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Focusing issue is a small refractor (or think it is)

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#1 ValhallaObserver

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Posted 16 May 2018 - 04:14 PM

All,

 

I have SV60MM refractor I recently acquired for using when I plan to do some hiking this summer to darker spots than suburbia. During daytime and nighttime, when I try to focus the object is blurry or when looking at a planet I get a large disk that is not in focus. The focus gets better as I move the rack and pinion focus all the in to the minimum stop. Is there something wrong with the telescope, the focuser, the operator, or maybe the 2" Astrotech diagonal. Eyepieces make no difference. I have typically been trying with an ES 68 24mm or a 11mm ES82 eyepiece. Eyepieces seem to make no difference. Help!

V/O



#2 aeajr

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Posted 16 May 2018 - 04:25 PM

I always recommend you post a link to anything you discuss so we can be sure.   Is this your scope?

http://www.stellarvu...-from-only-499/

 

 

 

Post a couple of photos of the set-up from different angles. 

 

 

Try this. 

 

Is the diagonal all the way into the focuser? 

 

When you put the eyepiece in the diagnal, lift it out of the diagonal just a little, maybe 1/4" and then lock it in place and see if you can get it to focus.   I have a couple of eyepieces that require this. 

 

Worth a shot. 


Edited by aeajr, 16 May 2018 - 04:34 PM.


#3 tony_spina

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Posted 16 May 2018 - 04:48 PM

Sounds like you don't have enough infocus with the 2" diagonal.  Do you have an 1.25" diagonal ?


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#4 vtornado

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Posted 16 May 2018 - 04:54 PM

You can also try not using the diagonal, and just put the eyepiece in the focuser  barrel. 

 

It may create an out focus problem,

because you have taken too much distance out of the light path.    If it looks like you can't reach focus without the diagonal with the

focuser all the way racked out, don't insert the eyepiece all the way into the barrel.

 

My ST80 will not come to focus with some eyepieces without a diagonal


Edited by vtornado, 16 May 2018 - 04:58 PM.


#5 Redbetter

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Posted 16 May 2018 - 05:56 PM

Does this scope have any sort of extension tube in the focuser?  If so, remove it and try again.  What I saw in a search was that a TS variant of the same was that came to focus with a 31T5.  I would consider it a fatal deficiency of a 60mm wide field scope if it couldn't come to focus with 2" eyepieces using a 2" mirror diagonal.  While it will be fine for imaging, I wouldn't want to be stuck in 1.25" for visual in this scope. 

 

The 1.25" eyepieces you are using shouldn't even require all that much inward focus compared to some of the big 2" wide fields. Is your 1.25" to 2" adapter flush, raised, or even "high hat" style?   

 

By comparison the AT60ED with 2" diagonal can reach focus for visual with a 31T5 and a 55 Plossl.  The 31 requires the most inward travel of the TV range (except for the 17 Ethos which requires 0.01" more) and the 55 has the most outward travel.  The difference between the two is 1.54" which is a match for the ~40mm difference I read from the draw tube.  

 

Have you tried a 1.25" diagonal?  That might be the only viable option for visual if there is not an extension tube in the way at present. 


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#6 Mike W.

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Posted 16 May 2018 - 09:32 PM

Could you post a pic of the focuser end of the scope, like maybe the back half of the scope?



#7 SteveG

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Posted 16 May 2018 - 09:42 PM

The website states it will work visually with the 2" star diagonal. It also mentions the scope has a threaded extension tube. Make sure you've removed that tube to use it visually, as others have noted.



#8 sg6

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Posted 17 May 2018 - 08:59 AM

As above, check if the scope has the extension tube already in place. It reads that you ue a 2" diagonal OR the extension tube and the optional flattener. Just yours may have had the extension tube already put on - makes it easy to ship I suppose.

 

The Astrotech diagonal may however be longer then expected, doubtful however.

Any chance of borrowering a different one from someone?

 

Just in case check that there is not an adaptor in the diagonal that hasto be removed, it is a common trouble on Skywatcher scopes here. Someone at SW has done a good design job but it looks like both adaptors are meant to be in place when that is incorrect so users get really puzzled. With exactly the problem you describe.

 

Suspect there is no real problem (I would hope not) but more a case of a bit of confusion. Bresser and ES scopes seem to be supplied for AP so they need one of the supplied extension tubes added for visual, but they don't say this.



#9 ValhallaObserver

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Posted 17 May 2018 - 11:53 AM

Thanks. I plan to call Stellarvue.  Think I should send to them as a nice little item and see what or if they can figure it out. I am such a rookie. Things I tried yesterday.

 

!. tried moving the diagonal in and out. No change.

Tired a 1.5" did not seem to make a difference.

The kit included a 1.5" adapter I tried no improvement.

No idea how to check scope collimation. I did not try the AT 2" diagonal in another scope yet.

 

I need to take photo. A good idea.

 

V/O



#10 Sky Muse

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Posted 17 May 2018 - 07:17 PM

You can check the collimation very easily with any refractor, and with something as inexpensive as this...

 

*EDIT: https://agenaastro.c...refractors.html

 

You have to cover the front, the aperture, to check...

 

collimation-092415.jpg

 

Hope this helps.


Edited by Sky Muse, 17 May 2018 - 11:26 PM.

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#11 vtornado

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Posted 17 May 2018 - 09:38 PM

Hi Sky Muse, give me a few more sentences, so I can figure out what you are talking about?

 

If I cover the front aperture and put a collimation cap in??  Seems kind of dark to see anything??

 

Thanks,

VT


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#12 Sky Muse

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Posted 17 May 2018 - 11:24 PM

Hi Sky Muse, give me a few more sentences, so I can figure out what you are talking about?

