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Tell me about your Televue Telescope

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#501 NC Startrekker

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Posted 21 June 2020 - 07:37 AM

Quite ingenious Tim!



#502 skysurfer

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Posted 21 June 2020 - 07:44 AM

I used to have a Genesis, bought it in 1995 and was happy with it, but it had a single speed focuser which I could not remove for travel, so my carry-on luggage was a bit too long. So in 2012 I ordered a Moonlite focuser and even then it was absolutely impossible to remove the original focuser, so I returned the focuser and sold the Genesis.

I found a 110 ED f/7 refractor, which had an equal quality as the Genesis. I tested them side by side. I still have it now and am very happy with it and for travel and it fits easily 'under the seat in front of you'.


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#503 Astroman007

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Posted 21 June 2020 - 08:04 AM

Quite ingenious Tim!

Seconded!



#504 Tim C

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Posted 21 June 2020 - 08:33 AM

Thanks NC Startrekker and Astroman007.  I was basically trying to copy the focus lever device TeleVue used to sell, not sure what they called it.  I'm happy with it, it's light as a feather and I put heat shrink tubing around the dowels to make it more grippy so it stays inserted into the focus knobs.

 

Tim


Edited by Tim C, 21 June 2020 - 08:35 AM.

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#505 NC Startrekker

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Posted 21 June 2020 - 10:37 AM

Thanks NC Startrekker and Astroman007.  I was basically trying to copy the focus lever device TeleVue used to sell, not sure what they called it.  I'm happy with it, it's light as a feather and I put heat shrink tubing around the dowels to make it more grippy so it stays inserted into the focus knobs.

 

Tim

waytogo.gif



#506 Spikey131

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Posted 21 June 2020 - 06:47 PM

Thanks NC Startrekker and Astroman007.  I was basically trying to copy the focus lever device TeleVue used to sell, not sure what they called it.  I'm happy with it, it's light as a feather and I put heat shrink tubing around the dowels to make it more grippy so it stays inserted into the focus knobs.

 

Tim

Tele Vue Focus Lever, FCL-0001.  You have duplicated it well, at least functionally.

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#507 Tim C

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Posted 21 June 2020 - 07:14 PM

Fancy!

 

Tele Vue Focus Lever, FCL-0001.  You have duplicated it well, at least functionally.



#508 25585

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Posted 22 June 2020 - 04:55 AM

Afternoon project... a fine focus lever for my old school TV76.  I don't really need it for regular astronomy but planning to take the scope out to Yellowstone in a couple of weeks and I think it will come in handy if I try some daytime photography through it with a DSLR.

How does more leverage give finer focus? Fine focus knobs are usually smaller than maIn focus ones.


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#509 NC Startrekker

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Posted 22 June 2020 - 07:28 AM

How does more leverage give finer focus? Fine focus knobs are usually smaller than maIn focus ones.

Tim, Starlight Instruments now makes several sizes of large diameter knobs to replace the fine focus knobs on their FeatherTouch focusers to provide finer focus. It allows finer focus because the travel arc at the outside diameter of a large knob or that swept out by the end of a lever is significantly longer than that around a small knob. So both tactile and visual you can make small adjustments out at the wider arc which then translates to significantly smaller movements along the arc the fine focuser would normally follow. Movements smaller than you would unlikely be able to make with these aids. Hope I made sense here. 


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#510 ckwastro

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Posted 22 June 2020 - 08:23 AM

I have the Feathertouch large fine-focus knob on my 12.5” Teeter, and I can tell you it is much easier to make fine adjustments with it than with the standard smaller reduction knob.

 

7F0492CC-5038-442C-9E0D-5C0306D6A10D.jpeg


Edited by ckwastro, 22 June 2020 - 08:35 AM.

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#511 caronb

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Posted 22 June 2020 - 01:46 PM

How does more leverage give finer focus? Fine focus knobs are usually smaller than maIn focus ones.

I wanted to to try something similar without making a lever so I used one of my wife's quilting clips.  It fits perfectly and works very well.  It is now part of my gear.  I've used it a couple of times and there is a small advantage to using some sort of lever.  I find that I can refocus when changing eyepieces quicker and fine focusing with this eliminates some of the shakes.

 

Focus Clip

Edited by caronb, 22 June 2020 - 01:49 PM.

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#512 Tim C

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Posted 22 June 2020 - 06:02 PM

that blue clip looks like it was made for the focus knob... perfect fit.  I do something similar for my SCT focus knob by tying a cable tie around the knob and then clipping the tag end to about one inch.  It does really well, especially since the cable tie is a bit flexible which reduces the shakes even further.

 

Tim


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#513 Echolight

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Posted 22 June 2020 - 06:22 PM

I have the Feathertouch large fine-focus knob on my 12.5” Teeter, and I can tell you it is much easier to make fine adjustments with it than with the standard smaller reduction knob.

 

attachicon.gif7F0492CC-5038-442C-9E0D-5C0306D6A10D.jpeg

That's a beauty!


