184 replies to this topic

[Bomber Bob]

Gotta give a shout-out to the kindly CNer who sent me the lens from his black Monolux 60x800 to test & potentially buy.  W-O-R-K has really slowed me down!  This past weekend I got the lens out of the cell, and started experimenting with spacers.  Will post some pix tomorrow...

 

Classic Scopes & Classy Folks -- the Best Forum on this site!

 

Making & Testing Foil Spacers:

 

 

Good old Reynolds Wrap!  My default spacer is 1 layer, 2 mm wide, and extends in from the flint edge about 2 mm.  I do a quick check for Newton Rings using the fluorescent bulb in the hall bath.

 

This lens was like The 3 Bears:  1 layer too thin, 3 layers too thick; so, I pounded the 3 layers with a rubber mallet, rolled the foil piece flat, and got centered & symmetrical Rings.  Each spacer is about 6 mm long, and I temp tape these tabs to the edge.  Now that I'm happy with the spacing, I'll apply a tiny bit of glue off a Stick using a tightly wound Q-Tip.  Let that set for a couple of days, then use my X-Acto to prune off the foil & tape.

 

Finally, I'll do a final lens cleaning, then put it back in its cell.

 

BIF:  There's about a dozen or so "chips" in the R3 (sky face) edge of the flint.  Not 1 is large enough to be a Clam -- nothing radiating out from the microscopic impact points.  But... I had to choose my 3 x 120* spacer points carefully!  Anywho, it must be abnormally flinty flint glass...

 

Otherwise, both elements are in excellent condition.  No scratches.  No coating degradations.  Bet it does well on my DPAC Rig, and in star & sky testing.  With luck, I can adapt its cell to my KDS-63/800 or my V60/700 (& use extenders).

Edited by Bomber Bob, 10 February 2022 - 05:04 PM.

[aoirotukiko]

Compass Instrument & Optical Co.,Inc. first used  Monolux mark on 1954-06-24.

Southern Precision Instrument Co. first used  SPI mark on 1951-09-01.

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[aoirotukiko]

Bushunell  first used  SKY CHIEF mark on 1958-05-08.

Asahi Kogaku Kogyo Kabushiki Kaisha (Asahi Optical Industry Co.、Ltd.) registered  JUPTER  mark on 1957-01-30.

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[badback]

Here's an old, very well made, 60 x 800 Bushnell Sky Chief.

It sure looks good in the pic although it is a beater... but

what the hell... I sure do love them "BEATS." 

 

 

[jragsdale]

Interesting Sky Chief, Asahi focuser and Towa finder?

[Kasmos]

Bushunell  first used  SKY CHIEF mark on 1958-05-08.

Asahi Kogaku Kogyo Kabushiki Kaisha (Asahi Optical Industry Co.、Ltd.) registered  JUPTER  mark on 1957-01-30.

I found the same information online but have trouble with the first use date.

 

I have two Gray and Blue Sky Chiefs (60/910mm) that are the type that looks like they are made by RAO and match the one shown in a 1958 Coast Instruments catalog so it's very hard to believe they didn't use the name earlier. Especially since I've seen similar but different earlier versions with lower serial numbers. I would also think the Asahi made ones pre-date them since the later Gray and Blue Sky Chief II is more like the RAO type. It might be a case of them not being completely truthful with the first use date since the application date (1967) was so much later.

 

 

As you can see this Sky Chief is more like the later Sky Chief II.

I find it really hard to believe that any of the Asahi Sky Chiefs were made between the two or made afterwards 

Edited by Kasmos, 13 February 2022 - 05:10 AM.

[Bomber Bob]

Black Monolux 60x800 -- Testing

 

I feel like the subject of a Classic Beatles song...

 

He say, "one and one and one is three"

Got to be good looking 'cause he's so hard to see
Come together, right now, over me

 

On rare occasions, things just seem to come together...

 

Lens is clean & re-assembled.  There was enough side clearance in the cell to tape the 2 elements together, and maintain their alignment:

 

 

AND... the Monolux cell threads perfectly onto my Vixen 60's tube:

 

 

IF the clouds will stay away, I'll get to star & sky test it tonight -- after adding Extenders to the 700mm FL Vixen!!

 

[Even if it passes the sky tests, I'm still gonna DPAC this lens, since I didn't have a rig back when I had that sweet black Monolux OTA.]

