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18" Galaxy gets the real test this coming week

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#1 CHASLX200

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Posted 09 May 2021 - 06:33 PM

Jupiter is now high enough to give my 18" Obsession it's first real test.  So one morning this week before sunup and gonna see if the Galaxy mirror is worth keeping or will i sell the scope or have the mirror refigured.  On deep sky and the moon it seems fine, but i have a feeling it will not have the snap that my Zambuto scopes did.


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#2 Bill Jensen

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Posted 09 May 2021 - 06:38 PM

Hoping it is a keeper for you. You have put a bit of effort getting the structure/cell fixed up, so hopefully the mirror can now perform to its best. 



#3 CHASLX200

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Posted 09 May 2021 - 06:42 PM

Hoping it is a keeper for you. You have put a bit of effort getting the structure/cell fixed up, so hopefully the mirror can now perform to its best. 

I think most anyone would be thrilled with the mirror but i am not a normal Dob user since i only view planets at very high powers. My kind of seeing will bring out the worst in any optic and this is where having the best pays off.



#4 Keith Rivich

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Posted 09 May 2021 - 06:59 PM

Jupiter is now high enough to give my 18" Obsession it's first real test.  So one morning this week before sunup and gonna see if the Galaxy mirror is worth keeping or will i sell the scope or have the mirror refigured.  On deep sky and the moon it seems fine, but i have a feeling it will not have the snap that my Zambuto scopes did.

I have two Galaxy Optics mirrors...my 18 and 25".

A friend of mine has 20" and 36" Galaxy mirrors.

All are of excellent quality and perform extremely well.


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#5 siriusandthepup

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Posted 09 May 2021 - 07:11 PM

I'm hoping yours is as good as the Galaxy 18" f4.5 I used to have.

 

I have a fond memories of Mars at opposition showing both (at the same time) Phobos and Deimos favorably placed at 580x (3.5mm Vixen LVW).

 

Mars looked great as well with no hint of excessive magnification. Sharp edges and good contrast on surface details.

 

No problems with planets with that mirror.



#6 a__l

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Posted 09 May 2021 - 07:13 PM

https://www.cloudyni...s/#entry2908093

 

Read dave b. Moderator Astromart.  Regret that he left this forum long ago.


Edited by a__l, 09 May 2021 - 07:42 PM.


#7 CHASLX200

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Posted 09 May 2021 - 07:24 PM

I'm hoping yours is as good as the Galaxy 18" f4.5 I used to have.

 

I have a fond memories of Mars at opposition showing both (at the same time) Phobos and Deimos favorably placed at 580x (3.5mm Vixen LVW).

 

Mars looked great as well with no hint of excessive magnification. Sharp edges and good contrast on surface details.

 

No problems with planets with that mirror.

It has a Strehl of 0.919.

 

Like i said Deep sky is fine and Mars looked ok but was so small it was not much to look at back in Feb. Did see some detail.  Have not looked at Jupiter or Saturn yet.



#8 Tyson M

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Posted 09 May 2021 - 10:04 PM

My 25" galaxy mirror has 92.9 strehl I think.

 

Either way I think it is a decent mirror based on my lunar observations of it. I bet you will like it.



#9 CHASLX200

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Posted 10 May 2021 - 05:50 AM

Almost rolled out the scope this AM but too many high clouds.  Nice warm nites for this week with lows around 74f should make for good seeing.



#10 peleuba

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Posted 11 May 2021 - 10:21 AM

It has a Strehl of 0.919.

 

Like i said Deep sky is fine and Mars looked ok but was so small it was not much to look at back in Feb. Did see some detail.  Have not looked at Jupiter or Saturn yet.

 

 

Chas,

 

Like you I have a lot of experience with having only owned Zambuto mirrors up through 14.5".  But my club has a 16" Galaxy mirror that is amazingly good.  It was the first mirror that showed me color - reds and pinks - in the Orion nebula complex, repeatedly.  I had it tested and I think the Strehl was something like .930 with a deep center.  Since then, I have seen other Galaxy mirrors and I would rank them highly.  I think Jerry Wilkerson was the optician.

 

So, I would not let the numbers on the paper lead you astray.  Use the mirror.  I think it will be very good.  And, if the structure is in good shape with a decent cell/mirror support an 18" scope is a potent observing package in the steady Florida skies.   


Edited by peleuba, 11 May 2021 - 10:22 AM.

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#11 tommm

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Posted 11 May 2021 - 10:34 AM

Jupiter is around 20 deg altitude max these days, correct?  The seeing in FL is good enough at that low an altitude that it won't be the limiting factor, not the mirror? 



#12 CHASLX200

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Posted 11 May 2021 - 06:18 PM

Jupiter is around 20 deg altitude max these days, correct?  The seeing in FL is good enough at that low an altitude that it won't be the limiting factor, not the mirror? 

Most times the seeing is near dead still this time of year before sun up.  It was cloudy again this AM. The seeing in the summer is never good for my area after sun down.  My best seeing of the year is in FEB on super warm and humid nites with sea fog about to come onshore.  Maybe later this week i can try it out.



#13 CHASLX200

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Posted 12 May 2021 - 05:36 AM

I am thrilled to say the mirror is good. Rolled out the scope this AM and Jupiter shows enough detail to last someone a lifetime of viewing with a 8 and 7mm eyepieces.  Saturn takes on a 3d look as the rings really start to show some detail when you get into a scope this size. Plenty of brightness with a 7mm Delite. 

