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TV 101 F 5.4 Genesis SDF Florite.

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#1 dscarpa

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Posted 18 April 2019 - 09:47 AM

 Sounds good! Is it?  It's a 4 element. David 


Edited by dscarpa, 18 April 2019 - 09:49 AM.


#2 Muffin Research

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Posted 18 April 2019 - 10:32 AM

It's a classic, Build like a tank, very nice widefield views to be had and even fun planetary excursions up to 180x beyond that it gets a bit wishy-washy I feel. you also need very short focal ep's for that or something barlow.



#3 Tyson M

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Posted 18 April 2019 - 10:43 AM

I'd buy this scope for the wide FOV's with the occasional lunar /planetary in mind. Looks like a great package. 


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#4 terraclarke

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Posted 18 April 2019 - 10:45 AM

I like mine! My shortest ep is a Vixen (Japan) 2.5mm LV. It works well and puts the magnification at ~220X.
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#5 Jon Isaacs

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Posted 18 April 2019 - 10:56 AM

Dave:

 

I believe the fluorite element is not in the objective but rather in the rear section that functions as a focal reducer,  field flattener.  Things are not as rosy as it would seem. 

 

Company 7 has page on the NP-101 along with the history of the TeleVue Petzvals. 

 

http://www.company7....es/tvnp101.html

 

"The TeleVue "NP101" telescopes introduced in August 2001 are the first large TeleVue Apochromatic refractors which Company Seven found to be truly competitive if not superior in optical and mechanical performance to the best 4 inch aperture Apos ever made. These provide false color-free, sharp, clear and high contrast images. The TeleVue NP101 series also remain the worlds fastest, mechanically compact, flat field apochromatic 4 inch telescopes."

 

In my view,  the NP-101 is very good at high magnifications, best of the 4 inch TeleVues. But what sets it and the other TeleVue Modified Petzvals apart from other of visual 4inch scopes they offer a very wide,  very flat field of view.  These are scopes suited for observers who spend a lot of time under dark skies. 

 

If I were only viewing from my San Diego backyard, I would choose something different. 

 

 

Jon



#6 Phillip Creed

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Posted 18 April 2019 - 10:57 AM

If you don't mind a little blue bloat and a somewhat small fully-illumated field, you can also do imaging with it.  No field flatteners required, either.

I've used one up to around 200X on planets and it was quite sharp.  No visible CA.  Slight purple around Vega once you're past 150X, but that's about it visually.

 

It's one scope I had that I wish I didn't sell.

Clear Skies,

Phil


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#7 Muffin Research

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Posted 18 April 2019 - 11:16 AM

I like mine! My shortest ep is a Vixen (Japan) 2.5mm LV. It works well and puts the magnification at ~220X.

ah and others report fine behaviour at 200x as well then it must be my eyes :) I think they don't do well at 0,5mm exit pupil and lower 

For me 180x seemed the sweet pot on the high magnification side with the genesis.

But that thing really shines with a low powered Nagler or Panoptic.

with a nice alt-az mount a good chair perfect for a night out under an open sky.



#8 MCinAZ

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Posted 18 April 2019 - 11:54 AM

  I bought one of these four years ago as a step up from a Synta 80 ED doublet. It's a nice little telescope. The only aspect I found less than ideal was the single screw to secure an eyepiece. It was difficult to prevent a 2" diagonal or camera from rocking about the pivot point. I fabricated a replacement eyepiece receiver a couple of months ago to address that issue. The focuser, while single speed, operates smoothly and doesn't exhibit any appreciable backlash, though I do see a little bit of image shift when changing directions.

 

  Image quality is very good across the field and as others have noted, you will probably see a faint violet glow only when viewing the brightest stars. I don't do a lot of high magnification viewing with this telescope, but on occasion I've observed with a 4.8 mm Nagler and the images it produces are quite satisfactory. It's been a great telescope for public astronomy events, and I will sometimes mount it side-by-side with a 135 mm Maksutov to provide both wide field and higher magnification views of the same object.

