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For Fans of the Sub-60mm Classics

Classic Equipment Optics
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#26 Terra Nova

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Posted 29 April 2021 - 02:47 PM

As a Cincinnati local, this scope is calling my name!

Me too! More so than Gold Star! :lol:


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#27 CharlieB

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Posted 29 April 2021 - 03:11 PM

Take your pick -  they are all fine scopes.

 

40-50.JPG


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#28 CharlieB

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Posted 29 April 2021 - 03:13 PM

And this one.  A few cuts above the rest.

 

DSC_1025 - Edited.jpg


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#29 photiost

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Posted 29 April 2021 - 03:27 PM

And this one.  A few cuts above the rest.

 

attachicon.gifDSC_1025 - Edited.jpg

which one is that ?



#30 Terra Nova

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Posted 29 April 2021 - 03:50 PM

which one is that ?

Nippon Kogaku 50mm refractor.


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#31 Bomber Bob

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Posted 29 April 2021 - 04:05 PM

Size matters after all. My lower limit is 60mm as determined from that experience. So please, don’t shoot the messenger. I wasn’t speaking critically of anyone other than myself.

 

No attribution from me.  Notice that I ditched all of my 60mm EQs, including the CZJ & Goto.  For me, an 80mm EQ is as easy to deal with as a 60, and can dig deeper -- like the scary light C80 + Mizar SP (or, on the VG2).  I did keep the SYW 60 F7, but it's a "crossover" OTA -- and was originally a partner for the Dakin 4 (until I saw how well it performs!).


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#32 Jon Isaacs

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Posted 29 April 2021 - 04:23 PM

There are people in other forums with 24" Dobs on easy to move trolleys who look at anything sub 18" and say the same thing. Patrick Moore was Britains number one "Aperture Zealot" who told a nation that "anything smaller than a 6" reflector or 4" refractor would be useless for any kind of meaningful astronomy" (Galileo just shrugged "yeah... whatever")

 

 

I could be one of those people, I do value and promote the advantages of large aperture telescopes.. but I'm not, I also value and promote the advantages of small telescopes.   

 

6182642-Obsession lifting by handles CN.jpg
 
I'm lucky enough to be in a situation where I can view through a wide range of apertures but that won't last forever... i started with a worn out 60mm with one two element eyepiece, no finder, lashed to a equally worn out department store tripod..
 
I was happy.
 
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#33 Terra Nova

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Posted 29 April 2021 - 04:24 PM

Size matters after all. My lower limit is 60mm as determined from that experience. So please, don’t shoot the messenger. I wasn’t speaking critically of anyone other than myself.

 

No attribution from me.  Notice that I ditched all of my 60mm EQs, including the CZJ & Goto.  For me, an 80mm EQ is as easy to deal with as a 60, and can dig deeper -- like the scary light C80 + Mizar SP (or, on the VG2).  I did keep the SYW 60 F7, but it's a "crossover" OTA -- and was originally a partner for the Dakin 4 (until I saw how well it performs!).

Same here JW. Of my stash of 60mm scopes, my Takahashi, one of my two Unitrons, both the Zeiss T2 and T1, the Swift (AVA), the Goto, and the RAO Monolux are all gone. Only my Mayflower and one of the Unitrons in that caliber remain. I can’t believe how much I’ve cut back. I can now count all my scopes on both hands.


Edited by Terra Nova, 29 April 2021 - 04:27 PM.

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#34 sdedalus83

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Posted 29 April 2021 - 04:33 PM

I finally snagged one of these air spaced Vixen 50s. With the slower objective, it has much less CA than my binoculars and modern 50mm finders. Terrestrial views with a 26mm plossl were very sharp. Are they f5 or 6? I need to reposition one spacer to get the Newton rings centered. It’ll be a good companion for my MN66 or on its own with a small tripod. The build quality, baffling and focuser are all excellent.

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#35 DreamWeaver

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Posted 03 May 2021 - 05:24 PM

Here's my favorite sub-60mm clasic.  It's a Micronta (aka Radio Shack) 50mm x 500mm from the mid 1950's.  I was able to see the shadow of Ganymede transit Jupiter one night with a 6mm Ortho.

