StellaLyra Dobsonian Series - Owners thread

[Piero]

On 13/08/2021 at 20:31, omo said:

 

Like the large screws for collimating and the springs on said screws. Would like to know if the fans on the base actually have an effect in helping cool the tube

 

 

 

The triangle to the left is misaligned. Not sure why, but it looks like those triangles can rotate freely. Whilst they should float freely, they should not rotate, otherwise this will unbalance the mirror back support causing astigmatism and spherical aberration due to changes in the mirror figure.

I don't really know why manufacturers / telescope makers still opt for a 9-point over a 6-point mirror cell. The additional RMS error of the 6-point mirror cell is completely negligible vs the 9-point and the 6-point mirror cell is considerably easier to make as it does not involve any triangle (easier => less chance to get it wrong => more consistent support...).

Anyway, the proper fix to the problem above would be to create a flexible ring structure connecting the triangles so that these can still move but not rotate. Whatever solution you go, PLEASE don't screw the triangle to any support in order to prevent their rotation. That non-solution - unfortunately used by some professional telescope makers.. - introduces a hell of issues as triangles won't be able to float freely causing the mirror figure to deform due to the mirror own weight. Rather than doing that, pay a quick look before using the telescope and align them manually if needed.

 

Piero

Edited August 19, 2021 by Piero

[CraigT82]

Have a look at this thread to see a good method of triangle alignment...

https://stargazerslounge.com/topic/378864-16-inch-f5-with-nichol-optics/?do=findComment&comment=4120933

[Louis D]

I've sometimes seen thin wire loosely connecting the flotation triangles on large Dobs and had wondered what it was there for.  They're usually not strung particularly tightly, and now I know why.  It's just there to prevent gross rotation of individual triangles.

[Stickotron]

Now that you've owned it for a while how are you finding your StellaLyra dob? How are the optics? Any issues or niggles? @omo

I ordered the 8" version of it earlier today, should arrive tomorrow with darker clouds forecast for a few weeks 😂

I was initially holding out to purchase a bresser messier 8" but seen this earlier today on here (haven't checked on here for ages as it was making me sad waiting for the bresser stock) but the RACI, dual focuser and impatience made me just go for it - prefer the colour as well. I couldn't justify buying a 200P/XT8 vs a bresser but I feel this balances out against its pros and cons.

[Rallemikken]

I have an 8" of theese, with the black and white collimation screws. Already found a couple of design flaws. First, the nut that is embedded in the lower base plate came loose. Glued it in place, and dug out a slightly longer bolt that allowed me to fit a big spacer and nut on the underside. Also trimmed the small, shiny tube spacer 0.5mm to get everything tighter.

Then I mounted my Canon 600D, and as expected, could not find focus. Set out on an endevour to rise the primary mirror 15mm, hope that is enough. On my way, I found two more flaws: The upper plate in the mirror cell looked like a propeller. Seriously twisted. It would not lye still on the table, 3-4mm twist. Now, that may be irrellevant, the mirror resides on three points, but it looked amateurish.

What is worse, the black collimation bolts (M6*25mm bolts, not nuts like SW) is threaded into open holes in the upper mirror cell plate. Theese holes aligns perfectly with the EDGE of the mirror. You have no control of how well the mirror is secured, and the bolts can reach the mirror if you either overthighten the original, or swap for longer ones, like I will do. The solution was to make three M6*50mm pinbolts, and screw those into the mirror cell plate (take care, not all the way in, leave one mm). Then I secured them with a M6 nut on the underside so they will not rotate. I did some measures, and decided to wind down another nut in addition, to achieve the desired 15mm I set out for. Then I slipped down a wide spacer for the spring to sit on. The springs are wide, much wider than the 6mm bolt, so I found three smaller springs that went inside the original. Now everything is tighter, and feels more rigid. On top of the springs I slipped on another wide spacer, before I put on the lower base plate. Another set of three spacers, before everything is secured with M6 nuts. The white knobs must also be replaced with longer ones.

