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Celestron 6SE Collimation


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Hi to all, I have joined in the hope of upgrading my very basic knowledge on telescope mechanics and Collimation amongst other things. I brought a Celestron NexStar 6SE second hand which also has the StarSense camera. When I managed to get out on a couple of clear nights the StarSense seemed to be doing its thing ok. Well, kind of - I picked a couple of stars to go to and when I looked through the eyepiece there was nothing. Did this a few times and same result. So I then I decided to try the moon, the scope moved and I saw the white glint from the eyepiece. I looked through and then started focusing and focusing but the moon still remained blurry ?.

So I started searching on the inter web about this and came across Collimation. What I can’t seem to find out tho is can I Collimate the scope with the StarSense camera on or do I need to put the finder scope back on? Sorry this is probably a very silly question but I really can’t find any info about this. As I am extremely new to this all I was trying to avoid taking things off and keep simple until I could get me and the scope to my astronomy club (unsure when this will happen with the complexities of childcare- a long story!) However, I’m keen to get viewing so I wanted to try the Collimation myself and I am unsure if it can be done with star sense on.

Any help really appreciated. Thank you.

Kerry

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Hi, Kerry, and welcome to SGL.

The 6SE is a great scope - the starsense will make no difference.

You collimate when looking through the eyepiece at a star. Unfocus is slightly and you will start to see concentric rings around the star. The crucial word is concentric - if they are "lopsided" your collimation is out and needs to be corrected. This is done by tiny - repeat tiny - adjustments to the three screws on the secondary - there are plenty of videos on Youtube that show how this is done. BE VERY CAREFUL. You do NOT want to damage the front plate by having your allen key slip. Longer term, it might be worth investing in a set of Bob's Knobs to make the process easier.

Enjoy the journey.

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Collimation means adjusting the internal optics of your telescope to get them properly in line for best performance. DO NOT attempt this as a beginner without expert advice.

What you seem to be referring to as "collimation" is adjusting the Starsense setup so that it all works properly with the telescope. The Starsense instructions IIRC imply that you remove your finder. I suggest that you not do this, as it is useful to have a finder in addition to the Starsense, as I'll explain. When you first run the Starsense (setup) it is normal that it will not find anything at all accurately.  There is a part of the instructions where you tell it to find a bright star (it will go somewhere close to it), and the instructions then tell you to get the star into the eyepiece.  You can do this just the once without a finder, but it's a struggle.  Much easier if you left a correctly aligned finder in place - just use the finder...  and then follow the Starsense instructions to digitally align the Starsense with the telescope.  

Once done, the Starsense should get the desired object into a 25mm eyepiece field every time.

As for the finder, I have a red-dot finder permanently mounted on my C8 as well as the Starsense.  For planetary imaging I add an optical finder, making three...

As for focusing, the C6 (like all SCTs) has a large depth of focus. If it is not focused, and you try to focus on the Moon, you will probably wind and wind without getting anywhere. You need to focus on a bright star, which will show as a point of light (in focus) or as a large ring with a dark center (out of focus). In the latter case, wind the focus in the direction that makes the ring smaller.

 

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Thank you demonperformer for the information. Much appreciated. 

Thank you also cosmic Geoff- with the StarSense it came already mounted on the telescope and when looking through the instructions it shows removing the finder and putting the StarSense in its place. Is there some kind of attachment so both can be on at the same time? I was thinking the StarSense was working fine as it found the moon ok and I was thinking it must be a Collimation problem because couldn’t see any stars and the moon was a complete blur (and yes I was wind, wind, wind and getting upset thinking I’ve brought a broken scope). So from what you are saying it is the StarSense not aligned correctly?

Thank you for your time. Kerry:)

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The C8 has various attachment points around the rear casting, marked by pairs of dome headed screws, and the C6 should be similar. You just have to work out what points you have available and whether you have a suitable bracket or have to order one. On my C8, the Starsense is mounted below the centre line and the finder is above, and there is also a mount point on the side.

As I said above, the Starsense is not aligned by default and you have to digitally align it during the setup process. If you don't have the manual you can download one.

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Hi, thank you again. Unfortunately, the 6SE only has one mounting point on the right. I have seen some other posts about using double sided tape to mount the finder scope and I have seen the Orion dual mounting bracket but I don’t think that would work. 

During my set up with the starsense I put in the correct date, time and location and then selected auto align. It seemed to do its thing but I’m no expert. I presumed this would be the correct procedure and I would be good to go. I was feeling I wish I could have a quick peek through the finder to double check but didn’t think I could have both on. I will have to do some more research. I was just eager to be out and view and sad I have run into these issues. A learning curve I suppose : ). 

Thank you for your advice, really appreciated.

Kerry

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Kerry, I suspect your problem is not collimation but focusing related. The collimation would need to be a long way out to leave the moon as a complete blur, what it does do is reduce the level of fine detail available and make stars impossible to focus to fine points.

