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Mayflower 816 flakes between the glass?

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#1 shredder1656

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Posted 07 December 2017 - 05:40 AM

It seems everything arrives at once.  Regardless, I received my beautiful Mayflower 816 over the past weekend.  I have not had much time to focus on it.  However, I had it out for a few frigid minutes on the past Sunday morning.  I was a little underwhelmed, so I am praying that either I was doing something wrong (would not be shocked), or that a previous owner reassembled the objective incorrectly. 

 

This morning was the first time I have pulled it out since the first endeavor.  I was up early, so I had some time.  I dusted the lens, and more closely inspected it.  There are some definite light scratches that I hope are insignificant.  I sent a picture to a couple of members, and they thought it was coating only.  However, I cannot even see them this morning after cleaning the outside of the lenses.  So, maybe they were just smudges.  Regardless, I now see tiny flakes between the glass. After cleaning the outside, I was happy to see that it looked much improved, but these flakes are they something that would precipitate disassembly and cleaning?  Or, will I just need to give it a observing test before that can be determined. 

 

Anyway, this scope has a variety of extra parts and pieces.  Some are marked "Tasco Deluxe".  There is a zoom, and a sun diagonal that are both in boxes marked as such.  The scope, mount, tripod, and drive, all appear to be in decent to good+ shape.  As long as the lens is good to go, everything is cosmetic, and not bad at that.  Really a very nice scope.

 

I am hoping that my first outing with this guy was a fluke.  I had no filter, and the moon was huge and nearly blinding.  So, I realize that it probably washed out detail, but I was still expecting to see distinct crater detail at low powers for sure, and hopefully at higher powers.  With a hybrid diagonal, and a 25mm ep, the view was not exceptional.  Maybe I was expecting too much.  I definitely need another shot before I form a defensible opinion.  I am optimistic.  Too many more experienced people vouch for them to not be hopeful. 

 

Here are a few pics.  Any clue on the junk in the space between the glass?

 

2017-12-07 05.15.47.jpg 2017-12-07 05.16.27.jpg 2017-12-07 05.18.39.jpg 2017-12-07 05.19.53.jpg 2017-12-07 05.20.15.jpg


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#2 shredder1656

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Posted 07 December 2017 - 05:41 AM

A couple more.  Sun prism diagonals are not save to use, are they?

 

2017-12-07 05.21.07.jpg 2017-12-07 05.21.41.jpg


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#3 deSitter

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Posted 07 December 2017 - 07:05 AM

Wedge is fine with a N3 neutral density filter on the eyepiece. Those flakes will not affect the performance, and are probably easily removed. This is said to be a very good scope. If the performance is poor, almost surely the objective is incorrectly installed.

 

-drl


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#4 walter a

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Posted 07 December 2017 - 07:10 AM

Your on a roll, That's another nice find.
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#5 CharlieB

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Posted 07 December 2017 - 07:16 AM

That should be a very fine scope, so the objective may have been put back together incorrectly.  If you know someone who has a DPAC setup, you could find out if that's the case.  Those flakes could be paint that has come loose. The Sun diagonal is safe if you have the proper ND filters.  They should be in the kit, but if not, don't use the diagonal.  The clock drive is a nice bonus.

 

Nice score, and I'm sure it will turn out just fine.


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#6 happylimpet

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Posted 07 December 2017 - 08:22 AM

Moon always looks unremarkable when full. Give it a couple of days...


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#7 rcwolpert

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Posted 07 December 2017 - 08:28 AM

The flakes between the glass elements and less than spectacular performance is a good indication someone took the lens apart. I'd clean that baby up, and if you can't do a DPAC, at least see if you get Newton's rings, and if they are concentric and centered.


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#8 DAVIDG

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Posted 07 December 2017 - 10:27 AM

Wedge is fine with a N3 neutral density filter on the eyepiece. Those flakes will not affect the performance, and are probably easily removed. This is said to be a very good scope. If the performance is poor, almost surely the objective is incorrectly installed.

 

-drl

 Be careful if you purchase a "netural density filter". Neutral density many times is expressed in photographic F-stop. For solar work used with a Herschel wedge  you need an OPTICAL DENSITY of 3  which reduces the light by log of transmission or 1000:1   or 0.1%. When you do solar observing the light needs to by reduced by 100,000:1  which is optical density of 5.  A Herschel wedge reflective 5% of the light so it has an optical density of  log (0.05) = 1.3 . This is added to the OD 3 filter and your at an OD of 4.3. You need a little more filter so you use a polarizing filter to get you OD 5. 

 Baader makes a true OD 3 filter https://www.highpoin...y-filter-fnd3-1   The issue is that it 1.25" in diameter and you'll need one that is 0.965" if that is what the size of the eyepieces that your Herschel wedge uses. 