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#514 ckwastro

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Posted 23 June 2020 - 10:03 AM

That's a beauty!

Thanks!



#515 laedco58

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Posted 23 June 2020 - 10:43 AM

My NP127 riding on my recently acquired from bravofoxtrot Gibraltar HD5.

CA95E78A-1ADE-4981-813B-63F7AAD15695.jpeg


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#516 areyoukiddingme

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Posted 23 June 2020 - 06:31 PM

Spent a couple hours comparing my Televue 101 with 92mm A-P Stowaway last night.

 

Targets were the double double, Jupiter and Saturn.

 

The 101 shows a tiny bit of astigmatism at the edges, but outside the last 5% of field everything was sharp.

 

The Stowaway gives a more clinical/white view of stars, but I found the color in the double double (to me cold blue and red in both pairs) was more apparent in the Televue.

 

When Jupiter finally got high enough for a decent view, I used my 3-6 Nagler zoom and found I preferred the view in the Televue. The Stowaway is very sharp and clinical, but I could see details with less effort in the Televue, and again, the colors seemed more saturated in Jupiter and Saturn.

 

The double double is a easy split in both, so I'll aim for harder targets to see if I can separate them further.

 

Nonetheless, I pushed the magnification on both (using a 1.6x Nikon barlow on the zoom), up to 326x in the Stowaway and 288x in the Televue (but tried to compare like-for-like magnifications in the side-by-side comparisons). Both ate up the higher magnifications easily, and neither showed any evidence of chromatic aberrations. 

 

Other than that, the lack of a fine focus control on the Televue was the only other standout difference.

 

My plan was to compare both, eventually sell the Televue and replace with something in the 120-130mm range. So far it's not going well!


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#517 Spikey131

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Posted 23 June 2020 - 06:45 PM

Spent a couple hours comparing my Televue 101 with 92mm A-P Stowaway last night.

 

Targets were the double double, Jupiter and Saturn.

 

The 101 shows a tiny bit of astigmatism at the edges, but outside the last 5% of field everything was sharp.

 

The Stowaway gives a more clinical/white view of stars, but I found the color in the double double (to me cold blue and red in both pairs) was more apparent in the Televue.

 

When Jupiter finally got high enough for a decent view, I used my 3-6 Nagler zoom and found I preferred the view in the Televue. The Stowaway is very sharp and clinical, but I could see details with less effort in the Televue, and again, the colors seemed more saturated in Jupiter and Saturn.

 

The double double is a easy split in both, so I'll aim for harder targets to see if I can separate them further.

 

Nonetheless, I pushed the magnification on both (using a 1.6x Nikon barlow on the zoom), up to 326x in the Stowaway and 288x in the Televue (but tried to compare like-for-like magnifications in the side-by-side comparisons). Both ate up the higher magnifications easily, and neither showed any evidence of chromatic aberrations. 

 

Other than that, the lack of a fine focus control on the Televue was the only other standout difference.

 

My plan was to compare both, eventually sell the Televue and replace with something in the 120-130mm range. So far it's not going well!

If you got the NP127 you would never miss the NP101.  I think.....


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#518 areyoukiddingme

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Posted 23 June 2020 - 07:47 PM

If you got the NP127 you would never miss the NP101.  I think.....

That's exactly the thought I have had. I like the 101 (mine is pre-NP) so much, that even though it really isn't necessary to keep above and beyond the Stowaway, I would miss it. And a 127 would complement the 92mm nicely.



#519 BravoFoxtrot

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Posted 23 June 2020 - 10:15 PM

My NP127 riding on my recently acquired from bravofoxtrot Gibraltar HD5.

attachicon.gifCA95E78A-1ADE-4981-813B-63F7AAD15695.jpeg

Absolutely stunning!  I suspect the views are even better!


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#520 ckwastro

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Posted 24 June 2020 - 08:30 AM

Spent a couple hours comparing my Televue 101 with 92mm A-P Stowaway last night.

 

Targets were the double double, Jupiter and Saturn.

 

The 101 shows a tiny bit of astigmatism at the edges, but outside the last 5% of field everything was sharp.

 

The Stowaway gives a more clinical/white view of stars, but I found the color in the double double (to me cold blue and red in both pairs) was more apparent in the Televue.

 

When Jupiter finally got high enough for a decent view, I used my 3-6 Nagler zoom and found I preferred the view in the Televue. The Stowaway is very sharp and clinical, but I could see details with less effort in the Televue, and again, the colors seemed more saturated in Jupiter and Saturn.

 

The double double is a easy split in both, so I'll aim for harder targets to see if I can separate them further.

 

Nonetheless, I pushed the magnification on both (using a 1.6x Nikon barlow on the zoom), up to 326x in the Stowaway and 288x in the Televue (but tried to compare like-for-like magnifications in the side-by-side comparisons). Both ate up the higher magnifications easily, and neither showed any evidence of chromatic aberrations. 

