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Upgrade from William Optics Megrez 72FD to Zenithstar 81

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#1 jaimac

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Posted 12 August 2020 - 02:34 AM

I am planning to upgrade from William Optics Megrez 72FD F/6 to 2019 Zenithstar 81 F/6.9.  William Optics has a nice package on sale for the Zenithstar which includes flattener and guide scope. Will this upgrade improve views and pictures? Is 9 mm a significant improvement in a refractor? I don’t know what lens the Megrez uses. The new Zenithstar uses FLP-53 and of course heavier than the Megrez. 



#2 Jon Isaacs

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Posted 12 August 2020 - 05:16 AM

Hi;

 

When a William Optics scopes is designated FD, that means FPL-53 Doublet.

 

Visually, you will see more. It's not a major upgrade like a 102 mm would be but it's noticeable.

 

Jon


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#3 Sandy Swede

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Posted 12 August 2020 - 05:53 AM

Please check my math, but 72mm = 4,072mm2 area.  81mm diam = 5,153mm2 area, an increase of 1,081mm2, or 26.5% larger than the 72mm.

 

Pop quiz:  In percentage terms, how much more surface area does a 10" mirror have compared to an 8" mirror?

Hint: Area of a circle = Pi times radius squared.


Edited by Sandy Swede, 12 August 2020 - 06:03 AM.


#4 Jon Isaacs

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Posted 12 August 2020 - 12:00 PM

You can do it as a ratio;

 

(82/71)2 = 1.265625

 

Your math is fine.

 

Jon



#5 awong101

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Posted 12 August 2020 - 01:03 PM

I'm tempted and it looks like the package comes with some great savings! (I still think $200 for a field flattener is basically highway robbery)

 

And I'm not even properly mounted up for a scope this size yet. Haha



#6 jaimac

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Posted 12 August 2020 - 11:44 PM

Although the light gain from the 81mm scope is 26%, the eye might perceive it different. 

 

WO bundle comes with a guide scope, rings, and a telescope matching flattener. I ended up ordering a flattener from Astro-Tech which is like half the price of my 72mm telescope. They should make a scope right the first place instead of band aid for each defect.


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#7 awong101

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Posted 13 August 2020 - 11:25 AM

Although the light gain from the 81mm scope is 26%, the eye might perceive it different. 

 

WO bundle comes with a guide scope, rings, and a telescope matching flattener. I ended up ordering a flattener from Astro-Tech which is like half the price of my 72mm telescope. They should make a scope right the first place instead of band aid for each defect.

??? 

 

The WO ZS81 has defects?



#8 jaimac

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Posted 13 August 2020 - 11:56 AM

No defects. Trying to figure out if 26% light gain is big difference to the eye/camera.


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#9 awong101

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Posted 13 August 2020 - 12:01 PM

No defects. Trying to figure out if 26% light gain is big difference to the eye/camera.

I am seriously tempted by the package... I don't think I can piece together those 4 items for $1000 (new).



#10 jmccown

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Posted 14 August 2020 - 11:14 PM

Please check my math, but 72mm = 4,072mm2 area.  81mm diam = 5,153mm2 area, an increase of 1,081mm2, or 26.5% larger than the 72mm.

 

Pop quiz:  In percentage terms, how much more surface area does a 10" mirror have compared to an 8" mirror?

Hint: Area of a circle = Pi times radius squared.

Pie R square? No! Pie are Round!



#11 toromus

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Posted 16 August 2020 - 03:18 AM

I think I bought the last one from William Optics. 
 

All they had left was the red version. I’m pretty stoked to get it. Everyone seems out of stock on everything was originally going to get the Explore Scientific ED80 FPL100, but the morning I went to buy it they had just sold the last one, so after some research, this was the next best thing that was available. What’s weird? I can barely find anything online about the Zenithstar 81. The GT81 there are plenty of reviews. The 71? The same. Just not this specific scope. If the 81 performs the way everyone says the 71 does, I’m sure I’ll be happy. I’ve been imaging on a 6” Meade Newtonian, so I’m sure this will be a nice upgrade. I hope so anyway. 

**edit: grammatical error. 


Edited by toromus, 16 August 2020 - 03:20 AM.

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#12 awong101

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Posted 16 August 2020 - 10:54 AM

I think I bought the last one from William Optics. 
 

All they had left was the red version. I’m pretty stoked to get it. Everyone seems out of stock on everything was originally going to get the Explore Scientific ED80 FPL100, but the morning I went to buy it they had just sold the last one, so after some research, this was the next best thing that was available. What’s weird? I can barely find anything online about the Zenithstar 81. The GT81 there are plenty of reviews. The 71? The same. Just not this specific scope. If the 81 performs the way everyone says the 71 does, I’m sure I’ll be happy. I’ve been imaging on a 6” Meade Newtonian, so I’m sure this will be a nice upgrade. I hope so anyway. 

**edit: grammatical error. 

I think you did :)

 

I was checking the price/inventory yesterday or the day before, and it was still available. 

 

And now the package is all gone.



#13 OldManSky

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Posted 17 August 2020 - 01:28 PM

Although the light gain from the 81mm scope is 26%, the eye might perceive it different. 

 

WO bundle comes with a guide scope, rings, and a telescope matching flattener. I ended up ordering a flattener from Astro-Tech which is like half the price of my 72mm telescope. They should make a scope right the first place instead of band aid for each defect.

But...I already have a guide scope, so I wouldn't want one included...

 

You can often get scopes as bare OTA, bare OTA with rings, bare OTA with rings and flattener, or more extended 'packages.'  Adding accessories as an all-in-one package is nice, if that's what you want.  It isn't what everyone wants, and not having them isn't a defect :)



#14 jaimac

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Posted 17 August 2020 - 10:09 PM

Finally, ordered the last AT102EDL. Missed the Zenithstar 81 package, debated on TV-76 on classifieds and when I saw the AT102EDL in stock, I couldn't resist and ordered it. Over one month of searching classifieds for refractor is now over but wait for the scope to arrive starts. 



#15 m9x18

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Posted 18 August 2020 - 03:23 PM

Aside from the decision process, the waiting for the scope to arrive is the hardest part.  ; )



#16 m9x18

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Posted 18 August 2020 - 03:52 PM

Then after the scope arrives, it's the waiting for a nice clear night to have a good first light!  Haha.  : )



#17 ris242

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Posted 18 August 2020 - 04:02 PM

Hi;

 

When a William Optics scopes is designated FD, that means FPL-53 Doublet.

 

Visually, you will see more. It's not a major upgrade like a 102 mm would be but it's noticeable.

 

Jon

Sorry came late to this..........but Jon where does it say FD means FPL-53?

 

 

message #15............

 

https://www.cloudyni...88fd-f56-glass/




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