 

 

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#36 DreamWeaver

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Posted 03 May 2021 - 05:28 PM

But I can see how with all this "Pawer"!  lol.gif

 

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#37 Kokatha man

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Posted 03 May 2021 - 07:24 PM

Skyline (KD) 40mm @  f/20

.

That's a "DK" or more specifically a Dai Ichi Kogaku! (I ain't gunna bother to check my spelling for my second post in this thread! :lol: )

 

As I said I don't know if any of the various scopes they made were consistently good or bad, except that my 80x1200mm (f15) is a good'un! waytogo.gif

 

I called it a 76mm scope in my post on p.#1 but that's a mistake as the text in the Jovian image attests to...& I forgot to say that although the mount featured worms & wheels on both the RA & Dec, it was hopelessly under-engineered for such a long/relatively heavy scope - why it has an EQ6 for a permanent mount now! ;)


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#38 Kokatha man

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Posted 04 May 2021 - 07:05 AM

That's a "DK" or more specifically a Dai Ichi Kogaku! (I ain't gunna bother to check my spelling for my second post in this thread! lol.gif )

 

As I said I don't know if any of the various scopes they made were consistently good or bad, except that my 80x1200mm (f15) is a good'un! waytogo.gif

 

I called it a 76mm scope in my post on p.#1 but that's a mistake as the text in the Jovian image attests to...& I forgot to say that although the mount featured worms & wheels on both the RA & Dec, it was hopelessly under-engineered for such a long/relatively heavy scope - why it has an EQ6 for a permanent mount now! wink.gif

Sorry, losing my marbles somewhat..! :lol:

 

I got confused with the post about my D-I K which was actually in that other ("most under-rated scopes...etc") thread with my reference to p.#1..! ohmy.gif


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#39 LukaszLu

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Posted 04 May 2021 - 08:50 AM

Before others read to much into my above response, I can see that I need to clarify it. I was speaking from a point of introspection rather than prescribing what I think others should or shouldn’t do, hence my use of first person pronouns rather than second. I get it that a lot of folks very much enjoy collecting and using smaller 40mm to 50mm refractors and I think that’s great. My point was that, I’ve had a 50mm F12 refractor that was optically quite good. Other than confirming that to myself and acknowledging it to others (that 50mm refractors can perform well and yield good results within the defraction limits of their aperture), I didn’t see any point in keeping it and was happy to give it to my grandson on his ninth birthday. It was just as easy for me to use one of my 60mm refractors, and one of them would show me more. For me, using the 50mm scope didn’t challenge me or offer me a unique experience, but I do get that. I think we all have upper and lower thresholds in terms of the minimum and maximum apertures we find practical and useful. Size matters after all. My lower limit is 60mm as determined from that experience. So please, don’t shoot the messenger. I wasn’t speaking critically of anyone other than myself.

It sounds reasonable, but it does not seem to take into account the advantages of small scopes designed for maximum comfort and mobility. I mean typical spotting scopes that allow you to get different magnifications without having to carry a box of eyepieces.

 

I myself was tempted by the zoom mentioned here by Diego. Unfortunately, I had to send it for repair due to a faulty position of the prism, which I could not remove. But it is an extremely convenient and portable 40 mm small scope that you can take with you on any occasion.

 

Using it has its charm - despite the chromatic aberration and poor contrast, which is typical for multi-lens systems such as zoom or eyepiece adapter. And that's all the game is about! If we were to compete for the tiniest detail observed, then also 60 mm is below the limit determined by average weather and seeing conditions. In my opinion, 75-80 mm lenses are close to the border in average seeing - at least at my place.

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#40 Terra Nova

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Posted 04 May 2021 - 09:21 AM

It sounds reasonable, but it does not seem to take into account the advantages of small scopes designed for maximum comfort and mobility. I mean typical spotting scopes that allow you to get different magnifications without having to carry a box of eyepieces.

 

I myself was tempted by the zoom mentioned here by Diego. Unfortunately, I had to send it for repair due to a faulty position of the prism, which I could not remove. But it is an extremely convenient and portable 40 mm small scope that you can take with you on any occasion.

