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TeleVue NP101 vs Genesis SDF

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#1 chuckscap

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Posted 07 February 2020 - 09:52 PM

How much better is the NP101 for imaging and visual?   I'm going to buy used, there are a lot more Genesis SDFs for sale and typically half the price.

 

Thanks!

 

Chuck



#2 Spikey131

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Posted 07 February 2020 - 10:48 PM

This is from the Company 7 Website:

 

"For 1993 TeleVue offered an improved version of the "Renaissance" and "Genesis" optical design, these were identified with the suffix "SDF". The most obvious improvement was the color correction accomplished by a change of the type of glass employed in the front doublet lens. The effective focal length of the SDF is 540mm at f5.4, an increase over the older design. By this time the Genesis SDF fittings were anodized black, with both SDF telescopes including a captive retracting lens shade/dew cap. This would evolve in 1998 into the current TeleVue "101" telescope; incorporating one of the best 4 inch SD objective optics in the world - remaining the worlds fastest, flat field apochromatic 4 inch telescope - and the "Renaissance" the most beatiful."

 

http://www.company7....evue/telal.html

 

So the Genesis "SDF" was an improvement over the Genesis, and the Tele Vue 101 an improvement over this.  The focal length an f/ratio have been the unchanged from the SDF to the NP101.  It sounds like the optics were improved going from SDF to the TV101, and the mechanics were improved going to the NP101. How much better the optics are I cannot say.


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#3 Phillip Creed

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Posted 07 February 2020 - 11:40 PM

The SDF, to my eyes, had a small amount of chromatic aberration after hitting about 150x on stars like Vega. It is very well controlled and visually, the SDF iteration of The Genesis Device is the better purchase given used prices. You're gaining very little visually in going from the SDF to the NP-101, but paying double the price on the used markets.

The NP-101 is, well, utterly flawless. I could see zero false color. Dead solid perfect.

The question in my mind is where the TV-101 stacks up. This was the iteration after the SDF but before the NP-101.

Clear Skies,
Phil
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#4 SteveG

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Posted 07 February 2020 - 11:47 PM

Genesis

SDF

TV101

NP101

 

Is the order. I would love to own even the SDF, and will probably get one once I move to a warmer climate.


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#5 chuckscap

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Posted 08 February 2020 - 08:22 AM

Thanks all.



#6 Jon Isaacs

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Posted 08 February 2020 - 11:56 AM

I think if you want to astro-photography, you want the NP-101 and preferably the IS version if you are going to use a full size DSLR.  

 

The optics were changed going from the TV-101 to the NP-101, the scope is shorter, the objective and rear elements are designed as a group, it's not just an objective in the front with a flattener-reducer in the rear, the front elements cannot be used alone.

 

Jon


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#7 areyoukiddingme

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Posted 08 February 2020 - 12:11 PM

I have the 101, which for visual shows no color on any object at any magnification. I think there are some who have compared with the NP visually, and say it's 99% of an NP.

 

But for A-P, I'd agree that the NP is likely the best bet.


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#8 Phillip Creed

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Posted 08 February 2020 - 12:47 PM

I think if you want to astro-photography, you want the NP-101 and preferably the IS version if you are going to use a full size DSLR.

The optics were changed going from the TV-101 to the NP-101, the scope is shorter, the objective and rear elements are designed as a group, it's not just an objective in the front with a flattener-reducer in the rear, the front elements cannot be used alone.

Jon

The NP101 is the obvious choice if you have a full frame camera. But for crop sensor sizes, would the TV101 have the necessary amount of color correction?

The SDF had a tiny bit of color error at high powers visually. In images, it shows up as a bit of "blue bloat" on bright stars. But it's certainly good enough for casual imaging or learning the ropes of astrophotography.

My question about the TV101 is if the color correction is superior to the SDF.

The NP101 is the sure thing, I know that.

 

Crazy question, perhaps, but has anyone done a direct side-by-side comparison between a TV101 and an SDF?

Clear Skies,
Phil



#9 areyoukiddingme

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Posted 08 February 2020 - 01:24 PM

https://www.cloudyni...-apo-refractor/



#10 25585

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Posted 08 February 2020 - 02:33 PM

A pre-owned Takahashi FSQ 106 is worthy of consideration.



#11 stevew

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Posted 08 February 2020 - 02:59 PM

Genesis

SDF

TV101

NP101

 

Is the order. I would love to own even the SDF, and will probably get one once I move to a warmer climate.

I believe the biggest changes where from the original Genesis to the SDF, and then from the TV101 to the NP101.

I used to own a wonderful SDF. It was my first Apochromat and it really changed things for me. The scope would go from 16X with a beautiful flat field to over 200X without flinching.

