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Odd Dob

Hi. Have telescope, will gaze

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I've had my dob for a few weeks now and thought I'd say hello. It's my 1st telescope.

Surprisingly clear skies in my little corner of England. Even from my back garden, on my 1st ever night out I just pointed my telescope towards something interesting looking and BANG! there was Venus. Went looking for Saturn, and could clearly see the rings and some of its moons within minutes.

Thinking I was now invincible, I get cocky and and go looking for some deep space stuff. Hmmm, that proved a bit more tricky. Saw the Orion nebula (just) but everything else has been a bit elusive tbh. Luckily I saw an absolutely gobsmacking view of jupiter at some ungodly hour on sunday, so I'm all fired up again.:)

Quite like my scope, but the collimating issues it has are terrible. Found a little compressable rubber ring on one of the supporting arms which seemed to serve no function that to be slightly compressable and throw my collimation out. Throwing it away seems to have not damaged anything. I've also worked out that as long as I've properly collimated once, after extending the scope I can do a quick and dirty re-collimation by sticking in a Cheshire eyepiece, loosening one of the arms and sliding it until the thing lines up. I'm fairly sure that's not the way to do it, but it seems to work.

Anway, that's enough about me.

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Hi Mr Dob,

A warm welcome to SGL, hope you enjoy the forum and your Dob.

John.

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Hello Odd Dob. Welcome to the Forum, and how nice you chose a Dob as your first scope. You don't need to fight the technicalities of the Equatorial Mount, and get really frustrated before you find anything to look at.:) T he Dob. is a nice simple but very effective learning tool, and you will benefit a great deal as you climb the learning curve. I'm just a bit perplexed at you having to loosen one of the spider arms to gain reasonable collimation. That is not a conventional operation, but, if it works for you, then who am I to interfere.:D Anyway, best of luck with your observations, and if you need any advice, there's loads of it here on the forum for you, just ask away.

Ron.:)

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Welcome to SGL Odd Dob.

Same as Ron I'm a little concerned about using the spider arms to adjust collimation. This is a very strange practise. Also whats the little rubber thing you chucked away. Was it an original part of the scope?

Anyway there's plenty of good advice here about collimation have a read up.

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Welcome to SGL Odd Dob.

Same as Ron I'm a little concerned about using the spider arms to adjust collimation. This is a very strange practise. Also whats the little rubber thing you chucked away. Was it an original part of the scope?

I think I may not have explained myself clearly :). There are three extendible poles supporting the part of the telescope holding the secondary mirror. If the extendible poles aren't all extended equally, it knocks the collimation off. If I stick in the Cheshire after extending it and the collimation is off and I know I've collimated recently, I found that it's sometimes down to one of the poles just needing an extra tug and not being fully extended. I'm not adjusting the lengths of the poles to achieve collimation routinely :D

While I'm talking about collimation, hi to astro baby. You're collimation guide is ace!

The little rubber ring thing is a bit of a mystery. It was only on one of the poles, and was coming in between the end of the pole and the catch on the frame that acts as a stop during extension. I was going to take some pictures of the ring and where it came from and post it on here, see if anybody else knew what it was all about. It was only on one of the arms, and the scope NEVER held collimation between retraction and extension with the ring in situ, due to it causing variable degrees of extension and and knocking the second mirror off a bit by virtue of only being on one arm. Most odd. My assumption is there should be one on all 3 arms, but the others never made it out of the factory. The only function I could possibly see them having would be to soften the juddering from the scope reaching full extension - but as it extends quite slowly anyway, I don't think it's a problem.

Hmmm. I've though about this too much....

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I understand now. I thought you meant the spider vanes holding your secondry mirror but you mean the truss poles. As you have the fllex tube dob these can be retracted up and down.

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