Jump to content


Photo

Japanese shoot out

  • Please log in to reply
32 replies to this topic

#1 Rutilus

Rutilus

    Surveyor 1

  • -----
  • Posts: 1874
  • Joined: 17 Dec 2010

Posted 02 December 2012 - 02:38 PM

For the past week I have been doing a visual side by side test of my newly made
Carton 100mm f/13 Achromat refractor and Takahashi TSA-102S.
Here are some of the findings I obtained.

Star Test - Carton, extremely nice ring patterns each side of focus, the lens does show a very
slight amount of Over-correction. In focus on Vega, a very tiny amount of C.A. Visible.

Tak - Perfect ring pattern. Vega is pure white with absolutely no trace of C.A.

Double -stars - The Carton is one sublime double star splitter, with beautiful star images
and extremely delicate first diffraction ring. Only when viewing brighter stars like Rigel
and Alpha Gem did I detect just a small trace of C.A.

Tak - Yet again a superb scope on the doubles, simply beautiful eyepiece views.

Conclusion - Both instruments as good as each other. Apart from the small trace of C.A.
on the brighter stars, I could not detect a difference between the scopes.
Diffraction ring and colour the same in both scopes. Only at the very higest power did the
Airy disk in the Carton start to take on a yellowish tint (normal for an Achromat).
I kept going from each scope trying to find a noticeable difference, but in the end I
simply called it a draw. For example on the difficult (for a 4 inch) eta Gem, the views
were identical, which was the case for all the other stars observed.


Jupiter - With the planet close to opposition this was a very good time for the 4 inch scopes.
I always tend to use a yellow filter for the planets as it helps me see more detail, even with the Tak
I stick the filter on.

Carton - Without the yellow filter, a very tiny amount of a C.A. is visible around Jupiter,
also extremely small amount of light scatter. Background is a wonderful solid black.
The eyepiece view has a warmer tone when compared compared to the Tak.
With the yellow filter, wonderful planetary views. The belts displayed bays and notches
running along their length. Festoons easily seen, along with a belt in the Equatorial Zone.
Both the N.E.B and S.E.B. showed quite a large amount of internal structure and detail.
The rift in the S.E.B. showed considerable detail for a 4 inch scope.

Nice views of the Great Red Spot, with pale orange colour visible. Smaller oval BA visible.
Then joy upon joy I even observed 3 white ovals in the southern hemisphere belt.

Tak - as the above but no C.A. visible around the planet. I've yet to see any C.A. on
any object I observe with the scope, even Sirrius and Venus are totally C.A. free images.

Conclusion - Both instruments the equal of each other in the amount of detail visible.
The Tak does seem to take higher powers slightly better, but it is of no advantage as
it is empty magnification. Both scopes gave some really wonderful detailed views,
very good considering they are only 4 inches.

The Moon - Three words to say hear regarding the Carton views, APO, APO, APO.
Observing at 40x, the views were quite simply stunning. The moon had a 3D like appearance
(yes, I know it is not real, but that is how it appeared) against the purist jet black background.
Only when you increase the magnification do you start to pick-up a very slender C.A. fringe on the limb.
No C.A. is visible across the lunar surface, the shadows are black with Lunar features razor sharp.

The contrast in the Carton is extremely good. On the night of the Full Moon, I observed at low magnification
with binoviewers. The views were outstanding, sharp details visible, the crater rays were a staggering
sight to behold. Different colouration hues in the Mare regions clearly visible.

Tak - I'm starting to sound like a broken record, but again the same as above, but without any C.A.
The views of the craterlet markings and albedo features exactly the same in both scopes.

Overall conclusion.

The Carton lens is one superb piece of glass, it never did a task better than the Tak, but it
was the equal of the Tak.
The Tak has the advantage that it is easier to transport and may not be affected by the breeze so much,
and if you want to get into A.P. then I guess you would go with the TSA.

So far in my life, this Carton has to be the finest Achromat refractor I have so far used.
It is a clear notch up from the fine and wonderful Towa, circle K and Vixen scopes that I used
for many many years.


Now we come to the cost. All the parts for the Carton build were obtained used, and the total build cost me
180 U.K. pounds. I guess the price for a used TSA or FS scope would be anywhere from
1,000 to 1,500 U.K. pounds.

After the seeing the views I've had with the Carton, I would say that the build was a bargain.

This whole exercise does bring up for me the question regarding lens coatings.
The Carton appears to have a single coating of MfG with a Bluish tint in the reflected light.
The Tak is Multi-coated with a Greenish tint.
Yet if the multicoating has an advantage, I am not seeing it in the visual observations.
A few years ago I repeated the exercise with my old Towa 80mm f/15 scope, in that test the Tak
had a clear advantage over the Towa, and even my Sky-watcher Achromat with coated optics
showed a better view when compared to the Towa.

I'm not sure what the engineers at Carton were doing back in the 70s and 80s, but they were doing something
very right indeed with this lens.