[Mr Spock]

11 minutes ago, Rallemikken said:

What is worse, the black collimation bolts (M6*25mm bolts, not nuts like SW) is threaded into open holes in the upper mirror cell plate. These holes aligns perfectly with the EDGE of the mirror. You have no control of how well the mirror is secured, and the bolts can reach the mirror if you either overtighten the original, or swap for longer ones, like I will do. The solution was to make three M6*50mm pinbolts, and screw those into the mirror cell plate (take care, not all the way in, leave one mm). Then I secured them with a M6 nut on the underside so they will not rotate. I did some measures, and decided to wind down another nut in addition, to achieve the desired 15mm I set out for. Then I slipped down a wide spacer for the spring to sit on. The springs are wide, much wider than the 6mm bolt, so I found three smaller springs that went inside the original. Now everything is tighter, and feels more rigid. On top of the springs I slipped on another wide spacer, before I put on the lower base plate. Another set of three spacers, before everything is secured with M6 nuts. The white knobs must also be replaced with longer ones.

With my 12" I placed a round plate between the secondary holder and the screws (replaced with Bob's Knobs) to get round the issue with the bolts fitting into holes in the holder. I can now collimate perfectly - it was impossible before.
I also replaced the primary springs with stronger ones. All good there now too. I also find the white knobs too short, but I just tightened the collimation bolts more.

[johninderby]

I wish GSO would use heavy duty CNC primary mirror cells like Bresser. Not a fan of those light weight cast cells.

[FLO]

@Rallemikken Do you actually own a StellaLyra Dobsonian?  Or is it another similar model manufactured by GSO? 

Steve

[FLO]

4 hours ago, johninderby said:

I wish GSO would use heavy duty CNC primary mirror cells like Bresser. Not a fan of those light weight cast cells.

John, I understand you are SGL's No.1 fan of Bresser Dobsonians (we stock them too - nice telescopes) but FWIW my own 10" StellaLyra Dobsonian mirror-cell collimates nicely and holds alignment well. 

When GSO first released Newtonian / Dobsonian telescopes (I owned one, a 'Revelation' model bought from TH) their collimation springs were not stiff enough. But that was well over a decade ago! The mirror cells and springs fitted to the StellaLyra Dobsonians discussed here are not the same. 

HTH, 

Steve 

[Mr Spock]

The mirror cell on mine is fine. I see no need for anything ‘better’. 

[Rallemikken]

6 minutes ago, FLO said:

@Rallemikken Do you actually own a StellaLyra Dobsonian?  Or is it another similar model manufactured by GSO? 

Steve

It's the real thing! Purchased from you this spring, from Norway. And don't get me wrong; I'm not complaining! I couldn't get a better scope for this price anywhere else. Especially the focuser and secondary mirror holder impressed me. But theese scopes are always objects for tinkering, and there is a lot that can be done. The reason I want to use my DSLR are for planetary imaging, I already have a 200PDS/HEQ5 rig for DSO imaging.

All in all, I'm satisfied, but the thing with the central bolt in the base should be sorted out. When mounted, it was wiggle. Not much, but everybody responds to that by tightening the bolt. Which will do nothing, because the mentioned shiny tube is to long. When you later try to unlock this bolt, the nut-part in the lower plate comes out with the bolt. Just stupid engineering.And the bolt itself should be metric, not UNC.

[FLO]

7 minutes ago, Rallemikken said:

It's the real thing! Purchased from you this spring, from Norway. And don't get me wrong; I'm not complaining! I couldn't get a better scope for this price anywhere else. Especially the focuser and secondary mirror holder impressed me. But theese scopes are always objects for tinkering, and there is a lot that can be done.

I asked only because I don't recall anyone reporting the problems you shared 😇 

Dobsonians do seem to attract tinkerers. I am sure Johninderby will agree. 

Steve 

[Rallemikken]

14 minutes ago, Mr Spock said:

The mirror cell on mine is fine. I see no need for anything ‘better’. 

Agree, but many are used to SkyWatcher's cells. On those you can tighten the securing bolts hard, without loosing collimation or damaging anything. When they are spread out like on the StellaLyra, you have to take care NOT to overtighten, or things start to twist. Anyway, they shall not be tightened hard, no big deal. Screw them in so they just touch the upper plate.

[FLO]

5 minutes ago, Rallemikken said:

Agree, but many are used to SkyWatcher's cells. On those you can tighten the securing bolts hard, without loosing collimation or damaging anything. When they are spread out like on the StellaLyra, you have to take care NOT to overtighten, or things start to twist. Anyway, they shall not be tightened hard, no big deal. Screw them in so they just touch the upper plate.

