12" Dobsonian

[charmedkelly]

Hi Guys! 

I'm probably posting this in the incorrect forum but here goes....

I have a 12" Dobsonian and i got it out tonight and took at look at saturn and Jupiter but i noticed it was as crisp as its usually been in the past, the planets weren't as 

clear and it they both had like a haze around them, I wasn't sure if it was because of the atmosphere or whether it was my Telescope? 

I was using a 31mm Wide Eyepiece and then a 9mm to get a more detailed view, but both eyepieces continued to show it hazy and not very crisp... 

 

Wondered if you guys had any advice on what i can do, or if i'm doing something wrong?

 

Thank you 

 

Kelly 

[charmedkelly]

not jupiter lol sorry guys put the wrong planet in there

[emadmoussa]

It's either visibility isn't great this evening (I know it's terrible down here), or you need to fine tune your collimation. But visibility and seeing conditions are more likely to be the cause. 

[charmedkelly]

Yeah i was thinking i may have to Collimate the scope, (which in all fairness i'd probably fail at....

 

[emadmoussa]

10 minutes ago, charmedkelly said:

Yeah i was thinking i may have to Collimate the scope, (which in all fairness i'd probably fail at....

 

It's usually about practice, and it doesn't take long to master it really. What's astronomy gear if it were devoid of fiddling? 

[bingevader]

The planets are rather low at the mo and so prone to more atmospheric interference.

What do other objects look like?

Have you tried a star test?

Cheers.

[Tim]

Was the mirror affected by dew by any chance?

[Stu Todd]

+1 for dew on your mirror.

If your images were crisp before, then it's obviously not collimation.

 

[Stu]

1 hour ago, Stu Todd said:

+1 for dew on your mirror.

If your images were crisp before, then it's obviously not collimation.

 

I would agree with this. Haze around a planet is not something immediately connected to collimation issues. It could be few on the primary, secondary or eyepiece. It could also possibly just be high hazy cloud? Try the scope another night and then have a check for these things and see where you go.

[charmedkelly]

Hi Guys, Thanks for all the replies, 

Dew could have been an issue not gonna lie, i made the mistake of not getting the scope out early enough, so the mirrors were probably dewed up. 

Yeah they were crisp before, but what i should have mentioned that was probably over a year ago when i last tok a look at saturn. 

for now i'm putting it down to the fact my scope was probably dewed up and so was the eyepiece, and probably atmosphere issues. 

 

one question though

 

is there any kind of galaxy around the location of saturn.  i came across a kinda smudge in the sky, which i thought looked like a galaxy. There wasn't a cloud in the sky so i know it wasn't a cloud of any kind??

 

Best

[Stu Todd]

There are all sorts of objects in that part of the sky, just off the top of the lid of the "tea pot" of Sagittarius. Plenty of famous nebulae, globular clusters etc. FOV here is 20 degrees, chart from CdC.

[charmedkelly]

thanks for the chart, i'll have to redownload Stellarium and start documenting locations and what i find

 

Thanks again !

[JOC]

On ‎16‎/‎08‎/‎2018 at 22:52, charmedkelly said:

which in all fairness i'd probably fail at....

Probably I was about a scared of undoing screws on my telescope (when it essentially 'worked') as it was possible to get.  I prevaricated endlessly before I finally bit the bullet.  Here are my two pieces of advice:

1.  Look online at videos of people doing collimation (even with laser collimators), it will give you the confidence to loosen the screws and know you can retrieve the situation.  However, under no circumstances would I use that alone to collimate your telescope........see number two.

2.  Follow Astrobaby's guide here:  http://www.astro-baby.com/astrobaby/help/collimation-guide-newtonian-reflector/ to the absolute letter - do not deviate, do not change, do every step she recommends with almost slave-ish addiction and you will end up with a perfect job.  Put the telescope in a horizontal position to work on it (protects your mirror from dropped things).

Two things I found useful to know - A) gently loosening the central screw in the centre of the secondary mirror helps to turn the other ones, B )  When you tighten the screws sometimes you have to make allowance for final movement that occurs with the last turn - a bit of fiddling once you have figured out how the last tighten affects things allows you to repeat the process with the now expected movement allowed for.  Oh, yes and allow about 2 hours the first time you decide to try it!