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Original Genesis

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#1 oldtimer

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Posted 11 October 2024 - 05:53 PM

Was there more than one version of what is referred to as the 'original' 100mm F5 Genesis'?  I have read here that it was a Petzval design with a F13 front acho lense  which contained no 'special' glass.  I have also read that somewhere that one of the four (front or back?) lense groups contained a fluorite element???

 

If you know for sure please let me know.

 

Gary (oldtimer)



#2 25585

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Posted 11 October 2024 - 06:40 PM

https://www.cloudyni...elevue-genesis/

 

 

https://www.cloudyni...-glass-changes/


Edited by 25585, 11 October 2024 - 06:42 PM.

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#3 MisterDan

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Posted 11 October 2024 - 07:13 PM

"Quick shot" of my own understanding:

 

The original Genesis (1988) was an f/5 Petzval refractor utilizing a "long-focus" crown/flint objective (f/10-f/11ish) and a sub-aperture reducer/flattener forward of (but near) the focuser.  The reducer/flattener utilized a Fluorite element, but that element neither improved nor degraded the inherent chromatic error of the objective.  Tele Vue did tout the f/5 Genesis as an apochromat, but I'm guessing the moniker relates to the "relative" and apparent chroma of the Genesis when compared to a native f/5 crown/flint Fraunhofer.

 

There was no other version of the f/5 Genesis.

 

The Genesis SDF succeeded the f/5 Genesis in 1993, and it was an f/5.4 Petzval whose objective incorporated an "SD" crown element.  The objective remained inherently "long," and chromatic aberration was reduced to apochromatic levels.

 

The earlier Renaissance (1984) was an f/5.5 Petzval but did not incorporate Fluorite or any other special-dispersion elements.

 

Best wishes.

Dan


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#4 TOMDEY

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Posted 11 October 2024 - 09:04 PM

I have the early version (one of the very first F/5 Genesis) and find that a green filter significantly improves the photographic resolution in white light. In the visible (eye, white light) is really a very nice scope, even at F/5. Probably explained by a combination of "regular" residual chromatic and also spherochromatism. To this day it's still one of my favorite refractors. I've got bigger and I've got better... but the TV Genesis sits on the same pedestal right next to the original original TeleVue 13mm Nagler Eyepiece!       Tom


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#5 Jon Isaacs

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Posted 12 October 2024 - 01:16 AM

I have the early version (one of the very first F/5 Genesis) and find that a green filter significantly improves the photographic resolution in white light. In the visible (eye, white light) is really a very nice scope, even at F/5. Probably explained by a combination of "regular" residual chromatic and also spherochromatism. To this day it's still one of my favorite refractors. I've got bigger and I've got better... but the TV Genesis sits on the same pedestal right next to the original original TeleVue 13mm Nagler Eyepiece!       Tom

 

A friend has owned a couple of the F/5 Genesis's. I spent some time with them. To my eye, they were not planetary/double star scopes, the chromatic aberration was quite apparent, not the crisp views of the gas planets I expect of a 4 inch apo, not comparable to the NP-101 or even an F/7 ED doublet.

 

Jon


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#6 TOMDEY

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Posted 12 October 2024 - 02:24 AM

A friend has owned a couple of the F/5 Genesis's. I spent some time with them. To my eye, they were not planetary/double star scopes, the chromatic aberration was quite apparent, not the crisp views of the gas planets I expect of a 4 inch apo, not comparable to the NP-101 or even an F/7 ED doublet.

 

Jon

That's consistent with Neil English's contention that nothing beats a (really good) slow classic doublet --- visually. I think there's some truth to that. One can argue that technically it shouldn't be true... but the eye is a peculiar sensor, with a lot of underdcorrected crhomatic aberration of its own... supposedly -2D in the deep blue! But one (at least young observers) can subconsciously rack the eye's focus and merge the colors somehow so the object appears to be sharply and correctly rendered. Problem is that's only true at 1x "naked eyes". When one looks thru a telescope... especially at high mag... the chromatic of the scope overpowers the eye's agility, in proportion to the magnification. Something like that, which seems believable. No way for me to test that theory at my age. I have no accommodation whatsoever anymore.