Attached Thumbnails

  • post-15477-0-98602200-1417302459.jpg

Edited by stevew, 08 February 2020 - 06:15 PM.

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#12 Spikey131

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Posted 08 February 2020 - 05:26 PM

A pre-owned Takahashi FSQ 106 is worthy of consideration.

If one could find one even close to the price of a pre-owned SDF or TV101......


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#13 Tyson M

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Posted 08 February 2020 - 05:27 PM

I had no idea the TV101 was an improvement on the SDF.  Interesting!



#14 alnitak22

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Posted 08 February 2020 - 07:57 PM

A pre-owned Takahashi FSQ 106 is worthy of consideration.

Do you see that scope anywhere in the OP?


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#15 Jon Isaacs

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Posted 09 February 2020 - 09:30 AM

My suggestion:

 

Call TeleVue and ask them. They'll tell you.

 

Clive Crewey tells his story of calling Televue when he was just starting out, getting Al on the line. He asked about the TV-85. Al told him that for anything that fit in the field of view, a decent 6 inch Dob would be better. Clive bought the Dob and later the TV-85.

 

Jon


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#16 m9x18

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Posted 09 February 2020 - 11:01 AM

My suggestion:

 

Call TeleVue and ask them. They'll tell you.

 

Clive Crewey tells his story of calling Televue when he was just starting out, getting Al on the line. He asked about the TV-85. Al told him that for anything that fit in the field of view, a decent 6 inch Dob would be better. Clive bought the Dob and later the TV-85.

 

Jon

Yes, and to piggyback on to Jon's post, once you  find out from TeleVue what the differences are, please post back and tell us what they said.


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#17 25585

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Posted 09 February 2020 - 01:43 PM

From the Company 7 pages 

"For 1993 TeleVue offered an improved version of the "Renaissance" and "Genesis" optical design, these were identified with the suffix "SDF". The most obvious improvement was the color correction accomplished by a change of the type of glass employed in the front doublet lens."

 

 http://www.company7....opes/tv101.html

http://www.company7....np101_2001.html



#18 25585

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Posted 09 February 2020 - 01:46 PM

I am looking for a brass tubed TV Renaissance, 85 or Ranger. They are rare.  


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#19 Doug Culbertson

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Posted 09 February 2020 - 01:53 PM

I am looking for a brass tubed TV Renaissance, 85 or Ranger. They are rare.  

https://astromart.co...-reduced-463536

 

She usually marks her ads as sold if they sell. 


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#20 25585

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Posted 09 February 2020 - 03:29 PM

Do you see that scope anywhere in the OP?

Always good to know of alternatives :)



#21 alnitak22

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Posted 09 February 2020 - 03:42 PM

Always good to know of alternatives smile.gif

Always bad to hijack a thread. If everyone chimed in with alternatives, well....if I have to explain it.....Anyway...he didn’t ASK for alternatives. He listed two scopes and wanted to know about experiences with those two. Period. 


Edited by alnitak22, 09 February 2020 - 03:43 PM.

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#22 25585

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Posted 09 February 2020 - 04:16 PM

Always bad to hijack a thread. If everyone chimed in with alternatives, well....if I have to explain it.....Anyway...he didn’t ASK for alternatives. He listed two scopes and wanted to know about experiences with those two. Period. 

Sorry to the OP if that was how it appeared. FSQs are quadruplets & astrographs, so it was a FYI post only.

 

I own a Genesis, & would only ever retire it if I got a SDF or either 101.hd

 

My wish for a brass one is to have a neat engraving on the tube for a special reason.



#23 Uwe Pilz

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Posted 10 February 2020 - 02:01 AM

I ask all of you to stay on track. I had to remove some unnecessary and slightly unfriendly stuff.


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#24 riot1013

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Posted 10 February 2020 - 11:22 AM

I had a TV101 and it was not suitable for photography at all as it exhibited a lot of coma. After talking to MR. Nagler he said that those scopes were not designed to be flat on a camera sensor so they exhibit field curvature and coma photographically.  The Genesis will be in the same boat.  If you have any aspirations of strapping a camera to your scope you will want an NP or NPis.

 

See my discussion from last year:  https://www.cloudyni...th-televue-101/


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#25 Jon Isaacs

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Posted 10 February 2020 - 11:40 AM

I had a TV101 and it was not suitable for photography at all as it exhibited a lot of coma. After talking to MR. Nagler he said that those scopes were not designed to be flat on a camera sensor so they exhibit field curvature and coma photographically.  The Genesis will be in the same boat.  If you have any aspirations of strapping a camera to your scope you will want an NP or NPis.

 

See my discussion from last year:  https://www.cloudyni...th-televue-101/

 

:goodjob:

 

Questions like this one, they are easily answered by the manufacturer.  

 

Jon




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