   You can also use Welder's glass of the correct Shade Value with the Herschel wedge.  The Shade value = 1 + 7/3(OD)  were OD equals the optical density So if you have filter made of #8 Welders Glass  8 = 1 + 7/3(OD), the Optical design is 3. 

 

             - Dave 


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#9 shredder1656

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Posted 07 December 2017 - 01:07 PM

Your on a roll, That's another nice find.


Yes, I have been. LOL. Just ask my wife.

But, my saving grace is that I sacrificed a few items from another hobby to fund my new addiction. I'm bordering on haveing maxed that budget, though. So, I've been trying to go cold-turkey. It's hard to ignore the classifieds, etc.

Just one more...and then another, and so on. LOL

#10 shredder1656

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Posted 07 December 2017 - 01:23 PM

The flakes between the glass elements and less than spectacular performance is a good indication someone took the lens apart. I'd clean that baby up, and if you can't do a DPAC, at least see if you get Newton's rings, and if they are concentric and centered.


To see the rings I need to be under florescent light, correct? If I see them is that indicative of a correctly assembled lens?

I actually could see them, but they appeared to be centered off to one side of center. It was a quick look, and maybe the lens needs to be centered directly under the light... Does it?

#11 deSitter

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Posted 07 December 2017 - 02:03 PM

 

The flakes between the glass elements and less than spectacular performance is a good indication someone took the lens apart. I'd clean that baby up, and if you can't do a DPAC, at least see if you get Newton's rings, and if they are concentric and centered.


To see the rings I need to be under florescent light, correct? If I see them is that indicative of a correctly assembled lens?

I actually could see them, but they appeared to be centered off to one side of center. It was a quick look, and maybe the lens needs to be centered directly under the light... Does it?

 

Forget that for now, make sure it's assembled right (ask if help needed) and then star test it. Don't even worry about cleaning it other than those flecks.

 

-drl



#12 shredder1656

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Posted 07 December 2017 - 02:21 PM


The flakes between the glass elements and less than spectacular performance is a good indication someone took the lens apart. I'd clean that baby up, and if you can't do a DPAC, at least see if you get Newton's rings, and if they are concentric and centered.

To see the rings I need to be under florescent light, correct? If I see them is that indicative of a correctly assembled lens?

I actually could see them, but they appeared to be centered off to one side of center. It was a quick look, and maybe the lens needs to be centered directly under the light... Does it?
Forget that for now, make sure it's assembled right (ask if help needed) and then star test it. Don't even worry about cleaning it other than those flecks.

-drl

Understood. I was somehow under the impression that the rings, if observed, indicated that it WAS assembled correctly. My mistake.

#13 DAVIDG

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Posted 07 December 2017 - 02:29 PM

 The fact that your seeing interference rings is  a very good indication that the two elements of the lens  have the two inner faces in the correct order.  The issue still could be that the whole lens is reserved in the cell  ie the flint element  is facing the sky when should  be facing the eyepiece end of the scope. There is easy way to tell thou, just  look at the edges of the elements by looking into the lens. The crown element should be facing the sky and it will have the thinnest edge and the flint should be in the rear and it should have a thicker edge.

   The fact the rings are off center means that the spacing between the elements is not uniform. That is usually caused be uneven pressure on the elements and/or the spacers have moved and are not 120° centers. So check that the spacers are at the correct position and if not move them until they are. Then slowly tighten the retainer ring so the interference rings stay round and centered. This should be just when the retainer ring makes light contact with the glass. The lens should have a slight rattle in the cell. You don't want the retainer jammed tight against the glass since that can easily distort them or even cause them to break when the temperature drops and the cell contracts.

 

                      - Dave 


Edited by DAVIDG, 07 December 2017 - 02:34 PM.

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#14 shredder1656

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Posted 07 December 2017 - 03:05 PM

The fact that your seeing interference rings is a very good indication that the two elements of the lens have the two inner faces in the correct order. The issue still could be that the whole lens is reserved in the cell ie the flint element is facing the sky when should be facing the eyepiece end of the scope. There is easy way to tell thou, just look at the edges of the elements by looking into the lens. The crown element should be facing the sky and it will have the thinnest edge and the flint should be in the rear and it should have a thicker edge.
The fact the rings are off center means that the spacing between the elements is not uniform. That is usually caused be uneven pressure on the elements and/or the spacers have moved and are not 120° centers. So check that the spacers are at the correct position and if not move them until they are. Then slowly tighten the retainer ring so the interference rings stay round and centered. This should be just when the retainer ring makes light contact with the glass. The lens should have a slight rattle in the cell. You don't want the retainer jammed tight against the glass since that can easily distort them or even cause them to break when the temperature drops and the cell contracts.

- Dave


I will check those details tonight. I don't have much free time tonight, but that shouldn't take much time. Changing anything, though, will take a bit longer.

I appreciate everyone's input and knowledge.

