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Critique of Classic 80mm F15's

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#1 Bonco2

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Posted 19 January 2020 - 05:04 PM

Towa, Tasco and many others offered a very standardized OTA and mount in the 60's thru the 80's or so. I'm sure they sold a gazillion of them. The equatorial mounts were very marginal in my opinion. I semi restored one and still found it unacceptable. The wooden legs were floppy, hard to manage and were very shaky.  If you extended them to max height for comfortable observing they were terrible. More steady and solid tho when not so extended.

The OTA's on the other hand seemed to be well made. Focusers, finders, and dew shields were functional and attractive. Optically,  I don't have much experience and would like to hear other opinions. The first one I bought had a huge clamshell. So I replaced it with a Carton lens. The second one I owned didn't hold up to the Carton lens so I replaced it with same great results. So I cannot critique the optics of these classics as I've only viewed thru one example. I'm guessing that like Unitron's the optical quality was not standard. Would like to hear other experiences. I will say that the OTA with Carton lens mounted on my Unitron 142 mount is a wonderful performer and is  a keeper.

Bill


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#2 Russell Smith

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Posted 19 January 2020 - 05:08 PM

"I'm sure they sold a gazillion of them"


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#3 39cross

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Posted 19 January 2020 - 05:46 PM

My Sears 6639 has great optics but a similarly shaky mount. On a stable mount it's a lot of fun to use, it's a great star-splitter and planet viewer.  It would be kinda cool to have it in a tube that was long enough to get rid of the extension focusing tube, and1.25" to boot.


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#4 Bomber Bob

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Posted 19 January 2020 - 06:12 PM

My 6336 has the same OTA & mount as the others; but, it's on a pedestal that I improved / dampened, and I have no problem focusing & using it at 80x / inch (250x).  For a while, I had the same EQ on a heavy-duty wood surveyor tripod; and again, it was a stable platform.   IOW:  The tripods are too flimsy.

 

Optically, the (Royal) Astro Optical 76mm F15 versions are the most reliably good -- a "safer" choice than a Towa 339.  The APL, Hino, Hiyoshi, & Yamamoto versions are also more reliable than the Towa.  Poor Towa!  Volume was their business model.  If you happen to get an outstanding 339... you're a lucky buyer.

 

But yes, when I put my 6336 OTA on a Vixen Polaris, Mizar AR-1, Goto 106, or Takahashi EM-1S, I can wring the last little bit of fine performance from this refractor.  When I want zero vibrations, I put it on a Meade StarFinder that'll carry an 8" Newtonian -- doesn't take all the frustrations out of imaging, but at least the stability of the system isn't an issue.


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#5 Bonco2

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Posted 19 January 2020 - 06:32 PM

Bob,

Good points. Me thinks the Royal Astro 76mm is in another league. Seems their optical quality control was better than Tasco, Towa etc. However I bet there are some out there that are good optical performers.

Bill


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#6 Russell Smith

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Posted 19 January 2020 - 06:38 PM

But not 80mm f15. Just saying

#7 Kokatha man

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Posted 19 January 2020 - 06:39 PM

I've only had a sample number of 1 of the 80/1200mm scopes (D-I K) & I have decided that it would not be terribly usable on the original GEM...but on an EQ6 it is a joy to use with excellent optics! waytogo.gif

 

Not quite the same but almost, our Yamamoto/SYW 76/1400mm is a good scope but imo not up to the Dai Ichi Kogaku...straying further from your thread's focus Bill, I hope to soon appraise the qualities of a Royal Astro classic - but not a refractor, a 100/1000mm Newt. smile.gif


Edited by Kokatha man, 19 January 2020 - 06:39 PM.

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#8 Chuck Hards

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Posted 19 January 2020 - 07:03 PM

I've got a Towa 80mm wearing Meade livery, it's got a pretty good figure and not a bad performer.  It came stock on the old EQ-3 which is borderline for visual use above medium powers, hold your breath and don't move when you have the magnification up there.  A RA drive helps more than anything else.  But the Monolux 80x1200mm has that exquisite H.O.C. lens, plus it takes 1.25" eyepieces easily.  Needless to say the Meade doesn't get used much.  The Monolux on the Jaegers 1" shaft mount is 80mm perfection.

 

I also have the same Towa in early Orion livery, pretty much BNIB, but I am pretty sure that one will end up on the downsizing pile one of these years. 


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#9 clamchip

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Posted 19 January 2020 - 08:00 PM

When I see a Towa 339 or one of the same Towa's with a different badge like the Jason Saturn

for sale it usually needs rescuing. It seems with these a few screws fall out and get lost and that's

it, the guillotine.

