Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

AP130EDF f/6 or Takahashi FS128 for planetary

  • Please log in to reply
122 replies to this topic

#26 Jeff B

Jeff B

    Cosmos

  • *****
  • Posts: 8,163
  • Joined: 30 Dec 2006

Posted 17 October 2021 - 09:20 AM

Here's the Yoshida refractor ratings plotted against aperture. As can be seen, the Tak 128 and AP 130 are very close in rating, and it would be closer if the Tak had another 2mm of aperture :-)

 

attachicon.gifYoshidar refractors.PNG

Interesting plot.  Too bad it stops at 160mm.

 

It's also nice to see folks posting real observations and comparisons.

 

Jeff


  • Marcus Roman likes this

#27 Lagrange

Lagrange

    Mariner 2

  • -----
  • Posts: 211
  • Joined: 16 Apr 2007

Posted 17 October 2021 - 12:05 PM

The fast f/6 focal ratio of the AP130 may require better eyepieces to avoid aberrations than in the slower f/8.1 Tak. Another way to say this is some eyepieces that work OK in the Tak may show aberrations in the AP.

There might not be a huge difference but the slower focal ratio should definitely be more forgiving which could be significant with eyepieces that are a bit borderline in their image quality with the A-P. I've also read that slower scopes tend to be less affected by poor seeing than faster ones but again, I wouldn't know how visible the difference would be in this case.


  • 25585 likes this

#28 RichA

RichA

    Skylab

  • *****
  • Posts: 4,488
  • Joined: 03 Jun 2010
  • Loc: Toronto, Canada

Posted 18 October 2021 - 01:33 PM

Interesting plot.  Too bad it stops at 160mm.

 

It's also nice to see folks posting real observations and comparisons.

 

Jeff

Well, if the 160 AP is at the top there, the 175mm AP would probably be similar.



#29 lylver

lylver

    Viking 1

  • *****
  • Posts: 998
  • Joined: 15 Feb 2017
  • Loc: France

Posted 18 October 2021 - 04:52 PM

I had a look a few times in a AP130 f6.3 EDF and in fluorite (Vixen FS102), Zeiss A 130f18.(semi-apo), SkyW 120ED, Tak FS102, Altaïr 130f7 EDT.

Eyepiece suffers in the f/6-f/7 refractors, you need to put more money in. Radians vs Pentax VW and Nikon Nav-SW was the winner.

The Tak & Vixen accept modern orthos, but not well the oldest versions.

Zeiss A which is not apo gave the better rendering with his native Abbe Orthos.

Jupiter is the most difficult target for non apo, Altaïr and AP works well on it, giving colorless image.

But for sharpness inside BES and GTR, fluorite and semi-apo are at level or beyond : longer focal length help on tuning focus on the right color : you cannot do that on a locked focus apo, all blur simultaneously.

It is subtle at f/8 but very easy at f/18.

For strict visual and a perfect clean image, I recommend a bit longer f/D than f/6, which is more suited for photography.

The 130f/9 LZOS is a better choice in my opinion, with Vixen SLV maybe HR or Tak TOE for planetary and pentax XW for DSO


  • leviathan, 25585, Marcus Roman and 2 others like this

#30 Paul Hyndman

Paul Hyndman

    Apollo

  • -----
  • Posts: 1,393
  • Joined: 13 Jul 2004
  • Loc: CT Shoreline

Posted 18 October 2021 - 04:55 PM

Well, if the 160 AP is at the top there, the 175mm AP would probably be similar.

smile.png No chart needed... it is indeed sweet, albeit a handful for a geezer to schlep about and mount.

 

 

post-4271-0-32188800-1534467099.jpg


  • Paul G, Scott Beith, Scott in NC and 10 others like this

#31 Deadlake

Deadlake

    Messenger

  • -----
  • Posts: 447
  • Joined: 27 Jun 2020

Posted 18 October 2021 - 05:12 PM

I had a look a few times in a AP130 f6.3 EDF and in fluorite (Vixen FS102), Zeiss A 130f18.(semi-apo), SkyW 120ED, Tak FS102, Altaïr 130f7 EDT.
Eyepiece suffers in the f/6-f/7 refractors, you need to put more money in. Radians vs Pentax VW and Nikon Nav-SW was the winner.
The Tak & Vixen accept modern orthos, but not well the oldest versions.
Zeiss A which is not apo gave the better rendering with his native Abbe Orthos.
Jupiter is the most difficult target for non apo, Altaïr and AP works well on it, giving colorless image.
But for sharpess inside BES and GTR, fluorite and semi-apo are at level or beyond : longer focal length help on tuning focus on the right color : you cannot do that on a locked focus apo, all blur simultaneously.
It is subtle at f/8 but very easy at f/18.
For strict visual and a perfect clean image, I recommend a bit longer f/D than f/6, which is more suited for photography.
The 130f/9 LZOS is a better choice in my opinion, with Vixen SLV maybe HR or Tak TOE for planetary and pentax XW for DSO


