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Triple Nickle - Restore & More

ATM classic equipment refractor
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#26 Senex Bibax

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Posted 06 March 2020 - 07:44 AM

Steel Stick is great for non-load bearing parts. The 900 PSI is, I think for gas or liquid pressure. JB Weld is also good for these sorts of fixes, I've even used it in some parts of motorcycle engines.

BIF:  SteelStik says it'll hold at up to 900 PSI...  I wouldn't trust it on a cracked mount part; but, something like a cast focuser flange, or the outer shell of a lens cell, and I think it would hold.  So, as a metal filler, it should do fine (I hope), but if it falls out of a tube hole, that's not a show-stopper.



#27 G-Tower

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Posted 06 March 2020 - 08:22 AM

https://www.youtube....h?v=PcGwkyzmPmA

 

I couldn't help myself.

Even more unremarkable then the B&L Aero Tessar lens. lol.gif 



#28 Spectral Joe

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Posted 06 March 2020 - 10:20 AM

Steel Stick is great for non-load bearing parts. The 900 PSI is, I think for gas or liquid pressure. JB Weld is also good for these sorts of fixes, I've even used it in some parts of motorcycle engines.

900 psi is the bond strength, it means that it would take 900 pounds of pull to separate two parts  bonded by a 1 square inch area of adhesive. Of course, it depends strongly on the surface preparation, bond thickness, and other factors.



#29 Bomber Bob

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Posted 10 March 2020 - 05:42 PM

SteelStik took the paint well, too.  You'd have to know where to look to see the minute traces of the fillers.

 

Sunday Dinner didn't have any huge Styrofoam cups, but they did have a 6-pack of black plastic cups with a football logo on the outside.  Not a problem -- I'll flock over that decal.  They're a good fit for the TN5, as the mouth diameter is almost exactly 1" smaller than the tube interior.  Home Depot has the black PVC pipe couplings.  I'll use one as a frame for this cone, and I'll slide it to the best position for the light path -- pretty much what I did for that Tasco 999VR.  Lightweight & flexible -- can't beat that with a stick.

 

The lens cell slides in from the front, and there are alignment marks on the cell and the tube interior, so I sanded down to the metal on the front third of the tube.  I'll make a ring of flocking to fit from the cell to the tube end.  I put a coat of chalkboard black on the focuser plate and rear part of the tube.  It's curing in my man cave... glad the odor isn't strong!



#30 Bomber Bob

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Posted 18 March 2020 - 07:38 PM

Coke Cup Conic Baffle

 

ATM 5x5T - Restore S12 (Coke Cup Baffle).jpg ATM 5x5T - Restore S13 (Coke Cup Baffle).jpg

 

Naturally, as a Southerner, I just had to use a Coca-Cola Cup!   Found a scrap piece of thin-walled brass tubing that fits snugly in the threaded back plate.  Cut a hole in the cup bottom, and this cone fits over it.  Due to the Coco-Wuhan #19, I'm working from home, and will sand & paint everything flat black tomorrow if it stays rain-free.  This assembly will be easy to remove by the next owner (or, by me, if I think of a better solution).


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#31 Bomber Bob

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Posted 20 March 2020 - 05:54 PM

Got all the parts sanded & painted today.  I used Testor's flat black model paint on the cup -- does well on plastics (naturally); and, the brush-on chalkboard black on the metal stuff.

 

I'll give these a week or so to air out, then get her re-assembled.



#32 Bomber Bob

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Posted 21 March 2020 - 05:09 PM

Blackening the TN5

 

ATM 5x5T - Restore S15 (Blackened Parts).jpg ATM 5x5T - Restore S16 (Tube Interior Rifling).jpg

 

"Rifling" the interiors:  Just before the paint sets, I use a small brush moistened with paint to create horizontal grooves.

 

ATM 5x5T - Restore S17 (Cone Interior Rifling).jpg ATM 5x5T - Restore S18 (Baffle Interior Rifling).jpg

 

Even the small baffle gets the rifling treatment.


Edited by Bomber Bob, 21 March 2020 - 05:12 PM.

