74 replies to this topic

[Brollen]

With Tinky (https://www.cloudyni...l= tinky tim53), I had the opposite problem with UPS.  The seller packed the fully-assembled scope, with tabletop stand, in a single thin-walled cardboard box and filled the space around the scope with styrofoam peanuts.  It was taped reasonably well, but still was more of a cardboard "bag" than a box when it arrived.  I heard the UPS truck coming up the hill, so I was out at the end of the driveway to meet him when he stopped.  He actually warned me of the packing, and waited while I opened the box in front of him before driving away.  Amazingly, there was no damage.

 

[edit:  It's been a long time since this shipped, and I had forgotten about the foam-filled bags that were in the box around the scope.  So it wasn't as bad as I thought I had remembered it.  

 

In other news, if you really want to know how best to pack a scope for shipping, buy something from Chip sometime.  I bought his 8" Schmidt camera a while back.  It was by far and away the best packed item I've ever seen.  Ever!]

-Tim.

 

Tim53 - that is an amazing thread on how you restored Tinky. I plan to read it more closely. And I wish that my scope arrived without issue - this is a pain, but its not the worse I've experienced and its not as if I am without scope - I've got others to view through until this one comes online.

[Brollen]

I have found out in my cases that USPS handles packages much more carefully that UPS.

I have used USPS myself without incident. 

Edited by Brollen, 21 March 2020 - 11:24 AM.

[Spectral Joe]

I've shipped a number of fragile items, only using ups when I had to. I noticed a sharp decrease in rough handling when I started sticking these on the box:

 

https://www.amazon.c...ref_=ast_bbp_dp

 

Cheap insurance, people behave better when being watched by someone or something. Not a good substitute for good packing, though.

[dave brock]

Maybe when you have bought a fragile item, ask the seller to take some photos as he packs it and send them to you so you can ok the parcel before shipping?

[Garyth64]

I sold two scopes to one person.  I packed both separately as best I could, and sent them UPS.  The wood boxes were encased with 2" Styrofoam.

 

Both scopes arrived at the same time to the buyer, and both were damaged!  The internal wood brackets on both were broken!

 

I could see maybe one getting damaged, but both?  Obviously both were handled the same way.  Just how hard, or how far, did they slam it or toss it?

 

The next scope I had sent out, I had UPS pack it themselves.  It arrived safely.  Hmmm, funny how that happened.

[CHASLX200]

I sold two scopes to one person.  I packed both separately as best I could, and sent them UPS.  The wood boxes were encased with 2" Styrofoam.

 

Both scopes arrived at the same time to the buyer, and both were damaged!  The internal wood brackets on both were broken!

 

I could see maybe one getting damaged, but both?  Obviously both were handled the same way.  Just how hard, or how far, did they slam it or toss it?

 

The next scope I had sent out, I had UPS pack it themselves.  It arrived safely.  Hmmm, funny how that happened.

After UPS broke my $1200 pellet gun i never used them again after 2005.

[starman876]

After UPS broke my $1200 pellet gun i never used them again after 2005.

must have been an Angel

[Brollen]

I sold two scopes to one person.  I packed both separately as best I could, and sent them UPS.  The wood boxes were encased with 2" Styrofoam.

 

Both scopes arrived at the same time to the buyer, and both were damaged!  The internal wood brackets on both were broken!

 

I could see maybe one getting damaged, but both?  Obviously both were handled the same way.  Just how hard, or how far, did they slam it or toss it?

 

The next scope I had sent out, I had UPS pack it themselves.  It arrived safely.  Hmmm, funny how that happened.

That’s crazy...

 

Like you, I’m sure the seller of my C8 had the best of intentions when he packed the scope and I have no reason to think otherwise. Hindsight is 20/20. But I’m happy to to say that the seller and I have reached terms - so all is good. I’m looking down the road, not behind! Looking forward to trying to bring this C8 online.

Edited by Brollen, 21 March 2020 - 08:05 PM.

[orion61]

The scope can be further damaged in shipping.....

I can supervise over the phone or PC.. no need to ship it.

[Brollen]

Still waiting on UPS to resolve the claim. They have blown through their initial timeline... but things are crazy all over so this is to be expected.

 

Once the claim is resolved, I plan on spending time on the scope - hopefully this weekend. I'd like to start opening it up assessing any new damage I might find, check the existing orientation of optical elements such as the corrector and start re-assembly. I've been studying a number of pages I've found dealing with C8s and other SCTs, so I'm feeling armed with knowledge... and this isn't my first time opening up an SCT as well.

