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Missing foil spacers ? On Evostar 120

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#1 camman

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Posted 14 May 2021 - 09:19 PM

Hi guys i purchased a Evostar 120 achro secondhand recently. I Noticed there is no foil spacers. Which is odd. Wondering if someone had taken them out.  If so would i be getting this level of performance out of it. It seems to perform nicely ? The star tests were using a longpass 495 filter. The line is a heat plume

Drift imaging 

EVOSTAR-SHARPER-png-2.png

 

01-10-03-lapl8-ap1-2.png

01-07-17-lapl8-ap1-2.png

]DSC00919.jpg


Edited by camman, 14 May 2021 - 09:54 PM.


#2 KevH

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Posted 14 May 2021 - 09:27 PM

Synta stopped using foil spacers on most of their refractors. I suspect yours has a thin plastic spacer in it which is difficult to see.

#3 camman

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Posted 14 May 2021 - 09:50 PM

Synta stopped using foil spacers on most of their refractors. I suspect yours has a thin plastic spacer in it which is difficult to see.

Oh ok, didnt know that. Not sure how old this secondhand one is. Any idea what year they did this ? Thanks for the info Kev



#4 camman

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Posted 14 May 2021 - 09:53 PM

Out of interest how good or bad are these star tests here, of the Evo 120s generally ?



#5 ButterFly

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Posted 14 May 2021 - 10:13 PM

APOs can be quite different inside and outside focus when looking at all colors.  Use a green bandpass filter instead of a 495 longpass, which is nearly all of visual. 



#6 camman

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Posted 14 May 2021 - 10:57 PM

APOs can be quite different inside and outside focus when looking at all colors.  Use a green bandpass filter instead of a 495 longpass, which is nearly all of visual. 

Yes i understand. I was using the scope that night. The test was just a afterthought



#7 Rutilus

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Posted 15 May 2021 - 04:19 AM

Oh ok, didnt know that. Not sure how old this secondhand one is. Any idea what year they did this ? Thanks for the info Kev

This is the spacer ring taken out of my Evostar-120.  Regarding the age there are a few things that can help

to date the scope. i.e. what color is the scope tube.  Your scope appears not to have a collimatable lens cell,

my scope does. My scope was made in the year 2006, so they were using the spacer ring back then. 

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  • mico-cn.jpg

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#8 Jon Isaacs

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Posted 15 May 2021 - 04:42 AM

APOs can be quite different inside and outside focus when looking at all colors.  Use a green bandpass filter instead of a 495 longpass, which is nearly all of visual. 

 

Yes i understand. I was using the scope that night. The test was just a afterthought

 

According to the first post, this is the Evostar 120 mm Achro. I assume it's the 1200mm x 1000mm, F/8.3.

 

Jon


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#9 camman

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Posted 15 May 2021 - 06:53 AM

According to the first post, this is the Evostar 120 mm Achro. I assume it's the 1200mm x 1000mm, F/8.3.

 

Jon

Yes Jon that is correct

 

This is the spacer ring taken out of my Evostar-120.  Regarding the age there are a few things that can help

to date the scope. i.e. what color is the scope tube.  Your scope appears not to have a collimatable lens cell,

my scope does. My scope was made in the year 2006, so they were using the spacer ring back then. 

I really have no idea of the year. cheers for the info



#10 camman

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Posted 15 May 2021 - 06:53 AM

evo.jpg



#11 Rutilus

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Posted 15 May 2021 - 10:48 AM

You have quite a young one. Circa. 2010 to the present.


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#12 camman

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Posted 15 May 2021 - 05:40 PM

You have quite a young one. Circa. 2010 to the present.

Thanks for that info.. Again i didnt know that.



#13 GOLGO13

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Posted 15 May 2021 - 06:57 PM

A Ronchi test could be worth considering. Not sure if those are still being sold. It’s an eyepiece that gives good information in a situation like this. If there were no spacers, the two pieces of glass would likely be touching in the middle.
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#14 GOLGO13

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Posted 15 May 2021 - 07:41 PM

https://optcorp.com/...iece-10-101-150

 

This will tell you if there are any obvious abberations.

 

If you need to add spacing, this material works the best: https://cricut.com/e...foil-matte.html

 

Make sure you don't lose count as you are stacking those. You just cut little rectangles and stack them as high as needed. The Ronchi test helps a lot...unless you can read the star test when adjusting spacing.

 

Only do this if you need to...it's hard to tell from your star tests. Not perfect obviously, but could be fine in usage.


Edited by GOLGO13, 15 May 2021 - 07:42 PM.


#15 camman

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Posted 18 May 2021 - 10:48 PM

https://optcorp.com/...iece-10-101-150

 

This will tell you if there are any obvious abberations.

 

If you need to add spacing, this material works the best: https://cricut.com/e...foil-matte.html

 

Make sure you don't lose count as you are stacking those. You just cut little rectangles and stack them as high as needed. The Ronchi test helps a lot...unless you can read the star test when adjusting spacing.

 

Only do this if you need to...it's hard to tell from your star tests. Not perfect obviously, but could be fine in usage.

Thanks. Was thinking of getting a ronchi grating, for my other scope. So yes would be useful



#16 peleuba

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Posted 19 May 2021 - 03:48 PM

The star tests were using a longpass 495 filter.

 

 

01-10-03-lapl8-ap1-2.png

01-07-17-lapl8-ap1-2.png

 

 

What camera did you use to take the star test image?  The quality of the image and your technique is quite good!  Did you use a Powermate or any other relay lens or auxilary optics to lengthen the focal length of the scope?

 

Regarding the scope:  I see several zones, and a little spherical error.  But nothing too bad.


Edited by peleuba, 19 May 2021 - 03:50 PM.


#17 camman

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Posted 23 May 2021 - 01:06 AM



What camera did you use to take the star test image?  The quality of the image and your technique is quite good!  Did you use a Powermate or any other relay lens or auxilary optics to lengthen the focal length of the scope?

 

Regarding the scope:  I see several zones, and a little spherical error.  But nothing too bad.

 



What camera did you use to take the star test image?  The quality of the image and your technique is quite good!  Did you use a Powermate or any other relay lens or auxilary optics to lengthen the focal length of the scope?

 

Regarding the scope:  I see several zones, and a little spherical error.  But nothing too bad.

Hi i used a QHY 462c camera Baarder longpass. 495nm as i was getting ready to image that night. The scope wasnt totally cool i dont think. Either prime focus or 2x barlow. cant remember exactly ? The scope seems to be performing quite well.For the lunar image I used a 3X GSO Barlow under poor seeing using drift method with a motor tracking at wrong speed. (dont ask)

evo-120-sgl-png-4-png-5.png


Edited by camman, 23 May 2021 - 01:43 AM.

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