 

Using it has its charm - despite the chromatic aberration and poor contrast, which is typical for multi-lens systems such as zoom or eyepiece adapter. And that's all the game is about! If we were to compete for the tiniest detail observed, then also 60 mm is below the limit determined by average weather and seeing conditions. In my opinion, 75-80 mm lenses are close to the border in average seeing - at least at my place.

And then there are always binoculars. I love using my binoculars.


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#41 LukaszLu

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Posted 04 May 2021 - 10:06 AM

And then there are always binoculars. I love using my binoculars.

Of course - everyone has their own preferences and there is no point in discussing them. However, binoculars have been present on the optics market for a very long time, and yet the optical industry began efforts in the 1950s to create a new category of small spotting scopes that could easily obtain various magnifications. This is one of the advantages of scopes of this kind, which is often forgotten (and is not always provided by binoculars). Initially, this was done quite ineptly, using a heavy and large eyepiece adapter. The idea was actually realized only by the later zooms from the 1970s - such as this 40 mm telescope.


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#42 Diego

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Posted 04 May 2021 - 02:53 PM

It sounds reasonable, but it does not seem to take into account the advantages of small scopes designed for maximum comfort and mobility. I mean typical spotting scopes that allow you to get different magnifications without having to carry a box of eyepieces.

I myself was tempted by the zoom mentioned here by Diego. Unfortunately, I had to send it for repair due to a faulty position of the prism, which I could not remove. But it is an extremely convenient and portable 40 mm small scope that you can take with you on any occasion.

Using it has its charm - despite the chromatic aberration and poor contrast, which is typical for multi-lens systems such as zoom or eyepiece adapter. And that's all the game is about! If we were to compete for the tiniest detail observed, then also 60 mm is below the limit determined by average weather and seeing conditions. In my opinion, 75-80 mm lenses are close to the border in average seeing - at least at my place.

Indeed it's a nicely built spotting scope...all aluminum with no plastic parts. The zoom is nice that you don't have to refocus. Mine had a dirty prism...some of the grease from the zoom mechanism manged to get on to it. Not being able to clean it without further disassembly, I held my breath and went in for a complete teardown. The prism is held by tiny Allen set screws, but seems to have some glue also. I successfully cleaned it without any harm...this is the before pic

IMG_20210407_203628~3.jpg

Edited by Diego, 05 May 2021 - 04:59 AM.

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#43 LukaszLu

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Posted 04 May 2021 - 03:47 PM

Hi Diego, I have the same problem - the prism is dirty on the side of the lens (probably smeared with grease), and I have the impression that it is set not quite correctly, which can be seen at maximum magnification - although looking at your photo showing a similar setting, I am not sure about it. I unscrewed the Allen screws, but I do not know why they are used if the prism is permanently glued? The element does not budge - did you manage to dismantle the prism? I gave up and sent the equipment to the service technician ... I think he will try to disassemble the prism by heating this glue ...

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Edited by LukaszLu, 04 May 2021 - 03:49 PM.

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#44 Diego

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Posted 05 May 2021 - 05:10 AM

Hi Diego, I have the same problem - the prism is dirty on the side of the lens (probably smeared with grease), and I have the impression that it is set not quite correctly, which can be seen at maximum magnification - although looking at your photo showing a similar setting, I am not sure about it. I unscrewed the Allen screws, but I do not know why they are used if the prism is permanently glued? The element does not budge - did you manage to dismantle the prism? I gave up and sent the equipment to the service technician ... I think he will try to disassemble the prism by heating this glue ...

Most binoculars also have glue on the prisms in spite of being firmly held down with spring steel straps. I think it's sort of a safety measure to keep the prisms aligned if it should get dropped or bumped.

To remove the prism, I took a thin razor blade and cut the glue on the side nearest to the wall of the aluminum body. From the eyepiece side I used a wooden chopstick to very carefully push the prism free. Previously I marked the position of the prism with a pencil.

After thoroughly cleaning the tiny glass, I placed it back and used a soldering iron to remelt the glue, which seems extremely similar to modern hot glue; it only required a few seconds to remelt; sort like a touch-up. The last step is snugging down the tiny set screws to lock the prism in place. Good luck!!

Edited by Diego, 05 May 2021 - 05:14 AM.