Attached Files



#2 Astrojensen

Astrojensen

    Fly Me to the Moon

  • *****
  • Posts: 5369
  • Joined: 05 Oct 2008
  • Loc: Bornholm, Denmark

Posted 02 December 2012 - 03:12 PM

Excellent mini-review! I have, as you may know, an Antares 105/1300 (actually 94/1300...) and I believe it's also a Carton lens. I know of no manufacturer other than Carton that has made a 105/1300mm objective. 105mm is the actual physical diameter of the glass, not the free aperture.

Mine has a not entirely perfect star test. There's something funny about it on one side of focus, a brighter center in the diffraction disk. This is probably mostly of academic interest, as the images are razor sharp in focus with a very clear snap to them. It eats doubles for lunch and has no trouble at all showing craterlets in Plato and things like that. There's very little false color and what little there is is taken care of by either using a binoviewer with Baader corrector or huygenian eyepieces when in single eyepiece mode. The complete elimination of false color by my Zeiss huygenians is startling to see, when compared to my orthos.

It is a shame that the OTAs from Antares are so shabby. These superb lenses deserve better. I just haven't got around to do something about it.


Clear skies!
Thomas, Denmark

#3 Mr Onions

Mr Onions

    Two Time International Photographical Competition Winner

  • *****
  • Posts: 6625
  • Joined: 14 Apr 2007
  • Loc: Newcastle upon Tyne.

Posted 02 December 2012 - 03:13 PM

Great article.
I'm very frustrated that I can't use the 4" Carton for transport reasons but, I do use the 60mm version.
I'm not all surprised at your findings.
What a great job you have made of the build too.
Very well done.

#4 Spyke

Spyke

    Mercury-Atlas

  • *****
  • Posts: 2694
  • Joined: 22 Jul 2003
  • Loc: Scotland

Posted 02 December 2012 - 03:32 PM

Darn! Another "get on and finish your Carton build" post!

Those 100mm f13s are getting good press all over the place. Very nice comparison, and two very fine telescopes there by the way!

Ant:cool:

#5 Stellarfire

Stellarfire

    Apollo

  • -----
  • Posts: 1313
  • Joined: 10 Jul 2011
  • Loc: Switzerland

Posted 02 December 2012 - 04:20 PM

Thank you for this highly interesting comparison! I enjoyed it from the first to the last word.

Stephan

#6 SteveG

SteveG

    Skylab

  • *****
  • Posts: 4427
  • Joined: 27 Sep 2006
  • Loc: Seattle, WA

Posted 02 December 2012 - 04:23 PM

I would love to see an ed100 in this comparison!

#7 Bonco

Bonco

    Gemini

  • *****
  • Posts: 3450
  • Joined: 17 Apr 2006
  • Loc: Florida

Posted 02 December 2012 - 04:49 PM

Replaced the lenses in my Tasco Model 10K and my Towa model 339 with Carton lenses (80mm f/15.) The Carton lens is excellent in every way.
Bill

#8 Mr Onions

Mr Onions

    Two Time International Photographical Competition Winner

  • *****
  • Posts: 6625
  • Joined: 14 Apr 2007
  • Loc: Newcastle upon Tyne.

Posted 02 December 2012 - 05:13 PM

I rate my 60mm Carton lens right up with the Lomo 80mm f/6 in terms of sharpness and contrast.
The Lomo beats it hands down on colour correction of course.

#9 Ain Soph Aur

Ain Soph Aur

    Viking 1

  • *****
  • Posts: 713
  • Joined: 10 Aug 2011
  • Loc: West Tennessee

Posted 02 December 2012 - 06:44 PM

Very nice review! I have a Sheldon Faworski sourced Carton 100/1300 objective mounted in a custom Crawmach OTA. While I don't have another 100mm to compare, I can vouch for the amazing views through this scope. It is my favorite scope by far, absolutely wonderful for planetary, lunar and double stars! I'm planning on buying a binoviewer next year.

I've been doing a lot of Jupiter and Lunar viewing lately and haven't noticed any CA on either, and only notice a mere hint on the brightest stars like Vega. If it clears up tonight I plan on doing more Jupiter and Lunar viewing and will specifically look for CA.

#10 Daniel Mounsey

Daniel Mounsey

    Vendor (Woodland Hills)

  • *****
  • Vendors
  • Posts: 5480
  • Joined: 12 Jun 2002

Posted 02 December 2012 - 08:03 PM

Rutilus,

First, thank you for taking the time to make your comparison. The refractor forums actually need way more hands on comparisons rather than the common, technical hypotheticals that pollute the forums these days. I just wish to add a few things.


How did you rate your seeing conditions?
Where was the observation made?
If you used diagonals, which ones?
What magnifications were you using?
What eyepieces were you using?
What kind of temperatures?
What did you see around the airy discs on stars with one optic vs. the other at high magnification?

#11 Ain Soph Aur

Ain Soph Aur

    Viking 1

  • *****
  • Posts: 713
  • Joined: 10 Aug 2011
  • Loc: West Tennessee

Posted 02 December 2012 - 08:45 PM

If it clears up tonight I plan on doing more Jupiter and Lunar viewing and will specifically look for CA.