 

I experience chromatic in all refractors (and traditional binoculars)... even the extremely good, highly acclaimed ones. When I'm birding and looking for the colors of the feathers etc... gets a wee bit distracting/annoying.   Tom


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#7 Jon Isaacs

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Posted 12 October 2024 - 03:29 AM

That's consistent with Neil English's contention that nothing beats a (really good) slow classic doublet --- visually. I think there's some truth to that. One can argue that technically it shouldn't be true... but the eye is a peculiar sensor, with a lot of underdcorrected crhomatic aberration of its own... supposedly -2D in the deep blue! But one (at least young observers) can subconsciously rack the eye's focus and merge the colors somehow so the object appears to be sharply and correctly rendered. Problem is that's only true at 1x "naked eyes". When one looks thru a telescope... especially at high mag... the chromatic of the scope overpowers the eye's agility, in proportion to the magnification. Something like that, which seems believable. No way for me to test that theory at my age. I have no accommodation whatsoever anymore.

 

I experience chromatic in all refractors (and traditional binoculars)... even the extremely good, highly acclaimed ones. When I'm birding and looking for the colors of the feathers etc... gets a wee bit distracting/annoying.   Tom

 

The NP-101 is based on a 4 inch F/11.5 SD doublet (presumably FPL-53) with a matched ED reducer flattener. So it has that slow double but an ED doublet that provides very good color correction.

 

Have you spent much time with an NP-101? The color correction is quite excellent even out of focus. Very different than an original Genesis.

 

Jon


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#8 25585

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Posted 12 October 2024 - 05:11 AM

A friend has owned a couple of the F/5 Genesis's. I spent some time with them. To my eye, they were not planetary/double star scopes, the chromatic aberration was quite apparent, not the crisp views of the gas planets I expect of a 4 inch apo, not comparable to the NP-101 or even an F/7 ED doublet.

 

Jon

I go up to 100x with mine. For some things Baader semi-apo filters help. I have enough other refractors to use for bright objects the Genesis would show too much CA or too little detail of.


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#9 TOMDEY

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Posted 12 October 2024 - 11:19 AM

The NP-101 is based on a 4 inch F/11.5 SD doublet (presumably FPL-53) with a matched ED reducer flattener. So it has that slow double but an ED doublet that provides very good color correction.

Have you spent much time with an NP-101? The color correction is quite excellent even out of focus. Very different than an original Genesis.

Jon

I've actually avoided looking through an NP-101 for fear it would make me hate my precious old Genesis. I believe I would love the 101 and want to pick up one used. I notice they move pretty fast when one pops up here and there.    Tom


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#10 Spikey131

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Posted 12 October 2024 - 11:30 AM

Never looked through a Genesis.  But I have the NP101, and have used it to good effect at 540x on double stars.

 

It is the most color free scope I have (and I have an AP130GT).


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#11 Don W

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Posted 12 October 2024 - 02:49 PM

My first “apo” telescope was a Genesis. Loved the wide field views. Didn’t use it on the planets and I never, under any circumstances point my telescopes at the moon!

 

I still use my Genesis SDF. One of my favorite scopes.

 

SDF Small.jpg

 

Nuke the Moon.jpg

 

DonW


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#12 Jon Isaacs

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Posted 12 October 2024 - 02:49 PM

I've actually avoided looking through an NP-101 for fear it would make me hate my precious old Genesis. I believe I would love the 101 and want to pick up one used. I notice they move pretty fast when one pops up here and there.    Tom

 

:waytogo:

 

There are a lot of eyepieces I have avoided for that very same reason.

 

Jon


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#13 TOMDEY

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Posted 12 October 2024 - 03:14 PM

My first “apo” telescope was a Genesis. Loved the wide field views. Didn’t use it on the planets and I never, under any circumstances point my telescopes at the moon!

 

DonW

Yes, this is true. In actual practice I used/use my Genesis almost exclusively for low power targets like the splashy big Messiers, star fields, cruising the Milky Way, etc. But I also had good luck with it taking film images of the bigger ~Deep Sky~ targets. It was hit and miss back then and that stock focuser was terribly squirrely when trying to focus and image. I eventually replaced the focuser with a nice Feather Touch. My Genesis is pretty beat up from hard use --- but still images as good as it ever did. I also recall that it was very expensive for the time. Refractors have come way down in inflation-adjusted $$$ --- and people still complain that they're "getting ripped off". We actually got if very good now-a-days. --- except for the light pollution.   Tom


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#14 Kitfox

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Posted 12 October 2024 - 07:22 PM

My Genesis with the screw on dew shield and original style focuser knobs was handed over to me directly by Al himself in 1989. That alone makes it a keeper. And the year after I obtained it, I was in the FL keys at the spring equinox new moon for the first of its three complete Messier marathons with it. This is why you get one of these.  Wide, flat fields and low magnification sweeping. They aren’t planetary scopes, never were. There were plenty of scopes among its contemporaries that were amazing at high magnification work. But few that could do what a 4”, 500mm f.l. scope could do. The fact that the Genesis sold well is probably the only reason Al Nagler is still making scopes and not just eyepieces. 