 

Nix On The Test:  I'd need at least 2 additional extenders.  Plan 2:  See if I can adapt the lens / cell to my Kenko 63x800.

Edited by Bomber Bob, 12 February 2022 - 09:51 PM.

[badback]

Interesting Sky Chief, Asahi focuser and Towa finder?

This Bushnell came with the finder mount but was missing the actual finder.

 

long ago I had purchased a finderless 40mm finderless Monolux.

Post#10: https://www.cloudyni...mm#entry4251031

 

I eventually bought a similar.complete finder and finder mount for that
Monolux although it was actually designed for a 60mm scope. Some

"exact" parts are nearly impossible to find so one must endeavor

That finder worked great but the finder mount had a different radius

and fit like 60mm clown shoes on a 40mm Hobbit.

 

Recently I bought a two in one scope deal on Goodwill (cheap) just

to get the correct finder mount replacement for the Monolux.

 

 

Fortuitously my now spare finder found a home and was a perfect fit

for the finderless Mr. Bushnell. Although unlikely original the finder

alignment set screws from my spare also fit perfectly.

How cool is all this? "PARTS IS PARTS!!!

[jragsdale]

Excellent story! I think there's an Asahi finder on eBay at the moment if you're interested, but a finder is a finder, especially if the vintage fits.

[aoirotukiko]

The discussion here is very interesting.

 

Toyo Jitsugyo KK  (Oriental Trading Company,Ltd.) registered  BUSHNELL TRIPLE TESTED  mark on 1956-09-21.

Toyo Jitsugyo KK is an export trading company. The Kugahara factory made binoculars, but I don't think they made astronomical telescopes.

 

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[DouglasPaul]

If these have been posted here my apologies, just didn't want to go through the whole thread..  

 

VIXEN SIRIUS-60L

https://zenmarket.jp...ode=c1029904099

[DIYDarren]

Folks- I have another stray thread on this, but wanted to consolidate here.

 

Here is a "Lunar" branded Asahi that is ostensibly identical to the Sky Chief that Badback is showing above. 60 x 800 sounds right even though its not marked. Just showing another variant. Just picked it up haven't tested the optics yet. Objective is non-blackened edges and no orientation marks. The tube is very well baffled (I think) with I believe 3 baffles within the OTA and another 2 within the focuser tube.

 

 

 

 

 

 

 

 

Darren

[Bomber Bob]

Just to add here, the Monolux 60x800 did not have a good DPAC Test today:

 

 

That "bloom" or hot spot kept me from assessing the lens at 3 or 4 bars.  It's caused by large & deep coating damage on the back (eye) side of the flint element.

 

However, it does produce excellent Newton Rings, so it may turn out to be a decent lens -- despite a previous owner's worst efforts!  I say this because the skinny micro-bars are ramrod straight, identical width, and with no edge curving.

Edited by Bomber Bob, 02 March 2022 - 09:23 PM.

[Terra Nova]

Just to add here, the Monolux 60x800 did not have a good DPAC Test today:
 
Monolux 60-800 DPS01 TST BRS IV2.jpgMonolux 60-800 DPS02 TST BRS IF2.jpgMonolux 60-800 DPS23 TST BRS IF2.jpg
 
That "bloom" or hot spot kept me from assessing the lens at 3 or 4 bars.  It's caused by large & deep coating damage on the back (eye) side of the flint element.
 
However, it does produce excellent Newton Rings, so it may turn out to be a decent lens -- despite a previous owner's worst efforts!

Yikes!

[Bomber Bob]

Yikes!

My reaction, too!  It's like something was inside the tube, and the lens end got swung around & around, while the thing rolled & marred the coatings.... the glass is not scratched.  I also wondered:  If a frac is left outside for nights with high humidity & sub-freezing temps, would FROST form on the lens??  Anywho, you can look at my KDS-63 results from today, and see the difference.  The KDS has perfect coatings...

[Kasmos]

Just to add here, the Monolux 60x800 did not have a good DPAC Test today:

 

Monolux 60-800 DPS01 TST BRS IV2.jpgMonolux 60-800 DPS02 TST BRS IF2.jpgMonolux 60-800 DPS23 TST BRS IF2.jpg

 

That "bloom" or hot spot kept me from assessing the lens at 3 or 4 bars.  It's caused by large & deep coating damage on the back (eye) side of the flint element.

 

However, it does produce excellent Newton Rings, so it may turn out to be a decent lens -- despite a previous owner's worst efforts!  I say this because the skinny micro-bars are ramrod straight, identical width, and with no edge curving.