I like these scopes so I rescue them from their embarrassing predicament. A cleaning and

sometimes paint and stain, and usually missing a bunch of screws.

They are a very nice kit, with all the accessories they come with. 

I enjoy observing with them, but end up releasing them back out into the world. I have no trouble

selling these classic refractors, they are very popular. They look smart and a nice size 80mm.

Robert

This one most of the 'major' pieces were in the box and a careful search of the garage floor turned

up pretty much everything else. 

 

post-50896-0-31621400-1536096676.jpg


Edited by clamchip, 19 January 2020 - 08:56 PM.

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#10 clamchip

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Posted 19 January 2020 - 08:54 PM

Classic Japanese f/15 refractor, how sweet it is!

 

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post-50896-14074277174748_thumb.jpg

 

 


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#11 ccwemyss

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Posted 19 January 2020 - 09:37 PM

I'll second Chuck on the 80mm HOC. Mine is ATCO badged, and before I got the Unitron 142 optics sorted out, I was using it on that mount. It's wonderfully sharp. And it's very nice not having to deal with the draw tube. Now that the early 142 objective is working well, the ATCO is back to its native mount, which isn't nearly as stable.

 

There is also an early 80mm Meade 300/Towa 339 in the loaner set. I've only tested it briefly, and it seems quite good. I also like the 80mm HOC Selsi 247, but at 910mm fl, it does have more visible color than the f15s. 

 

The 75mm Royal Astro scopes in the set all perform well, but again, their mounts leave something to be desired, and like the Meade, they have the long draw tube, and need to be broken down into many pieces to fit in their boxes. 

 

Chip W. 


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#12 wfj

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Posted 19 January 2020 - 11:11 PM

While I’ve been searching for parts to repair my 3” Tinsley, I’ve put the lens in a Towa and had another one side by side. 
 

What I’ve noticed is that the Towa’s undercorrection leads to not so crisp focusing and an “airbrushed” appearance for lunar/planetary features at high mag. While the Tinsley lens has an exact focus with none of that “too smooth” appearance - after a while both seeing artifacts and details resolve. 
 

I’ve shown this to others and there are some who prefer the Towa lens. Not me.


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#13 Terra Nova

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Posted 20 January 2020 - 01:53 PM

I have yet to look thru ANY Towa that would be my preference. While I acknowledge that some (Towas) are better than others I think there are choices beyond.


Edited by Terra Nova, 20 January 2020 - 01:56 PM.


#14 clamchip

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Posted 20 January 2020 - 05:08 PM

Here's a article by Mr. Siple on the Towa 339:

http://www.rosecitya...005/2005_09.pdf

 

Robert



#15 clamchip

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Posted 20 January 2020 - 05:15 PM

A few of the many name tags.

Top photo, early font.

Middle, 'Disco' font, appeared in the mid 1970's

Bottom, Jason Saturn.

 

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Edited by clamchip, 20 January 2020 - 05:18 PM.

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#16 Terra Nova

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Posted 20 January 2020 - 05:26 PM

Here's a article by Mr. Siple on the Towa 339:

http://www.rosecitya...005/2005_09.pdf

 

Robert

His summary statement at the end of the article reads:

 

The Towa 80mm refractor tele- scope, though not great in aperture, delivers high contrast and sharply defined images of the denizens of our galaxy and beyond.

 

If you re-read my statement (post #13), I did not imply that all Towa suck. They don’t! As I said, some are better than others. They are, as acknowledged by John Siple in the quote above. Many are fair to middlin’ as they say in this part of the country. That can be taken as pretty darned good. It’s more than serviceable. But to me, there is a difference between serviceable and superlative and some indeed fit within this range. But if you want superlative, you need to look beyond Towa. 


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#17 clamchip

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Posted 20 January 2020 - 06:14 PM

His summary statement at the end of the article reads:

 

The Towa 80mm refractor tele- scope, though not great in aperture, delivers high contrast and sharply defined images of the denizens of our galaxy and beyond.

 

If you re-read my statement (post #13), I did not imply that all Towa suck. They don’t! As I said, some are better than others. They are, as acknowledged by John Siple in the quote above. Many are fair to middlin’ as they say in this part of the country. That can be taken as pretty darned good. It’s more than serviceable. But to me, there is a difference between serviceable and superlative and some indeed fit within this range. But if you want superlative, you need to look beyond Towa. 