 

Clear skies!

Edited by Brollen, 26 March 2020 - 07:54 AM.

[DAVIDG]

 Let me save you a ton of time and frustration from some who  actually designs and makes optics vs what is written by those that don't. It does not matter how you rotate the optics. I'll say it again it does not matter how you rotate the optics. They are a figure of revolution which means they are rotationally symmetrical.  What is important is that the secondary is centered on the the mounting plate, the corrector is centered in it's cell and then using the ID of the corrector cell as a reference surface and the center bolt on the secondary as the other reference point you center the secondary. Then you can collimate the optics.  Many time the optics are not correctly centered from the factory so don't trust how the secondary was glued to the mounting plate. Measure it yourself. 

   The alignment marks on the optics were put on them when they were placed in testing jig and then aligned. They were used to get them aligned in the jig if they were removed to save time. They have nothing to do with canceling  optical errors. So don't  waste your time worrying about rotating the corrector and/or the secondary. If they are correctly centered it will make no difference and if they are not correctly centered you never get the optics to properly collimate.

 

           - Dave

             Director Mt Cuba Observatory

             25 Awards from Stellafane, 10 in optics

             Contributor to books on optics like "Telescopes, Eyepieces and Astrographs"  

[unitron_man]

 Let me save you a ton of time and frustration from some who  actually designs and makes optics vs what is written by those that don't. It does not matter how you rotate the optics. I'll say it again it does not matter how you rotate the optics. They are a figure of revolution which means they are rotationally symmetrical.  What is important is that the secondary is centered on the the mounting plate, the corrector is centered in it's cell and then using the ID of the corrector cell as a reference surface and the center bolt on the secondary as the other reference point you center the secondary. Then you can collimate the optics.  Many time the optics are not correctly centered from the factory so don't trust how the secondary was glued to the mounting plate. Measure it yourself. 

   The alignment marks on the optics were put on them when they were placed in testing jig and then aligned. They were used to get them aligned in the jig if they were removed to save time. They have nothing to do with canceling  optical errors. So don't  waste your time worrying about rotating the corrector and/or the secondary. If they are correctly centered it will make no difference and if they are not correctly centered you never get the optics to properly collimate.

 

           - Dave

             Director Mt Cuba Observatory

             25 Awards from Stellafane, 10 in optics

             Contributor to books on optics like "Telescopes, Eyepieces and Astrographs"  

So are you saying that in the Celestron factory (mass production) the technician did not rotate the corrector, or the secondary to obtain the optimal image?

[tim53]

So are you saying that in the Celestron factory (mass production) the technician did not rotate the corrector, or the secondary to obtain the optimal image?

That is exactly what he will tell you.

 

Cogitate for a moment...

 

The biggest source of potential error in building one of these would be if the optical surface isn't exactly parallel and concentric with the physical substrate - the glass on which the optical surfaces are ground and polished.  So, given a jig fixture that is used to test the optics while they are being final figured, the optician wants to minimize errors that could crop up by moving the optics back and forth from the jig to the bench, they'll make marks on the optics to line up with marks on the jig, and eliminate imprecisions that might be introduced if there is a "wedge" to either mirror that would cause the mirror to be off-axis in the jig.  

 

So, in effect, the technician is deliberately NOT allowing rotation of the corrector, secondary, or primary with respect to the JIG, so that minimal collimation adjustments will be needed in the final OTA.  But collimation will be necessary, because each OTA differs in very small amounts from the jig's dimensions. 

 

-Tim.

Edited by tim53, 26 March 2020 - 04:30 PM.

[unitron_man]

So why is it that the marks on the primary, secondary, and corrector all line up in the final OTA? If it didn't matter, wouldn't you see random alignments of those jig marks?

[DAVIDG]

So are you saying that in the Celestron factory (mass production) the technician did not rotate the corrector, or the secondary to obtain the optimal image?

   Yes they rotated them but there is misunderstanding of why  they were doing. You need to get three optical elements aligned  to test them. The test jigs holds them by the edges or the backs and  the backs of the primary and the secondary are not precision ground to optical surface. So when you place them in the jig you rotate them to get them aligned because they are not perfectly round and the optical axis and mechanical axis not perfectly aligned. It has nothing to do with canceling optical errors. Celestron would hand figure the secondaries. That requires taking it in and out of the test jig. So to get it  back in the same place along with corrector plate and primary you mark them so you can get them back in the jig in the same place. That saves a lot of time and allows you test them quickly and then get back to figuring them. 

