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Sears Discoverer Model no. 3 4454 80mm f15 reputation good or bad?

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#1 MER

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Posted 25 January 2021 - 02:51 PM

I have someone that has offered to sell one of these. I suspect there are several folks here that had one back ion the day. 

I am looking for a refractor to do white light solar observing. Thought 80-90 mm is plenty of light gathering and the f15 will give me some decent magnification.

 

So is this a good scope for my purposes? What were your thoughts now or back in the day?

 

 

Many Thanks!

Mike


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#2 Sky Muse

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Posted 25 January 2021 - 03:09 PM

I have someone that has offered to sell one of these. I suspect there are several folks here that had one back ion the day. 

I am looking for a refractor to do white light solar observing. Thought 80-90 mm is plenty of light gathering and the f15 will give me some decent magnification.

 

So is this a good scope for my purposes? What were your thoughts now or back in the day?

 

 

Many Thanks!

Mike

That's a fine achromat you have.  It was probably made by the optical-house "Towa" of Japan, or another.  It's simply branded "Sears".  I have a Sears(Towa) 60mm f/11 from the early 1970s, and my very first telescope.  The only drawback with these older achromats is that they are formatted to use .965" eyepieces, the old Japanese standard.  The current standard is the American 1.25", with a somewhat larger barrel diameter.  You can get a hybrid star-diagonal to use the larger ones.  I have this one, and a steal at this low price...

 

https://farpointastr...-1-25-open-box/

 

You can purchase a ready-made solar-filter, or make your own.


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#3 Jethro7

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Posted 25 January 2021 - 03:29 PM

I have someone that has offered to sell one of these. I suspect there are several folks here that had one back ion the day. 

I am looking for a refractor to do white light solar observing. Thought 80-90 mm is plenty of light gathering and the f15 will give me some decent magnification.

 

So is this a good scope for my purposes? What were your thoughts now or back in the day?

 

 

Many Thanks!

Mike

Hello Mike,

I have a Crescent D60 F/700 (Towa) cir 1958 and you know what? The views are a lot better than I ever though they would be. I have the GSO 9.65 to 1.25 hybrid star prism diagonal so I can use modern eyepieces with this scope. The old eyepieces are just junk and these held the scopes performance back. Many of these scopes came with a Solar viewing device.

        

                ( DO NOT EVER USE THE SOLAR VEWING DEVICE, NEVER )

 

HAPPY SKIES AND KEEP LOOKING UP Jethro


Edited by Jethro7, 25 January 2021 - 09:10 PM.

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#4 Wildetelescope

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Posted 25 January 2021 - 08:44 PM

I have someone that has offered to sell one of these. I suspect there are several folks here that had one back ion the day. 

I am looking for a refractor to do white light solar observing. Thought 80-90 mm is plenty of light gathering and the f15 will give me some decent magnification.

 

So is this a good scope for my purposes? What were your thoughts now or back in the day?

 

 

Many Thanks!

Mike

I have the TOWA branded version of that scope. It is an excellent example of what a long focal length achromat can be.   Over the years, Sears sourced telescopes from a number of different Japanese optics houses.  You should look carefully at the trade mark on the focuser.  If it is a T in a circle, that is Towa.    You should post the question over in the Classic Scopes group.  They will be able to tell you all you need to know.  

 

Cheers!

 

JMD


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#5 Wildetelescope

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Posted 25 January 2021 - 09:30 PM

Hello Mike,

I have a Crescent D60 F/700 (Towa) cir 1958 and you know what? The views are a lot better than I ever though they would be. I have the GSO 9.65 to 1.25 hybrid star prism diagonal so I can use modern eyepieces with this scope. The old eyepieces are just junk and these held the scopes performance back. Many of these scopes came with a Solar viewing device.

        

                ( DO NOT EVER USE THE SOLAR VEWING DEVICE, NEVER )

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

I am continually amazed at the quality of a 1971 sears version of that 60 mm scope that I got for 50 bucks off eBay.   My young  son uses it and loves it.   Stars are sharp as can be.  Just a faint green rind on a full moon, which is to be expected.  We use a hybrid mirror diagonal.  On a roll of the dice, I got him a Russel optics 50 mm Plossl with an 1.25 inch barrel.  It works GREAT for wide field views with that little scope.  I think I might "borrow" it the next time I have my 80 mm F15 out:-). You can have a lot of fun with these old long focal length achromats, and not spend a lot of money.  