#15 shredder1656

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Posted 09 December 2017 - 07:03 AM

Any thoughts on how I can remove this retaining ring?  The notches seem incredibly small to me.  I have not found a wrench with pins that are this small.  I tried a flat screwdriver blade from a "precision" kit, but I cannot get the ring to budge. 

 

What am I missing here?

 

2017-12-09 06.52.32.jpg

 

 



#16 walter a

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Posted 09 December 2017 - 08:43 AM

Screw driver! careful one slip and the lens is pooched, Most of these rings can be removed with bamboo or hard wood fondue skewer but for the tight ones you might need the two prong lens tool.

Edited by walter a, 09 December 2017 - 09:38 AM.


#17 DAVIDG

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Posted 09 December 2017 - 11:16 AM

 You need to put force on both slots in the retainer ring at the same time. If not it seems like the ring was tighten down with 10,000 lbs of force. The best tool is  an optical spanner wrench. Here is a  picture of mine. You can get lighter duty ones on Ebay for under $15. https://www.ebay.com...QgAAOSwr8xZ5dcX

   I have also used a thin piece of metal of the correct thickness to fit in the slots and  cut to the correct length to fit across the retainer ring. My local hardware store has a display of brass strips and tubes so I have used a brass strip of the correct thickness to make the "wrench".  Be sure that there isn't a tiny set screw that might also be holding the ring from the turning. 

 I also suggest cutting a piece of cardboard to go over the lens to protect it in just case something slips. 

 

               - Dave 

 

spanner.jpg


Edited by DAVIDG, 09 December 2017 - 01:01 PM.

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#18 shredder1656

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Posted 09 December 2017 - 02:51 PM

Dave, I have to say THANKS!  There definitely is an itsy-bitsy set-screw that *retains* the retaining ring.  I looked and looked for it, but was convinced that it was set-screw free.  But, after I put some gentle, but firm pressure on the retaining ring notches with my homemade spanner wrench, I knew that there had to be one somewhere.  I finally located it under a suspicious speck of crud.  It blended in with the threads so well I almost missed it. 

 

I have not disassembled the lens completely, but now I know I can.  Either tonight, or early tomorrow morning, when I have some free and quiet time, I will dive in. 

 

Just to get me by until I can get a spanner wrench nailed down, I used a 1x2 and two screws spaced 80mm apart.  I only allowed them to protrude enough to reach the notches.  The length of wood allowed me a 2nd layer of protection from accidental contact with the lens surface.  Not a very sophisticated nor inconspicuous solution, but worked perfectly. 

 

For other's reference, see the set-screw. 

 

2017-12-09 14.50.32.jpg 2017-12-09 14.37.16.jpg

 

 

 

 

 

 


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#19 shredder1656

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Posted 09 December 2017 - 04:36 PM

The kids went outside to enjoy the snow, and do a little tromping around.  I had a few minutes, so I went ahead and slid the lens out.  The picture attached is marked to clarify the way this lens came out of the cell. 

 

I have not cleaned the lens yet.  There is a ton of crud inside the cell and in the threads.  I just finished cleaning the crap out of that.  There were NO marks on the edge of the lenses AT ALL.  NOTHING.  I marked it with a sharpie to keep things oriented as I found them. 

 

Does this look correct?  How do I tell if the crown is flipped, but in its proper place? 

 

2017-12-09 16.19.24.jpg

 

 

 


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#20 deSitter

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Posted 09 December 2017 - 05:09 PM

Crown is the convex one, toward the sky as here. The two sides have slightly different curvature, the steeper more curved side faces the flint. 

 

-drl



#21 deSitter

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Posted 09 December 2017 - 05:11 PM

I am wondering if this is in fact the objective that was originally in the scope. Never have seen the two elements have differing ground glass appearance.

 

-drl


Edited by deSitter, 09 December 2017 - 05:13 PM.

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#22 deSitter

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Posted 09 December 2017 - 05:17 PM

How to tell which is the steeper more curved side - look at the reflection of a lamp, you'll see two, ignore the one that is upside down. Flip the lens, do the same. The steeper side will make the smaller erect image. That side faces the flint.

 

-drl


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#23 shredder1656

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Posted 09 December 2017 - 05:58 PM

I am wondering if this is in fact the objective that was originally in the scope. Never have seen the two elements have differing ground glass appearance.

 

-drl

I am wondering the same.  I hope that it isn't replacement glass, but might be my luck. 

 

Any way to tell.  There were no orientation marks at all.



#24 shredder1656

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Posted 09 December 2017 - 05:59 PM

How to tell which is the steeper more curved side - look at the reflection of a lamp, you'll see two, ignore the one that is upside down. Flip the lens, do the same. The steeper side will make the smaller erect image. That side faces the flint.

 

-drl

 

Do you do this with the crown and flint married together, or just the crown alone?



#25 shredder1656

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Posted 09 December 2017 - 06:05 PM

No more flakes.  I will see how it does. 

 

2017-12-09 17.55.16.jpg 2017-12-09 17.54.40.jpg

 




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