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Quality of optics in the early, first-generation Tele Vue f/5 Genesis.

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#26 aztrodog

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Posted 15 May 2020 - 05:20 PM

I'm glad the Internet did not exist back in the day, otherwise I would have read in some "forum" my Genesis was an achromat and that I was using it on the wrong objects. Some of you just crack me up smile.gif

 

Let's get something clear, the ---- original ---- f/5 Genesis is NOT an achromat. I've owned plenty of 4" achromats of various focal lengths over my 30+ years in astronomy. Instruments ranging from recent vintage "Made in China" Meade/Celestron branded to a Lundin crafted 1914 Alvan Clark with plenty of Made in Japan Unitrons and Vixens in between. The tiny amount of color in the Genesis (mainly outside and inside of focus) is not even remotely close to I see in any 4"  f/15  achromat....let me say that again...not even remotely close.  

 

Let's also get something else clear, the -----original----- f/5 Genesis CAN be a great instrument to view our solar system neighbors . Only reason why I say it can is because of apparent sample to sample variation as some owners have posted. My particular scope soaks up magnification without loss of contrast / definition. I regularly use a 5X Powermate and 7mm Pentax and 10mm Ethos for planetary/Moon and double star viewing. Just like with above mentioned achromats I have also had the privilege to own several 4" APOs, from the legendary AP Traveler to the also superb Vixen flourites. I eventually sold all of my 4" refractors, except for THE ---original----- f/5 Genesis. It can do it all, terrestrial viewing, high power planetary and awesome get lost in space wide field views. 

 

So Martin, I certainly hope you land a good one. Either way, please be sure to check back in and let us know what your initial impressions. 

 

Angel


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#27 jimandlaura26

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Posted 15 May 2020 - 06:13 PM

For such minor color issues as some have reported, what would be a recommendable "minus violet" (?) filter to clean that up if I choose to? Or would an MV filter be advisory at all?

I recommend a Baader Semi-APO filter as well as a Moon and Sky Glow filter (see Alpine Astro for details). These Neodymium based filters are high quality - can leave them installed in front of diagonal and do not excessive dim or shift color. The latter filter is great for reducing lunar and man-made light pollution. I keep one installed on my diagonal all the time on both my apos.


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#28 Astroman007

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Posted 16 May 2020 - 10:07 AM

I'm glad the Internet did not exist back in the day, otherwise I would have read in some "forum" my Genesis was an achromat and that I was using it on the wrong objects. Some of you just crack me up smile.gif

 

Let's get something clear, the ---- original ---- f/5 Genesis is NOT an achromat. I've owned plenty of 4" achromats of various focal lengths over my 30+ years in astronomy. Instruments ranging from recent vintage "Made in China" Meade/Celestron branded to a Lundin crafted 1914 Alvan Clark with plenty of Made in Japan Unitrons and Vixens in between. The tiny amount of color in the Genesis (mainly outside and inside of focus) is not even remotely close to I see in any 4"  f/15  achromat....let me say that again...not even remotely close.  

 

Let's also get something else clear, the -----original----- f/5 Genesis CAN be a great instrument to view our solar system neighbors . Only reason why I say it can is because of apparent sample to sample variation as some owners have posted. My particular scope soaks up magnification without loss of contrast / definition. I regularly use a 5X Powermate and 7mm Pentax and 10mm Ethos for planetary/Moon and double star viewing. Just like with above mentioned achromats I have also had the privilege to own several 4" APOs, from the legendary AP Traveler to the also superb Vixen flourites. I eventually sold all of my 4" refractors, except for THE ---original----- f/5 Genesis. It can do it all, terrestrial viewing, high power planetary and awesome get lost in space wide field views. 

 

So Martin, I certainly hope you land a good one. Either way, please be sure to check back in and let us know what your initial impressions. 

 

Angel

Thank you. All of you. The "achromat" part that some of you have been complaining about I got from the scopeviews.co.uk review. Perhaps not entirely true, but I do have a policy of instilling very low expectations in myself for whatever gear is coming my way. Then I am rarely disappointed, and often thrilled for years on end (as with my TV-85, or R7 Black Beauty).

Nevertheless, the efforts of many of the posters in my thread to clear up some misunderstandings I had is much appreciated. I will certainly report back here after enjoying the scope for a night or few. It is not expected to arrive until the 29th of this month, maybe later (or sooner).

I certainly do not mind "retro" views of the solar system, and I do understand that by and large any scope can be used to view anything; some are just better at certain things than others.