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#33 Bomber Bob

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Posted 21 March 2020 - 05:10 PM

ATM 5x5T - Restore S19 (Focuser Plate Blackening).jpg ATM 5x5T - Restore S20 (Baffle Attached).jpg

 

Being a Pack Rat paid off (again):  I had that 3" wide scrap of brass that made a great baffle -- and cone holder-downer.

 

ATM 5x5T - Restore S21 (Cone Attached).jpg ATM 5x5T - Restore S22 (Cone to Eye View).jpg

 

A few shiny bits remain that I may touch up with my tiniest paint brush.  For some reason, it doesn't want to stick to the end of the focuser tube's brass.


Edited by Bomber Bob, 21 March 2020 - 05:17 PM.

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#34 Bomber Bob

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Posted 21 March 2020 - 06:59 PM

Through a Lens, Darkly...

 

ATM 5x5T - Restore S23 (Lens to Eye View).jpg

 

It's much darker now.  I may get a chance to see just how much tonight -- if the current cloud gaps hold.

 

ATM 5x5T - Restore S24 (OTA Reassembled).jpg ATM 5x5T - Restore S25 (Ready to Mount).jpg

 

In any event, she's ready to go, and waiting patiently in my shed.  (Yeah, I got my fingers & toes crossed -- makes walking kinda tricky, though.)


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#35 Bomber Bob

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Posted 21 March 2020 - 10:35 PM

Initial testing tonight, and the results are similar to that Tasco <Z> 999VR:  Glare down, contrast up, but it can't make a funky lens less funky.  Overall, it's a better sweeper than before -- too bad the seeing cut down the number of stars!


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#36 deepwoods1

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Posted 22 March 2020 - 08:54 AM

Looks very nice! Thanks for bringing us through the journey!


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#37 macdonjh

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Posted 22 March 2020 - 09:06 AM

Through a Lens, Darkly...

 

I got it, PKD.  But I thought you thought it was an aerial camera lens, rather than a copier/ scanner lens...



#38 Bomber Bob

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Posted 22 March 2020 - 10:31 AM

I really don't know where this lens came from, and I doubt the eBay seller did, either.  Best guess is a salvaged aerial camera, but who knows?  I do search eBay occasionally for aerial cameras.  If a complete one every came up at a low price, I'd nab it.  

 

What I'd like to see for myself:  Did the original lens assembly correct for the field curvature?  I have to think they would, but I'd like to confirm it.  In Googling, I saw tons of these, and all the complete sets had additional smaller lenses in the optical train.  The TN5 is missing those.

 

With the TN5 and Stubby (my 6" F4 Newt), I have 2 large fast grab & go scopes that the VersaGo can carry.  BOTH need about the same amount of time to temperature adjust.  The TN5's 3-element lens + cell is massive.  Removing the 2" focuser's dust-cap helps.  The TN5 is sharper overall, but both scopes are good up to about 200x.  Above that, the center area at best focus & correction is small, and no fun on an alt/az!

 

I built the all-Mizar AR-1 + ShortPod for Stubby, so y'all know it's a Keeper.  After what I saw last night, I may build a pedestal option for my VersaGo, or an all-new pedestal alt/az for the TN5.  With all the dovetail hardware, I can't get to directly overhead with the VG on a tripod, and hauling out my Meade StarFinder + 5' pedestal is overkill -- defeats its portability advantage.  When I'm sweeping a wide arc, I hate bumping into the tripod hub!!



#39 Bomber Bob

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Posted 22 March 2020 - 10:48 AM

All that's left...

 

- Focuser Hole:  The original lock knob hardware came off.  Gonna check McMaster-Carr for a 3/8" threaded knob with a short shaft.  I can thread the remaining metal, so it'll be more than decorative.

 

- Duo-Scope:  Lots of options.  I bought that vintage Orion-branded 1980s 60mm finder with the idea of converting it to an RFT that rides with the TN5, which is why I put that massive Vee-block back on the scope.  It was made in Japan, and has a very good lens.  However, it would be easy to convert the finder bracket to carry my Tak FC-50.  Or, since the TN5's color scheme is sorta Mizar, maybe add one of their 68mm fluorites.  (I like having a fluorite companion on my EDs -- keeps 'em honest.)  The added weight is too much for the VG, which is another reason to build a heftier pedestal alt/az...



