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Old 09-12-2011, 11:02 AM
eskimo
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Celstron focal reducer

I refuse to pay what ozscopes are asking for the f6.3 reducer

OPT & Optics Planet wont ship to Aus...there is a way around this but thought you guys might have better, easier way or can point me to a reasonably priced reducer?
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Old 09-12-2011, 11:14 AM
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Buy a meade one for $169 from Bintel. No difference. Or buy one 2nd hand from me. I have a near new 6.3 Meade reducer you can have for $120 inc postage
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Old 09-12-2011, 01:33 PM
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mithrandir (Andrew)
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Or consider Hirsch. I bought my 6.3 from them via ebay. I have not seen any complaints about quality.
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Old 09-12-2011, 01:58 PM
Poita (Peter)
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I have the Meade and the Celestron reducers, they look the same at first glance, but the Meade is not as good as the celestron.

They often come up second hand, give astromart etc. a look
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Old 09-12-2011, 02:38 PM
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Marke (Mark)
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I have a Celestron reducer never used if you want to make me an offer
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Old 09-12-2011, 04:31 PM
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Quote:
Originally Posted by Poita View Post
I have the Meade and the Celestron reducers, they look the same at first glance, but the Meade is not as good as the celestron.

They often come up second hand, give astromart etc. a look

I have both as well and cant say I have noticed visualy or imaging any difference...Some of earlier ones were made in Japan and supposedly better bt dont think this is case any more for either brand.
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Old 09-12-2011, 11:34 PM
Poita (Peter)
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Quote:
Originally Posted by cventer View Post
I have both as well and cant say I have noticed visualy or imaging any difference...Some of earlier ones were made in Japan and supposedly better bt dont think this is case any more for either brand.
Odd, there is a huge difference between the two I have. Both are Japanese.
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Old 10-12-2011, 12:12 PM
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Visionoz (Bill)
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What's the huge difference - in quality? in fit&finish? or you can see something lacking one from the other when looking through them and results are like chalk & cheese? Would be interested to know for reference

Cheers
Bill

Quote:
Originally Posted by Poita View Post
Odd, there is a huge difference between the two I have. Both are Japanese.
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Old 13-12-2011, 12:47 AM
Poita (Peter)
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Fit and finish look about the same, though the coatings look different, but the real difference is in the quality both visually and when photographing.
The Meade has a focal length of about 145mm vs 230mm for the Celestron, so they are quite different and back-focus issues are obviously more pronounced with one over the other.
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Old 15-12-2011, 01:07 AM
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Visionoz (Bill)
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Quote:
Originally Posted by Poita View Post
... though the coatings look different, but the real difference is in the quality both visually and when photographing.
...
Thanks Peter - so which is the better one? in quality of both visually & photographing? Is it the Meade or Celestron?

Cheers
Bill
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Old 15-12-2011, 01:54 AM
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Merlin66 (Ken)
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Peter,
I'm surprised you have a x0.63 Meade reducer with a focal length of 145mm...
There was "one bad batch" produced to my knowledge before it was corrected and the focal length reverted to the 220mm.
I had two or three reducers (both Meade and Celestron) over the years - not much to choose between them.
The current x0.63 reducers are all 220mm focal length.
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Old 15-12-2011, 06:20 AM
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Originally Posted by Merlin66 View Post
Peter,
I'm surprised you have a x0.63 Meade reducer with a focal length of 145mm...
There was "one bad batch" produced to my knowledge before it was corrected and the focal length reverted to the 220mm.
I had two or three reducers (both Meade and Celestron) over the years - not much to choose between them.
The current x0.63 reducers are all 220mm focal length.
so what does this "focal length" mean to me? would someone like to please explain to this.... um..... idiot
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Old 15-12-2011, 07:13 AM
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Merlin66 (Ken)
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Like any lens the reducer has a focal length, this is the distance from the lens to the point of focus. i.e. if you used it to image the Sun onto a piece of paper, when the image on the paper is smallest, it's at the focal point.
This distance for a x0.63 reducer is usually 220mm.
Why is this important?
When fitted to the telescope, the actual reduction (ie x0.63) is achieved with a fixed distance between the lens and the CCD chip in the camera, for the standard reducer this distance is 105mm.
If the focal length of the reducer is say only 145mm, then this distance would be close to 70mm - a big difference from the anticipated 105mm.
Hope this helps.
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Old 15-12-2011, 11:07 AM
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rainwatcher (Peter)
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I have seen many focal reducers that appear to have a single lens, maybe just the cheap ones but i can not find any optical data on the better ones. My question is, do they not introduce chromatic abberation ?
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Old 15-12-2011, 05:17 PM
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Peter,
The smaller 1.25" filter screw-in type reducers you may have seen, are achromatic doublets and were initially designed for use with small chipped webcam to give a wider field of view.
The larger Celestron/ Meade reducers were designed for SCT's.
Yes, there's always a compromise... there will be some chromatic aberrations (minor) and some field distortion (lack of flat field).
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Old 15-12-2011, 08:35 PM
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Quote:
Originally Posted by Poita View Post
Fit and finish look about the same, though the coatings look different, but the real difference is in the quality both visually and when photographing.
The Meade has a focal length of about 145mm vs 230mm for the Celestron, so they are quite different and back-focus issues are obviously more pronounced with one over the other.
Peter, with those specifications you wound up with one of the bad reducers from Meade. Presumably they were made in China to incorrect specifications which they later reverted to the original, without offers of replacement.
I have a Meade made in Japan and it's excellent and have taken many photos at f6.3 with flat stars to the edge with my 10" SCT.
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  #17  
Old 15-12-2011, 11:42 PM
Poita (Peter)
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Quote:
Originally Posted by Merlin66 View Post
Peter,
I'm surprised you have a x0.63 Meade reducer with a focal length of 145mm...
There was "one bad batch" produced to my knowledge before it was corrected and the focal length reverted to the 220mm.
I had two or three reducers (both Meade and Celestron) over the years - not much to choose between them.
The current x0.63 reducers are all 220mm focal length.
I checked it again, the Meade is definitely 145, guess I got a lemon.
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