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EdgeHD Corrector Plate Removal reveals Poor Celestron Tooling ?

Celestron Equipment Optics SCT
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#1 Paul J

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Posted 13 April 2021 - 04:09 PM

So... after summoning up the courage, I finally got around to removing the corrector plate on my 8” EdgeHD, cleaning necessary, really bad water stains on the interior of the corrector (made the mistake of leaving it outside under a supposedly breathable cover) .  I had been forewarned of the silicon sealing compound that Celestron for some reason believed was a necessary finishing touch to their ‘flag ship’ range of SCTs and dealt with it with my trusty Stanley knife.  However, on removing the corrector plate and cleaning away the excess silicon I was surprised to find very poor finishing along one edge of the corrector.  It looks for all the world like grip marks from tooling, I have no knowledge of the manufacturing process so this is just me adding 2+2.  I realise that regardless of the implied quality of the EdgeHD range, these are commercially manufactured optics, however it still struck me as poor quality control from Celestron.  Easy to disguise in this case, as they say ‘out of sight out of mind’.  Has anybody else found this with Celestron optics?

 

Kind Regards

Paul.

 

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Edited by Paul J, 13 April 2021 - 04:13 PM.

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#2 pyrasanth

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Posted 13 April 2021 - 04:47 PM

I'm presuming that there is no doubt in your mind that you have a corrector plate and not a sheet of plate glass?- I'm sure if this were so the images would be pretty bad.

 

I normally find most aspects of Celestron QA reasonable but never brilliant however this looks like a slip in the wrong quality direction. I would mention it to Celestron support and get their comments but I don't think they will offer you a new corrector plate!


Edited by pyrasanth, 13 April 2021 - 04:48 PM.


#3 MikiSJ

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Posted 13 April 2021 - 04:54 PM

These appear to be machining marks that are only visible when disassembled. I don't believe that Celestron supports removing front collector plates as part of normal maintenance.

 

Just clean the plate as best you can, remember how you took it apart so as reassemble the plate to what the factory did so you can go out and look at stuff.


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#4 junomike

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Posted 13 April 2021 - 04:56 PM

Not surprised.  No use spending more time (money) on something irreverent.


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#5 Spikey131

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Posted 13 April 2021 - 05:13 PM

So... after summoning up the courage, I finally got around to removing the corrector plate on my 8” EdgeHD, cleaning necessary, really bad water stains on the interior of the corrector (made the mistake of leaving it outside under a supposedly breathable cover) .  I had been forewarned of the silicon sealing compound that Celestron for some reason believed was a necessary finishing touch to their ‘flag ship’ range of SCTs and dealt with it with my trusty Stanley knife.  However, on removing the corrector plate and cleaning away the excess silicon I was surprised to find very poor finishing along one edge of the corrector.  It looks for all the world like grip marks from tooling, I have no knowledge of the manufacturing process so this is just me adding 2+2.  I realise that regardless of the implied quality of the EdgeHD range, these are commercially manufactured optics, however it still struck me as poor quality control from Celestron.  Easy to disguise in this case, as they say ‘out of sight out of mind’.  Has anybody else found this with Celestron optics?

 

Kind Regards

Paul.

How do the stars look through your Celestron 8 EdgeHD?



#6 Cpk133

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Posted 13 April 2021 - 05:20 PM

Purchased new?  Where was the silicone?  I've never heard of silicone applied to a corrector, sounds like a DIY project.  I don't think there was anything gripping the edge of the corrector that would have left marks, glass isn't malleable after all.  The plate his held by a vacuum when it's figured.  The marks could be rough grind of the periphery when the blank was made from float glass.  


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#7 Paul J

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Posted 13 April 2021 - 05:30 PM

How do the stars look through your Celestron 8 EdgeHD?

Images are fine, corrector cleaning and refitting went without a hitch.  Was just curious if other people had similar experience with Celestron QC.

 

Paul.


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#8 Paul J

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Posted 13 April 2021 - 05:49 PM

Purchased new?  Where was the silicone?  I've never heard of silicone applied to a corrector, sounds like a DIY project.  I don't think there was anything gripping the edge of the corrector that would have left marks, glass isn't malleable after all.  The plate his held by a vacuum when it's figured.  The marks could be rough grind of the periphery when the blank was made from float glass.  

Actually the Edge was bought second hand, however the the use of the silicon compound is genuine.  Every post about EdgeHD corrector removal I have read relates the same story.  The compound does not cover the entire circumference of the corrector, just 4 points loosely aligned it would appear (at least in my case) with the nylon tipped grub screws which hold the corrector in place.  In 3 of the points the compound is only about 2cm long, however in the case of the section shown in the photo as you can see the compound covered the entire section affected by the ‘teeth marks’.

 

Kind Regards

Paul.



#9 Paul J

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Posted 13 April 2021 - 05:55 PM

I'm presuming that there is no doubt in your mind that you have a corrector plate and not a sheet of plate glass?- I'm sure if this were so the images would be pretty bad.

 

I normally find most aspects of Celestron QA reasonable but never brilliant however this looks like a slip in the wrong quality direction. I would mention it to Celestron support and get their comments but I don't think they will offer you a new corrector plate!

I was almost tempted to go down this route, however, nasty as the teeth marks look, the images delivered by the scope don’t appear to be affected.  Very stable seeing on Monday night enabled me to achieve very good collimation, and the star test looked spot on.  So I’m just going to chalk it up to experience.

 

Paul.