 

  Collimation is set at the factory and if the telescope hasn't been mishandled should be good indefinitely. There are threads in this forum devoted to adjustment of this parameter, as it is a non-trivial exercise. If you're considering the purchase of one of these telescopes, it would be best to determine if there are any collimation issues, and if so, this is something you want to undertake on your own. Last I heard, you could still send the OTA to Tele Vue for servicing. That would probably be my choice should something happen to my telescope, but it's not an inexpensive option.



#9 dscarpa

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Posted 18 April 2019 - 12:11 PM

 I thought my cousin would go for it because it's a complete setup. Just talked after he read your responses and he wants something that would do high magnification   better.   Because of the fluorite thoght it was better CA wise.  Thanks!  David


Edited by dscarpa, 18 April 2019 - 12:15 PM.


#10 25585

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Posted 18 April 2019 - 12:52 PM

Looking for a brass one!


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#11 Mike W

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Posted 18 April 2019 - 12:57 PM

ah and others report fine behaviour at 200x as well then it must be my eyes smile.gif I think they don't do well at 0,5mm exit pupil and lower 

For me 180x seemed the sweet pot on the high magnification side with the genesis.

But that thing really shines with a low powered Nagler or Panoptic.

with a nice alt-az mount a good chair perfect for a night out under an open sky.

Genesis or Genesis SDF? Two different scopes! The SDF has special dispersion glass in the obj. and fluorite in the petzval elements, f5.4 v/s f/5 for plain Genesis.


Edited by Mike W, 18 April 2019 - 01:29 PM.

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#12 KerryR

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Posted 18 April 2019 - 01:13 PM

I so, so, so, so, miss mine after selling it years ago, and it wasn't even the SDF version...


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#13 Jon Isaacs

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Posted 18 April 2019 - 01:51 PM

Looking for a brass one!

 

Brass adds weight..Some might like the look but I think lighter is better in the field.

 

Jon


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#14 KerryR

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Posted 18 April 2019 - 02:07 PM

Brass adds weight..Some might like the look but I think lighter is better in the field.

 

Jon

This is probably worth noting, especially considering the Genesis is a pretty heavy scope for it's size in the first place...



#15 terraclarke

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Posted 18 April 2019 - 02:16 PM

I don't think it's a coincidence that many Genesis owners have 2.5 mm Lanthanums in their eyepiece cases. Apparently, all this glass doesn't bother the Genesis. With the new 5X barlow, and a Nagler Type II in place, you'd have 4+4+8=16 elements in the optical path. Owners tell me there's no breakdown in image quality. The Genesis held its own against the AP and the Tak.”- Ed Ting (Comparative review of TV Genesis SDF, Takahashi FS102, and Asto Physics Traveler.)

 

 

http://scopereviews.com/page1c.html#6


Edited by terraclarke, 18 April 2019 - 02:16 PM.

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#16 25585

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Posted 18 April 2019 - 03:52 PM

I don't think it's a coincidence that many Genesis owners have 2.5 mm Lanthanums in their eyepiece cases. Apparently, all this glass doesn't bother the Genesis. With the new 5X barlow, and a Nagler Type II in place, you'd have 4+4+8=16 elements in the optical path. Owners tell me there's no breakdown in image quality. The Genesis held its own against the AP and the Tak.”- Ed Ting (Comparative review of TV Genesis SDF, Takahashi FS102, and Asto Physics Traveler.)

 

 

http://scopereviews.com/page1c.html#6

5mm gets me 100x which is enough in my original F5 500mm. 50-75× is its best range. A pair of Genesis would make a great bino scope.



#17 MCinAZ

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Posted 18 April 2019 - 04:02 PM

 I thought my cousin would go for it because it's a complete setup. Just talked after he read your responses and he wants something that would do high magnification   better.   Because of the fluorite thoght it was better CA wise.

