76 replies to this topic

[sdedalus83]

I really like that GEM! It looks like the ones Stellarvue sold around twenty years ago. I can’t tell the difference between it and the Mizar GEMs from the pics. Are they the same or just similar?

I think the Kenko has a worm gear on the dec axis like the GSO, while the Mizar has a tangent arm. I’d though the GSO was a copy of the Mizar but maybe it’s closer to the Kenko.

[Bomber Bob]

That's correct.  Mizar EQ is like TAK, while Kenko NES / KES is like Vixen Polaris / SP.

[Bomber Bob]

You’re forgetting your long gone DX8!

Thanks... you tryin' to cause flash-backs??

[Kasmos]

You’re forgetting your long gone DX8!

Maybe because they stink and really don't count as SCT.

 

I kid, it's actually a very nice scope....

[sdedalus83]

Maybe because they stink and really don't count as SCT.

Poorly figured, excessively fast Cassegrain with an optical window.

[Terra Nova]

Maybe because they stink and really don't count as SCT.

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[Bomber Bob]

Maybe because they stink and really don't count as SCT.

 

Yep, and they don't.  With mine, Criterion really didn't try... Out Of Round plate glass, for starters; and, it went downhill from there.  So, since I haven't owned an 8" Classic Celestron, Meade, or Takahashi SCT (or, an even rarer Mizar version), I have no real point of reference.

 

What I do know:  Kenko made VG CAT optics -- at least as good as Vixen.  These two brands I've owned & tested.

[Bomber Bob]

Kenko was consistent on hardware, too:  Those cheap plastic hinged rings that I bought for the 125C also fit the SL125 -- great!  I took all that original mounting block hardware off, put these rings on an SVBONY 20cm Vixen dovetail, and now she's on the AR-1 + ShortPod.  Motorized Tracking is a must for me when tweaking collimation.

 

She's all set now.  Looks like I might get an hour before the clouds slide in from Mississippi...

 

AND, another wasted effort:  Got Deneb centered, started working the 3 grubs, and the pattern got much worse, and in the opposite direction.  The whole secondary assembly had slipped.  Tried to get back, got aggravated, and swapped the SCT for the Mizar GT-80, as the first bank of clouds appeared  on the horizon.

 

So...  Gonna bring it back in.  Re- re-center the holder, tighten it down more than I did the first time, and try again the next clear night.  I thought I got it snug the first go round (didn't want to over-torque it & risk cracking it).

Edited by Bomber Bob, 04 December 2021 - 06:55 PM.

[Kasmos]

Maybe because they stink and really don't count as SCT.

 

Yep, and they don't.  With mine, Criterion really didn't try... Out Of Round plate glass, for starters; and, it went downhill from there.  So, since I haven't owned an 8" Classic Celestron, Meade, or Takahashi SCT (or, an even rarer Mizar version), I have no real point of reference.

 

What I do know:  Kenko made VG CAT optics -- at least as good as Vixen.  These two brands I've owned & tested.

I probably shouldn't have posted that and sorry if I made anybody angry. It's just that the consensus is that they were mostly bad.

[Bomber Bob]

NES EQ Upgrades:

 

So far, I've found just one small paint scratch on the underside of the polar axis -- so, I'm calling it Mint Condition.

 

Since it currently has no drive, I put on a pair of VG quality Mizar long flexible slow-motion cables.  They're springy, but despite their 18" length, are stiffer than the one shorter Kenko cable that came with it.

 

I ordered another 2-knob SVBONY brushed metal Vixen dovetail clamp for it.  The Kenko scope foot, short dovetail, and top mount clamp will be boxed & labelled... KEEP!  

 

Non-Kenko Single-Axis Drives

 

- Celestron AstroMaster:  I'd have to cut & reshape its metal bracket, but it would attach to the polar axis casting where the original Kenko Quartz Drive housing bolts on.  But... its housing is BIG, and would make using the clutch lever tricky...

 

- B&L / Bushnell 78-5001 System with Hand Controller:  Motor is much smaller, and resembles that of the Celestron / Vixen Polaris EQ drives (IIRC, it has the same number of Pin-In on the socket).  But... to mount it w/o blocking the clutch lever, I'd have to drill & tap a 5/16" hole in the axis casing -- youch!  -- for the 2" long chrome rod that the motor attaches to...

 

Given its condition, I'm not gonna do either of these options.  It's just too pretty for a Redneck Mod.  

[RichA]

I probably shouldn't have posted that and sorry if I made anybody angry. It's just that the consensus is that they were mostly bad.

