Page 1 of 1
Jupiter appears like white spotty LED traffic lamp on my dobsonian
Posted: Sat Sep 18, 2021 3:26 pm
by Irwin88
Hi.
This is my first post here. I'm using a 12" Dobsonian and have just started to look at the night skies this week. I suppose it is collimated since the moon looks large and extremely clear with my 1.25" 90 deg diagonal, moon filter and 40mm Plossl. Collimation with the secondary mirror was easy, but I'm not too sure about the primary mirror since I adjusted the collimation screws and nothing happened. Since I could see the moon clearly, I assume collimation is fine.
Unfortunately, when I looked at Jupiter, it appeared like a white- coloured spotty LED traffic lamp. I have attempted this on two different days this week and the effect is still the same. I was expecting an image of the Jupiter that we are so used to.
Troubleshooting???
* Lack colour filters (blue to see Jupiter?)
* Wrong lens used?
* Collimation issues?
* Something is wrong with my eyes?
Specs for Dobsonian:
* Aperture = 305mm (12 inches)
* Focal length = 1524 mm
* Focal ratio = f/5
My telescopic gear (which were randomly bought since I'm a trial-and-error beginner) are:
* 1.25" 10-30mm Zoom Eyepiece (pair with moon filter, but not as good as 40mm Plossl)
* 1.25" 9mm Plossl (eyepiece seems too small to see anything, little use for this)
* 1.25" 40mm Plossl (best for viewing moon and Jupiter)
* 1.25" 5x Barlow Lens (not sure what it's for, unable to view anything through it)
* 2" 26mm Eyepiece (eye needs to be a few cm from the eyepiece to see anything)
* Moon filter, CLS filter, UR/IR filter, UHC filter
I hope some of you can help me to identify what I am lacking. Thank you very much.
Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian
Posted: Sun Sep 19, 2021 12:29 am
by Airconvent
How did you collimate it? A large object like the moon is extremely forgiving for bad collimation.
Did you choose a star to do your collimation ? Do watch the youtube videos that provide tutorials on how to do it.
Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian
Posted: Sun Sep 19, 2021 8:31 am
by Irwin88
Thanks for your reply. Initially I tried to follow the manual but it was confusing. Later, I found this useful video at
https://youtu.be/ht0WAEpya1o. However I could not see the red laser light on the collimator (3:00 in video) from the back of the telescope.
Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian
Posted: Mon Sep 20, 2021 10:13 pm
by Irwin88
I have managed to collimate both the primary and secondary mirrors using the method in the youtube video. Problem still persists so I don't think it's the collimation.
Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian
Posted: Mon Sep 20, 2021 10:55 pm
by Airconvent
You must be doing something wrong. Are you in correct focus or way out of focus ? Are you using the right eyepiece? Start with a longer one like 40mm, once Jupiter is centred, switch to your 10-30mm. Then rotate down from 30mm to 10mm,
Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian
Posted: Tue Sep 21, 2021 6:07 pm
by Irwin88
Thanks for the advice. The 1524mm focal length and 40mm Plossl eyepiece gave me 38x magnification. So perhaps that is not enough. I did try the 10 to 30mm eyepiece but I find the eyehole small and difficult to look through since I'm wearing specs, I did not stick with the 10 to 30mm eyepiece for long. I will attempt your method if the sky allows me too.
Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian
Posted: Wed Oct 06, 2021 1:37 am
by vernonfarmer39
Irwin88 wrote: ↑Sat Sep 18, 2021 3:26 pm
Hi.
This is my first post here. I'm using a 12" Dobsonian and have just started to look at the night skies this week. I suppose it is collimated since the moon looks large and extremely clear with my 1.25" 90 deg diagonal, moon filter and 40mm Plossl. Collimation with the secondary mirror was easy, but I'm not too sure about the primary mirror since I adjusted the collimation screws and nothing happened. Since I could see the moon clearly, I assume collimation is fine.
Unfortunately, when I looked at Jupiter, it appeared like a white- coloured spotty LED traffic lamp. I have attempted this on two different days this week and the effect is still the same. I was expecting an image of the Jupiter that we are so used to.
Troubleshooting???
* Lack colour filters (blue to see Jupiter?)
* Wrong lens used?
* Collimation issues?
* Something is wrong with my eyes?
Specs for Dobsonian:
* Aperture = 305mm (12 inches)
* Focal length = 1524 mm
* Focal ratio = f/5
My telescopic gear (which were randomly bought since I'm a trial-and-error beginner) are:
* 1.25" 10-30mm Zoom Eyepiece (pair with moon filter, but not as good as 40mm Plossl)
* 1.25" 9mm Plossl (eyepiece seems too small to see anything, little use for this)
* 1.25" 40mm Plossl (best for viewing moon and Jupiter)
* 1.25" 5x Barlow Lens (not sure what it's for, unable to view anything through it)
* 2" 26mm Eyepiece (eye needs to be a few cm from the eyepiece to see anything)
* Moon filter, CLS filter, UR/IR filter, UHC filter
Miami Video Production Company
I hope some of you can help me to identify what I am lacking. Thank you very much.
i did have the same problem with you with my first days but i saw a youtube how to fix it. it has pretty good tutorials out there man try it out!
Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian
Posted: Thu Oct 07, 2021 1:45 pm
by VinSnr
Irwin88 wrote: ↑Sat Sep 18, 2021 3:26 pm
Hi.
This is my first post here. I'm using a 12" Dobsonian and have just started to look at the night skies this week. I suppose it is collimated since the moon looks large and extremely clear with my
1.25" 90 deg diagonal, moon filter and 40mm Plossl. Collimation with the secondary mirror was easy, but I'm not too sure about the primary mirror since I adjusted the collimation screws and nothing happened. Since I could see the moon clearly, I assume collimation is fine.
Unfortunately, when I looked at Jupiter, it appeared like a white- coloured spotty LED traffic lamp. I have attempted this on two different days this week and the effect is still the same. I was expecting an image of the Jupiter that we are so used to.
Troubleshooting???
* Lack colour filters (blue to see Jupiter?)
* Wrong lens used?
* Collimation issues?
* Something is wrong with my eyes?
Specs for Dobsonian:
* Aperture = 305mm (12 inches)
* Focal length = 1524 mm
* Focal ratio = f/5
My telescopic gear (which were randomly bought since I'm a trial-and-error beginner) are:
* 1.25" 10-30mm Zoom Eyepiece (pair with moon filter, but not as good as 40mm Plossl)
* 1.25" 9mm Plossl (eyepiece seems too small to see anything, little use for this)
* 1.25" 40mm Plossl (best for viewing moon and Jupiter)
* 1.25" 5x Barlow Lens (not sure what it's for, unable to view anything through it)
* 2" 26mm Eyepiece (eye needs to be a few cm from the eyepiece to see anything)
* Moon filter, CLS filter, UR/IR filter, UHC filter
I hope some of you can help me to identify what I am lacking. Thank you very much.
Hi Irwin, I read from above that you use a 1.25" 90 deg diagonal on your dob??? The 90 deg star diagonal should not be used on a dob. I hope you didn't use that to look at Jupiter!
Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian
Posted: Fri Oct 08, 2021 5:07 pm
by RKaji
Oops I use 1.25" 90, need to review what else I'm doing wrong since I haven't been doing it all that long)))