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How hard is it to make a reflector as good as mid-price ED or Apo refractor?

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164 replies to this topic

#151 johngwheeler

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Posted 06 May 2018 - 04:37 PM

Thanks for all the responses to my question.

I think I can be reasonably confident in saying that the answer is “yes, you can build a refractor-like reflector, but you’ll need to pay a lot more than a mass-produced scope” (and probably have a longer waiting time)

Just last night, I got out my old 8” Skywatcher Newtonian OTA, collimated it and turned in on Jupiter and Omega Centauri. Both were really nicely resolved, and really just as good as my Orion 110mm ED (my “mid-price” refractor) in terms of sharpness and pin-point stars (in the center of the field). The diffraction effects are a bit unattractive and there is coma at the edge of field, but overall there was a lot more detail and a brighter image. And this was a $300 OTA.

My 6” SkyWatcher Mak was still soft in comparion even after 3-4 hours outside. Not sure why - unable to thermal equalize, the seeing, or just poor optics? I have rarely (if ever?) had what I would call “razor sharp” detail on planets with this scope.

I’m going to keep playing with the Mak and SCT to see if I can get better performance with cooling, insulation or even installing fans, but it does seem easier to get the Newt to perform.
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#152 barbie

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Posted 06 May 2018 - 06:37 PM

No one has got a dog Zambuto that i know of.

Sorry to burst your bubble Chas but I've actually seen a less than "stellar" sample of a Zambuto. And yes, it was properly cooled and collimated!


Edited by barbie, 06 May 2018 - 06:39 PM.


#153 Dzukielis

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Posted 07 May 2018 - 10:12 AM

I guess I'm very lucky!!  Oh, and check your spelling while you're at it!

I congratulated you with luck  without sarcasm. And english is not my language, it's remains what i have learned at school some 20 years ago, so sorry for mistakes, it will never be perfect and as i don't use it each day  like you do. 

 

Many good points above, but in most cases you get what you pay for.  My refractor is also "poor man's "  instrument and is nothing to feel bad about it. 

 

Best scope -  which you have and use  ! Cheers, love , peace and unity flowerred.gif    lol.gif


Edited by Dzukielis, 07 May 2018 - 10:15 AM.

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#154 barbie

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Posted 07 May 2018 - 02:12 PM

I congratulated you with luck  without sarcasm. And english is not my language, it's remains what i have learned at school some 20 years ago, so sorry for mistakes, it will never be perfect and as i don't use it each day  like you do. 

 

Many good points above, but in most cases you get what you pay for.  My refractor is also "poor man's "  instrument and is nothing to feel bad about it. 

 

Best scope -  which you have and use  ! Cheers, love , peace and unity flowerred.gif    lol.gif

By the way, I'm a Mrs. not a Mister! My reflector is neither cheap or a "poor man's instrument".lol.gif

No sarcasm intended, just trying to correct your incorrect information on imported optics!grin.gif


Edited by barbie, 07 May 2018 - 02:25 PM.


#155 csrlice12

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Posted 07 May 2018 - 04:13 PM

 

And you aren't going to find anyone with a 10" triplet apo.

 

Uh...http://www.telescopengineering.com



#156 Starman1

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Posted 07 May 2018 - 05:50 PM

Hmm.  Only $49K for the OTA.



#157 CHASLX200

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Posted 07 May 2018 - 05:54 PM

Sorry to burst your bubble Chas but I've actually seen a less than "stellar" sample of a Zambuto. And yes, it was properly cooled and collimated!

Maybe it was a fake blake. Or Pinched.  I just can't buy it.



#158 Starman1

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Posted 07 May 2018 - 07:05 PM

And if it was bad, the owner should have sent it to Zambuto.  Carl would have tested it and corrected it and recoated it on premises.



#159 areyoukiddingme

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Posted 07 May 2018 - 07:36 PM

Maybe it was a fake blake. Or Pinched.  I just can't buy it.

Me neither. I'd bet that the primary was getting pinched by the cell, bad coatings, or perhaps a bad secondary.


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#160 CHASLX200

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Posted 07 May 2018 - 07:41 PM

Me neither. I'd bet that the primary was getting pinched by the cell, bad coatings, or perhaps a bad secondary.

I agree.



#161 CHASLX200

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Posted 07 May 2018 - 07:42 PM

And if it was bad, the owner should have sent it to Zambuto.  Carl would have tested it and corrected it and recoated it on premises.

You bet he would have made it right.



#162 NHRob

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Posted 08 May 2018 - 05:34 AM

I agree.

I agree also.



#163 BillP

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Posted 08 May 2018 - 07:54 AM

Sorry to burst your bubble Chas but I've actually seen a less than "stellar" sample of a Zambuto. And yes, it was properly cooled and collimated!

I've had the same experience with premium hand made Apos as well.  You can get a dog regardless of the maker is the bottom line.  No such thing as perfect QA or perfect production (whether hand or machine made).  And realize that only a small percentage of amateur astronomers post on astro boards, so more stuff is going on than you can read on forums that's for sure!

 

And as others have said, if those folks return the mirror I'm sure it will be fixed at no charge (frankly though, many purchasers would have no idea they have a sub-par optic).  Same for production optics, when I've gotten less than optimal optics, the vendors have always accepted the returns with refund or replacement.  So never an issue with them either.  The vast majority of reputable sellers, premium or not, have good customer service.


Edited by BillP, 08 May 2018 - 08:02 AM.


#164 turtle86

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Posted 08 May 2018 - 08:57 AM

Me neither. I'd bet that the primary was getting pinched by the cell, bad coatings, or perhaps a bad secondary.

 

Exactly.  Just because the views weren't good doesn't necessarily mean the mirror was the culprit, even if it was cooled and collimated.  Too many other possibilities, including seeing, pinched optics, etc.


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#165 Pinbout

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Posted 08 May 2018 - 09:54 AM

Exactly.  Just because the views weren't good doesn't necessarily mean the mirror was the culprit, even if it was cooled and collimated.  Too many other possibilities, including seeing, pinched optics, etc.

https://www.youtube....D0mD0JM&index=7




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