Hi everyone
, I'm new here (first post) and bought my first telescope last week - a 12" Bintel Dob. I've had nothing but problems with it ever since though, and was wondering if anyone here could give me some good advice with collimation and the state of my mirrors.
The problems started when buying it from Bintel - I recieved a phone call from Bintel a while after ordering it because they got the credit card number wrong. I was told that it would arrive the next day, but it arrived 2 days later instead. After putting the mount together (ran into problems there too due to there being mistakes on the instructions and parts list), the telescope wouldn't fit! After a couple of hours of trying to figure it out, I called up Bintel and found that they had given me the wrong mount. I was told I would recieve the new mount the next day. It took another 2 days. I put it all together, take off the cover on the front end and look inside. I found the secondary mirror covered in dust, and the edge of the plastic box connected to it covered in what looked like saw dust of plastic shavings wich might also be what the secondary mirror itself is covered in. The primary mirror was in worse shape. It had even more dust, a couple of small solid objects on its surface (maybe deep scratches), and a few scratches, one being about 4cm long. The back of the primary mirror also had a mark where it had been chipped on its edge. This is the way it was on delivery. It was the very first time the insides were exposed since they collimated it at the shop.
I finally get to use it, and did a test on the moon. I was very dissapointed in what I saw. Barely any craters were visible, it was a big distorted blur. The telescope was supposed to be collimated at the shop, but it was far from collimated. I had to try collimating it myself with the laser collimator I bought. The laser was supposed to come with instructions, but the only collimating instructions I could find was in the basic instruction manual. It was very confusing and the drawings in the manual were nothing like my telescope. After trying to figure it out for a while, the best I could come up with was to do it on my own by using common sense, and put the collimating laser into the focuser, then adjust the 3 screws on the secondary mirror to aim it in the small centre ring of the primary mirror. Then I adjusted the primary mirror screws to make the laser shine right back into the centre of the collimator. After that I could see the moon clearly, though certainly not as clear as it could be. I also spotted jupiter, which was only a tiny blob. After changing to the 2x barlow and 9mm eyepiece, it was still a very small blob, but just big enough to notice the main cloud bands. I had to adjust the focuser to a pinpoint in order to get enough detail to see those clouds, it was very prone to blurring. The next night, I managed to see the orion nebula, but couldnt get anything else. The orion nebula was about as bright as a weak smudge on the eye piece. If it wasnt for the fact that it moved with the stars, I would have dismissed it as such. I could only just make out some of its cloud shapes. Below are a couple of pictures of the mirrors. It was hard to get a good picture of the dirt on the primary mirror, but if you look at the secondary mirror, the primary is much worse than that and looks like sand paper when a torch is shined onto its surface. You can see some of the solid material (or scratches) and part of the large scratch near the top around the torch light reflection, can't see most of the dark markings though which is on the lower half.
http://img520.imageshack.us/img520/6...ymirrorfb6.jpg (20kb)
http://img119.imageshack.us/img119/9...ymirrorvv2.jpg (37kb)
All night and day, I tried again to collimate it, even looking online for guides but they are all pretty much the same and jibberish to me, because they explain things that dont apply to this telescope, missing the most important information and referring to multiple things under the same name (for example the screw, the mirror, and the excessive use of abbreviations that have multiple meanings that have absolutely nothing to do with anything). The guides all say to do this or that, but the actual effect of such actions is nothing like what the guides say.
There are 2 ways I can allign the mirrors, and neither make much difference to what I see through an eyepiece...
Manual Allignment - Focuser ring alligned to the middle of the dark spot in the centre. Can't get it exact without a sight tube or something. The laser says it's far from the centre of the primary mirror, and shines back into the wall the telescope is pointed at.
Laser Allignment - Puts everything way out of position, but the laser does point to the centre of the primary mirror and back to itself. I think the laser might not be showing centre properly, because when I spin it in the focuser, the allignment moves in a cirle.
Either way, the view I get is very dissapointing. My last collimation attempt ended up with having both the laser and manual allignment fairly close to each other. Below is a picture of how it looks through the focuser, but moving it around since I collimated it might have moved it out of position a tiny bit. I want it perfectly alligned, and I don't even mind if it takes hours to do, just knowing HOW to do it is the problem.
http://img119.imageshack.us/img119/1...imationto2.jpg (30kb)
My questions are...
1. . Is the magnification I'm getting what it should be? Should Jupiter be a small blob even with a 9mm and 2x barlow? Will buying another eyepiece be the right choice?
2. Is a faint smudge view of Orion what I should expect? I can't see anything else and for a telescope like this, I expected MUCH more.
3. What should I do about this mirror damage and contamination? How serious is it? I can see my own reflection clearly by looking at it, but with a torch I can see that it's covered in dust. Maybe this is the reason why I can't see much from the telescope. Bintel told me when I ordered it that I shouldn't try to clean it myself. I don't want to send it back again if I can help it. I've gone through enough nonsense with it already.
4. How do I actually collimate the telescope? (without buying more accessories). All the guides I've seen (including here) just dont make any sense to me. The view they describe is not the view I see, and the screws they say to turn do something different on mine. The only collimation tool I have is a laser collimator and the battery sets only lasted an hour each so ive gone through all my batteries now. I might be able to get a few minutes out of the batteries if I'm lucky.
It looks like they have given me an old display model. It's dirty and damaged, and all I can really see so far is the Moon, Jupiter and a faint Orion. I can't see anything else with it and might as well be using cheap binoculars. It is of such poor quality that I can put on the dust cover and remove the small peep hole, and I get almost the same quality image as I do with the cover off.
I'm thinking about getting a refund or dumping this junk at the tip
. I apologize for my frustration, it's just that I've invested a lot of time, effort and money into this and it's driving me up the wall. But even if I get it exchanged for a new one, I still have no idea how to do collimation properly. If I do figure it out, I'll probably write a guide myself and fill in all the important blanks that the others missed. As far as I can tell (and I'm sure I'm wrong somewhere), you collimate with a laser by doing this...
1. Loosen all 4 screws on the secondary mirror. Looking through the focuser, hold the secondary mirror capsule (without touching the mirror of course) and tighten up the big middle screw into a position where the secondary mirror is centred to the focuser. If you need to move the secondary mirror up/down the tube, you will need to tighten/loosen the 3 small screws a bit as well.
2. Put the laser into the focuser and tighten up/tape the laser so that it sits in the middle without wobbling. let the laser opening face the back of the telescope
3. Adjust the 3 small screws so that the red dot reflects into the middle of the primary mirror where the small ring is. You need to look down the tube to do this, and be careful not to let the laser reflect into your eyes.
4. Loosen the screws on the primary mirror, and tighten then up while watching the laser opening. The screws will move the red dot around, and you need to adjust it so that the red dot reflects back into the middle of the collimating laser where the light comes out.
I've been majorly let down by Bintel. If it was an honest mistake, even a few, I wouldn't mind. But this is rediculous, even worse than DELL.
