW the manual that comes with it tells you pretty much all you need to know.
raymo

[inertia8]

Raymo/Pete,

Having just taken responsibility for an ASV loan scope, a Bintel 8" Dob, it has a RACI finder scope and the mechanism for focusing the finder is exactly the same as you described. Hold the objective, slacken off the knurled ring, then rotate the objective to focus and tighten the knurled ring to secure focus.

Mozzies, thanks for the tips Suzy, I was out using the dob for the past 3hrs and the coil I lit, plus the Bug off wasn't working 100%, I'll try a box fan.

Reasonably good viewing in Melb tonight, managed to wait long enough for Eta carina neb and its nearby cluster and NGC open cluster to be visible from my deck... breathtaking some of these objects!

[Suzy]

Pete, I got scared off with using repellents.
Apparently, a lot of people don't like using coils because it's not good to get that stuff on the mirror ? I don't know how true this is or how many people still do it. Perhaps someone who knows would like to comment. I read a thread a few years back.
And as for the RID or Aeroguard it's an instant killer to eyepiece glass if that stuff gets on them. So I'm extremely careful on where I put it on and only do rarely and with caution. So I ended resorting to the fan, which really did work the best.

[creeksky]

Thanks raymo, inertia and Suzy.
Yes, I had heard insect repellent is bad, I did not rub it on with fingers, nor spray near scope. (20 metres away)just sprayed my legs-so they went for my face so did that too and put on a long sleeved shirt.
The fan idea is a great, but a bit wary of running it across the road and wet grass and electricity.
I will have a play with the finder scope, glad you have an 8 inch to try Inertia, have fun!

[gaa_ian]

Those are some great tips there on controlling the Mozzies as well as protecting your EP's and Mirrors !
Thanks Suzy, I have a little battery power fan I use for camping, so I will try that next Obs night :-)

[BeanerSA]

Unless you use "parafocal" eyepieces, where the focus point is always at the same place, you are always going to have to re-focus after changing eyepieces. Different physical length eyepieces = different focal points.

[Suzy]

Thanks Ian, so glad to be of help. I actually got that beaut tip about the fan from Jeanette Lamb :) .

Pete, to protect it from wet grass caused by dew, I wrap up in a plastic bag & tie a knot where the socket connects to the lead.

[creeksky]

For some reason I keep "playing with" the center screw on the crayford focuser?
Either thinking it is the eyepiece screw or making a difference to the focus ,maybe even a fine tune to make faint fuzzies appear?:)
I get a fright when the EP and all drops down further than I expect ,when changing EPs.
Sometimes it all goes to faded star donuts, and I have to reassess and play with that screw.

Should I just leave it set tight or firm and not touch it?

Thanks Suzy I could try the plastic bag trick or Ians idea maybe even a USB fan.
If I start having elec handy next it will be a cd player, celophane red desk lamp laptop and tablets.
I could make a hijab head cover out of mossie netting, with eye holes cut out.

[raymo]

I have to assume that you are referring to the silver screw either on the bottom or the top of the focuser. It is a lock screw, and must be left
loose when focusing. It only needs nipping up when you want to prevent the weight of a large heavy eyepiece, or a camera, from causing the focuser to move thus losing focus. Just pop any eyepiece all the way in and focus as necessary. If the focuser starts to slip, there are four screws on the bottom of the focuser that can be nipped up a little. When you change eyepieces you have to refocus, unless as Paul said, you have what are known as parfocal ones.
Takes seconds to refocus, just turn the focuser in the direction that makes the doughnut smaller, and keep going until the object is sharp.
Did you sort out the finder focusing?
It just occurred to me that you might be referring to the smaller silver wheel on the end of the focuser shaft. If so, you have a dual speed focuser, and
the small wheel is geared down by a factor of 10, which makes fine focusing easier.
raymo

[creeksky]

Thank you raymo, it is to hold the focuser, if I tighten it the focuser will no move, must be for heavier EP or 2 inch EP.I will leave it alone.

Haven't tried the sight scope yet it's been 40C and don't want to cook the mirror or with thunderstorms around be struck by lightening- it is 2015.:)

Just taken with tablet to the east, sun shining on storm.
http://i60.tinypic.com/13z790i.jpg
Have been trying to construct a denver chair, as jupiter gave me a back ache, but worth it!
http://i58.tinypic.com/2u7yick.jpg
Taken now tiny moon in the west.

[Suzy]

Nice pics Pete :thumbsup:.
If you spanned left a bit more you would've caught gorgeous Venus low on the horizon with the crescent Moon (setting in the west), has been a beautiful sight these last couple of days. But never mind that, it's still a really lovely pic :thumbsup: I love the crescent stage of the Moon, it's so picturesque. Thank you for sharing your pics :).

[raymo]

I understand the lightning, but you won't cook the mirror; you can look at the sun with the appropriate filters.
raymo

[NTgazer]

Definitely don't use high deet content repellants like bushmans it ruins some plastics and rubbers. A Thermacell is my best defence and a battery operated fan - 18V makita especially when it's hot and humid

[creeksky]

Yes, have sorted the finder scope the black rubber O ring had been pushed further inside the holder than needed,(it came that way) Now the finder is not on an angle but aligned with scope and enough free play to adjust,also it's focuser I now know how to use.
As a friend once said to me many times "read the manual"

[creeksky]

I have almost finished my version of a Denver chair.
Has taken 8 hours to build, cost zero, all from wood I had laying around, and screws.
Still have to make more notches for height adjustments (as I don't have a bevel)
Nor sure how to use one, so had to adlib.
It takes my weight, (65kilos) but it creaks a bit -creeky-sky- chair.:D
Going to make a moveable foot rest too somehow.....and a metal cross brace+ a cushion.

http://i60.tinypic.com/6tpnj6.jpg

http://i61.tinypic.com/2zrqnn7.jpg

Looks like a clear night coming up yippie, but I am tired from building the chair....

[creeksky]

Had a terrible night observing, well before moon rise, Jupiter was ok apart from heat haze.
Even with 25 mm (with the later problem)
Went looking for DSOs near the large mallengenic cloud but for some reason the 25mm now makes all stars appear to be like saturn or small galaxies?
I don't think it is collimation, as if I rotate the EP the saturn/galaxy beams turn with it?
I did notice the outside of scope had quite a bit of dew, after an hour of observing.
The 10mm was ok but too limiting for wide FOV.
Does the 25mm need cleaning? How do I fix this?
What is going on?:(

[doppler]

If there is dew around the first thing that fogs up on my dob is the secondary mirror, a quick blast with a hair dryer sorts that out.

Rick

[raymo]

Probably had dew on the EP. A gentle twirl with a cotton bud inside and out will remove it. If dewed up EPs become a recurrent problem for you,
you can get an EP dew heater that wraps round the EP. You can also get primary and secondary mirror dew heaters.
raymo

[creeksky]

Thanks raymo, will try that, I better get some solar panels to run alll these extra gadgets I need, hair dryers ,due heaters and fans for mossies:)
Feel like I am setting up a film studio, all I need now is the mothership to do a roll over the valley mountains and capture it with a web cam attached.:rofl:
Might be cheaper to build a mudbrick observatory with bamboo dome......?

[raymo]

Is the sun out at night where you live then Pete?
raymo

[creeksky]

No, I plan to create a cylindrical light gathering panel to harness distant suns, it will be 4 feet wide.
Which will solve solar energy during the night.
At least enough to trickle charge a small red led.:)
With a mirror and lenses it will be a dual purpose telescope.

[raymo]

Sounds like a great invention, perhaps you could market them.
raymo