Edited by Kitfox, 12 October 2024 - 08:57 PM.

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#15 Jon Isaacs

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Posted 13 October 2024 - 08:48 AM

My Genesis with the screw on dew shield and original style focuser knobs was handed over to me directly by Al himself in 1989. That alone makes it a keeper. And the year after I obtained it, I was in the FL keys at the spring equinox new moon for the first of its three complete Messier marathons with it. This is why you get one of these.  Wide, flat fields and low magnification sweeping. They aren’t planetary scopes, never were. There were plenty of scopes among its contemporaries that were amazing at high magnification work. But few that could do what a 4”, 500mm f.l. scope could do. The fact that the Genesis sold well is probably the only reason Al Nagler is still making scopes and not just eyepieces. 

 

Old-timer was asking about the optical prescription of the original Genesis. While the original Genesis was not a planetary/double star scope, later versions of the 4 inch TeleVue Petzvals became better and better so that they are both low power wide field scopes and excellent planetary-double star scopes as well.

 

In today's market, your 100% right. Buy an F/5 Genesis if your looking for a 4 inch that excels at the low power wide field views.

 

Jon


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#16 Reptilicus

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Posted 13 October 2024 - 10:30 PM

I purchased my Genesis f/5 new back in April of 1988. It isn’t perfect and could care less. 36 years old and still versatile and awesome…

 

Many memorable observations behind this little gem. Some that float to the top; 4 planetary transits- 2 Venusian/2 Mercurial and the flares produced by NOAA AR10486 (Halloween Solar storm of 2003) before the great sunspot made its visual appearance (in white light) around the southeastern limb…to name a few.

 

Bill

 

 

 

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#17 25585

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Posted 14 October 2024 - 07:47 AM

That is like mine, chrome drawtube and knobs, black dewshield. waytogo.gif


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#18 azure1961p

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Posted 14 October 2024 - 09:11 AM

Old-timer was asking about the optical prescription of the original Genesis. While the original Genesis was not a planetary/double star scope, later versions of the 4 inch TeleVue Petzvals became better and better so that they are both low power wide field scopes and excellent planetary-double star scopes as well.

 

In today's market, your 100% right. Buy an F/5 Genesis if your looking for a 4 inch that excels at the low power wide field views.

 

Jon

So apertures aside, the Ranger with all it's CA for me actually had terrific high-power views, albeit, with some fringe.   Saturn was always tack sharp (130x) seeing obliging.  You mean the OG (,,original Genesis) was really optimized as a Milkyway sweeper?

 

All these years I thought it did it all. Never looked through that particular TV.

 

Pete



#19 25585

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Posted 14 October 2024 - 04:06 PM

Mine is fine to 100x, with a 5mm eyepiece. Way better than fast non-ED achros from China. 


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#20 JeremySh

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Posted 15 October 2024 - 10:07 AM

That is like mine, chrome drawtube and knobs, black dewshield. waytogo.gif

Do you have the H-alpha paraphernalia as well, Richard?



#21 25585

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Posted 15 October 2024 - 04:42 PM

Do you have the H-alpha paraphernalia as well, Richard?

No, I am only a night sky observer.


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#22 betacygni

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Posted 16 October 2024 - 01:32 AM

No, I am only a night sky observer.

Really need to fix that, you’re missing out on the best star!
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#23 25585

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Posted 16 October 2024 - 06:28 AM

Really need to fix that, you’re missing out on the best star!

Maybe a Quark one day. Solar prominences interest me more than spots.


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#24 Rick-T137

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Posted 16 October 2024 - 07:27 AM

Maybe a Quark one day. Solar prominences interest me more than spots.

There is so much more to see on the Sun than just "spots" using a white light filter (such as the umbra and penumbra of the spots themselves, pores, faculae, granules, limb darkening, watching the surface evolve over days or even hours, etc). Even in my 102mm achromat the view is breathtaking!


Edited by Rick-T137, 16 October 2024 - 09:06 AM.

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#25 bbyrd

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Posted 16 October 2024 - 08:18 AM

A long time ago I owned a  Genesis, serial #1001. Low power showed better with this refractor. I eventually passed it on to a Astromart member on the west coast. They showed it to Al Nagler and Al confirmed the scope was probably the first one released to the public but prototypes were also made.


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