   If you make and test optics you understand why this is done. One also needs to understand that  the optical  figures are figures of revolution. That happens naturally because how they are polished. If not you have major fabrication problems and rotating them won't fix the problem.  Also the optical elements have greatly different powers, the corrector is almost zero  while the secondary and primary have a good amount but different. So the odds are very low that 1) the production method would introduce an asymmetrical zone and 2) the power of that error would have the same magnitude but also opposite in sign to cancel each other. 

    Look at any real test image of SCT optics and you don't see asymmetrical errors what you  do see are  rotationally symmetrical ones like turned edge, holes, hills, over or undercorrection. These can not be reduced or cancelled  reduced by rotating the optics. The only way to fix them is refigure on or more surfaces. 

   What is required collimate the optics  is to center the optics correctly and that has nothing to do those marks. You can get those alignment marks perfectly aligned but if the elements are not centered you never get a good image because you'll never get them correctly collimated.  The misunderstanding of the purpose  keeps getting repeated  while the were the true critical information doesn't get emphasized  

 

               - Dave 

[Brollen]

 Let me save you a ton of time and frustration from some who  actually designs and makes optics vs what is written by those that don't. It does not matter how you rotate the optics. I'll say it again it does not matter how you rotate the optics. They are a figure of revolution which means they are rotationally symmetrical.  What is important is that the secondary is centered on the the mounting plate, the corrector is centered in it's cell and then using the ID of the corrector cell as a reference surface and the center bolt on the secondary as the other reference point you center the secondary. Then you can collimate the optics.  Many time the optics are not correctly centered from the factory so don't trust how the secondary was glued to the mounting plate. Measure it yourself. 

   The alignment marks on the optics were put on them when they were placed in testing jig and then aligned. They were used to get them aligned in the jig if they were removed to save time. They have nothing to do with canceling  optical errors. So don't  waste your time worrying about rotating the corrector and/or the secondary. If they are correctly centered it will make no difference and if they are not correctly centered you never get the optics to properly collimate.

 

           - Dave

             Director Mt Cuba Observatory

             25 Awards from Stellafane, 10 in optics

             Contributor to books on optics like "Telescopes, Eyepieces and Astrographs"  

 

Any reference sites that have pictures as well as verbiage of what you describe? I think I follow, but pictures are worth a thousand words!

 

So the alignment marks don't matter so much - more so the centering of the optics. I assume this includes the corrector plate?

Edited by Brollen, 26 March 2020 - 06:40 PM.

[DAVIDG]

 It is simple. When you glue the secondary back on make sure it is centered on the metal mounting plate. A digital caliper is perfect or even a good ruler.  Now you put the secondary back into the cell in  the corrector.The secondary cell is made up of two pieces that screws together. So you can loosen it by turning one piece and holding the the other enough so you can move the secondary cell around in the corrector.

   I position the secondary cell in the corrector so one of the three alignment bolts is straight up ie at the 12:00 o'clock position and the others ones at 4 and 8. This will make it easier to align the secondary. 

   Now  use the ID of the corrector cell and the OD of the glass corrector as reference surfaces. Measure at many places around the diameter and set the gap between them as evenly  as possible.  Don't put the retainer ring on yet. Measure from the ID of the corrector cell to the center bolt on the top of secondary cell. Again measure at many places.  It should be centered. If not move the secondary cell in the corrector so it is. Now carefully left the corrector and secondary out of the scope and careful tighten the secondary cell. Put the corrector/secondary back into the scope. Set the gap between the ID of the corrector cell and the OD of the glass corrector. Double check the secondary cell is still perfectly centered in the scope. If so install three cork spacers at 120° centers in the gap between the corrector and the ID of the cell. Install the retainer ring and carefully tighten the bolts evenly. The bolts should just be snug not tight. Now you can use the three outer alignment screw to align the secondary.

  What you have done is precisely center the secondary and corrector. 

 

                     - Dave 

[unitron_man]

http://www.astronomy...aryremoval.html

[Jon Isaacs]

My 2 cents:

 

Given that the scope was poorly packaged, I am not sure why one would expect UPS insurance to cover anything.  Sure, you can hope that they will pay but put yourself in UPS's shoes, a fragile instrument that was not properly packaged..  

 

I don't know how far the item was shipped but I think of what it's like to ride in the back of trailer. no shocks, 120psi tires, a hard bed.  That'll vibrate anything loose that's not well packaged and well protected.