#40 wrnchhead

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Posted 22 March 2020 - 10:57 AM

So what is your conclusion about this whole journey? Is that lens just not worth it? I see that you said it was OK up to 200x, do you think it offers anything that your basic short tube 80 does not?
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#41 Brent Campbell

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Posted 22 March 2020 - 11:04 AM

Built a couple of scopes with those back in the day....most unremarkable

I built one too.  It was heavy ackward and unremarkable.



#42 Bomber Bob

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Posted 22 March 2020 - 11:08 AM

So what is your conclusion about this whole journey? Is that lens just not worth it? I see that you said it was OK up to 200x, do you think it offers anything that your basic short tube 80 does not?

 

Yes, it was worth the time & expense.  It's a good 5" RFT, which is all I intended it for.  The goofy lens gathers a lot of light, and it easily out-resolves my 80mm F5 RFT (that rides on my 826).

 

IOW:  Aperture wins.  

 

It has better color correction than my Jaegers 4" F5 achro, too.

 

Again, I wouldn't spend a whole lot of money on one of these.  If a similar lens in its cell popped up at $50 - $75, I'd give it a try.  There were so many designs & makers, there's no guarantee that a particular lens would make an astro-scope.  The fact that a previous owner built a good OTA around this one made it an easier buy for me.


Edited by Bomber Bob, 22 March 2020 - 11:13 AM.

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#43 Bomber Bob

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Posted 22 March 2020 - 03:09 PM

Here's a sample Moon shot I made with the TN5 + GSO 2.5x APO Barlow back in 2017:

 

ATM 5 F5 - Moon 20170801V03A64R01G2.jpg

 

IIRC, I used the 64-bit beta version of AutoStakkert! to process 70% of about 5200 frames with my ASI120MC.

 

Not too bad for a salvaged non-astro lens.

 

I tried to image Saturn that night, too.  But, it was too low, and the top-most needles of a pine tree several houses down intermittently blocked it.


Edited by Bomber Bob, 22 March 2020 - 03:28 PM.

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#44 Bomber Bob

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Posted 23 March 2020 - 06:54 AM

I built one too.  It was heavy ackward and unremarkable.

Compared to what?  I don't think my OTA is any heavier than a typical Jaegers 5" F5.  Based on the similar-size aerial cameras I've seen online, if an owner used the original military-spec hardware, then it would be a very heavy instrument.  The TN5's lens cell is machined aluminum rather than a lighter casting, but I'd rather have it for a lens this size.  Otherwise, the tube, back plate, & focuser are standard.

 

I don't have any trouble balancing & using it on the VersaGo, which is not a top-tier alt/az mount -- and mine is used, to boot.

 

Optically, it does have that smallish center zone.  But again, the resolution there is very good; and, compared to my Jaegers 4" F5, it has better color correction.  I got the whole Beehive in that zone at 30x, and the view was fantastic.  It performs well with a Radian 4 @ 170x -- about as high as I care to go with an alt/az.  On  an EQ mount with tracking, I've observed the Moon at 243x with a Nagler 7 + 2.5x Barlow.  It's not a scope that I'd haul out for lunar/planetary observing, but IMO it does well for an RFT -- better than my 60mm or 80mm F5 RFTs.


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#45 Terra Nova

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Posted 23 March 2020 - 08:49 AM

Optically, it does have that smallish center zone.  But again, the resolution there is very good; ... but IMO it does well for an RFT -- better than my 60mm or 80mm F5 RFTs.

I’m not certain that I understand this statement but I think it’s the source of the negative criticism. At least for me, a Richest Field Telescope should give low-power wide-field views with pinpoint stars and sharp views (good resolution given that magnification) across most, if not all the views. One should not need to concentrate on just the center of the field, with an RFT, the whole point is taking in an expansive, sweeping view. If it is rapidly shifting to bloated stars and pin-cushion comets that deteriorates radially and exponentially from that central sweet spot, I would find it awkward and disorienting. That’s been the problem with the the telescopes that I have seen that were made from aerial camera lenses.