If you find a bright star, can you adjust the focus from being refocused through a point where the star is as small as possible and then it stars to get bigger again? If you get the star to its smallest point and then go to the moon, how does it look? I assume you are using the diagonal with the scope?

One other key point if and when you do collimate is that the star must be centred when checking if everything is concentric. As soon as the star is off centre it will appear non concentric even in a properly collimated scope.

I would check the things I've said before touching the collimation.

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Hi Stu, thank you for replying. When I point to a star I can’t even see it and the odd time I saw some sort of light glare. I tried to focus but nothing happened. Then because I thought maybe the starsense hadn’t aligned properly I tried the moon and that was in view but so blurry.  Maybe I will try going to a star again and try to get to the smallest point like you suggested and then the moon. Because I was seeing no stars this is why I was thinking it would have been good to check the star is there in the finder scope for alignment. I hadn’t realised about the dual mounting that has been mentioned in previous replies from others. Do you think it would help to check alignment if I can get the finder scope on some how? I was thinking the doubled sided 3M tape I have seen mentioned when I have been researching dual mounting as the 6SE only has one mount option.

Thank you, Kerry

 

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Stars can be very hard to see if they are way out of focus. Your plan of the finder may be worth trying, at least you could then perhaps manually find a bright star like rigel or betelgeuse and try focusing on them.

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Only one finder mounting point? Take a good look at this picture of a C6 OTA:

https://www.firstlightoptics.com/optical-tube-assemblies/celestron-c6-xlt-optical-tube-assembly.html

This may be rotated at 90 degrees compared with your 6 SE, but I can clearly see two mounting points, one used for the finder and another (marked by two dome headed screws) closer to the camera - probably below the centre line on yours.  You'd have to find a finder shoe that fits on the unused mounting point.  The dome headed screws aren't there to hold the scope together - they are for mounting stuff on.

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Are you able to point the scope by daylight at something at least a couple of miles away? The further the better. This might just be a distant horizon but something with fine detail would be best - a mast on a hill, a steeple etc. In a given eyepiece you'd then try to focus on this target, which ought to be possible so that you get a reasonable image. Use the diagonal if that's what you're going to use at night and then if you leave the focus like this it will be good enough to give you recognizable stars once out at night. At least if you have a rough focus you've removed one variable. When miles out of focus you can often see nothing at all.

Olly

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Normally do not need to touch collimation on a NexStar 6SE

Which eyepiece were you using

Try with 25mm first, then work down from there

Most scopes generally come with a 10mm and 25mm

Did you also undo the locking screw underneath the focuser

If too tight, will not allow the focuser to move in and out

When you were looking at the moon, you try adjusting up and down, left right, hand controller, to bring into view

John

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Hi,  thank you everyone for your help. I have been trying to view with the star diagonal and a 25mm eyepiece. I have not messed around with any screws at all. I have tried focusing at a roof top as far as I could in the day. I can’t seem to focus it still. I must be completely pants at this. Also I’m sure I only have the one mount point on the right. My scope doesn’t look like the picture you linked cosmic Geoff. I’m hoping it’s definitely user error and I haven’t brought a faulty second hand scope. My husband will kill me ?

Could it be a firmware update needed for the starsense? Could this be contributing to the issue in any way?

thanks 

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I dont own a starsense but i have been looking into getting one. I think from what you are saying you need to calibrate the starsense to the scope. From what ive read once this is done on the initial set up you shouldnt have to do it again. 

Ive only read up on it briefly, but once you fit it and get it working, you need to set it to find a star, then select the calibration option in the menu, adjust the scope to centre on the star then save it and thats it aligned. From then on you just power it up and let it do its thing itself. Theres probably you tube videos out there that will make it easier. 

I think the focus issue might be a seperate problem altogether. As suggested above, might be best to play about with it during the day. Ive got the same scope and i used the top of a distant pylon to set up the focus and red dot finder, so that might be worth a shot. 

 

Hope this helps 

Brian

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I'd recommend anyone with a new telescope to get in touch with their local Astro Society - where you'll find people who will be happy to spend time so you can get the most out of your scope

As you're close to Peterborough, your nearest one is the Peterborough AS at  http://www.peterborough-as.co.uk/

They're meeting next on 7th March, the talk itself should be interesting for you as it'll give you an idea of what to look for at this time of year, and if you're able to take your scope along with you, you may well find someone who's happy to have  a look  afterwards to see if they can give advice on the problem you're having with the focus.

In the meantime, I'd second Olly's advice to take it out in the daytime and check if you can get it focused on anything - preferably as distant as you can - not the Sun of course, but any distant hills, trees, street lights or aerials would be good. 

 

 

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Hi, thank you again everyone. I am already with the Peterborough society, joined October 2018. Looks like I’m going to have to give up and wait until I can get the scope to them (I’m hoping to make the March meet). I was trying to get to using it on my own but unfortunately this hasn’t happened ?.

I am using the star diagonal and 25mm eyepiece. I will have to give it a shot outside in the day again. Wish me luck ?

Thank you everyone for your time. Kerry

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