Don't let people's personal feelings prevent you from posting useful information.  That's what Twitter is for. 

[Bomber Bob]

Secondary Assembly Centering...

 

Simple Design + All Metal Construction = Rugged

 

As it turns out, the pressure from the threaded collar / baffle keeps the assembly centered on the corrector, rather than (as I thought) the center bolt that attaches to the machined aluminum disk / backer for the mirror.  Between that disk & the mirror is a 3mm thick cork disk:

 

 

From the outside in:

 

- 3 grubs in the external disk adjust mirror tilt;

- 1 hex bolt runs through the disk and into the mirror backer;

- An anodized black brass THIN washer goes over threaded half of the outer disk;

- Then the baffle threads on to hold the assembly in position.

 

The Baffle is about 6mm wider than the mirror, so there's at least 3mm clearance around the mirror for its movements; and, you can loosen / tighten the baffle without touching the mirror -- nice!

 

I'd thought about replacing the 3 grubs with small thumbscrews; but, the Kenko design is more rugged, so I left it alone.  I did some experimental tapping, jostling, & man-handling to see if there's slippage... Nope.

 

This assembly had been messed-with by a previous owner:  The hex bolt wasn't all the way in the backer.  Once that was secured, there's not much room for the grubs to move, so collimation will be similar to that Meade 2045 that I had a while back.  IOW:  Sensitive!

 

Before I locked the baffle, I got it centered on the corrector +/- 0.3mm with my digital calipers.  And, before I locked the retaining ring, I got the corrector centered in its cell within the same tolerances.

 

Y'all, these optics are now sooper-dooper clean!  I went through more than a dozen Nikon lens tissues.  Scope is so clean that it squeaks. 

Edited by Bomber Bob, 11 December 2021 - 03:47 PM.

[tturtle]

Kenko NES EQ Cleaned:

 

Kenko SC125L S11 - Restore (NES EQ Clean LS FL.jpgKenko SC125L S13 - Restore (NES EQ Clean RS FL.jpg

 

I really like the styling of this Kenko!

 

It was mostly dusty.  I did have to polish away small rust flecks on the counterweight shaft -- shiny now.  Ditto for the springy slow-motion cable.  Used the round metal brushes from my rifle cleaning kit to scrub all the rust inside the c/w bore.

 

Kenko SC125L S15 - Restore (NES EQ Clean Dovetail Clamp).jpg

 

Party Pooper!  Kenko's dovetail is about 3mm narrower than the Vixen standard.  OTOH, Kenko did something cool:  The dovetail that attaches to the scope's base plate has a small notch in the back; and, the clamp has a tiny Allen Head screw about in the middle of the clamp's track...  the scope cannot slide out of the clamp.  I like that security -- I get tired out there!

The mount looks very nice with that particular set of wood legs.  The legs look like you did some refinishing on them, no?

Edited by tturtle, 11 December 2021 - 03:48 PM.

[Bomber Bob]

The mount looks very nice with that particular set of wood legs.  The legs look like you did some refinishing on them, no?

Thanks!  Yes, the legs are from a 1960s Eagle USA-made surveyor tripod.  Original finish was that off-white "wash" stuff, and it was streaked & worn.  I sanded that off, went over the legs with a rag, then applied a couple of thin coats of Minwax (IIRC, the walnut / gun-stock color) with another old rag rather than a brush.  After than set, I sprayed on a thin layer of satin Olympic clear-coat...

 

The hardware is HEAVY chrome on nickel.  I like having dual clamps on each leg -- it can carry very heavy loads without slipping.

[Bomber Bob]

Kenko and... Vixen?

 

I noticed last night on ZEN [where else?] that a seller had put together a mix of Kenko & Vixen optics & hardware.  What really caught my eye:  He'd put a Vixen MD-6 (?) dual-axis drive system on a Kenko NES EQ like mine -- without mods (that I could see).

 

My B&L Bushnell Banner 1000 had just a single-axis drive.  Looking at the MD-6 (from a Vixen Super Polaris) on the NES... yep, identical hardware.

 

So, I have another option to motorize my NES.  The sticking point (as with my Mizar EQs) is finding that matching spur gear that bolts to the slow-motion rod...  Any of these would work:

 

- Banner 1000 S/A Drive

- Kenko NES Drive(s)

- Vixen Super Polaris Drive(s)  Okay... the example I saw turned out to be an after-market Vixen-compatible drive system that connects via serial cable with a PC for external go-to capabilities.  A real Vixen SP drive has a proprietary "Vee" rail on top that wouldn't work with a Kenko NES (or, older KES) EQ mount.  So, back to something Kenko-made IF my NES just has to have motorized tracking...