The LZOS is cheaper then the AP or a TOA. I find my 130/F6 LZOS very good on all objects of interest.
  • Scott Beith, AZStarGuy, 25585 and 1 other like this

#32 lylver

lylver

    Viking 1

  • *****
  • Posts: 998
  • Joined: 15 Feb 2017
  • Loc: France

Posted 18 October 2021 - 06:02 PM

The LZOS is cheaper then the AP or a TOA. I find my 130/F6 LZOS very good on all objects of interest.

I got the optic formula :K8-OK4-TK12 Schvabe LZOS glass

Yes a good apochromat, but with some level of spherochromatism that cannot gives the level of contrast for maximum magnification in visual. TMB would not have designed the f/9 version if it was perfect for visual.

As Roland Christen wrote, you need lambda/8 peak rms or more on critical wavelength band to reach that.

Between LZOS and AP, AP has the best mechanical design and baffling. You see it when dissasembling an AP 130 EDF for transport.

 


  • Marcus Roman likes this

#33 Deadlake

Deadlake

    Messenger

  • -----
  • Posts: 447
  • Joined: 27 Jun 2020

Posted 19 October 2021 - 03:16 AM

Between LZOS and AP, AP has the best mechanical design and baffling. You see it when dissasembling an AP 130 EDF for transport.

I agree the AP130GTX is more stream lined build, but for car based transport it's a wash between the two, however the LZOS is 2 kg heavier. The AP130GTX is impossible to get hold off, and costs a 1/3 more and is slightly slower. I would suggest that only going with a TOA-130 will you see refinement in dealing with spherochromatism, but thats a loss of speed which would not suite my use case.

I bought mine with NV is mind, so speed of the scope matters in trying to get as close to F2 as possible (using a 55mm TV Plossl + adapter as well). The only other scope was an FSQ-130, and thats even harder to find and more expensive then the AP130GTX.  

Good thing my LZOS lens has a RMS of 0.024 @ 532 nm (green line)...



#34 Paul G

Paul G

    Cosmos

  • *****
  • Posts: 9,585
  • Joined: 08 May 2003
  • Loc: Freedonia

Posted 19 October 2021 - 09:03 AM

I am a lunar/planetary observer and owned both the FS128 and the AP130 EDF f6 at the same time. I side by sided them over a period of nearly two years, eventually sold the FS128. Both are superb scopes, and I would be happy using either. But the AP130 f6 had a bit better contrast (expected based on the design of each scope), gave more detail in the festoons of Jupiter (a result of the optical design of the Tak, there is no single point at which all of the blue is in focus), and the colors were more true in the AP (the FS128 gives a slight yellow tint to the moon and planets, again a result of the optical design).

 

Both are fantastic scopes, the AP is just a bit better.


  • Scott Beith, Adam S, Paul Morow and 1 other like this

#35 payner

payner

    Mercury-Atlas

  • *****
  • Posts: 2,808
  • Joined: 22 Mar 2007
  • Loc: Bluegrass & SW Appalachian Regions, Kentucky

Posted 19 October 2021 - 10:56 AM

I suppose the AP130 models are triplet scopes, correct?



#36 Paul G

Paul G

    Cosmos

  • *****
  • Posts: 9,585
  • Joined: 08 May 2003
  • Loc: Freedonia

Posted 19 October 2021 - 02:41 PM

I suppose the AP130 models are triplet scopes, correct?

Yes, the 130 EDF f6 is an oiled triplet, so only two air/glass surfaces to four in the FS128.



#37 Lagrange

Lagrange

    Mariner 2

  • -----
  • Posts: 211
  • Joined: 16 Apr 2007

Posted 20 October 2021 - 07:57 AM

Yes, the 130 EDF f6 is an oiled triplet, so only two air/glass surfaces to four in the FS128.

Presumably the greater correction afforded by a good triplet over a good doublet is the main factor in the difference you saw and I'd expect a good air-spaced triplet would have had the edge on the FS-128 as well.. Assuming the coatings were reasonably good would the difference between having two or four surfaces be visible?



#38 Deadlake

Deadlake

    Messenger

  • -----
  • Posts: 447
  • Joined: 27 Jun 2020

Posted 20 October 2021 - 08:52 AM

I can see the different between my triplet and doublet. I’d opine that more light at different wavelengths is focused into the airy disk. However I’d love to know if that’s not the case? Focus with the triplet is easier.