 

JMD


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#6 Jethro7

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Posted 25 January 2021 - 09:59 PM

I am continually amazed at the quality of a 1971 sears version of that 60 mm scope that I got for 50 bucks off eBay.   My young  son uses it and loves it.   Stars are sharp as can be.  Just a faint green rind on a full moon, which is to be expected.  We use a hybrid mirror diagonal.  On a roll of the dice, I got him a Russel optics 50 mm Plossl with an 1.25 inch barrel.  It works GREAT for wide field views with that little scope.  I think I might "borrow" it the next time I have my 80 mm F15 out:-). You can have a lot of fun with these old long focal length achromats, and not spend a lot of money.  

 

JMD

Hello JMD,

I bought mine on Ebay a while back for $110.00 delivered. I did not really know that much about it, just that it was a nice example of a classic scope. I started viewing the threads on the "Classic Telescopes, EBay, Facebook and Craigs List" Topic on CN. Oh Oh there was a string of threads on this exact scope one of our Community members was going to buy it and then I saw his last thread "Sold" frown.gif  I apologized to him. It turned out to be near mint. Bomber Bob, dated it around 1958. The eyepieces that came with it were just terrible. When I able to use modern eyepieces oh my this was a surprise using a TV 32 Plossl was amazing. This was last Summer and viewing Jupiter Saturn and The Moon were a joy. Yes there is CA with these scopes but not enough to bother about. Some times I like bringing it out on my sessions. I think it is the nostalgic views that remind me of the Joy's of discovery when I was a kid. I have a passion for Long focal lengh scopes. They are sadly out of Voque these days. Replaced by Super fast short Achros. My Altair Starwave Ascent 102 ED F/1122 has given me the very best views of the Moon and planets that I have ever seen. I have a dream to find or build a 6" F/15 + at some point.  I keep looking for a GOTO Kogaku 80mm + scope for the collection and use. These are supposed to be one of the very best of the classics scopes ever made certainly an art form due to their very high manufacturing standards . Of course the price reflects that to. Towa scopes are very common and branded under many names, there for can be had for a bargan. 

 
HAPPY SKIES TO YOU AND KEEP LOOKING UP Jethro

Edited by Jethro7, 26 January 2021 - 07:30 PM.

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#7 Bomber Bob

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Posted 26 January 2021 - 06:22 PM

It's a re-branded TOWA 339, which was their Flagship Refractor.  I won a Tasco branded version back in 1978, and logged 1000s of hours with it.  Excellent lens, so I upgraded the accessories to 1.25" barrels -- Meade RG eyepieces really helped it pop.

 

The bad thing about Towa is that their quality isn't consistent between each scope -- they sourced optics from multiple makers.  In general, if it's from before ~ 1980, it should deliver excellent views -- with the right accessories.  Those "bundled" with the scope are average to poor...


Edited by Bomber Bob, 26 January 2021 - 06:22 PM.

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#8 AndresEsteban

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Posted 27 January 2021 - 10:16 PM

 

Hello JMD,

I bought mine on Ebay a while back for $110.00 delivered. I did not really know that much about it, just that it was a nice example of a classic scope. I started viewing the threads on the "Classic Telescopes, EBay, Facebook and Craigs List" Topic on CN. Oh Oh there was a string of threads on this exact scope one of our Community members was going to buy it and then I saw his last thread "Sold" frown.gif  I apologized to him. It turned out to be near mint. Bomber Bob, dated it around 1958. The eyepieces that came with it were just terrible. When I able to use modern eyepieces oh my this was a surprise using a TV 32 Plossl was amazing. This was last Summer and viewing Jupiter Saturn and The Moon were a joy. Yes there is CA with these scopes but not enough to bother about. Some times I like bringing it out on my sessions. I think it is the nostalgic views that remind me of the Joy's of discovery when I was a kid. I have a passion for Long focal lengh scopes. They are sadly out of Voque these days. Replaced by Super fast short Achros. My Altair Starwave Ascent 102 ED F/1122 has given me the very best views of the Moon and planets that I have ever seen. I have a dream to find or build a 6" F/15 + at some point.  I keep looking for a GOTO Kogaku 80mm + scope for the collection and use. These are supposed to be one of the very best of the classics scopes ever made certainly an art form due to their very high manufacturing standards . Of course the price reflects that to. Towa scopes are very common and branded under many names, there for can be had for a bargan. 

 
HAPPY SKIES TO YOU AND KEEP LOOKING UP Jethro

 

Jethro, I don't get how an 80 mm f/15 Achromat with a CA index equal to 4,76 will "They are sadly out of Voque these days. Replaced by Super fast short Achros. "
No fast achromat will replace a 80 mm f/15 achromat, in terms of chromatic aberration, contrast and definition provided doublets (both scopes) have good figures! It's simple Physics!

On teh otehr hanbd you mention "My Altair Starwave Ascent 102 ED F/1122 has given me the very best views of the Moon and planets that I have ever seen.", Ok, no doubt about it, but now it's not an achromat but a semi-APO refracto debause de doublet has an ED element! So we're comparing two different leagues. Achoprs vs. Semi-APOs (ED doublets). That's not fair, IMHO!

