CROSSHAIRS on Newtonian 150/750

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CROSSHAIRS on Newtonian 150/750

Postby JonKennedy » Thu Oct 20, 2016 10:57 pm

I have a Newtonian 150 - 750P / Skywatcher

I see crosshairs!!!!

I bought a laser collimator and it is perfectly aligned using this with both lasers hitting the centre DOT on the main mirror and the target on the collimator!
When I look at anything through the scope I can still see the CROSSHAIRS of the scope.
I have read many articles and watched many videos about this problem but I STILL have the same problem no matter what I do. I hope you could help me!!!!

I am looking forward to hear from you
JonKennedy
 
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Re: CROSSHAIRS on Newtonian 150/750

Postby Gfamily2 » Fri Oct 21, 2016 9:22 am

JonKennedy wrote:I have a Newtonian 150 - 750P / Skywatcher

I see crosshairs!!!!

I bought a laser collimator and it is perfectly aligned using this with both lasers hitting the centre DOT on the main mirror and the target on the collimator!
When I look at anything through the scope I can still see the CROSSHAIRS of the scope.
I have read many articles and watched many videos about this problem but I STILL have the same problem no matter what I do. I hope you could help me!!!!

I am looking forward to hear from you

Hi,
It's very hard to say what the problem is, but here are a few questions to see if we can help.
When you say you can see the 'crosshairs' through the eyepiece, do you mean the 'spider' that holds the secondary mirror in place?
What eyepiece are you using?
Is this the same with all eyepieces?
When you rotate the eyepiece, does the angle of the crosshairs change accordingly?
Are the targets you're looking at (stars, moon) in focus or are you only seeing the crosshairs?
Do you also see the shadow of the secondary mirror in its cell?
Scopes: Meade 8" SCT, Skywatcher 127mm Mak
For imaging: Pentax K5, Asda webcam, Star Adventurer (new toy)
For companionship: Mid Cheshire Astronomical Group.
Gfamily2
 
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Re: CROSSHAIRS on Newtonian 150/750

Postby andrewt » Mon Jun 12, 2017 5:35 pm

He did not come back.
Following on:
At night I don't see the secondary and it's 3legged spider.
But during the day after doing a collimation check I see the secondary and spider.
It is dead centre when my eye is on centre, but it moves around as I allow my eye to move off centre.
Is that normal? I wear specs so I am a bit further away from the eyepiece.

equipment:
150mm mirror, 750mm focal length, 51mm secondary, 40mm and 25mm plossl. 12.5mm & 6.5mm are rubbish so lie in the drawer gathering dust.
andrewt
 
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Location: Scottish Borders

Re: CROSSHAIRS on Newtonian 150/750

Postby Aratus » Mon Jun 12, 2017 8:02 pm

The secondary mirror needs to be centred through the eyepiece holder. Once it is centred you put your eye into a position where it looks centred and then continue collimating. You can then adjust the primary to centre the 'spider'. If you want to make things really easy get hold of a 'Cheshire Eyepiece'.
I use an 11" Celestron SCT (CPC 1100) on an equatorial wedge, with an 80mm refractor as a guidescope. They are housed in a 2.2m Pulsar observatory. I use a ZWO ASI1600MC for imaging.
Aratus
 
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Location: East Lincolnshire


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