Edited by Bomber Bob, 11 December 2021 - 11:25 PM.

[Bomber Bob]

Kenko and... BORG:

 

No smoking gun yet, but I can make a case that Kenko supplied OTA hardware to some early Borg fast achromatic refractors:

 

- Helical Focuser on the circa 2002+ Kenko KDS Series (63-540 & 63-800) is identical to the BORG fast achros.

- Sliding Dewshield on the KDS also identical with that hardware on 2 BORGs (so far that I've found).

- On models where Kenko uses the KDS AZ Mount, so does BORG.

- On models where Kenko uses the NES EQ Mount, so does BORG.  (Only a few Classic BORG "long" refractors so far, but I'll keep looking.)

 

[On ZEN, I got tripped-up by the "telephoto" descriptors for some of the BORG fast achros & EDs, though they are clearly refractor telescopes.]

 

I already know that during the 1980s, Bushnell, Kenko, & Pentax used some of the same OTA hardware.  I'm pretty sure now that about 15 years later, Kenko had a similar relationship with TOMY / OASIS / BORG.  Maybe some BORG Experts will chime in on these earliest refractors?

 

I started to post all this on the Vintage Finds or Miscellany thread, since it has nothing to do with the SC125L; but, since I may find that Kenko & Mizar shared hardware & such on CATs, it's at least related...

[Bomber Bob]

NES EQ + Drive + Battery Pack + Quartz Hand Controller:

 

 

The Controller for the Banner 1000 was smaller, plastic casing, & simpler -- but it may have been a later version than the one in this Accessories / Options Sheet...

[Bomber Bob]

Laser collimation of the SC turned out to be... a snap!  For one thing, the secondary mirror wasn't wobbling around on the loose hex bolt (before today, I thought maybe it was spring-loaded).  I was right about the grub screw adjustments:  They are fractions of a millimeter.

 

Hoping I get decent enough skies tomorrow night for the Moon & Jupiter.

[Bomber Bob]

Dual-Axis Drives for the NES?   Why, Yes!!

 

I've been searching for an original Kenko NES dual-axis drive system, but so far, no joy.  I went through something similar with the Mizar EQ mounts, which is why I went ga-ga over ZEN Market -- my very 1st buy on ZEN was a NOS Mizar MMD-III system -- with all the gears needed to fit & function.  This is a common problem when buying old EQ mounts:  The small spur gear that fits on the slow-motion control rod is almost always missing (since drives were usually optional); and, if you are lucky enough to find a drive, the spur gear was lost or left on the mount...

 

As of now, I've found 2 dual-axis drive systems that are compatible with the NES EQ:

 

- Orion TrueTrack:  The closest match!  Originally made for the Orion SkyView Deluxe mount -- which is eerily similar to the NES from the latitude hub & above.

 

- Sky-Watcher EQ4/5 Dual Axis:  Meant to have the OEM plastic cover over it, so ugly.  Doesn't line up with either pair of hex bolts on the NES RA / DEC axes, but RA unit has a top center hole that does align with the NES RA slo-mo casing underside, so no drilling into the NES required.

 

Both kits include the spur gear with Tak-like clutch-collar & rod extension to add a slo-mo cable / knob if desired.

 

** BIF:  Took less than 5 minutes to remove the original Kenko (narrow!!) dovetail clamp, and replace it with a dual-knob SVBONY Vixen style -- hex bolts aligned perfectly.

[Jae]

I took my JSO 5 inch apart and sent the mirrors to get higher reflectivity coatings as they seems dim compared to my C5+.    The Kenko construction looks identical.   

 

I'd be curious with your comparison to your C5.   Both relative brightness as well as resolution, etc.   My C5+ (second sample) is so good that it may be hard to get any better but the JSO is right there.

Edited by Jae, 17 December 2021 - 10:23 PM.

[Bomber Bob]

The white-tube C5 Spotter I had was about the same age as the SC125.  It was brighter using some of the same eyepieces than the SC125.

 

Based on the few views of Jupiter that I've had in the SC125, it is a better planetary SCT than the C5 Spotter & the 1970s C5 Astro.  (Keep in Mind:  Jupiter / Saturn were higher in the sky when I had my 2 x C5s.)  That's another reason to fix its focuser / moving primary mirror.   Besides the mirror, it's in my queue to re-paint, and I'm thinking of using the bright yellow that Kenko used with some of its other CATs...

[Bomber Bob]

For the New CNers...

 

- ALL telescope types have compromises, quirks, annoyances.