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#45 GreyDay

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Posted 05 May 2021 - 06:11 AM

However, binoculars have been present on the optics market for a very long time, and yet the optical industry began efforts in the 1950s to create a new category of small spotting scopes that could easily obtain various magnifications. This is one of the advantages of scopes of this kind, which is often forgotten (and is not always provided by binoculars). Initially, this was done quite ineptly, using a heavy and large eyepiece adapter. The idea was actually realized only by the later zooms from the 1970s - such as this 40 mm telescope.

The biggest setback for spotting scopes is the need to provide a RACI image at the eyepiece. A lot of spotting scopes use fast objectives (f6 or lower) to maintain a short portable OTA, I've found the longer spotters have much better correction for CA and usually a better optical train.

 

Zoom telescopes are compromised by manufacturers in order to bring these scopes to market and still make a profit. You have to consider that pricing a 40 or 50mm zoom scope would mean keeping the price lower than a typical 60mm refractor, otherwise nobody would buy them, hard to do when you need corrector lenses a zoom assembly and time consuming setup of a prism etc. Building a standard refractor is easy at the focuser end, three screws for the focuser body, insert the tube with rack, place the focuser pinion and spring plate, two more screws and you're done! Compare that to manufacturing/assembling a zoom scope focuser section with all those set screws, moving parts, extra lenses and we have at least one of the reasons why zoom scopes have a poor reputation. For cost to be low compromises were made.

 

A typical example is Tacso's 4VTE, a great objective spoilt by a poor corrector section, the design of which hadn't changed since old brass "navy" telescopes were introduced along with a zoom made with cheap lenses. Imagine if They'd put a little more money and effort into these scopes, how much better they could be. But then we'd be looking at Zeiss/ Swarovski prices and they lose appeal for the average person. I have a few spotters from 40-80mm all cost very little to buy, but i wouldn't spend a fortune on one when i could buy a small aperture ED and a good zoom EP for the same price.


Edited by GreyDay, 05 May 2021 - 06:15 AM.

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#46 LukaszLu

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Posted 05 May 2021 - 10:28 AM

You're right, a typical example of image corruption despite a pretty good lens are the first attempts from the 1950s equipped with an eyepiece adapter. My Towa gives a clear CA and has trouble achieving even focus across the field of view. I once asked Dave Trott about similar models from other brands - he said that none of the ones he has in his extensive collection gives a good image, including the Unitron models.

Well, but how could it be otherwise, since someone first uses a short focal length, which is already risky in itself, and then tries to reverse it using Barlow lenses and finally converts the image with a single erecting lens? This kind of production is based on additional savings, which is the lack of a full-size tripod and mount. It might help to a certain extent, but surely doesn't solve all the problems...


Edited by LukaszLu, 05 May 2021 - 06:06 PM.

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#47 LukaszLu

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Posted 05 May 2021 - 10:33 AM

Most binoculars also have glue on the prisms in spite of being firmly held down with spring steel straps. I think it's sort of a safety measure to keep the prisms aligned if it should get dropped or bumped.

To remove the prism, I took a thin razor blade and cut the glue on the side nearest to the wall of the aluminum body. From the eyepiece side I used a wooden chopstick to very carefully push the prism free. Previously I marked the position of the prism with a pencil.

After thoroughly cleaning the tiny glass, I placed it back and used a soldering iron to remelt the glue, which seems extremely similar to modern hot glue; it only required a few seconds to remelt; sort like a touch-up. The last step is snugging down the tiny set screws to lock the prism in place. Good luck!!

Thanks to Diego for these precious comments, my zoom is in the hands of the service technician, but I will pass on all your advice to him in a moment - I'm sure he will make use of them!


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#48 Diego

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Posted 05 May 2021 - 07:45 PM

Thanks to Diego for these precious comments, my zoom is in the hands of the service technician, but I will pass on all your advice to him in a moment - I'm sure he will make use of them!


Glad that I could help!!! Let us know how it went.

Sorry to the OP for slightly going OT.
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#49 Bowlerhat

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Posted 07 May 2021 - 06:04 PM

I like my E50/540 zeiss.

 

Zeiss Jena Teleminor (1)

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