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#26 Sky Muse

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Posted 16 May 2018 - 02:01 PM

I could fix that focusser, and to where it would be smooth as silk and a joy like no other.  I'd take the axes apart, too, and replace the "lubrication".  But at the heart of the kit, and at which most of the outlay lies...

 

60mm f15 Tanzutsu achromatic doublet3.jpg

 

...the achromatic-doublet, of good ol' reliable crown and flint glasses.  Pass me a glass of wine, and the cheese plate while you're at it.

 

It's not possible to get that 4" f/6.5 achromat as an OTA; only the 4" f/10...and the 80mm f/5 achromats...faint.gif .  Used, yes, but you'd never know if it was sold due to its optical quality, or rather the lack thereof.  Hopefully this one, now making its merry way across land and sea, will be well-figured.  The greater bulk of the cost of the kit goes towards the refractor, the doublet.  Everything else is thrown, tossed, into the bargain.

 

It's the refractor we're after(at 2:40)...

 

https://www.youtube....h?v=mh-QR_qi5JU


Edited by Sky Muse, 16 May 2018 - 06:02 PM.


#27 tony_spina

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Posted 16 May 2018 - 06:12 PM

If you don't have some around the house order 6 - 12" Velcro straps. Rap 2 straps on each leg to help brace the legs. This will remove a good amount of the flex from the tripod legs especially if you extend the legs up



#28 organge

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Posted 16 May 2018 - 06:42 PM

Great tip Tony!

 

Potentially if the mount is non-viable what kind of a full deal apart from wooden tripod legs tweak should I be looking at? Jon?



#29 tony_spina

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Posted 16 May 2018 - 07:09 PM

The other thing you can do is add rings and a dovetail bar.  This will help in getting better balance especially if you go with 2" diagonal and/or heavy eyepieces 

 

IMG_3698-5.jpg
 
As you can see I did some major mods.  I added a 2-speed focuser from an SW120 and added a 50mm finder along with 2" diagonal 

Edited by tony_spina, 16 May 2018 - 07:11 PM.

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#30 Sky Muse

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Posted 16 May 2018 - 07:29 PM

 

The other thing you can do is add rings and a dovetail bar.  This will help in getting better balance especially if you go with 2" diagonal and/or heavy eyepieces 

 

 
 
As you can see I did some major mods.  I added a 2-speed focuser from an SW120 and added a 50mm finder along with 2" diagonal 

 

The original focusser of that 4" had a drawtube that could accept a 2" visual back, from what I had read in the past, but 2" oculars would not come to focus.  It's good to see that it can be done with another focusser.



#31 bvillebob

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Posted 16 May 2018 - 09:26 PM

Just be sure you understand that a small f/6.5 achromat will work fine for wide angle deep sky views, but will be severely limited for looking at the planets and the moon due to its short focal length and chromatic aberration.  The problem of course is that an 80mm refractor doesn't have enough aperture to really show you much in the way of DSO's, and the short achromat won't be much for planets, so it's of limited long term use.  An f/10 or f/11 achromat would give much better high power views, or an ED scope in shorter focal length.



#32 Sky Muse

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Posted 17 May 2018 - 03:50 AM

Just be sure you understand that a small f/6.5 achromat will work fine for wide angle deep sky views, but will be severely limited for looking at the planets and the moon due to its short focal length and chromatic aberration.  The problem of course is that an 80mm refractor doesn't have enough aperture to really show you much in the way of DSO's, and the short achromat won't be much for planets, so it's of limited long term use.  An f/10 or f/11 achromat would give much better high power views, or an ED scope in shorter focal length.

The achromat in question is a 102mm, a medium-sized refractor.  Serious observations of the planets will be difficult if not impossible to come by, granted, but views of the Moon should be satisfactory.  At a dark site, for a refractor 4" is considerable, and for the brighter and brightest deep-sky objects at least.  During the day, the telescope can be used terrestrially with an Amici; and for solar observations even, with a safe white-light filter.  Quite the contrary, it has a great deal of potential, and for years to come, if not decades.  


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#33 organge

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Posted 18 May 2018 - 06:05 PM

Today I received the scope and picked up three eyepieces along with Barlow lens - unfortunately the vendor forgot to send new prism along with the scope and that will arrive Monday. Just had a quick peek at the moon earlier and it is beautiful. The scope itself looks well built and the mount/tripod is sturdy enough. It settles quickly after 2-3s.