#39 Paul G

Paul G

    Cosmos

  • *****
  • Posts: 9,585
  • Joined: 08 May 2003
  • Loc: Freedonia

Posted 20 October 2021 - 11:47 AM

Presumably the greater correction afforded by a good triplet over a good doublet is the main factor in the difference you saw and I'd expect a good air-spaced triplet would have had the edge on the FS-128 as well.. Assuming the coatings were reasonably good would the difference between having two or four surfaces be visible?

I would assume so. However, in my location under the jet stream seeing is usually not good enough to see any difference at all between the two scopes, takes a really nice night to tease them out (except for the slight yellow color which is visible even in poor seeing).


  • Lagrange likes this

#40 Lagrange

Lagrange

    Mariner 2

  • -----
  • Posts: 211
  • Joined: 16 Apr 2007

Posted 20 October 2021 - 07:58 PM

I would assume so. However, in my location under the jet stream seeing is usually not good enough to see any difference at all between the two scopes, takes a really nice night to tease them out (except for the slight yellow color which is visible even in poor seeing).

Something I remembered reading about the Tak FS series scopes is that they were generally better corrected in yellow and red than many of the scopes that came after them, but this was at the expense of worse performance in blue and violet. For certain targets like Mars it might be an advantage but if you're someone who notices blue haloes or wants a cooler image then the newer models should get closer to that ideal with their more balanced optimisation at different ends of the spectrum.

 

It would be interesting to see how good a doublet Tak could make today if they brought out a new FC-125, especially if they were willing to make use of a wide air gap as in the FOA-60. Of course that needs a longer and more robust lens cell which means a heavier and less well balanced scope compared to a foil-spaced design so you lose some of the advantage of having a doublet in the first place.


  • Paul G and Lookitup like this

#41 PowerM3

PowerM3

    Ranger 4

  • *****
  • Posts: 328
  • Joined: 31 Aug 2010

Posted 09 November 2021 - 08:57 PM

Finally did a comparison of the FS-128 and AP 130GT. The views are more similar than different. Unfortunately on the night of the comparison seeing was not great so I could not really crank up the power on Jupiter. Contrast on both scopes is amazing! For those curious on more info check out the YT video on the comparison: https://youtu.be/GvpZC2j4tS8

Attached Thumbnails

  • comp.jpg
  • small.jpg

  • Paul G, Scott in NC, Adam S and 10 others like this

#42 Adam S

Adam S

    Mercury-Atlas

  • *****
  • Posts: 2,604
  • Joined: 21 Dec 2005
  • Loc: ABQ, NM

Posted 09 November 2021 - 10:53 PM

I've owned them both and would call it a draw.  The AP wins for physical size and moving around and  loading in the car, the Tak wins for its extra focal length and ease of eyepiece selection.   Great telescopes, I sold the Tak to fund the AP because my name came up after 9 years.  I don't feel as if I gained in optics, I gained in physical size (although the AP weighs deal more).

 

One other consideration, customer service with AP is better than Texas Nautical.   TNR is by no means bad, AP is the next level up of customer service original owner or second hand user.


Edited by Adam S, 09 November 2021 - 10:55 PM.

  • 25585 and Marcus Roman like this

#43 fedele

fedele

    Ranger 4

  • -----
  • Posts: 304
  • Joined: 07 Jan 2021

Posted 10 November 2021 - 08:41 AM

I've owned them both and would call it a draw.  The AP wins for physical size and moving around and  loading in the car, the Tak wins for its extra focal length and ease of eyepiece selection.   Great telescopes, I sold the Tak to fund the AP because my name came up after 9 years.  I don't feel as if I gained in optics, I gained in physical size (although the AP weighs deal more).

 

One other consideration, customer service with AP is better than Texas Nautical.   TNR is by no means bad, AP is the next level up of customer service original owner or second hand user.

couldn't the TSA120 be an option?


  • Paul G, Adam S and 25585 like this

#44 Paul G

Paul G

    Cosmos

  • *****
  • Posts: 9,585
  • Joined: 08 May 2003
  • Loc: Freedonia

Posted 10 November 2021 - 09:51 AM

Presumably the greater correction afforded by a good triplet over a good doublet is the main factor in the difference you saw and I'd expect a good air-spaced triplet would have had the edge on the FS-128 as well.. Assuming the coatings were reasonably good would the difference between having two or four surfaces be visible?

 

 

I would assume so. However, in my location under the jet stream seeing is usually not good enough to see any difference at all between the two scopes, takes a really nice night to tease them out (except for the slight yellow color which is visible even in poor seeing).