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#10 davidc135

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Posted 14 April 2021 - 08:22 AM

It's just out of sight cosmetics, as said above, and not relevant to performance.  David


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#11 Cpk133

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Posted 14 April 2021 - 01:18 PM

Actually the Edge was bought second hand, however the the use of the silicon compound is genuine.  Every post about EdgeHD corrector removal I have read relates the same story.  The compound does not cover the entire circumference of the corrector, just 4 points loosely aligned it would appear (at least in my case) with the nylon tipped grub screws which hold the corrector in place.  In 3 of the points the compound is only about 2cm long, however in the case of the section shown in the photo as you can see the compound covered the entire section affected by the ‘teeth marks’.

 

Kind Regards

Paul.

Interesting, first time I've heard of it, good to know.



#12 Old Speckled Hen

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Posted 14 April 2021 - 06:51 PM

Actually the Edge was bought second hand, however the the use of the silicon compound is genuine.  Every post about EdgeHD corrector removal I have read relates the same story.  The compound does not cover the entire circumference of the corrector, just 4 points loosely aligned it would appear (at least in my case) with the nylon tipped grub screws which hold the corrector in place.  In 3 of the points the compound is only about 2cm long, however in the case of the section shown in the photo as you can see the compound covered the entire section affected by the ‘teeth marks’.

 

Kind Regards

Paul.

Hi, Paul.

Very interesting.

I do wonder why celestron would include a way of centering, or fine tuning the centering, of the corrector plate, then glue it in place.

If anything was going to get glued you would think it would be the farstar type secondary type holder.


Edited by Andrew Brown, 14 April 2021 - 06:54 PM.

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#13 Nightfly

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Posted 14 April 2021 - 08:13 PM

My vintage 1983 Meade 2080 corrector plate has a clean beveled edge all the way around.  Good machining practices are a clue to overall quality IMHO. 

 

Edge HD optics may be good, but the bean counters force shortcuts on the factory floor, leaving companies to live or die on dollars and cents accumulated by the sum of "time and material saving techniques"! 


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#14 LauraMS

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Posted 14 April 2021 - 11:32 PM

I have removed the corrector plate of my Edge11 because I had issues with my hyperstar assembly. There was no silicone.
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#15 Old Speckled Hen

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Posted 15 April 2021 - 03:14 AM

My vintage 1983 Meade 2080 corrector plate has a clean beveled edge all the way around.  Good machining practices are a clue to overall quality IMHO. 

 

Edge HD optics may be good, but the bean counters force shortcuts on the factory floor, leaving companies to live or die on dollars and cents accumulated by the sum of "time and material saving techniques"! 

Somewhat Ironic post!   band2.sml.gif


Edited by Andrew Brown, 15 April 2021 - 03:15 AM.

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#16 nemo129

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Posted 16 April 2021 - 10:44 AM

I have removed the corrector plate of my Edge11 because I had issues with my hyperstar assembly. There was no silicone.

Same here...no silicone. I had to remove the corrector on my EdgeHD 11" as when I went to install my Optec Secondary Mirror Focusing System the Fastar assembly had issues and would just rotate when I attempted to unscrew it, so I had to take the corrector off and use strap wrenches to get the Fastar assembly "unstuck". There was no sign of any silicone adhesive on my sample and the edges of the corrector were smoothly finished all around the periphery. I guess YMMV.


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#17 JuergenB

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Posted 16 April 2021 - 10:50 AM

Maybe the first owner of the telescope wanted to make the optics water-proof?

 

Juergen


Edited by JuergenB, 16 April 2021 - 10:51 AM.

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#18 Paul J

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Posted 16 April 2021 - 11:06 AM

Maybe the first owner of the telescope wanted to make the optics water-proof?

Juergen



#19 Paul J

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Posted 16 April 2021 - 11:07 AM

Juergen, nope the silicon was definitely inserted at manufacture. I am not the only person to have found this.
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#20 PETER DREW

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Posted 16 April 2021 - 05:07 PM

I think the original corrector blank didn't quite clean up when being edged.  Being as it is purely cosmetic and not on the optical diameter Celestron would have deemed it acceptable.  Very early C8's had rough cut corrector edges which were centered with cork spacers at appropriate positions.  By the time Meade entered the SCT market with their ground edges, Celestron were doing the same.


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#21 JuergenB

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Posted 17 April 2021 - 10:28 AM

Juergen, nope the silicon was definitely inserted at manufacture. I am not the only person to have found this.

Alright, I see. Don't worry too much about the corrector edges, Paul. Only the optical performance counts.

 

Greetings to Scotland (which my wife and I couldn't visit because of the known reasons)! Instead, we now watch Dr. Who on BBC Channel dalek12.gif  regularly.

 

Slàinte

 

Juergen



#22 Gil V

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Posted 18 April 2021 - 07:48 AM

Let me tell you something.

When you break off the outer edge of a corrector to cut it to final size, you frequently get some odd edges where the glass cracks through to the other side. As long as it fits in the cell and the full aperture is clear, you are good to go.

Edited by Gil V, 18 April 2021 - 07:50 AM.


#23 starryhtx

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Posted 18 April 2021 - 04:51 PM

You don’t get what you pay for anymore
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#24 Broglock

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Posted 26 April 2021 - 08:27 PM

Read the Whitepaper on the EdgeHD and perhaps it will all become crystal or perhaps HD clear. Quality does come at a price and Absolute Perfect Quality, well like the difference between a Lincoln Continental and a Rolls Royce or perhaps a Corvette and a Koenigsegg. Yes, you could spend more for a higher quality Catadioptric!



#25 Jpurknz

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Posted 12 May 2021 - 04:57 AM

Sounds all too fimiliar with my queries around my chipped edges on a new secondary mirror. Perhaps Celestron QC isn't as high quality as we would be led to believe. Further to this the follow up support in rectifying these issues seems somewhat lacking.


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