#29 Astroman007

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Posted 16 May 2020 - 10:18 AM

And speaking of "a good one," does it look like I have a good one?

 

msg-3857-0-08503600-1589499941.jpeg

 

(Seller's photo, taken just prior to packing).


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#30 Don W

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Posted 16 May 2020 - 10:53 AM

It's pretty hard to tell from a picture. I'd say it looks good on that side. Can't tell if it has any glass in it. Were you expecting more?


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#31 Cotts

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Posted 16 May 2020 - 10:54 AM

I'm glad the Internet did not exist back in the day, otherwise I would have read in some "forum" my Genesis was an achromat and that I was using it on the wrong objects. Some of you just crack me up smile.gif

 

Let's get something clear, the ---- original ---- f/5 Genesis is NOT an achromat. I've owned plenty of 4" achromats of various focal lengths over my 30+ years in astronomy. Instruments ranging from recent vintage "Made in China" Meade/Celestron branded to a Lundin crafted 1914 Alvan Clark with plenty of Made in Japan Unitrons and Vixens in between. The tiny amount of color in the Genesis (mainly outside and inside of focus) is not even remotely close to I see in any 4"  f/15  achromat....let me say that again...not even remotely close.  

 

Let's also get something else clear, the -----original----- f/5 Genesis CAN be a great instrument to view our solar system neighbors . Only reason why I say it can is because of apparent sample to sample variation as some owners have posted. My particular scope soaks up magnification without loss of contrast / definition. I regularly use a 5X Powermate and 7mm Pentax and 10mm Ethos for planetary/Moon and double star viewing. Just like with above mentioned achromats I have also had the privilege to own several 4" APOs, from the legendary AP Traveler to the also superb Vixen flourites. I eventually sold all of my 4" refractors, except for THE ---original----- f/5 Genesis. It can do it all, terrestrial viewing, high power planetary and awesome get lost in space wide field views. 

 

So Martin, I certainly hope you land a good one. Either way, please be sure to check back in and let us know what your initial impressions. 

 

Angel

A tale of three 'Original" Tele Vue Genesis 4-inch, f/5 fluorite scopes. Each just like the one in Martin's pic with the gravy-coloured case.... 

 

1.  My friend bought one in about 1990.  The high power views of Jupiter and Saturn were outstanding!  Full of detail, contrasty.... I don't recall any intrusive false colour...  Wide-field viewing, superb.  Double stars, excellent.  Astrophotography, fabulous (with film, of course....) He still has it and swears by it!  So do I! Superb 4-inch scope.

 

so I bought one.  Identical model.

 

2.  My scope was all of the above except for the planetary viewing.  Mine was noticeably 'softer' than his.  Very noticeably.  Just couldn't seem to find good focus.  Less detail, less contrast...Side by side with the same eyepiece, same cool-down etc. mine was decidedly inferior.  Still was great on all the other stuff and I never was, primarily, a planetary viewer anyway.....  I kept the scope for about 5 years.....photography was its only use...

 

3.  Fast forward to the late 2000's.  I sold a G11 mount to a fellow that i knew from S. Ontario as well as us both being regulars at the Okie Tex Star Party.  He, too had purchased one of these same Genesis scopes and wanted to use it for photography with his new mount.   We corresponded regularly after the sale of the G11 because he just wasn't getting round stars in his images.  They were always oval.....He tore apart the mount.  He bought the newer, high precision worm gear.  He fretted over balance and the type of grease and I don't know what else. Oval. Stars. 

 

One night at OkieTex when it dawned on me that i might have to buy the mount back if it wasn't working, I popped by his site and there he was, fussing over the G11 with the Genesis sitting on top.  I suggested that he relax for an evening and we would try to split some binaries just for a change.  So, at 200x +/- on the very first star I looked and.......the diffraction pattern was oval!  Rotate the scope and the oval rotated.  The Genesis was astigmatic!!  Nothing wrong with the mount!  (Good news is that Uncle Al took the scope in and fixed it free of charge.....)  

 

So.  3 of these scopes and two had 'issues'.  

 

And a life lesson for some of you high-end refractor imager-only types who don't even have eyepieces (my friend in #3 didn't). You may be missing some useful information...

 

Dave 

 

p.s. Martin, I like that rug.  It really ties the room together....


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#32 bobhen

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Posted 16 May 2020 - 11:13 AM

These are Petzval refactors and are more susceptible to being bumped out of collimation. Even slight (hardly detectable) miss collimation "might" account for some of the disparity between observers when these scopes are used at higher powers.

 

Many years ago I took mine on a plane and checked it through. When I got home, it was slightly out of alignment.