Just my two cents!

Clear skies for us all!
Andy



#9 Jethro7

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Posted 28 January 2021 - 07:01 AM

Jethro, I don't get how an 80 mm f/15 Achromat with a CA index equal to 4,76 will "They are sadly out of Voque these days. Replaced by Super fast short Achros. "
No fast achromat will replace a 80 mm f/15 achromat, in terms of chromatic aberration, contrast and definition provided doublets (both scopes) have good figures! It's simple Physics!

On teh otehr hanbd you mention "My Altair Starwave Ascent 102 ED F/1122 has given me the very best views of the Moon and planets that I have ever seen.", Ok, no doubt about it, but now it's not an achromat but a semi-APO refracto debause de doublet has an ED element! So we're comparing two different leagues. Achoprs vs. Semi-APOs (ED doublets). That's not fair, IMHO!

Just my two cents!

Clear skies for us all!
Andy

Hello Andy,

You are right, But I was not trying to compare a ED with a Achro, I was just saying I like long focal length scopes. They only do a couple of applications very well, such as viewing the Moon and planets that is about all. I prefer the Lunar and Planetary views through my Altair102 ED F/1122  because the nature of this scope allows me to really run up the power really high before I lose the resolution. 

 

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

 

P.S. I made short my essay on this and refer to Jon's post below, Jon, stated this much better than my ramblings.


Edited by Jethro7, 28 January 2021 - 09:17 AM.


#10 Jon Isaacs

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Posted 28 January 2021 - 07:55 AM

Jethro, I don't get how an 80 mm f/15 Achromat with a CA index equal to 4,76 will "They are sadly out of Voque these days. Replaced by Super fast short Achros. "
No fast achromat will replace a 80 mm f/15 achromat, in terms of chromatic aberration, contrast and definition provided doublets (both scopes) have good figures! It's simple Physics!

On teh otehr hanbd you mention "My Altair Starwave Ascent 102 ED F/1122 has given me the very best views of the Moon and planets that I have ever seen.", Ok, no doubt about it, but now it's not an achromat but a semi-APO refracto debause de doublet has an ED element! So we're comparing two different leagues. Achoprs vs. Semi-APOs (ED doublets). That's not fair, IMHO!

Just my two cents!

Clear skies for us all!
Andy

 

A fast achromat will not replace an 80mm F/15 achromat.

 

However, a good quality 80mm F/7 FPL-53 apo/ed can certainly better it in terms of color correction, it is simple physics.  An 80mm F/15 has a chromatic blur that's 2x the diameter of the Airy disk, The 80mm F/7 has a chromatic blur that is 0.75 x the diameter of the Airy disk.  

 

Short focal length achromats are low power wide field scopes.  80mm F/15 achromats are high power, double star and planetary scopes.  

 

A good quality 80mm ED/apo is both.  

 

I trust Bomber Bob on this.  He's an active member of the Classics forum and has tested many classic scopes using DPAC.  

 

In my mind, the difficulty with these classic F/15 achromats is not the optics, though the fields of view will be quite narrow even with 1.25 inch eyepieces. The challenge is the long tube, it's about 4 feet long.  Besides just dealing with the long OTA and the awkward viewing positions , the standard mount and tripods were not really up to the task, very shaky, wobbly. This is not a good thing, particularly for a scope that is used at higher magnifications.

 

Bob would know more than I but the Towa mount on my 80mm F/11s were marginal.  

 

The 0.965 inch eyepieces are also an issue.  One would want to upgrade to a 1.25 inch Visual back. Hopefully the standard Vixen 36.4mm visual back would fit, otherwise, it's a problem.

 

Scopes like this had their place and time. Now, it's a classic that can be enjoyed but it's not such a user friendly scope.  I have owned several similar scopes and currently own a 60mm F/15 Carton.  It's a nice reminder of how things used to be and why things are different today.

 

Jon


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#11 ovgjr

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Posted 01 February 2021 - 11:31 PM

It's a re-branded TOWA 339, which was their Flagship Refractor.  I won a Tasco branded version back in 1978, and logged 1000s of hours with it.  Excellent lens, so I upgraded the accessories to 1.25" barrels -- Meade RG eyepieces really helped it pop.

 

The bad thing about Towa is that their quality isn't consistent between each scope -- they sourced optics from multiple makers.  In general, if it's from before ~ 1980, it should deliver excellent views -- with the right accessories.  Those "bundled" with the scope are average to poor...

Thanks for the information. I just bought a pre 1980 Towa 339. Hoping to do some upgrades to it.


Edited by ovgjr, 01 February 2021 - 11:51 PM.



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