 

- This SCT, like other SCTs, provides a large-aperture in a compact OTA, but:

-- You gotta collimate the optics.

-- The design needs temperature planning, monitoring, intervention.

-- In my case, the smaller SCTs feel crowded between the back plate & the center of the eyepiece.

-- A traditional SCT Rig isn't that light:  OTA + fork mount & base + wedge + steel-legged tripod.

 

Kenko addressed some of these annoyances by putting the SC125 on either the KDS alt/az or the KES / NES EQ mounts.  The result is a light-weight rig.  I wish Kenko had stuck with the JSO design -- using a standard rack & pinion focuser vs. the moving mirror.  I'm seriously looking at replacing the long tail-piece with a helical focuser -- like the Kenko 125C that I had -- I'm glad Kenko at least used a standard rear port.

 

My C5s were in the Fun Scope category:  I didn't use them for serious planetary, but that didn't make them any less fun for a couple of hours observing a variety of objects.  A typical 5" F14.4 refractor kit would NOT BE a grab & go like this Kenko!

[Bomber Bob]

3rd Collimation:

 

 

2nd Collimation was on the stars.  It looked good, but Jupiter at high power wasn't as sharp as I expected from an F14 SCT.

 

When I popped my primary Laser in, it showed very slightly OFF axis.  WITW?!

 

First, I verified that the corrector is centered in its cell; and, that the secondary assembly is centered on the corrector.

 

Then, I removed the BACK PLATE, and started checking.  All the components back here are metal, and well-made.  Very fine threads on the plate, but I suppose it could be cross-threaded.  The BAFFLE threads into the moving PRIMARY MIRROR PLATTER.  It wasn't threaded-in completely, so I corrected that.  

 

Next, I checked the PRIMARY MIRROR GASKET movements by racking it Full Back, Intermediate, and Full Forward, measuring the distance from the Gasket to the FOCUS STOP RING with my digital calipers.  No significant differences around the Baffle.  No slop.  Okay, is the mirror tilted on the Platter?  I don't have a good way to check this -- not to the sub-millimeters of any error.

 

The only mechanical issue I found was the very slightly loose Baffle.

 

I was ready to re-collimate.  Just in case the extension tube wasn't square with the axis, I removed it, and threaded the Vixen 36mm to 1.25" adapter directly into the back plate.  (It's only non-Kenko hardware on this scope.)  Before attaching the Laser, I inspected it visually, and the axis looks darn near perfect.  The Laser required small adjustments to the secondary (I hate its tiny Allen-head grubs!).  Now, I put the Kenko extension tube back on, and threaded the Vixen adapter into it.  Checked Good.  Finally, I swapped to my older & cheaper Orion Laser... Spot On.

 

With all that work, I expect the SC125L will do better the next night out.  It was very good before today, anyway.

 

Kenko's design is simple & rugged.  I did some "bounce tests" to simulate taking the scope on / off the mount, and collimation held.  IF the weather cooperates, I'll put it up against my C80P and Questar -- haven't used that one in a long while!

[Bomber Bob]

BEHR - Unmellow Yellow:

 

 

First Timer with this brand of spray-paint, and I'm pleased with the results.  It went on smooth -- no runs.  It is Bright, even in the shade.  It feels resilient, but only time & use will tell.  The, uh, tiny black specks... Gnats!  I don't know if the color or odor attracted them, but about a dozen made the fatal decision to be a part of the exhibit...

 

Only 1 label on the tube to deal with:

 

 

I masked it with blue painter's tape.  Hopefully it will peel away easily!  (Since I had JD powder-coat my 2 x black Vixen tubes, I had to remove those tube stickers, and they didn't go back on well - at all).

Edited by Bomber Bob, 20 March 2022 - 02:06 PM.

[Bomber Bob]

Pretty in Yellow...

 

 

Back Together Again!  [Cue Hall & Oates:   https://www.youtube....?v=yNk6ErNl89s]

 

Mercy!  I put a new blade in my X-Acto, but felt like I needed a scalpel to cut around the masked label...

 

Anyway, new exterior paint, plus new interior flat black -- the Behr turned out well.   Both ends thread-in, and you can "feel" when they're slightly off.  Yeah, big fat finger prints on the corrector that I gotta remove; and, I have re-collimate for the umpteenth time.  And, I have align the new finder.  But otherwise, she's ready to use...

 

Oh!  And The Label is obvious now!

 

And... gotta use more Q-Tips + Formula 409 to remove the dead Gnats...

Edited by Bomber Bob, 23 March 2022 - 06:10 PM.