Getting Focused

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Getting Focused

Postby Ric » Fri Dec 08, 2017 12:14 am

Good evening all, very newbie question for my first post!

Tonight was my first night out with my new Bresser Messier NT150L. The night sky has always been a passion and my wife bought this telescope for my birthday in recognition of that, needless to say I'm absolutely thrilled.

With recent weather I wasn't expecting much but after stepping out into the garden, I quickly located the Orion Nebula and I got to observe the stars of Pleiades, all in all pretty successful start.

However, getting started was slowed down with the focusing. Despite drawing the focuser all the way out, the image I was getting initially wasn't perfect but the focuser wouldn't allow any further movement to get it absolutely spot on, stars a little blurry. I needed to lift the eye piece mount out of its postition by about 1cm, tighten the three bolts, and then reinsert the eyepiece. I was then able to get those pin point stars.

For a newbie, this seems counter intutive and I guess I hadn't expected to do that. I guess I'm asking did I do the right thing, is there anything obviously wrong here. Or do I need to purchase myself an extender to ensure I get some comfortable focusing moving forward. Lots more Messier objects to track down!

Thank you to all in advance.
Ric
 
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Re: Getting Focused

Postby dave.b » Fri Dec 08, 2017 12:37 am

We're you using a star diagonal or just inserting the eye piece in to the end of the 'scopes focuser draw tube?
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Re: Getting Focused

Postby Gfamily2 » Fri Dec 08, 2017 1:37 am

dave.b wrote:We're you using a star diagonal or just inserting the eye piece in to the end of the 'scopes focuser draw tube?

As I understand it, this is a Newtonian scope, so a diagonal wouldn't usually be used.

To the OP - I've seen another report on Amazon co.uk that says they needed to pull out the EP to get focus. Have you bought 'new' ?, if so I suggest you get the vendor to replace it - or see if there is something in the accessories that needs to be added to use the eyepieces for visual work.

If bought second hand, you might consider getting either of...
Celestron's t-adapter (which effectively acts as an extension to your 1.25" focus tube)
or
Celestron's 2x Barlow with t-adapter (the same as above with a removable lens so you can use it as a 2x Barlow)
Scopes: Meade 8" SCT, Skywatcher 127mm Mak
For imaging: Pentax K5, Asda webcam, Star Adventurer (new toy)
For companionship: Mid Cheshire Astronomical Group.
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Re: Getting Focused

Postby Gfamily2 » Fri Dec 08, 2017 2:00 am

Oh, and "Hi" and welcome.

Do you have a local astro society to link up with? They are great for company and also for getting ideas - and if yours is anything like mine - great for advice on how to get the most from your scope.
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: Getting Focused

Postby Ric » Fri Dec 08, 2017 7:21 am

Thank you for the responses all, for clarity, no diagonal used here.

I have found a piece which isn't detailed in the manuals and there's no obvious way I see that it attaches to the focuser, I've attached image for clarification.

It has threads so it screws onto something. Again this part isn't detailed in the manual and doesn't seem to appear on the final assembly images.

Item was new so if this isn't an easy fix I'll discuss with them later today. Thanks again!.
Attachments
2.jpg
2.jpg (74.54 KiB) Viewed 113 times
Ric
 
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Re: Getting Focused

Postby dave.b » Fri Dec 08, 2017 11:28 am

"As I understand it, this is a Newtonian scope, so a diagonal wouldn't usually be used."
Ah, sorry missed that fact.

Some Newtonian focusers have an extension tube for visual work. This is to allow a camera to be directly connected (without the extension tube) and achieve focus.
Looks like you found the extension tube. :-)
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Re: Getting Focused

Postby EIZO » Fri Dec 08, 2017 11:45 am

I have had a few scopes in the past with this NOT a problem, problem.

I had an Orion Optics top 8" with crayford that needed an adapter to reach focus, it is not a problem, can happen with some eyepieces.

Ric is correct see above
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Re: Getting Focused

Postby dave.b » Fri Dec 08, 2017 12:09 pm

Ric said "It has threads so it screws onto something."

I recall that some Newtonian focusers have an insert that unscrews and is withdrawn to reveal a thread. Have a careful look to see if yours is like this.
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Re: Getting Focused

Postby Ric » Fri Dec 08, 2017 1:21 pm

Ahh .. some good detail, thanks all.

I was somewhat reluctant about taking things apart but I've clearly missed something with that tube, it came with the scope and not the mount so surely a part of the focuser.

If anyone has a YouTube video that might offer some insight into fitting then this would be appreciated, otherwise thanks again. I'm sure I'll have some more questions for you soon :D
Ric
 
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Re: Getting Focused

Postby Gfamily2 » Fri Dec 08, 2017 2:30 pm

Is yours the scope with the Hexagonal focuser profile?

Is it assembled as shown in diagram 10a on Page 13 of the Bresser user manual for the scope?

https://www.bresser.de/out/media/931dc0 ... abb48c.pdf
Scopes: Meade 8" SCT, Skywatcher 127mm Mak
For imaging: Pentax K5, Asda webcam, Star Adventurer (new toy)
For companionship: Mid Cheshire Astronomical Group.
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