 

I can’t imagine TV (which tests all of their refractors) allowing such a wide range of optical quality into the market with these scopes. I’m sure TV held the manufacture to a minimum spec on optical quality. But that was some time ago. 

 

Bob


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#33 stevew

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Posted 16 May 2020 - 01:14 PM

For such minor color issues as some have reported, what would be a recommendable "minus violet" (?) filter to clean that up if I choose to? Or would an MV filter be advisory at all?

Personally I'd rather put up with a small amount of C/A rather than viewing a yellow planet.

My advice would be to try it on the planets before purchasing a filter. Your scope may surprise you.


Edited by stevew, 16 May 2020 - 07:38 PM.

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#34 Bonco2

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Posted 16 May 2020 - 04:03 PM

Never saw a need for a correcting filter on my Genesis. Sure like an OXY 3 tho.
Bill

#35 213Cobra

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Posted 16 May 2020 - 04:51 PM

I'm glad the Internet did not exist back in the day, otherwise I would have read in some "forum" my Genesis was an achromat and that I was using it on the wrong objects. Some of you just crack me up smile.gif....

 

Angel

Oh.....it wasn't so different. We had the Astro forum on CompuServe, and a few astronomy newsgroups for that.

 

A friend I regularly observed with bought a Genesis in 1988 when the model first shipped, so I got recurrent experience with it for about a year until I moved across the continent to Los Angeles. It would have been easier to use at high power had we had the greater eye-relief, short FL eyepieces we have available today. But with a Dakin 2.4X + 4.8mm Nagler, that Genesis cast sharp, high-contrast 250X views on our retinas that were remarkable for the optics of the time, and tenable -- if nevertheless bettered -- today. And he didn't take any precautions physically. The Genesis traveled in its case but got tossed into a van, bouncing the logging roads to get to dark sites in Maine and New Hampshire. It never showed an oval star nor any other signs of optical misalignment.

 

Even then there were doomsayers in the pre-web fora warning buyers off Petzval / quad refractors. Can miscollimation happen? Yes. But it's only slightly above academic risk compared to other refractors, for most users of telescopes in this league. Else, how in the world do Tele-Vue, Takahashi, TS and Chinese OEMs sell all those quads? Flat field quads have great advantages visually. Unstable collimation risk is scant and no reason to steer clear.

 

Phil


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#36 saemark30

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Posted 17 May 2020 - 02:56 PM

What is the size of the fluorite element and how far down is it from the front 4" F/12 doublet?

There was an Astronomy article comparing the Televue Genesis, Celestron 4" F/9 Fluorite and Brandon 94mm F/7 models if I remember correctly.



#37 Phillip Creed

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Posted 17 May 2020 - 03:00 PM

I think the best minus violet filter for use with an f/5.0 Genesis is the Lumicon. It's not as aggressive in reducing violet vs, say, a Baader Fringe Killer. But in this case, less aggressive violet reduction = less color shift/yellowing of the image.

Clear Skies,
Phil
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#38 Bill Jensen

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Posted 19 May 2020 - 06:30 PM

And speaking of "a good one," does it look like I have a good one?

 

Astroman007, hopefully you will get it soon and give us your first light for you report. The cosmetic condition looked great in that picture. 

 

It has been a long time since I owned the original f/5 Genesis, and wish that I had never sold it. The optics were fine for me, and I was not concerned about some small amount of color. I have an Oracle3, but still would add back the Genesis (original or sdf) to the family. 


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#39 t.r.

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Posted 19 May 2020 - 07:12 PM

I sold mine too chasing the brass ring...wish I still had mine as well for sentiment.
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#40 bobhen

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Posted 20 May 2020 - 07:21 AM

I sold mine too chasing the brass ring...wish I still had mine as well for sentiment.

Now that I do most of my deep sky observing with an image intensifier, and with the Genesis working at F-5, I often think that it would have been nice if I had held on to mine as well.

 

At the low powers used, my much less expensive 102 mm F-5 achromat does really well with the intensifier. Of course, it cannot compete with a Genesis on the moon and planets.

 

Bob



#41 Astroman007

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Posted 20 May 2020 - 11:53 AM

Astroman007, hopefully you will get it soon and give us your first light for you report. The cosmetic condition looked great in that picture. 

 

It has been a long time since I owned the original f/5 Genesis, and wish that I had never sold it. The optics were fine for me, and I was not concerned about some small amount of color. I have an Oracle3, but still would add back the Genesis (original or sdf) to the family. 

Oh, I will!

 

As of yesterday the package was at the border.


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