Yes I agree, the Towa 80mm is above average and really very nice. But I have looked through

better 3-3.1 inch f/15's, but not by much of a margin.

I have the list in my head, I don't really wish to reveal it because I only have single examples I

used in my observations.

I can give a hint of the overall winner though:

 

post-50896-0-88084500-1518285829.jpg


Edited by clamchip, 20 January 2020 - 06:18 PM.

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#18 Bomber Bob

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Posted 20 January 2020 - 06:15 PM

I used my JTMA customized / Tasco-branded Towa 339 for about 10 years, and it was one of the better samples, but my older Royal 76mm F15 out-performs it at high power on lunar / planetary.  IME, an "average" Royal, Yamamoto, APL, Hino, or Hiyoshi is better optically than a "best" Towa...


Edited by Bomber Bob, 20 January 2020 - 06:16 PM.

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#19 pakman2

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Posted 20 January 2020 - 06:42 PM

So for us beginners, why would there be 76mm and also 80mm refractors as there is only a small change in diameter size or does it relate to how measurments were done? Thanks



#20 Terra Nova

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Posted 20 January 2020 - 07:35 PM

I used my JTMA customized / Tasco-branded Towa 339 for about 10 years, and it was one of the better samples, but my older Royal 76mm F15 out-performs it at high power on lunar / planetary.  IME, an "average" Royal, Yamamoto, APL, Hino, or Hiyoshi is better optically than a "best" Towa...

 

To be clear, I would have rather had either my 1970 Sears 6344 76mm x 1200mm (SYW), my late ‘50s Unitron 140 75mm x 1200, or my Goto 76mm x 1300mm than ANY Towa 80mm F15. However, I no longer have any of them because I’d ten times rather have my Tak FC76, that while an F8 and not an F16 is still sooo much better.


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#21 CHASLX200

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Posted 20 January 2020 - 07:45 PM

To be clear, I would have rather had either my 1970 Sears 6344 76mm x 1200mm (SYW), my late ‘50s Unitron 140 75mm x 1200, or my Goto 76mm x 1300mm than ANY Towa 80mm F15. However, I no longer have any of them because I’d ten times rather have my Tak FC76, that while an F8 and not an F16 is still sooo much better.

I love my Taks to look thru but looking at a nice 3" Unitron is a great thing to have set up in the house.


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#22 clamchip

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Posted 20 January 2020 - 08:56 PM

Amazingly out of I think 4 Towa 80's I've owned not one had a clamchip.

And these have been some pretty beat up rescue scopes.

Maybe its those plastic ring spacers?

Which reminds me, thinking back I've never seen such neglect as some of the

Edmund telescopes.

The one that take's the cake is my Edmund Deluxe Space Conqueror 4-1/4 inch.

I went out on a job and what did I see in the front yard? a Edmund Deluxe 

Space Conqueror!

I nearly had a coronary! $10 later it was mine!

 

Robert


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#23 Bomber Bob

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Posted 20 January 2020 - 10:59 PM

I love my Taks to look thru but looking at a nice 3" Unitron is a great thing to have set up in the house.

I know I'm biased, but my colorful 6336 OTA on its silver & black pedestal makes a prettier display.  Yes.  The Model 142 EQ is the superior mount, and my 6336 was a better 3" F15 than the Uni, and I did think about selling just the 142 OTA.  But... it was a 1950s, and I hate splitting up complete rigs -- especially when I don't have to.  And, it worked out:  The Mizar AR-1 is better than either the Royal or Uni mounts, and it's motorized.

 

Robert, if the Edmund 3" is as good as the 4" version, I missed out.  Could've had one 45 years ago, and might be running the STSI now.  Okay.  Maybe not that.  But... I might have gone on to be an astrometric planet-hunter.



#24 clamchip

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Posted 20 January 2020 - 11:08 PM

Yes the 3 inch Edmund Scientific is as good as it gets


Edited by clamchip, 20 January 2020 - 11:08 PM.

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#25 Bomber Bob

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Posted 20 January 2020 - 11:38 PM

Well then, shame on Edmund -- for making it so homely; and, the mount so primitive.  Swifts were the pinnacle of style back then, and way more $$$$ than my parents would spend, but the Sears 60mm EQ that I got for Christmas in 1974 was a work of industrial art compared to the Edmund refractors.  And the Tasco / Towa that I won in 1978, with its factory-installed drive, was both pretty & functional.  I drooled over both the Unitron & Mayflower catalogs -- but not the Edscorp.  (Had CN been around back then, I would've made an informed decision, and would've put performance over style.)


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