 

Other than that, the lack of a fine focus control on the Televue was the only other standout difference.

 

My plan was to compare both, eventually sell the Televue and replace with something in the 120-130mm range. So far it's not going well!

About 15 years ago a friend of mine and I compared my f/7 Stowaway and his NP-101 under dark skies. Targets were OCs, GCs, ENs, galaxies, and ending on Jupiter. Mechanics on both scopes are excellent so we stuck with optical comparisons.

 

In short our conclusions were that the NP-101 had a flatter field, which was to be expected with the Petzval design. Slight curvature could be seen in the Stowaway from the triplet objective, which was easily corrected with less than 1/4 turn of the fine focus. The NP went slightly deeper with the little extra aperture, and the Stowaway had slightly better contrast. Neither scope showed any hint of CA at higher mags, and Jovian details visible were the same and presented similarly. Keep in mind we spent several hours looking for these subtle differences. In short we concluded that both scopes were excellent and worthy of being lifetime instruments. 
 

I can see why you are having trouble deciding which one to keep. Honestly I think you’d be happy with either scope, and it may come down to some mechanical feature one has over the other. Optically, you can’t go wrong with either scope. Good luck! 


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#521 Astroman007

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Posted 24 June 2020 - 08:58 AM

My NP127 riding on my recently acquired from bravofoxtrot Gibraltar HD5.

attachicon.gifCA95E78A-1ADE-4981-813B-63F7AAD15695.jpeg

Envious!

 

 

Spent a couple hours comparing my Televue 101 with 92mm A-P Stowaway last night.

 

Targets were the double double, Jupiter and Saturn.

 

The 101 shows a tiny bit of astigmatism at the edges, but outside the last 5% of field everything was sharp.

 

The Stowaway gives a more clinical/white view of stars, but I found the color in the double double (to me cold blue and red in both pairs) was more apparent in the Televue.

 

When Jupiter finally got high enough for a decent view, I used my 3-6 Nagler zoom and found I preferred the view in the Televue. The Stowaway is very sharp and clinical, but I could see details with less effort in the Televue, and again, the colors seemed more saturated in Jupiter and Saturn.

 

The double double is a easy split in both, so I'll aim for harder targets to see if I can separate them further.

 

Nonetheless, I pushed the magnification on both (using a 1.6x Nikon barlow on the zoom), up to 326x in the Stowaway and 288x in the Televue (but tried to compare like-for-like magnifications in the side-by-side comparisons). Both ate up the higher magnifications easily, and neither showed any evidence of chromatic aberrations. 

 

Other than that, the lack of a fine focus control on the Televue was the only other standout difference.

 

My plan was to compare both, eventually sell the Televue and replace with something in the 120-130mm range. So far it's not going well!

My advice to you: keep both. cool.gif


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#522 Astroman007

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Posted 24 June 2020 - 08:59 AM

If you got the NP127 you would never miss the NP101.  I think.....

I'd dual mount them.



#523 Mike W

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Posted 28 June 2020 - 12:17 PM

For anyone interested I just started a new topic in "Mounts" on the new Gibraltar HD5.

Mike



#524 gnowellsct

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Posted 28 June 2020 - 04:14 PM

Aw c'mon, that's primarily a birding scope.

Smile when you say "birding scope," part-nuh!  

 

I didn't know about your Oracle.   You should mount it on top of the 102.  

 

Greg N



#525 gnowellsct

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Posted 28 June 2020 - 04:26 PM

How does more leverage give finer focus? Fine focus knobs are usually smaller than maIn focus ones.

Because people's hands are large and clumsy and inaccurate.  The clamp gives more leverage, which is not really the point.  It gives you the chance to make a small adjustment at a very wide radius which translates into a much smaller adjustment at the inside radius of the focus knob.  

 

And that is fine focus of a sort.

 

Fine focus knobs as provided by focuser OEMs are make small movements because they are geared that way.  The small knob intuitively says "I am for small movements."    

 

Fine focus knobs are usually better than using a knitting clamp, but often achieve no better at much greater cost.  Feather Touch makes wonderful focusers, I have two, but they also sell expensive adapters for SCTs which IME are pretty worthless.   It's the threading of the shaft that moves the mirror (in an SCT) that dooms it to coarseness.  It would be nice if there were a mechanical solution.  

 

In my experience fine focus doesn't really become a critical attribute till you are at 1 mm exit pupils or smaller.  My c8 really needs some kind of fine focuser because it is a good optic and can readily perform at 1mm exit pupil.  At 200x and above focusing gets to be delicate.  On the C14 you don't have those problems till you get to 356x and above, and those conditions are rare.  Plus the mirror is heavy and responds more accurately.  It's a weird mechanism, and the C14 is just a scaled up c8.

 

But I digress.  You do want fine focusers on your refractors, you can get by without them if you are innovative.  The industry has, I believe, generally moved beyond single-speed focusers in most applications.  Dual speed is just a thing that people want.

 

Greg N

 

 

 

Greg N




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