nothing through lense

[patch58]

hi all, bought my son dobsonian 200 about 18 months ago he came in the other night and said he couldn't see anything through the lense so the next morning i lined up on a telephone pole with the finder scope looked through the lense and nothing there like looking into fog or something terribly out of focus,can anyone please help,thankyou.

[Peter Drew]

There may be an extension tube needed to bring things to focus or maybe the object was too close ?

[Richardisgreat]

Have a look down the main tube at the condition of the primary mirror. Did you buy the scope new or used? Check the collimation of the primary and secondary mirrors. And perhaps the finderscope is not aligned with the scope. Im sure what ever the problem is its fixable. Which eyepiece did you use to look at the telephone pole and how far away was the telephone pole. I suggest using an eyepiece of 30mm or longer if trying to view anything closer than about half a mile away. You wont be able to focus on anything too close, its different to binoculars its a great scope. welcome to the forum

Clear skies

[Stargazer_00]

I assume if it's been bought 18 months ago then it's been used a lot or at least a little in that time and has previously shown views?

If that is assumed it's a matter of elimination. What has changed since the time it was working until now?

Has collimation been attempted?

Have any new accessories been added?

Has the scope fallen or undergone any other unfortuante accident?

Is it only one eyepiece that is effected or all?

and so on.

[AlexB67]

There may be an extension tube needed to bring things to focus or maybe the object was too close ?

From what I read another common mistake along those lines. I see some mods point this out a few times, there is an 2 inch and 1.25 inch adapter, you use one for the 1.25 inch eyepiece, not both together or something like that, I wonder if the issue is along those lines. I only got a 1.25 inch focuser, so do not know how to explain it better

[John]

From what I read another common mistake along those lines. I see some mods point this out a few times, there is an 2 inch and 1.25 inch adapter, you use one for the 1.25 inch eyepiece, not both together or something like that, I wonder if the issue is along those lines. I only got a 1.25 inch focuser, so do not know how to explain it better

This is spot on. You should only use the 2" adapter or the 1.25" adapter. If they are both in the scope at the same time (the 1.25" will actually fit into the 2" one) you can't get eyepieces to focus.

[patch58]

Thanks for the replies will look at the adapters , tried other eye pieces still the same the last time he took it out it was perfect , will keep you posted, thanks.

[patch58]

hi all,took it in to the shop where i bought it he had a look and said it had been knocked out of alignment,so its all sorted , just bought a laser collimator and will now get on youtube to see how to use it ,thanks for all the replies really appreciatr it.