 

Just not used to using a Dob pointed down so low. You could sit in a chair and view the planets they are so low to the south. Hate to see what better seeing and the planets being higher up would show.

 

This is for sure as big as a scope as my house is built for. Pain getting it out the door as it is easy to dump the whole scope out of the rocker box when lifting up on the handles. I have to pull the scope in and out of the door as hitting the bump up will cause the scope to dump out of the rocker box.  I did the flash light trick with the Tectron tools and got collimation to be very good.

 

Seeing was what i call fast seeing, like looking thru running water with the object snapping in dead sharp in and out very fast.  The rings of Saturn take on a look of tiny groves when the seeing would pop.

 

M13 and 15 looked very snappy and cored out, but a much darker sky would really help with deep sky. 


Edited by CHASLX200, 12 May 2021 - 05:37 AM.

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#14 Markovich

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Posted 12 May 2021 - 07:13 AM

Thats really good to hear Chas!



#15 siriusandthepup

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Posted 12 May 2021 - 07:21 AM

Grats, buddy!

 

Thanks for the report.

 

waytogo.gif

 

<edit> Now you should acquire that Vixen 3.5 LVW for Mars - 580x


Edited by siriusandthepup, 12 May 2021 - 07:23 AM.


#16 turtle86

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Posted 12 May 2021 - 09:11 AM

 

 

Just not used to using a Dob pointed down so low. You could sit in a chair and view the planets they are so low to the south. Hate to see what better seeing and the planets being higher up would show.

 

 

 

Last Friday I had to get on my knees to view Omega Centauri and nearby Centaurus A  in my 18"; the scope was pointed too low even for a chair.  It was a good night so it was well worth it.


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#17 a__l

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Posted 12 May 2021 - 02:58 PM

Last Friday I had to get on my knees to view Omega Centauri and nearby Centaurus A  in my 18"; the scope was pointed too low even for a chair.  It was a good night so it was well worth it.

I recommend changing the design of your 18". To avoid kneeling.
Move the axis of your focuser up in the UTA. So that it would be convenient to look through the eyepiece from top to bottom (at low ground dob direction).



#18 turtle86

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Posted 12 May 2021 - 05:21 PM

I recommend changing the design of your 18". To avoid kneeling.
Move the axis of your focuser up in the UTA. So that it would be convenient to look through the eyepiece from top to bottom (at low ground dob direction).

 

Thanks for the suggestion.  What I *really* need to do is move to a lower latitude so those objects would be better positioned!  

 

A few years ago I got to see Omega Centauri in a 16" scope on Mauna Kea in Hawaii, at 7000'.  Hawaii is only about 18 degrees north, so I didn't have to get on my knees.  lol.gif

 

That's a view I'll never ever forget. 


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#19 CHASLX200

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Posted 12 May 2021 - 06:21 PM

Make sure the mirror won't flop over going very low to the south.  A 16" would be a better choice with my narrow door.  If i could trade someone for a 16" F/5.5 with a great mirror and motions i would do it.



#20 CHASLX200

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Posted 12 May 2021 - 06:22 PM

Grats, buddy!

 

Thanks for the report.

 

waytogo.gif

 

<edit> Now you should acquire that Vixen 3.5 LVW for Mars - 580x

I got a 3.2mm.  I tried a 5mm Delite but the seeing was not that great using it.
 



#21 a__l

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Posted 12 May 2021 - 06:42 PM

Thanks for the suggestion.  What I *really* need to do is move to a lower latitude so those objects would be better positioned!  

 

 

It won't help you. There may be an interesting object that will be south (for the northern sky) or north (for the southern sky) or east or west. And located low to the horizon.
For example, an amateur Mr. Borisov from Crimea, who discovered the first interstellar comet, observes only near the horizon. He has an astrograph, not a dobson, but what if he gets lucky :)
I suggested that you make a convenient version of observations for 18". I did this in my 18" from the third edition (among other changes). In the first edition I had it done byrecommended Kriege. According to Kriege, for this telescope placement, the focuser axis will be parallel to the ground.



#22 turtle86

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Posted 12 May 2021 - 06:42 PM

Make sure the mirror won't flop over going very low to the south.  A 16" would be a better choice with my narrow door.  If i could trade someone for a 16" F/5.5 with a great mirror and motions i would do it.

No worries with my Starmaster, as the cell has three retaining clips for the primary.  I still try to be careful though.



#23 Voyager 3

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Posted 13 May 2021 - 06:49 AM

Make sure the mirror won't flop over going very low to the south.  A 16" would be a better choice with my narrow door.  If i could trade someone for a 16" F/5.5 with a great mirror and motions i would do it.

There was a 16" Teeter planet killer ( F/5.4 if I remember correctly ) not so long ago , in the classified .



#24 CHASLX200

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Posted 13 May 2021 - 06:19 PM

There was a 16" Teeter planet killer ( F/5.4 if I remember correctly ) not so long ago , in the classified .

My scope wants to dip down when i take it out the door.  It can't be very high up or it will hit the top of the door frame.

 

But nice thing about 18" is at 450x the image in nice and bright while in a 6" fract 450x is getting dim.  I still say the Newt is the best planet scope for my seeing anyways. I also notice color seems to pop more with a scope this size as i could see a lighter pink area inside the great red spot.


Edited by CHASLX200, 13 May 2021 - 06:29 PM.

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#25 siriusandthepup

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Posted 13 May 2021 - 07:05 PM

Please make a restraining strap to use while going in and out.

 

That way you can avoid the sadness when the whole thing dumps and your sweet mirror gets scratched or chipped. Believe me - been there done that!




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