I think it important you never tighten a collimation screw hard. Regardless of model. 

HTH, 

Steve 

[Mr Spock]

You should never use force to tighten any bolt. 
EQ-6 owners with bent bolts need to learn that rule 😜

[Guest]

On 13/08/2021 at 15:31, omo said:

Just to confirm this is the 12" scope

i got a bit distracted yesterday with another pier mounting adaptor for the Planet. I did get the base built last night though.

As per the OTA, the contents of the box are well protected

 

Small box contains the eyepiece holder which i will not fit. There is not a lot to it, if you have built one before you'll work it out easily. There are no instructions in the box but these are on Flo's site which those new to the hobby may find useful:  https://www.firstlightoptics.com/user/manuals/stellalyra_8_10_12_dobsonian_manual.pdf

You need a cross head screwdriver for fitting the handle, not many fixings to put it together

I really like the azimuth having the bearing much better than my previous 200p (quite a few things are in my opinion)

The most complex part of the construction would be the screw to hold the top and bottom base together

With the base is complete I felt it sitting last night in the living room, it needs a duster applied.

I'm going off on a tangent now but have you ever wondered how some objects can attract people and even trigger there imaginations? I am not meaning the tube either 🤔

I moved the base closer to the chair this morning as it was less in the way when my younger sister visited. Gail never had much interest in science, fiction or otherwise. Anyway I showed her the scope outside but it was the base that got her, quite taken she was moving it back and forward, next thing she clambers into the chair and has her feet on the base still toing and froing stating its quite therapeutic. What she then did was not so much for me.

She stands up  - on the base (so thats stress tested to 55ish kg then) then crouches down and is wiggling her bum trying to keep the base rotating a bit. This is priceless if i had a camera I would have, but had i asked her to wait, she would have moved quick enough to have Einstein reeling in confusion. She then astounds me "They used to sit like this in the Daleks didn't they EXTERMINATE EXTERMINATE"  🤣

55 years young, she really did hide behind the settee when Jon Pertwee was the Doctor.

Back to the scope and you have a range of adjustment to help with balancing the scope depending on your added bits and bobs, you do have to lift the tube out to accomplish this. Its graduated so you can keep the scope in balance on both sides. Will have to experiment with this further. You can use the same 4mm allen key that came with the scope to tighten the screws to the mount block / tension adjusters - just remember to slacken the knobs before you lift the scope into the mount.

A complete scope Resplendent in black

 

The focuser is very smooth, the screw nearest to the tube on its body is to lock it, the outer screw allows you to adjust the focusers tension, it has a brass compression ring on both 2" and 1.24" fittings so gouging of eyepiece barrels.

The finder shoe is the first irritation, it has a grub screw fitted, easily removed but why not just give it a second thumbscrew? I have a Baader finder shoe that will replace this once i find it.

Like the large screws for collimating and the springs on said screws. Would like to know if the fans on the base actually have an effect in helping cool the tube

Like the these, less chance of dropping a screwdriver compared to an allen key

Moving the scope proved to be interesting has to be done in two parts, a bit of a bear hug and a penguin shuffle for the OTA is required so as @Mark at Beaufort has done a few handles will be required.

On the subject of handles. Why do the manufacturers always put one on the front of the dob base - as soon as you pick it up its likely to drag the back edge on the ground, would one on each side not make a bit of sense?

One last pic before i go out to have a check on collimation having rediscoved the hotech and cap. I have not even got to looking at the ancillaries. Its very exciting - looking like i might get first light  later this evening, usually a new scope means i have to wait weeks

 

I have it's little brother called a Skyline here in the States.  It's a ten inch.  You will really want to consider changing those screws out on the secondary mirror to thumbscrews.  The springs under the primary mirror are not all that and I changed mine out and it made a world of difference.  My replacement knobs and springs came from Bob's Knobs.  The fan, believe it or not does work.  It sucks air out of the tube and draws air in.  My scope lives in my garage so it's always near ambient temperature and takes very little time to cool down. 

[Guest]

On 14/08/2021 at 05:06, John said:

With my 12 inch I flocked a section of the upper tube wall opposite the focuser / behind the secondary and also about 18 inches of the bottom end of the tube immediately above the primary mirror.

I also find using a light shield at the top end of the scope important in keeping unwanted light off the secondary and the inward end of the focuser when I'm using the scope at home where there are a few stray light issues.