 

There are companies that ship delicate instruments but you need to prepared to pay the cost, it'll be more than the scope is worth.  I use USPS because priority goes by air which means more gentle handling. 

 

Jon

[Brollen]

http://www.astronomy...aryremoval.html

Thank you - good read!

[Brollen]

My 2 cents:

 

Given that the scope was poorly packaged, I am not sure why one would expect UPS insurance to cover anything.  Sure, you can hope that they will pay but put yourself in UPS's shoes, a fragile instrument that was not properly packaged..  

 

I don't know how far the item was shipped but I think of what it's like to ride in the back of trailer. no shocks, 120psi tires, a hard bed.  That'll vibrate anything loose that's not well packaged and well protected.

 

There are companies that ship delicate instruments but you need to prepared to pay the cost, it'll be more than the scope is worth.  I use USPS because priority goes by air which means more gentle handling. 

 

Jon

Understood. UPS just continues to push out the resolution date way past the original date - crazy times we are in and I guess they must be impacted like everyone else. 

 

All things considered, you are probably right and they won't pay out. But there can be a sliver of hope until I hear.

 

I'm tired of waiting so I'll probably open the scope up this today or tomorrow and start assessing the damage looking at the bits and pieces involved in the reassembly.

 

I'll post about what my findings are. If we could only get some good viewing weather as well - this month of March feels like its been mostly Cloudy Nights!

Edited by Brollen, Yesterday, 12:05 PM.

[Brollen]

Well I feel like I've waited long enough and I wanted to take advantage of these cloudy days of late. So I opened her up.

 

I first carefully marked the current secondary/corrector position in relation to the tube. Then I carefully extracted the hex screws holding the corrector retaining ring, and laying them out in a way that I knew where they would go back.

 

The retaining ring came of so easily as did the corrector. No stick or grime holding it back. In fact they actually look shockingly good and clean for being in a 40 or so year old C8. I don't know how many owners have preceded me but I think they all took good care of this scope.

 

The inside of the OTA is nicely blackened and again remarkably clean - no peeling, or dust bunnies, etc. Lots of glass, which I'm thinking is from the diagonal which exploded when the package got dumped on the VB side.

 

Looking closer at the mirror it looks like maybe the secondary danced across it a few times - I have a photo where tried to capture this. But aside from that and the chips on the edge it looks OK.

 

The secondary also looked fine - no chips and the main surface looks fine. The inside of the secondary housing has a cork base... What would be the best adhesive to use to reattach the secondary?

 

Rather than attempt to dump the glass and shake things out, I took a small vacuum and cleaned out the inside of the tube.

 

Things are looking up. Here are some pics.

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[Brollen]

The secondary mirror as I said looked good. Flipping it over it was marked with both an alignment line and a number - 4691.

 

I checked the corrector to find its number. I was stunned at first because I could not find one. But I started looking more carefully and with some additionally light I finally found the corrector's number - also 4691! I was quite relieved to see this.

 

Here some additional photos of the two together.

 

 

Attached Thumbnails

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[DAVIDG]

 With the corrector off, this is good time to check the alignment of the primary mirror mount and the primary itself. If they are not aligned correctly you never get it the scope to  collimate correctly. 

   It is simple to do. Take two pieces of string and tape them across  the front of the scope with the corrector removed. Tape them so they form a cross and the ends are exactly at 0 and  180  and the other at 90 and 270 degrees. If you have laser collimator place it  in the focuser. The laser should hit exactly were the strings cross. If not the mirror cell/ focusing assembly is tipped and needs to be adjusted.

  If the laser does hit the exact center we still need to check the primary mirror because it can be tilted on the mount. Like I said the backs are not precisely ground  to match the optical surface. So stand back a couple of feet and look at the primary. You'll see the reflections of the string in it. Now move your head so the reflection are behind the strings. If the primary is correctly aligned the reflections when behind the strings will be exactly centered. If the reflections when behind the strings are off to one side the primary is tilted and needs to be adjusted. See my drawing.  So again can you spend hours getting those alignment marks aligned up but  if the corrector and secondary are not centered and the primary not aligned it will make no difference and you will  never get the scope to collimate correctly.

 

            - Dave 

 

    

[ccwemyss]

This is especially good advice, given how hard the scope was dropped on the tailpiece. But it's also good to verify that the laser collimator is true. Some of the cheaper ones need adjustment, or can go off-center when tightened in the tailpiece. 

 

Chip W.