 

What you have to understand is that aerial camera lenses are designed to produce radial distortion that increases outward from the axial center of the lens. It’s called image displacement. On the film frame, the axial center of the lens corresponds with the principal point PP of the frame. There are four fiducial marks in two opposite sets at either the center margins or the corners of each square film frame. Any set of two vertical points )corresponding to the top and bottom of a tree, tower, building corner, hill top or depression bottom (above or below the corresponding vertical datum point)) are displaced radially either away from or towards the the PP depending on (1) how high above or far below they are with regard to the vertical datum surface (the corresponding elevation of the PP) and (2) how far away they are away (radially) from the PP. This radial displacement is known as relief displacement and can be used to determine the object’s height or depth (ho) where ho = (d/r) x H, where d is the length of displacement, r is the radial distance from the PP to the top of the displaced object, and H is the height of the camera above the ground. Thus the corresponding field curvature produced in the image by the camera lens winds up being a very useful property of the images produced when it’s used formwhat it was designed for.

 

This is why these aerial lenses do a very good job doing what they are intended to do, and not such a good job doing things they aren’t intended to do, (like being used for telescopes that are focused to infinity).


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#46 Bomber Bob

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Posted 23 March 2020 - 09:47 AM

Terra, I was referring to high power (100x & above) viewing.  At low power, it's about the outer 10% of the field where stars streak -- they don't bloat.  For me, the image degradation is less noticeable or annoying than the coma in my 6" F4 Newt.

 

When I use a 2" 50mm Plossl at 14x, it's even less noticeable -- gives a great view of the M31 Trio (can't recall if I've tried M33 with it).

 

Again, I have no proof that it's a camera lens.  Based on the sheer numbers, that's likely, but it could have been from some other instrument.  And, I'm not recommending folks go out & buy these type lenses.  But, I've found that this one makes for a fun RFT, and pulls in more stars than expected from my urban backyard.


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#47 Terra Nova

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Posted 23 March 2020 - 10:07 AM

If it’s good at low power across the field (or most of the field) and as you say “this one makes for a fun RFT, and pulls in more stars than expected from my urban backyard”, then that’s a win-win in my book! Almost all RFTs are intended to be low-power, wide-field instruments and when used beyond that intention, that’s when questionable results occur. Same with the manufactured equivalents like the ST80 and ST120! They are wonderful instruments that provide great viewing fun when folks realize them for what they are; they aren’t general purpose telescopes really, they are niche scopes and should be used as such. I’ve had two ST120s in the past and really enjoyed them when using them for what they were intended.


Edited by Terra Nova, 23 March 2020 - 10:14 AM.

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#48 Bomber Bob

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Posted 23 March 2020 - 10:20 AM

IF I hadn't bought this scope... and, I saw a perfect (no Large Clam in its 2nd element!) 5" F5 lens + cell on eBay for $50, I can't say for sure that I'd buy it -- unless I had some scrap / extra parts in the shed that I could use to build a scope around it.  I have bought "orphan" lenses before, BUT they were cheap, and they were from refractors or binoculars.  Seller didn't know nuthin' about this one...

 

Lucky for me, someone else built a scope around it.  I don't have a lot of $$$ or time in it, and it's been a fun experiment -- the kinda stuff I did 40+ years ago with "stuff" from Jaegers, Edmund, etc.

 

Yes.  It's a fine low-power RFT.  I had no qualms giving my JaegerMeister 4 to the grandkids, and keeping the TN5 for myself.


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#49 Terra Nova

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Posted 23 March 2020 - 10:20 AM

When I use a 2" 50mm Plossl at 14x, it's even less noticeable -- gives a great view of the M31 Trio (can't recall if I've tried M33 with it).

That would give you a 9mm exit pupil, so you would, in effect,  only be using a portion of its total aperture.



#50 Bomber Bob

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Posted 23 March 2020 - 10:24 AM

That would give you a 9mm exit pupil, so you would, in effect,  only be using a portion of its total aperture.

That's where the Grand Old Parr comes goes in...  an unappreciated aide to deep-sky observing (especially on cold clear winter nights!).




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