As you know the Newton rings are created by the space between the two lenses so the eye side of the Flint may very well spoil the image.

[Bomber Bob]

As you know the Newton rings are created by the space between the two lenses so the eye side of the Flint may very well spoil the image.

That's why I've included caveats...  My secondary point:  Great Newton Rings may not produce a great final image...

 

But, this lens is exceptionally abused.

Edited by Bomber Bob, 03 March 2022 - 01:35 PM.

[strdst]

Hi JW,

 

When I sent that lens off to you I knew it could use a cleaning but hadn't noticed that the coatings were in such egregious condition. That was a shopgoodwill purchase in 2011. I was mostly inspired to purchase it for the tripod legs that looked Unitronish, the focuser knobs that looked Asahi Pentaxish, the case that had chains (instead of cloth lid straps), a lens that had foil spacers (instead of a plastic ring), and the brand Monolux. First light impression was that it performed just like a number (too many) of 60 X 700, 800, and 900 circleT scopes that I had purchased previously...all bad to very bad optically. Disappointed I sent the OTA to the Closet of Misfit Toys until you mentioned wanting to test such a lens.

 

Although I'm not capable enough to send a link, there is a short thread that I started that can be found in the CN classic telescopes archives titled "Where have all the coatings gone? Long time ago". Except for the "all" and "Long time ago" in the title the rest is mostly true. The thread describes the condition after cleaning a Swift 839 60mm objective with 91% isopropanol alcohol and cotton puff balls. DavidG and others chimed in to assure me that sometimes coatings fail.

 

I made a followup thread (that I can't find now) describing soaking the crown element in sulphuric acid (CROWN ONLY) which removed the remaining smeary coatings. It didn't alter the performance of the lens in star tests (already very good) but did alter the way I "felt" when looking at the lens, as in quite happy.

 

I'm wondering if you noticed if the coating loss seemed more evident after cleaning and before you tested it. Because the loss is on the flint glass, sulphuric acid isn't an option according to DavidG but it might produce a good diffraction pattern now that you have replaced the spacers. Looking forward to your first light impression.

 

 

 

 

 

 

 

 

 

 

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[Bomber Bob]

I'm wondering if you noticed if the coating loss seemed more evident after cleaning and before you tested it. Because the loss is on the flint glass, sulphuric acid isn't an option according to DavidG but it might produce a good diffraction pattern now that you have replaced the spacers. Looking forward to your first light impression.

 

In normal room lighting, it's not noticeable when looking into the lens from the front.  But bright light from the front, and it's obvious.  Yeah, I saw the pattern before cleaning, and hoped that cleaning would help (sometimes smeared dew that's dried will leave swirls & such).  Cleaning maybe made it more obvious because more light is getting through the crown + flint from the front...

 

But yes, I did see very faint straight bars at 8, and possibly at 6 (very hard to tell) with DPAC.  I know Dave G. will say that's not very sensitive, but it's better than nothing.  No BIG ISSUES at the center or edges.  And... it nailed focus at 802mm.  May not be a factor, but that is another factoid.  Since I haven't seen this before, I'm not sure how much coating deviations affect the final image...  EXCEPT, total light throughput...

 

I did do a crude day time Sun test this week, and I got a sharp solar limb at focus on a white screen.  I REALLY want to get the lens in a rig & star test it!!  Anybody wanna loan Ole BB an 60x800 OTA -- minus the optics??

Edited by Bomber Bob, 03 March 2022 - 04:01 PM.

[deSitter]

I'm wondering if you noticed if the coating loss seemed more evident after cleaning and before you tested it. Because the loss is on the flint glass, sulphuric acid isn't an option according to DavidG but it might produce a good diffraction pattern now that you have replaced the spacers. Looking forward to your first light impression.

 

In normal room lighting, it's not noticeable when looking into the lens from the front.  But bright light from the front, and it's obvious.  Yeah, I saw the pattern before cleaning, and hoped that cleaning would help (sometimes smeared dew that's dried will leave swirls & such).  Cleaning maybe made it more obvious because more light is getting through the crown + flint from the front...

 

But yes, I did see very faint straight bars at 8, and possibly at 6 (very hard to tell) with DPAC.  I know Dave G. will say that's not very sensitive, but it's better than nothing.  No BIG ISSUES at the center or edges.  And... it nailed focus at 802mm.  May not be a factor, but that is another factoid.  Since I haven't seen this before, I'm not sure how much coating deviations affect the final image...  EXCEPT, total light throughput...

