Some questions regarding Dobsonian reflectors

[richardda1st]

I'll be purchasing a 10" Dob as soon as I can sort out a few things such as:

(1) I'm leaning towards a Mead Lightscope 10", but I'm concerned about the rigidity and alignment of the 2 tube sections to each other.

(2) I have also been looking at the skywatcher 10" as the sliding design seems to look more accurate and easy to use.

(3) Is there any lose to image quality in an open section tube compared to one piece tube.

(4) The skywatcher doesn't have a cooling fan, is this important?

Is there any opinions out there on these subjects.

Any info/advice will be appreciated.

Thanks
Richard:whistle:

[PCH]

Hi Richard,

welcome to IIS :welcome:

I'll try to answer your questions, and doubtless other people will offer their views too. Here goes ...

1) The rigidity of the Meade Lightbridge and the Skywatcher design are both ok. I have the 12" Meade LB and the only difference between these designs and a solid tube type is that you have to align (collimate) the optics quickly before you view. It takes a few moments and is something you'll have to learn.

2) They're both as accurate as each other, - both are tried and tested designs. The Skywatcher (I don't have one of these) simple compacts for storage or transport, whereas if room is a problem with the Meade, you have to take it apart and put it back together (followed by a quick alignment of the optics).

3) There may be a slight loss of light and therefore image quality. What we usually do is put a black shroud around the truss (the sticks !) and this then simulates a full tube model.

4) The Skywatcher I believe has a primary mirror (the big one down the bottom) made of pyrex, which they claim isn't affected by temperature variations in the same way that the meade glass is. I've heard people say you should still have a cooling fan fitted though. So wait until some Skywatcher owners have offered a comment before making your mind up on this point.

Hope this all helps Richard. Above all have fun, and be prepared to empty your wallet, as this hobby is and endless list of bigger and better toys ;)

Cheers :thumbsup:

[mswhin63]

I too am interested in a 12". I noticed in the review of the Skywatcher the focuser end of travel drops a bit. I hope that is what it means. Is that similar to the Meade 12". Do they use the same focuer or same kind of focuser.

I like the Skywatcher collapsable design.

The only other thing i would like to know can the new Tracking or Goto motors for the 8 to 10" go on as a after-thought later. I don't have the budget for the tracking design and I really want a 12".

[Robh]

Richard,

I have a 12 inch Meade truss telescope. Don't know anything about the rigidity of the Skywatcher collapsibles but I believe that they have a Crayford focuser. My Meade Crayford focuser works fine.
There is no worry about the rigidity of the Meade. I can actually pick it up by the trusses and carry it, usually without too much effect on collimation. I would say both setups will require collimation checks after moving the scopes.
Loss of light is not a problem in an open tube design. However, a bright Moon or street lights can produce interfering glare in the lower tube. Anyhow, most of us avoid bright lights and do serious viewing at a dark site. I have never bothered with a shroud.
Whether the primary mirror is pyrex or BK7 glass probably isn't going to make a whole lot of difference. The main problem is the convection currents coming off the glass as it cools to the surrounding air. This gives images a hot or blurry effect. I use the fan to cool the mirror more quickly and it may also help to prevent dew on the primary. If you set up early in the evening with the Skywatcher, you will give the mirror time to cool down gradually for serious viewing. I find dew on the finderscope is a bigger problem.

The Skywatcher collapsible is quicker to assemble but the collapsed tubes will still be significantly longer than the bottom tube of the Meade, which can be carried as a separate item. Does it have to go in the boot of your car? I prefer to carry the scope with the tube vertical i.e. primary mirror horizontal (less jarring of mirror in frame). The collapsible will also be heavier to carry overall if weight is an issue.

Regards, Rob

[toryglen-boy]

The SW and Meade have different makes of focusers, they are both crayfords, but the one found on the SW is the same one found on the Synta/Orion scopes and is of good quality. I have since tightened up the action on my crayford on the SW, and its now much better, no sag at all :)

TBH, the Meade is made by GSO and is essentially a GSO scope, i have looked through two Meade LB's at star parties (a 12" and a 16") and TBH, i found the optically quality of the SW to be better.

;)

[Robh]

I'm willing to be objective about this. However, I would think it very difficult to compare the optical qualities of the two primary mirrors (secondaries of lesser importance). Did you compare say the Meade 12 inch and Skywatcher 12 inch at more or less the same time, under the same conditions (light and atmosphere) and with the same eyepieces. And did they both cool down over the same time period. And who did the collimations. Were they also checked? Then, it's still going to be a very subjective assessment.
Just defending my pride and joy, the Meade 12inch.

Regards, Rob.

[toryglen-boy]

Hi Rob

Actually, yes they were. It was at a star party, we arrived at the same time, setup at the same time, had the same time to cool down, the 12" owner even collimated with my laser collimator, and used my 32mm Meade, as he didnt have his handy, and we even looked at the same objects, with the same eyepiece, within a minute or so of each other.

