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Cleaning primary mirror.


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If you think you have the right gap, then that's fine.

The screws will only feel tight if you have gone too far and are pushing against the mirror. 

Do they feel very loose if not tightened? 

Edited by Laurieast
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19 minutes ago, Dave scutt said:

Does it matter if the screws on the clips are not tight otherwise I cannot slide a piece of card in between the clip and the mirror. 

Yes it might matter. They could eventually go loose. Is there no way to lower the primary in the cell ? usually there is some plastic screw points that you can raise or lower. or at least there is on my orion cell

 

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5 hours ago, Dave scutt said:

Yes it rotates now

From my experience if its rotating it can not be held too tight. It could still be a bit loose. which only really matters with collimation as you move the scope big movements around the sky the collimation of the primary can change and move around a bit. thats the only issue with a rather loose primary. Optically loose is safer. But collimation is variable. I would say if its now rotating in its cell. and your not having to really force it around. It should be fine now. Conversely if its moving around very easily thats ok too. But keep a eye on the collimation of the primary as you move the scope around if its going badly out. its too loose. mirrors are often not just held from above with the clips. but often the side of the mirror has points holding it. These are part of the loose tight setup. 

Edited by neil phillips
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Mirror back in and just had my first go at collinmation what do you think is it ok,  waiting for my laser to arrive so done with cap and Cheshire 20220727_211905.thumb.jpg.4ba30a5688dad4a93cc8fc226b136df1.jpg

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16 minutes ago, Dave scutt said:

Mirror back in and just had my first go at collinmation what do you think is it ok,  waiting for my laser to arrive so done with cap and Cheshire 20220727_211905.thumb.jpg.4ba30a5688dad4a93cc8fc226b136df1.jpg

Always hard to tell with a camera shot. But nothing glaring. Hard to tell how accurate under the focuser it is. Because the angle of the camera can make big differences 

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41 minutes ago, Spile said:

Your eyes are the best judge but based on your image the slight secondary tilt/rotation error is really not worth worrying about. More importantly I would confirm alignment of your primary with a cap. Aka https://astro.catshill.com/collimation-guide/

I done a star test last night and the rings were concentric. 

I got a laser collimator today to check it out but it's taken me nearly all day to collimate it.🤣

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7 hours ago, Dave scutt said:

I done a star test last night and the rings were concentric. 

I got a laser collimator today to check it out but it's taken me nearly all day to collimate it.🤣

I sometimes use a collimated laser to confirm the secondary is aligned but For reasons of trust due to potential registration issues, I prefer to use the Cheshire eyepiece and sight tube combination tool.

Whatever works for you.

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19 hours ago, Laurieast said:

Is that image from the front end of the tube, and that's why we can see the diagonal adjustment screws?

Have a look here:

https://www.astro-baby.com/astrobaby/help/collimation-guide-newtonian-reflector/

 

 

I had to check what those 4 screw marks where .

It's the inside of the collimation cap. 20220730_090044.thumb.jpg.ff982df4a0168fcf181552dfcca77560.jpg

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8 minutes ago, Dave scutt said:

I had to check what those 4 screw marks where .

It did not click at the time that there were four, I need to put my glasses on! 

My collimation cap is plain, so I was not expecting that, that's my excuse... 

image.png.a08e9244461221645b68b4fdeb47e6b9.png

 

 

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Posted (edited)

Whan I done a star test and everything was concentric .

How much more improved would the view be if I adjusted the secondary mirror slightly 

Edited by Dave scutt
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54 minutes ago, TBRHussaR said:

Guys, I just tried to clean my mirror, but there is a “film “ of some kind that I can’t get off….any tips /advice?

Hi TBRHussaR.

Could you add a photo I'm sure someone would be able to help you.

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12 hours ago, Dave scutt said:

Whan I done a star test and everything was concentric .

How much more improved would the view be if I adjusted the secondary mirror slightly 

It is within tolerance so in my opinion you would be wasting your time. 

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I've collimated the laser, the circle on the primary lines up with the cap as from photo above but the laser seems to be out.

The star test I done the other night was perfect so should I adjust so the laser hits the circle or leave it alone .

I measured the spider vanes and they are all equal. 

What else could I adjust. 20220731_144458.thumb.jpg.f64a21c75ffa39f407b2595b2ffc654e.jpg

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9 minutes ago, Dave scutt said:

I've collimated the laser, the circle on the primary lines up with the cap as from photo above but the laser seems to be out.

The star test I done the other night was perfect so should I adjust so the laser hits the circle or leave it alone .

I measured the spider vanes and they are all equal. 

What else could I adjust. 20220731_144458.thumb.jpg.f64a21c75ffa39f407b2595b2ffc654e.jpg

Focuser slop can also give different readings. You need a self centering eyepiece adapter. If your star test is good i would  trust that. Star test at high power

 

Edited by neil phillips
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2 minutes ago, neil phillips said:

Focuser slop can also give different readings. You need a self centering eyepiece adapter

 

I have one on the opticstar I will dive it a go and let you know.

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