 

I did do a crude day time Sun test this week, and I got a sharp solar limb at focus on a white screen.  I REALLY want to get the lens in a rig & star test it!!  Anybody wanna loan Ole BB an 60x800 OTA -- minus the optics??

Are some of the coatings flaked off? I think the coating is 1/4th wavelength of a specific frequency in thickness, likely in the green, and have similar refractive indices to glass - so the worst that could happen from the non-coated part is a slight change in optical path length compared to the coated part - and it can't be much, probably not enough to notice. Overall, the only discernible effect should be a slightly dimmer image. So the lens should perform just about as well as fully coated one. You could compare with a similar undamaged lens in a star test. Would be interesting to know.

 

-drl

[Bomber Bob]

Are some of the coatings flaked off?

 

No, it looks like someone tried to clean it, and whatever they used, it bore into the coating layer, and made the swirl patterns.  Could've been the chemical used, and/or the polishing tissue / cloth...

 

I didn't see any evidence that it harmed the glass.  You can see the extent of it -- and, that it stops where the lens cell blocked their motion...

 

BIF:  While the lens cell was off the KDS-63/800, I looked at adapting the Monolux cell to fit... honestly, the KDS tube is so over-sized that it would be tough to do -- and make sure the lens is square with the focuser.  Gonna go through all my extender tubes, and see if I can rig a long enough one to use it with the V60, since the M's cell threads on that OTA easy!

 

BIF2:  If Dave G doesn't chime in here, I'll shoot him a PM.  I have the M lens in a sealed Tupperware container... Is there a chemical whose FUMES could slowly remove the bad coating layer, without harming the Flint element??

Edited by Bomber Bob, 03 March 2022 - 05:40 PM.

[39cross]

Making & Testing Foil Spacers:

 

This lens was like The 3 Bears:  1 layer too thin, 3 layers too thick; so, I pounded the 3 layers with a rubber mallet, rolled the foil piece flat, and got centered & symmetrical Rings.  Each spacer is about 6 mm long, and I temp tape these tabs to the edge.  Now that I'm happy with the spacing, I'll apply a tiny bit of glue off a Stick using a tightly wound Q-Tip.  Let that set for a couple of days, then use my X-Acto to prune off the foil & tape.

...

I noticed the Newton's rings on my Asahi-Pentax are skewed off-center, closer to the edge than not, so I'm thinking of playing with spacers to see if I can improve it.  Do you use the glue to keep the spacer in place?

 

Somehow my serial number is not in the registry, it's 236809, if you'd like to add it!

[Bomber Bob]

I noticed the Newton's rings on my Asahi-Pentax are skewed off-center, closer to the edge than not, so I'm thinking of playing with spacers to see if I can improve it.  Do you use the glue to keep the spacer in place?

 

Somehow my serial number is not in the registry, it's 236809, if you'd like to add it!

If there's room in the lens cell for tape on the edges, I don't mess with gluing down the spacers.  But most times, the cell is too snug...  then, I use a Glue Stick + a flat toothpick or similar to put a TINY smear of glue on the lens, and immediately place the spacer at the edge mark that I've already made.  I try to get each spacer centered on that mark -- yeah, probably over-kill.

 

* When you can, shoot me a PM on your Asahi.  Overall condition, completeness, etc. -- the more details, the better! *  I have a temp file where I keep this info between Registry Updates.

[Kasmos]

From time to time I've wondered when Towa stopped offering the AT2 and ET1 line of telescopes.

 

Here's a very unique Scope Orbit 2265 that may possibly be the sucessor to the type ET1. 

What we normally see is the typical 60/900mm GEM like those later offered by Sears or Jason.

 

This 60/800mm no longer has the the thick and heavy focuser of the AT2 and ET1 and a mount unlike The ET2 or the later common Sears 900mm GEMs.

 

 

The GEM seems to have a much smaller and covered gear on the RA shaft.

 

And no setting circles.

 

Since it appears to have what I call the chunkier objective cell, my best guess is it's from about 1961.

 

I've done several searches and have never seen another like it.

Edited by Kasmos, 22 March 2022 - 03:12 PM.

[deSitter]

I haven't seen anything before 1967 with the teal color scheme. The Sears 6336 had a very very pale version of it, but really that is different enough to not qualify.

 

-drl