 

I have an issue though with slow motion control. The azimut works flawlessly but the altitude will only move up. You can get a glimpse of downward movement but after a second turn it slips. Any ideas?


Edited by organge, 18 May 2018 - 06:05 PM.


#34 organge

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Posted 18 May 2018 - 08:15 PM

Jupiter came to view to my balcony. It's bright! I have L shape balcony facing southwest and northwest. The planet is beautiful. I was able to see the bands and the moons. The planet looks great in both 8mm and 5mm eyepieces and stock diagonal. I hopped to a few stars as well. Just beautiful. Woke up the wife ( she didn't mind ) and showed her. She was astonished as well.

 

I am very happy with the telescope. Mount is sturdy enough for now but I certainly see the room for improvement. First on the list is the focuser. One knob actually unscrewed itself already. So I will need recommendations for a good focuser and further discussion on mount possibilities. I already mentioned the altitude slip issue downward and have to figure out what to do about that but overall, very, very happy. The whole telescope I can easily handle with one hand. Very light-weight.

 

Tomorrow forecast is bright night sky so I will be heading to the roof hoping to catch M13.


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#35 Sky Muse

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Posted 18 May 2018 - 11:40 PM

Sounds like you got a good one there; congratulations.

 

You should be able to adjust the axis to where it won't slip.  It may require some disassembling; check it out.  A knob loosening and perhaps falling off can be fixed, too.  Don't give up on the focusser just yet.  There are ways to improve those as well.  Take it all apart, and fix everything.  That's what I'd do.  If I had that kit here I'd have it tuned in no time.  You can do it, too.  Enjoy it.   



#36 organge

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Posted 19 May 2018 - 07:29 PM

Sky Muse : will take a look tomorrow what can be done. The thing is that when there is no scope on the mount the slow motion controls kind of work but as soon as I mount the OTA there are issues.

 

I just came from the roof of our building ( we have a nice communal area there ). I did a long session with Jupiter and oh boy it's beautiful. Very bright. Unfortunately I couldn't pinpoint M13. I could see the "trapezoid" and hunted M13 from Vega but just couldn't see it today. The stars at that part of the sky were also very faint. Let's just blame it on seeing conditions today smile.gif ( let's ignore the total newbiness ) Hope next weekend the weather will permit me to go to some nice darker place.

 

I was playing with barlow and eyepieces. Jupiter is okish even with 5mm and 2x barlow. I was pleasantly surprised. Can't even imagine how it would look through better optics. I see 80mm of many pounds in my future ( already put up one of my watches up for auction on ebay - wife thing .... sell one of the watches and buy whatever you want - well ok then ).

 

A little photo for the end. Find Jupiter!

scopeandjupiter.jpg


Edited by organge, 19 May 2018 - 07:32 PM.

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#37 tony_spina

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Posted 19 May 2018 - 08:59 PM

That great! In no time you will be a pro at this



#38 Sky Muse

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Posted 19 May 2018 - 10:57 PM

Sky Muse : will take a look tomorrow what can be done. The thing is that when there is no scope on the mount the slow motion controls kind of work but as soon as I mount the OTA there are issues.

 

I just came from the roof of our building ( we have a nice communal area there ). I did a long session with Jupiter and oh boy it's beautiful. Very bright. Unfortunately I couldn't pinpoint M13. I could see the "trapezoid" and hunted M13 from Vega but just couldn't see it today. The stars at that part of the sky were also very faint. Let's just blame it on seeing conditions today smile.gif ( let's ignore the total newbiness ) Hope next weekend the weather will permit me to go to some nice darker place.

 

I was playing with barlow and eyepieces. Jupiter is okish even with 5mm and 2x barlow. I was pleasantly surprised. Can't even imagine how it would look through better optics. I see 80mm of many pounds in my future ( already put up one of my watches up for auction on ebay - wife thing .... sell one of the watches and buy whatever you want - well ok then ).

You can certainly consider an 80mm ED doublet in future; a triplet if you expect to take pictures, but those cost much more.  However, I don't see the hurry, given your report on this one.  

 

Note that both axes of the mount, the altitude and azimuth, have plastic covers over them.  There are things to explore under those, given your issues.  Perhaps a trip to your local hardware, then to replace or add this and that. whistling.gif

 

Perhaps there are some set-screws on the outside that can be adjusted.

 

However, I don't have one of those before me, so I can't really push it.




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