I re-read my reply and it seems ambiguous. "I would assume so" was in response to your first sentence. Assuming the coatings were state of the art for the time I wouldn't expect the number of surfaces to be visually important because both scopes have very smooth optics, at least as important a characteristic for planetary observing as color correction.


  • Lagrange likes this

#45 Adam S

Adam S

    Mercury-Atlas

  • *****
  • Posts: 2,604
  • Joined: 21 Dec 2005
  • Loc: ABQ, NM

Posted 11 November 2021 - 07:56 PM

A perfect option.

 

couldn't the TSA120 be an option?


  • Paul G likes this

#46 sw196060

sw196060

    Apollo

  • *****
  • Posts: 1,078
  • Joined: 16 Apr 2020

Posted 12 November 2021 - 08:59 PM

It could be but, the OP asked specifically about the other two scopes.

#47 donadani

donadani

    Apollo

  • *****
  • Posts: 1,226
  • Joined: 20 Jul 2015
  • Loc: Germany

Posted 12 November 2021 - 11:47 PM

...and brightness difference on planets is obvious (to me) - sold two TSA´s 120 and stayed with the EDF... (and FS-128).

 

But same is true for the TEC140 vs. the EDF - and both are straight 10kg with rings and rail... so if you look for other options I would pick the bigger lens wink.gif and btw. size of the TEC is about the same as the FS... - but as mentioned before: a FS-128 is a timeless piece of kit so better stay with that laugh.gif laugh.gif laugh.gif

 

 

Found that ones:

 

 

...mmmh - that TSA was nice too ;)


Edited by donadani, 12 November 2021 - 11:53 PM.

  • Scott in NC, 3 i Guy, Paul Morow and 5 others like this

#48 Scott Beith

Scott Beith

    SRF

  • *****
  • Posts: 47,664
  • Joined: 26 Nov 2003
  • Loc: Frederick, MD

Posted 13 November 2021 - 11:39 AM

Finally did a comparison of the FS-128 and AP 130GT. The views are more similar than different. Unfortunately on the night of the comparison seeing was not great so I could not really crank up the power on Jupiter. Contrast on both scopes is amazing! For those curious on more info check out the YT video on the comparison: https://youtu.be/GvpZC2j4tS8

That was a good video.  



#49 gnowellsct

gnowellsct

    Hubble

  • *****
  • Posts: 19,198
  • Joined: 24 Jun 2009

Posted 13 November 2021 - 05:51 PM

Mike,

Gosh, why did you sell your FS128??

Well I'm not Mike but I had the GT130 and the FS128 and sold the FS128 to help pay for the GT130.

 

Anyhow I owned the FS128 for 7 or 8 years while on the AP waitlist and I would say it is the better scope for planets.  The reason is EXIT PUPIL.  The longer focal length of the FS128 provides a noticeably more comfortable view at 300x than the GT130.  The f/8.1 of the Tak makes a difference.   A 3.5 XW gets you to 300x in the FS128.  You need a 2.7 mm to do the same in the GT130, and 2.7mm is not easy to find.  I use the 2.5mm XO.  

 

I don't see the point of getting a five inch refractor for planets.  I have had great views but my C14, which I had set up side by side with the FS128 one night, totally blows away the FS128 and a 9.25 would open up some distance as well.  Don't forget that reaching exact focus is easier at a long focal ratio than a shorter one, one of the reason the FS128 has advantages over the GT130 and one of the reasons the bigger SCTs have an advantage over both (in addition to aperture and color rendition).    I have also had the experience of having a 10" Sky Watcher Dob (not mine) blow away the view in my AP 130, but you know, I don't buy refractors for planets.  I like it if they can do planets, and will take a look, but mainly I do not get them for planets.

 

But this is the refractor group so within the parameters of the question, the longer focal ratio scope, at near identical aperture, is better suited for planets.  Yes you can get the Astro-physics f/6.3 up to 300x but if you're going to spend any length of time doing this, you'll be more comfortable and get better performance at the FS128's f/8.1.  

 

GN


  • ewave likes this

#50 HARRISON SCOPES  Happy Birthday!

HARRISON SCOPES

    Vendor-Harrison Telescopes

  • *****
  • Vendors
  • Posts: 669
  • Joined: 05 Nov 2006
  • Loc: The Garden of England

Posted 13 November 2021 - 06:04 PM

In turbulent UK skies I think the fast cooldown of the 128 would provide better views in our mediocre seeing. In better conditions with more carefully selected eyepieces I think the superior corrections of the 130 would win.
All subtle differences, both wonderful optics.


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics