Jupiter appears like white spotty LED traffic lamp on my dobsonian

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Irwin88
Posts: 5
Joined: Sat Sep 18, 2021 2:01 pm
Favourite scope: Dobsonian

Jupiter appears like white spotty LED traffic lamp on my dobsonian

Post 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.
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Airconvent
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Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian

Post 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.
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Irwin88
Posts: 5
Joined: Sat Sep 18, 2021 2:01 pm
Favourite scope: Dobsonian

Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian

Post 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.
Irwin88
Posts: 5
Joined: Sat Sep 18, 2021 2:01 pm
Favourite scope: Dobsonian

Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian

Post 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.
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Airconvent
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Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian

Post 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,
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Irwin88
Posts: 5
Joined: Sat Sep 18, 2021 2:01 pm
Favourite scope: Dobsonian

Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian

Post 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.
vernonfarmer39
Posts: 2
Joined: Wed Oct 06, 2021 1:32 am
Favourite scope: Celestron Nextron 8SE

Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian

Post 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
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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!
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VinSnr
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Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian

Post 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!
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RKaji
Posts: 1
Joined: Wed Aug 04, 2021 5:18 pm
Favourite scope: noine

Re: Jupiter appears like white spotty LED traffic lamp on my dobsonian

Post 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)))
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