Irish stargazer
25-11-2011, 08:00 AM
What is the biggest bang for your buck? Why a dobsonian of course.
I have been thinking about getting a dob for some time now. The thought of lugging out a heavy equatorial mount, aligning and balancing , charging batteries and waiting for a circuit board to blow and many cancelled observing sessions due to my back finally made me go for it. Firstly,I would have to convince my better half that it would make a nice xmas present and not clutter up our rented house with more scopes and stuff. So I took her to the Sydney fish markets for a nice lunch, had a few glasses of Chardonnay and took a short stroll to the Bintel store, which by complete coincidence is just across the road fom our favourite eating place . The staff at Bintel were as helpful as anyone can be, offered her a seat on the "widows couch" which was strategically placed near the front door while they dragged out a Lightbridge and let me play around with it.The deal was done and the scope would be delivered in 2 working days.I really liked the widows couch. I wish they had them in womens clothes shops. The clothes shop owners probably realise that by making their partners stand all day while their wives/girlfriends look for items that you would let buy them anything, just to get out of the place and rest your feet and count the financial cost later.
Anyway, the scope arrived as planned with the packaging in good condition. It took about 30 minutes to assemble the base and mount the scope. Its is quite a handsome instrument and quite large. There were a few cosmetic defects on the scope. The main mirror had quite a few chips on the very outer edge which had been blacked out.These probably have no effect on peformance as the mirror is most liked turned down on the outer millimeter or so. The based looked quite flimsy being made of only chipboard. I was afraid the supplied screws woould split the panels when they were being inserted but it all fitted together quite nicely. The focuser is a Crayford type with a 10:1 fine adjustment. You have to manually turn a tension screw to get the correct level of tension. It comes with a Meade QX eyepiece which is not bad for a freebie and a revelation style red dot finder which is quite good.
They had no laser collimators in stock at the time but I took it outside to have a quick look. Out of the box it still gave good images, with good detail on Jupiter. With my 27mm Panoptic the field of view was fairly flat across most of the width of the FOV. However the first issue arose at the point, the scope balance was now top heavy and would sink at low altitudes without the break on full. I finally picked up a Orion lasermate delux and did the collimation. The collimation was jerky due to the secondary screws being too tight. The main mirror did not move smoothly either and the collimation would not hold unless the springs were at maximun tension and the screw/mirror stops in place. The images were good though once collimated but I knew some upgrades were necessary. This is what I did.
Replace the secondary screws with Bobs Knobs for a tool free collimation.
http://www.irishastronomy.org/media/kunena/attachments/913/bobsknobs.JPG (http://www.irishastronomy.org/media/kunena/attachments/913/bobsknobs.JPG)
Replace the springs on the main mirrow with Bobs Knobs springs. These make a huge difference. The factory supplied springs are really flimsy and cannot support the weight of a 12" mirror. The replacement is very easy and only takes a minute. Collimation was much smoother and the screw / mirror stops are no longer necessary
Added some Farpoint counterweights. The scope now balances perfectly without any brake required with the 27mm Panoptic
http://www.irishastronomy.org/media/kunena/attachments/913/counterweights_2011-11-24.JPG (http://www.irishastronomy.org/media/kunena/attachments/913/counterweights_2011-11-24.JPG)
Replace the finder with a Telrad. The one supplied is not bad but its no Telrad. There is no secondary mirror cover supplied. I took the leather bag from one of my Hyperion eyepieces and this fits perfectly over the secondary
http://www.irishastronomy.org/media/kunena/attachments/913/mirrorcover.JPG (http://www.irishastronomy.org/media/kunena/attachments/913/mirrorcover.JPG)
Will be heading out to the Pony Club tomorrow weather permitting to put the scope and upgrades through its paces so I will post some more info on how it all works.I will also be receiving a free box set of Meade 4000 eyepieces with filters and barlow which was part of the deal. A bargain at $1100
I have been thinking about getting a dob for some time now. The thought of lugging out a heavy equatorial mount, aligning and balancing , charging batteries and waiting for a circuit board to blow and many cancelled observing sessions due to my back finally made me go for it. Firstly,I would have to convince my better half that it would make a nice xmas present and not clutter up our rented house with more scopes and stuff. So I took her to the Sydney fish markets for a nice lunch, had a few glasses of Chardonnay and took a short stroll to the Bintel store, which by complete coincidence is just across the road fom our favourite eating place . The staff at Bintel were as helpful as anyone can be, offered her a seat on the "widows couch" which was strategically placed near the front door while they dragged out a Lightbridge and let me play around with it.The deal was done and the scope would be delivered in 2 working days.I really liked the widows couch. I wish they had them in womens clothes shops. The clothes shop owners probably realise that by making their partners stand all day while their wives/girlfriends look for items that you would let buy them anything, just to get out of the place and rest your feet and count the financial cost later.
Anyway, the scope arrived as planned with the packaging in good condition. It took about 30 minutes to assemble the base and mount the scope. Its is quite a handsome instrument and quite large. There were a few cosmetic defects on the scope. The main mirror had quite a few chips on the very outer edge which had been blacked out.These probably have no effect on peformance as the mirror is most liked turned down on the outer millimeter or so. The based looked quite flimsy being made of only chipboard. I was afraid the supplied screws woould split the panels when they were being inserted but it all fitted together quite nicely. The focuser is a Crayford type with a 10:1 fine adjustment. You have to manually turn a tension screw to get the correct level of tension. It comes with a Meade QX eyepiece which is not bad for a freebie and a revelation style red dot finder which is quite good.
They had no laser collimators in stock at the time but I took it outside to have a quick look. Out of the box it still gave good images, with good detail on Jupiter. With my 27mm Panoptic the field of view was fairly flat across most of the width of the FOV. However the first issue arose at the point, the scope balance was now top heavy and would sink at low altitudes without the break on full. I finally picked up a Orion lasermate delux and did the collimation. The collimation was jerky due to the secondary screws being too tight. The main mirror did not move smoothly either and the collimation would not hold unless the springs were at maximun tension and the screw/mirror stops in place. The images were good though once collimated but I knew some upgrades were necessary. This is what I did.
Replace the secondary screws with Bobs Knobs for a tool free collimation.
http://www.irishastronomy.org/media/kunena/attachments/913/bobsknobs.JPG (http://www.irishastronomy.org/media/kunena/attachments/913/bobsknobs.JPG)
Replace the springs on the main mirrow with Bobs Knobs springs. These make a huge difference. The factory supplied springs are really flimsy and cannot support the weight of a 12" mirror. The replacement is very easy and only takes a minute. Collimation was much smoother and the screw / mirror stops are no longer necessary
Added some Farpoint counterweights. The scope now balances perfectly without any brake required with the 27mm Panoptic
http://www.irishastronomy.org/media/kunena/attachments/913/counterweights_2011-11-24.JPG (http://www.irishastronomy.org/media/kunena/attachments/913/counterweights_2011-11-24.JPG)
Replace the finder with a Telrad. The one supplied is not bad but its no Telrad. There is no secondary mirror cover supplied. I took the leather bag from one of my Hyperion eyepieces and this fits perfectly over the secondary
http://www.irishastronomy.org/media/kunena/attachments/913/mirrorcover.JPG (http://www.irishastronomy.org/media/kunena/attachments/913/mirrorcover.JPG)
Will be heading out to the Pony Club tomorrow weather permitting to put the scope and upgrades through its paces so I will post some more info on how it all works.I will also be receiving a free box set of Meade 4000 eyepieces with filters and barlow which was part of the deal. A bargain at $1100