Dont get me wrong, the 12" Meade was still very good. But star images through the SW where just that little bit sweeter, with noticeably less coma

;)

[Robh]

Duncan,
I'm happy you like your scope. If I get a chance one day, I'll compare a SW 12 inch with mine.
Just one question? The geometric design of the trusses on the Meade make it quite stable under rotational forces. I often use the trusses to turn the scope.
How do you find the stability of the vertical trusses on the collapsible and can you use them to turn the scope?

Rob

[toryglen-boy]

Hi Rob

Yeah i use the truss poles to move it, i guess i dont think about it i just grab the pole and move it. I can find absolutely no flex in any movement on the SW, thats said, i think the SW has teh advantage in the fact the design is slighlty different, as the poles never come off. I can imagine with a 'proper' truss dob, the constant dismantling and rebuilding would introduce flex and thats not good news, the beauty of the SW is that it is never dismantled, it just slides up and down.

I wouldnt read to much into my last comments though, i thought the Meade was still a very good instrument, infact i am considering getting a 16" right now

:)

[GrahamL]

Regarding (Q3) .. not long after finishing my trusser with still very much the intention to make a light shroud I took it out at ISAN to a park surounded by vapour lights( within 30 mts) .. you could very easily read a book from any angle ..Aside the odd low alt angle washout of the view most of the time it was passable .. not going to make a habit of this choice of venue I sort of lost the light shroud idea somewhere.

both scopes will show you a lot of what the night sky has to offer .. good luck with your purchase :)

[trick]

As you have witnessed below Richard, whichever scope you buy you will defends its honour and your choice in buying it to the death. It is all a personal thing and a form of passion you may not encounter through any other means. TIC :fight:

[mswhin63]

With all the information below, I am sure I would have been happier with either unit. Many thanks for the input, I have though made my decision and wasn't really based on anything below.

I couldn't find a local store in Perth that sells Meade :rofl: so i will get the SW dob.

You input though made it very relieving especially after buying a dud.

Never mentioned my previous scope purchace SEBEN 1000/114 - 4" short tube with EQ2 mount - EBay #^&@. Should have got advice before-hand.

[richardda1st]

Hi Glenn
At the moment I have a Tasco 114mm x 500mm Reflector on an EQ mount (a surprise gift from my wife-say no more). :D But it has been great fun trying to do the impossible with this scope, namely trying to locate Pluto. Using a free software program “Cartes du Ciel” and a very carefully set up EQ mount (Ra & dec) I know that I’m looking at the right spot in space because I compare the faint star patterns from the software program to what I see through the scope. It’s great stuff even with an obviously negative result. Can Pluto be seen with an amateur scope, if so what spec scope would be required?

I prefer a collapsible dobsonian because I would like to be able to take it with me on trips with the family plus gear it will need to be compact. A 10” is at my maximum budget wise at this stage.

So I have some idea in using and adjusting the mirrors (but not with any type of collimators) with reasonable success.

Forum

Right, I’m making progress.
From what I can gather from the forum comments it seems to me that the Lightbridge and the Skywatcher are both good amateur scopes. Up till now, no one has said that either is a piece of junk, so this is good.

Am I right in saying that the skywatcher is marketed by Tasco, and the Lightbridge is marketed by Mead but is not a true Mead product? Not that the answers are very important, just interesting.

I must make that trip to York and Bintel to see what sort of deal I can wrangle, although it looks like I will get a better deal buying through the net.

Thanks to every one

Good seeing u soon

Richard:thumbsup:

[richardda1st]

Hi Malcolm, good luck with your purchase. Like you I just don't want to end up with a dud.

[Vartigy]

Hi Richard,

I bought a SW 8" collapsible Dob from Binocular Telescope and Optical World in Malaga (perth) (@ Malcolm) a few months back.
And I must say. It's the shizzle!

Easy to use. Easy to set up. Literally wheel it out onto my driveway, 30 seconds of setup and I'm gazing into deep space.

I've only had to collimate the primary once. That was after travelling with it back to Kalgoorlie.

No, don't need cooling fans. Unless you're viewing in that god forsaken daylight savings time summer where we have to wait an extra hour just for darkness.

The truss/collapsable part is sturdy and strong. Barely moves when extended. Be careful when collapsing it. Mine took off on me on my first time. I had to adjust a few tighteners so I could lower it back down smoothly.

The EP's (10mm and 25mm) that come with it are all you need when starting out with it. Decent quality plossls.

I've seen Venus, Saturn, Plenty of the moon. M42, LMC, SMC, And all along the milky way every time I take it out on the driveway. Mind you, out here its pitch black skys every night unless its a full moon.

The base plate rotation, azi, was quite jerky first time. Make sure you put the teflon washer between the plates. I left it out accidentally first time. Thought i'd bought an ikea product (spare parts). Also work the board a fair bit and find the nice smooth part, don't over tighten the base plate nut.

The Alti cradle is a great design. Smooth moving, yet holds in position with SW's patented tension knob. Takes some practice to find the right spot for you.

