FreeLists / az-observing / [AZ-Observing] Re: The Orion 120mm ED Refractor

[DBogan3220@xxxxxxx]

Ive gradually learned over the years in the APO world you get what you pay  
for. The Orion Catalog says they are using FPL 53 for the ED element  the glass 
I'm assuming its the Ohara brand out of Japan. If so that would  be a good 
point. The question I would have would be what are they using for the  mating 
elements. It is a triplet so that is a good point. Its a longer lens I  believe 
its around F9 another good point. Here the maker could get away with  using 
cheaper mating elements.This would keep the price down.  If it was  an F6 with 
zero color error as in my AP 130 F6 the raw glass elements will  cost the 
manufacturer more than what Orion is selling the scope for. Last point  is how 
well 
the figure of each surface has been executed and I would assume the  
centering of each element is not an issue and last the construction of the  
cell. Is 
it Temperature compensated?These are details that need to be addressed  and why 
a current 5 inch APO that meets all the above criteria cost 5k and the  
companies that make them are not getting rich doing it.  Last of course is  the 
mechanics of the tube assembly. and the focuser light baffles and so forth.  
This 
I think is where the orion would cut the corners the most to save money and  
increase profits. And yes this is a mass market scope so its more than likely  
going to be all machine optics with no one looking at the final product, this 
is  how the 6 inch F8 Achromats are made in china. 
 
 
In the long run you might just as well be happy with a 6 inch F8 or an  8 
inch F8 newtonian with a small secondary if planets are your bag and at the  
focal length that they are making this scope for that would be its main  
advantage. If your into wide field CCD imaging the Tak FSQ 106 or the Televue 
NP  101 
would be the better choices. Last thing is to watch the Ads on Astromart  
occasionally AP's TECs and Taks show up on the mart but at the higher prices.  
The 
Taks you might get a break on in price a bit. The AP's of course go for top  
dollar since Roland is only making the 160 F8 Triplet's at present,  The  
Travelers the 130's and 155's and of course the 180's have been all  
discontinued. 
TEC or Telescope engineering company makes a really decent 140 APO  I hear is 
every bit as good as the AP's and Takahashi. Along with their own 160  and 180 
mm Triplet APO objectives but the price is really high of the larger  sizes.
 
Clear Skies
Dwight L Bogan
 
 
 
 
In a message dated 8/4/2006 11:48:00 A.M. Pacific Standard Time,  
stan_gorodenski@xxxxxxxxxxxxx writes:
I am not  at present in the market for a refractor, but if I were to get 
one it  would be a 5". I noticed that Orion has a new OTA 120mm ED 
refractor they  call an APO. This seems to be a bit expensive considering 
that it is  probably mass produced, the tube probably does not compare to 
tubes for  TMB's and Takahashi's, and it probably is not a full APO. 
Unless those  selling used refractors on Astromart have become even more 
greedy since  the last I looked a couple years ago, it probably would be 
better to get a  used one that has a good reputation and is known for 
sure to be an APO.  Any opinions on the Orion ED?
Stan
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