NB: Mine is not a GSO, sorry

 

Where did get that light shield?

[wookie1965]

On 10/06/2022 at 09:17, Rallemikken said:

I have an 8" of theese, with the black and white collimation screws. Already found a couple of design flaws. First, the nut that is embedded in the lower base plate came loose. Glued it in place, and dug out a slightly longer bolt that allowed me to fit a big spacer and nut on the underside. Also trimmed the small, shiny tube spacer 0.5mm to get everything tighter.

Then I mounted my Canon 600D, and as expected, could not find focus. Set out on an endevour to rise the primary mirror 15mm, hope that is enough. On my way, I found two more flaws: The upper plate in the mirror cell looked like a propeller. Seriously twisted. It would not lye still on the table, 3-4mm twist. Now, that may be irrellevant, the mirror resides on three points, but it looked amateurish.

What is worse, the black collimation bolts (M6*25mm bolts, not nuts like SW) is threaded into open holes in the upper mirror cell plate. Theese holes aligns perfectly with the EDGE of the mirror. You have no control of how well the mirror is secured, and the bolts can reach the mirror if you either overthighten the original, or swap for longer ones, like I will do. The solution was to make three M6*50mm pinbolts, and screw those into the mirror cell plate (take care, not all the way in, leave one mm). Then I secured them with a M6 nut on the underside so they will not rotate. I did some measures, and decided to wind down another nut in addition, to achieve the desired 15mm I set out for. Then I slipped down a wide spacer for the spring to sit on. The springs are wide, much wider than the 6mm bolt, so I found three smaller springs that went inside the original. Now everything is tighter, and feels more rigid. On top of the springs I slipped on another wide spacer, before I put on the lower base plate. Another set of three spacers, before everything is secured with M6 nuts. The white knobs must also be replaced with longer ones.

Can you supply pictures of these mods please. 

Regards

Paul

On 10/06/2022 at 09:33, Mr Spock said:

With my 12" I placed a round plate between the secondary holder and the screws (replaced with Bob's Knobs) to get round the issue with the bolts fitting into holes in the holder. I can now collimate perfectly - it was impossible before.
I also replaced the primary springs with stronger ones. All good there now too. I also find the white knobs too short, but I just tightened the collimation bolts more.

As I am seriously thinking of getting one of these Dobs, never had one before but had a 200p and changed the springs on that flocked it, put thumb screws in the secondary holder and put a Lacerta 10:1 adapter on, I really should never have sold it to be honest. Back to the dob could you supply a picture of the ring as when I get one I want to make it perform the best it can thanks.

Regards

Paul

[Rallemikken]

4 hours ago, wookie1965 said:

Can you supply pictures of these mods please. 

I've made many mods on this scope, even before I've taken it into use. It came from FLO this spring, and it will not be dark enough her untill september. It might seem unfamiliar, thats because I've removed the fan, and dressed the edges and bottom of the mirror with flocking material. I've also painted the top and bottom end rings in a  less glossy black. Notice the scuff marks on the top end ring: It's caused by the retainer studs on the top cover plate. It was too tight, I had to use brute force to get it on and off. I used a knife and removed three of them. Now the cover is pretty loose. Remove two, and it still stays in place.

The collimation studs/pinbolts are M6x52mm. Theese are homemade, but you can buy them by the metre in hardware stores. Try to get some of good quality. They are threaded into the top mirror cell plate, be aware to stop before they reach the mirror. Then they are secured with the first nut. I dropped in an additional two nuts to reach focus on my DSLR. Now I collimate by turning the last nut, the studs stay rigid. The other three screws are M6x38mm, I think theese have been used on some furniture. DO NOT use force on theese, you can twist the top mirror cell plate.

The bolt I replaced on the base is UNC, that is; not metric. The green tint on it comes from a Volvo combine.... Now I can carry the base by the handle without worrying about the whole thing to disintegrate. During mounting I saw this flaw, and considered to turn the bottom plate upside down. I discarded this idea, because the top of the integrated nut also serves as base for the distance tube.

Under the top cover I have made an aperature mask, to avoid light on the focuser tube and the retainer nuts on the spider. I did this mod on my 200PDS, and it really made a huge difference. I also made an almost identical, that fits between the sides of the primary mirror, and the inside of the tube. It's mounted as high as possible on the mirror, without flipping over. The photo of this is slightly out of focus, but you can see a couple of places it doesn't fit 100%. It prevents ligh from entering from behind, and maybe also prevent reflektions from above. An alternative way of the traditional aperature mask.