 

If I cover the front aperture and put a collimation cap in??  Seems kind of dark to see anything??

 

Thanks,

VT

My bad, as I'm used to recommending those for the Newtonians. blush.gif   

 

In addition, you want to use a penlight of sorts to shine into the side of the tool to illuminate the interior of the optical tube.


Edited by Sky Muse, 17 May 2018 - 11:27 PM.


#13 Jon Isaacs

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Posted 18 May 2018 - 05:14 AM

All,

 

I have SV60MM refractor I recently acquired for using when I plan to do some hiking this summer to darker spots than suburbia. During daytime and nighttime, when I try to focus the object is blurry or when looking at a planet I get a large disk that is not in focus. The focus gets better as I move the rack and pinion focus all the in to the minimum stop. Is there something wrong with the telescope, the focuser, the operator, or maybe the 2" Astrotech diagonal. Eyepieces make no difference. I have typically been trying with an ES 68 24mm or a 11mm ES82 eyepiece. Eyepieces seem to make no difference. Help!

V/O

 

Hi:

 

From your description, you are running out of inward focuser travel since focus gets better all the way in.  As others have said, it's possible that you have extension tubes that need to be removed.  

 

If you could post a photo of the diagonal and focuser, racked all the way in, that would be a big help.

 

Jon



#14 ValhallaObserver

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Posted 24 May 2018 - 03:02 PM

Okay I cannot figure out how to post the photos I took. One was of the manual. It states "included with your scope is a small extension tube". This is a metal tube that goes between the focuser and the main body of the telescope. It came installed not as a separate part. Do I need to remove this? If so do you simply unscrew it or is there some other mechanism usually. If someone can help me with loading a photo I can upload a couple. Sorry for my lack of response to my post work and actually observing when I get a chance!

 

V/O



#15 gnowellsct

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Posted 24 May 2018 - 04:22 PM

The two main ways to attach focusers to tubes are

1. Three screws spaced at 120 degrees or
2. Threads on the tube.

So give it a good look and see how you can get it off. I'll give a warning that is liked not relevant. Some scope makers, specifically Takahashi, like to make sure the focuser in back and lens cell in front do not unscrew by putting in tiny grub screws which go through the threaded part of the focuser (or lens cell) and tighten directly again st the threads on the tube. If you don't see three obvious screws where focuser or extender is inserted into tube focuser=male, tube = female) but instead see the tube as male inserted into the focuser, then you probably have a threaded tube and need to check for grub screws or any other locking screw that prevents rotation.

That done removal is fairly straightforward. Focusers are fairly simple. Inspection should reveal how to remove extender.

If you retest focus under daylight conditions pick something far away.

So far as I know only Tak does the grub screw nonsense and maybe they've wised up and stopped. I swear to God anything to do with a focuser Tak is going to make unnecessarily difficult. Stellarvue has a history of intelligent machining you'll likely be fine.

Edited by gnowellsct, 24 May 2018 - 04:23 PM.


#16 ValhallaObserver

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Posted 24 May 2018 - 06:57 PM

Well still having trouble loading a photo. I can load a link from the online manual though. Page 7 or so I think the extension tube is installed. Not sure how to take it off exactly.It looks like the end that goes to the mirror the other end has 2 screws real screws FHCS and one **** can turn by hand. What seems to be the extension piece has the S/N 572 on it which I find odd.. Anyway see if the manual can help you give me some guidance. Will se if I can load the photos somehow but my scope looks like the manual shows.

 

https://www.stellarv...ual SV60EDS.pdf

 

V/O



#17 vtornado

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Posted 24 May 2018 - 09:30 PM

This site has a 1mb?  or 2mb limit on photos, and sometimes instead of saying it's too big, you just get an error message.

Try setting the resolution of your camera to 640x480, and make sure it saves as jpeg, not raw format.



#18 gnowellsct

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Posted 24 May 2018 - 09:34 PM

The extension looks female on the side raised to us and male on the side that is on the table.  The "mirror" as you call it is the diagonal and you pull that out by loosening the screws that are around it.   This is a normal thing to do.  Once you do that you can look inside.  At a minimum, get the diagonal off.  

 

To post pics, open your jpgs in PAINT. (Right click, select open with.... then select PAINT).   To the right of VIEW there is a little rectangle called RESIZE.  Set dimensions to 30%.  Resize, then do a SAVE AS.  That should cut the size of your photos dramatically.  If you do SAVE AS you still have the original.  You can of course do 50% or 20% or whatever you want, a little experimentation gets you underneath the CN maximum.  There is a free utiltiy called PIX RESIZER that you can download.  It can resize multiple pics at the same time and stores them all in a folder that you designate.

 

Greg N



#19 gnowellsct

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Posted 24 May 2018 - 09:34 PM

This site has a 1mb?  or 2mb limit on photos, and sometimes instead of saying it's too big, you just get an error message.

Try setting the resolution of your camera to 640x480, and make sure it saves as jpeg, not raw format.

500 mb I think.  



#20 gnowellsct

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Posted 24 May 2018 - 09:37 PM

Looks to me that he has three screw arrangement on the adapter that fits on to the tube.  I see two at 120 degrees.  Unscrew those and the focus assembly comes off.  GN



#21 Sky Muse

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Posted Yesterday, 02:21 AM

Under "Astrophotography" within the .pdf manual, remove the discombobulator...

 

https://imgur.com/lHvUlm9



#22 vtornado

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Posted Yesterday, 09:31 AM

500 mb I think.  

I assume you meant 500Kb.



#23 SteveG

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Posted Yesterday, 12:08 PM

Under "Astrophotography" within the .pdf manual, remove the discombobulator...

 

https://imgur.com/lHvUlm9

Agreed. He needs to remove the white "tube extension" and remount the focuser to the shorter tube.




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