"CA wise", I think the Genesis-sdf if quite good. But, in the end, it's a 100 mm aperture telescope so there's a limit to its performance as a high magnification telescope. If high magnification views are a priority, an SCT may be a better choice. It shouldn't be too difficult to find a good C9 1/4 OTA for less than the going price of an -sdf. As an added bonus, you would gain more than a full magnitude in aperture.



#18 Don W

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Posted 18 April 2019 - 04:05 PM

Not interested in selling mine any time soon. Great low to medium power views. Does ok at higher powers too. It's also a very good imaging scope.


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#19 junomike

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Posted 18 April 2019 - 04:45 PM

If you don't mind a little blue bloat and a somewhat small fully-illumated field, you can also do imaging with it.  No field flatteners required, either.

I've used one up to around 200X on planets and it was quite sharp.  No visible CA.  Slight purple around Vega once you're past 150X, but that's about it visually.

 

It's one scope I had that I wish I didn't sell.

Clear Skies,

Phil

I'm surprised by this as It's more of what I'd expect from the Non-SDF Genesis.



#20 dag55

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Posted 18 April 2019 - 04:58 PM

 Sounds good! Is it?  It's a 4 element. David 

I had one and wished I had never sold it. It would with very good seeing do 240x and be very sharp, try yours on a good night with a good diagonal and steady mount you might be surprised.

Dane



#21 Mike W

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Posted 18 April 2019 - 09:25 PM

This scope is a keeper! (TV102)

 

 

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#22 Muffin Research

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Posted 18 April 2019 - 11:48 PM

Genesis or Genesis SDF? Two different scopes! The SDF has special dispersion glass in the obj. and fluorite in the petzval elements, f5.4 v/s f/5 for plain Genesis.

Okay now that you mention it.. it might have been the regular genesis, all I remember is built like tank, amazing wide field views and fun magnified views up to 180x.



#23 KerryR

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Posted 19 April 2019 - 08:27 AM

Several years ago, I had the chance to side-by-side a Genesis (mine, the one I miss dearly), and a Genesis SDF. Under reasonably dark skies, I compared wide-field, double stars, and Jupiter, using TV Pans and Nags. If there was a difference, it was subtle enough (visual only) that I did not come away from the comparison with any telescope envy.

One thing: These scopes are very sensitive to collimation, and some, like mine, didn't hold collimation very well, 'til TV added some shims to the front cell for me. They're not tough to collimate, but it requires making a tool to do so. I suspect collimation might be at the root of many under-performing Geneses-- the high power performance after accurate collimation was night and day. Fine focus ability is also a significant aid at high power-- I put a Starlight Pinion retrofit on mine to that end.


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#24 Mike W

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Posted 19 April 2019 - 08:47 AM

Several years ago, I had the chance to side-by-side a Genesis (mine, the one I miss dearly), and a Genesis SDF. Under reasonably dark skies, I compared wide-field, double stars, and Jupiter, using TV Pans and Nags. If there was a difference, it was subtle enough (visual only) that I did not come away from the comparison with any telescope envy.

One thing: These scopes are very sensitive to collimation, and some, like mine, didn't hold collimation very well, 'til TV added some shims to the front cell for me. They're not tough to collimate, but it requires making a tool to do so. I suspect collimation might be at the root of many under-performing Geneses-- the high power performance after accurate collimation was night and day. Fine focus ability is also a significant aid at high power-- I put a Starlight Pinion retrofit on mine to that end.

The plain Genesis has much more CA on bright objects than the SDF, especially at high power. That's why above poster states best up to 180X and Terra uses her SDF up to 220X (2.5mm). I have owned both and the SDF was a much better scope.


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#25 Phillip Creed

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Posted 19 April 2019 - 10:55 AM

I'm surprised by this as It's more of what I'd expect from the Non-SDF Genesis.

The non-SDF Genesis has about the same CA as a 4" f/12 achromat.  It's good enough for visual work on planets, but you'll notice a bit of a color around bright stars and planets above 80X or so.

The SDF is substantially better, eliminating at least 70% or so of the color from the non-SDF.  Not perfect, but good enough to earn the title of a "visual apo".

Clear Skies,

Phil


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