The only changes I've added to the scope is a small platform to raise it up. Basically a 8" high box, 450mmx450mm. And I'm about to screw a magazine/paper holder/rack to the front of it for log book, AS&T mag, red torch etc.

Other than that. It's a fantastic rig.
I'm stoked with mine.

Aaron.

[mswhin63]

Well, I did it, purchaced the SW 12" DOB. Easy to set-up, Primary mirror required no collimination secondary only required a small amount so incredibly easy to do although laser coll does make it easy.

Definately no regrets, so much more light, can't wait to try in dark sky's. Definately show light pollution. Kwinana is a major manufacturing area and it shows.

It's a shame I am not feeling well otherwise would still be out there eyes on. Saturn was so clear compared to my old scope even with the rings almost side on to the planet was able to distingush the gap between the planet and rings.

Thanks to all on ICEINSPACE, ASWA and BTOW for all your assistance. :thumbsup:

[TJD]

hey i did the same thing i went to buy a 12'' meade but when i went to btow they only sold sw so i got a 12'' sw collapsible and i have to back up the sw here it is so easy to set up just take it out side colloimate(you do with most newts) it and your done that simple it even comes with an aperture mask and about a light shroud most people only use there scope for dso so they almost always observe when you dont need a light thingy magigy
get a sw only because its my best friend a bf stand up for each other dont they what ever you get its a telescope and thats all that matter just dont drop a scew driver on the primary mirror like i did good luck hope you get the right scope for you;)
yeh thank you iceinspace btow and aswa hey malcome dont tell that your previouse scope was a nexstar 6 se:P

[mswhin63]

Here is a link to my other one.
https://www.wit-usa.com/sms/shop/index.php?mode=view&idlistpos=4

I changed the lenses and the focuser needs to change although I can't find a decent replacement. The Barlow and Erecting lense massive Chromatic Aberation, and shakes big time.

Other than that not bad. :P

[richardda1st]

Have just purchased a "Mead Lightbridge 10" Dob". Now the long wait for delivery as the only one I could find is on the Gold Coast. I went for the Mead as it looks like it will be more compact when disassembled, hope I'm right. I would like to be able to take it with us (family of 4) on camping trips and the like.

Thanks everyone (especially RobH) for all the info, comments and opinions.
This forum caper is OK:thumbsup:

Richard:):D

[Robh]

Richard,
Just one other thing. If you're pushed for space, you can cart the bottom tube (rotated 90 degrees) in the base. Put a piece of carpet or rubber underlay in the base to protect the fan from the central bolt in the base.

All the best, Rob

[richardda1st]

All assembled, very easy, very nice.:D Heavier then I thought, I will not be putting the lower tube up in the space pod on the roof racks of my car as planed. Will fit nicely in its base in the back of the wagon. Robh, it will be OK without rotating tube.
I managed to get my act together last night and observed Saturn. A very thin layer of high clouds spoilt things a bit, and to much light pollution at my place. It was still OK, first with the 26mm than a 10mm plossl and even thought that the 6.5mm was OK also, considering the seeing was not the best. Must say that I miss the fine adjustment I am used to from my small old EQ mount. Will have to get used to the DOB way of doing things. Must also remember to turn the red dot finder of, I left it on all night and most of today. Very easy to use. Must get myself a laser collimator to fine tune the scope. I'm assuming the laser will do a much better job then just eye-balling as per the instruction.
Cloudy at the moment and looks like it will be all night, DAMN!:sadeyes:

[Glenhuon]

The laser is a great way to colimate, quick and easy. Just check that IT is colimated first, mine was out a tad when I got it. Have fun with the new scope.

Bill

[Robh]

When I bought my scope, I had either cloud or rain in darker skies (no moon) for 3 months. Very frustrating!

Rob

[TheoHE]

Hi Richard, it's been a few months since you were last on this thread but wondering what your opinion is now of the 10 inch Lightbridge? I have one on order after spending around a year mulling over my first scope. It had to come from the US first, should be in the eastern states around now then freighted to the West, so it's been a long wait. I am really looking forward to it's arrival. Have you needed to modify anything? Cheers Theo.

[richardda1st]

Hi Theo.:)

As you say, I haven't checked this thread for a while.
I am still satisfied with the LB, but I did have some issues. Instead of going over all the details here can I suggest that you check my statistics/threads and posts.

I find the LB very easy to move and setup. Since I fitted the altitude and azimuth scales I am enjoying it even more. Don't know why they're not fitted as standard, it wouldn't add to much to the cost.

I find that you must make sure that all the screws are tight, especially the ones securing the cast tube rings to the tubes. Make sure that the struts are also well seated and tight. I occasionally apply a tiny amount of fine oil to the thread of the strut screws, makes it very easy to tighten with little force.

Let us know how it goes.




Hi Bill,

I use an Orion Delux laser to collminate, very easy to use. Had mine checked (thanks EricK), twice, the first one died after a couple of months, Bintel exchanged it for a new. Both were slightly out but OK.


Richard:D