The outer ring with the numbers are made of steel, paper and transparent tape. Simple and homemade. I place the scope on the ground, find Polaris, and rotate the whole thing until the spirit level is pointing to zero. I might make a removable indicator point later, but will try out this first.

 

[wookie1965]

33 minutes ago, Rallemikken said:

I've made many mods on this scope, even before I've taken it into use. It came from FLO this spring, and it will not be dark enough her untill september. It might seem unfamiliar, thats because I've removed the fan, and dressed the edges and bottom of the mirror with flocking material. I've also painted the top and bottom end rings in a  less glossy black. Notice the scuff marks on the top end ring: It's caused by the retainer studs on the top cover plate. It was too tight, I had to use brute force to get it on and off. I used a knife and removed three of them. Now the cover is pretty loose. Remove two, and it still stays in place.

The collimation studs/pinbolts are M6x52mm. Theese are homemade, but you can buy them by the metre in hardware stores. Try to get some of good quality. They are threaded into the top mirror cell plate, be aware to stop before they reach the mirror. Then they are secured with the first nut. I dropped in an additional two nuts to reach focus on my DSLR. Now I collimate by turning the last nut, the studs stay rigid. The other three screws are M6x38mm, I think theese have been used on some furniture. DO NOT use force on theese, you can twist the top mirror cell plate.

The bolt I replaced on the base is UNC, that is; not metric. The green tint on it comes from a Volvo combine.... Now I can carry the base by the handle without worrying about the whole thing to disintegrate. During mounting I saw this flaw, and considered to turn the bottom plate upside down. I discarded this idea, because the top of the integrated nut also serves as base for the distance tube.

Under the top cover I have made an aperature mask, to avoid light on the focuser tube and the retainer nuts on the spider. I did this mod on my 200PDS, and it really made a huge difference. I also made an almost identical, that fits between the sides of the primary mirror, and the inside of the tube. It's mounted as high as possible on the mirror, without flipping over. The photo of this is slightly out of focus, but you can see a couple of places it doesn't fit 100%. It prevents ligh from entering from behind, and maybe also prevent reflektions from above. An alternative way of the traditional aperature mask.

The outer ring with the numbers are made of steel, paper and transparent tape. Simple and homemade. I place the scope on the ground, find Polaris, and rotate the whole thing until the spirit level is pointing to zero. I might make a removable indicator point later, but will try out this first.

 

Brilliant thank you very much really appreciate it. 

Paul 

[Astro_Dad]

Thought I’d pop over to this thread as now a proud owner of the 8” version. Useful to read through and see how others have modified and upgraded. Good post @Rallemikken , some useful ideas there. 

[Mr Spock]

Thought it might be an idea to add a few pics of the big lad...

[Guest]

On 18/08/2021 at 09:24, Louis D said:

You could make a dolly/trolley/buggy/cart for it with jacks at the corners.  You'd wheel it into position, and then drop the jacks to raise it off the wheels.  To move it, simply raise the jacks and wheel it to another location and drop the jacks again.  The jacks can even be used to help level the base on uneven terrain.

Something along the lines of this, but with a Dob platform:

You mean something like this

[cajen2]

Well, I've had the 8" version for about 9 months now and I find it excellent. I haven't modified it at all as everything works so well. The only additions I've made are a few magnets to act as counterweights and can be slid up and down the tube for different EPs, plus a TA Optics double finder mount so that I can use the RACI and a Baader RDF together.

Perhaps I'm just lucky but collimation of both primary and secondary have been a breeze and I see no reason to modify anything.

One point: take care when assembling the base that the bush is in the right place - it isn't easy to see on the exploded diagram. I've heard of people assembling it wrong and then complaining the shaft is wobbly or sticks. The rotation should be smooth with easy stiction adjustment.

[Mr Spock]

53 minutes ago, cajen2 said:

The only additions I've made are a few magnets to act as counterweights and can be slid up and down the tube for different EPs

You can't see it on my pics but under the tube, opposite side to the focuser/finder assembly, I have a strip of 2" industrial Velcro with a 2kg counterweight attached.