It did clear up nicely after dusk. Specifically looking for the presence of CA around Jupiter and none seen regardless of magnification. An amazing view to say the least!

#12 hottr6

hottr6

    Vanguard

  • *****
  • Posts: 2443
  • Joined: 28 Jun 2009
  • Loc: 7,500', Magdalena Mtns, NM

Posted 03 December 2012 - 01:02 PM

Antares 105/1300 (actually 94/1300...) and I believe it's also a Carton lens. I know of no manufacturer other than Carton that has made a 105/1300mm objective. 105mm is the actual physical diameter of the glass, not the free aperture.

Mmmmm. This is not my understanding. My sources suggest that the Antares Elite glass is sourced from a Vixen factory in China. :thinking:

#13 Astrojensen

Astrojensen

    Fly Me to the Moon

  • *****
  • Posts: 5369
  • Joined: 05 Oct 2008
  • Loc: Bornholm, Denmark

Posted 03 December 2012 - 01:33 PM

My sources suggest that the Antares Elite glass is sourced from a Vixen factory in China.


You mean a Vixen factory in Japan, right? Vixen did get at least some of their objectives from a subcontractor. Their fluorite apochromats came from Canon-Optron, it think (but I can't remember with certainty). I think there's a very real chance that the "Vixen supplier" Antares speak of is, in fact, Carton.

I'll need to check Galakuma's catalog collection and see if I can find any hints.


Clear skies!
Thomas, Denmark

#14 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20507
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 03 December 2012 - 02:04 PM

What kind of diagonal were you using in the Carton for the testing?

Regards,

Jim

#15 hottr6

hottr6

    Vanguard

  • *****
  • Posts: 2443
  • Joined: 28 Jun 2009
  • Loc: 7,500', Magdalena Mtns, NM

Posted 03 December 2012 - 02:59 PM

My sources suggest that the Antares Elite glass is sourced from a Vixen factory in China.


You mean a Vixen factory in Japan, right? Vixen did get at least some of their objectives from a subcontractor. Their fluorite apochromats came from Canon-Optron, it think (but I can't remember with certainty). I think there's a very real chance that the "Vixen supplier" Antares speak of is, in fact, Carton.

I'd like to think that you are correct, but Vixen does have a (subcontractor) glass factory in China (Synta? Bosma?).

Looking at the price comparison of the Antares 105 f/15 and Vixen 100 f/15, odds are that the Antares glass is sourced in China.

#16 Ain Soph Aur

Ain Soph Aur

    Viking 1

  • *****
  • Posts: 713
  • Joined: 10 Aug 2011
  • Loc: West Tennessee

Posted 03 December 2012 - 04:03 PM

Unless Antares/Vixen is using 'new old stock', I doubt any current Antares scopes are featuring Carton glass. And if there is such a thing as a Carton ~100mm f/15 objective made during the same era of the f/13 objectives, I want one!

#17 Astrojensen

Astrojensen

    Fly Me to the Moon

  • *****
  • Posts: 5369
  • Joined: 05 Oct 2008
  • Loc: Bornholm, Denmark

Posted 03 December 2012 - 04:25 PM

I'd like to think that you are correct, but Vixen does have a (subcontractor) glass factory in China (Synta? Bosma?).

Looking at the price comparison of the Antares 105 f/15 and Vixen 100 f/15, odds are that the Antares glass is sourced in China.


Vixen, like almost anyone else, are selling rebranded Synta ED 100 refractors and other Synta scopes. This is ironic, since Vixen is the very company Synta started copying in the first place. All the ubiqutious EQ-5 mounts are direct Vixen GP clones. They even copied the Vixen standard dovetail system, which, in retrospect, was a brilliant move.

The Vixen 100/1500 has not been made for almost 30 years. Antares is very highly likely using NOS objectives from the then subcontractor for Vixen long-focus 4" lenses. I am quite sure this subcontractor could be Carton, at least in the case of the 100/1300 objective. A *lot* of Japanese companies bought products and services from one another and relied on subcontractors and part suppliers, very much like China today.


Clear skies!
Thomas, Denmark

#18 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20507
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 03 December 2012 - 04:59 PM

Actually no. The odds are zero that the Antares Elite 105/1500, 105/1300 and 105/1000 optics were made in China.

https://www.teleskop.../info/p2424_...

They were New-Old-Stock optics made by a Vixen subcontractor located in Japan. The cheapness of the scopes Antares built using these Japanese optics arises out of the cheap OTAs and cells provided. The OTA is ultra-thin aluminum, seamed irrigation pipe. The lens cell vignettes the clear aperture down from 105mm to around 95mm.

Vixen likely did not use Carton as a subcontractor. In fact, I'm not sure that Carton also didn't use a lens subcontractor.

Regards,

Jim

#19 hottr6

hottr6

    Vanguard

  • *****
  • Posts: 2443
  • Joined: 28 Jun 2009
  • Loc: 7,500', Magdalena Mtns, NM

Posted 03 December 2012 - 05:10 PM

The odds are zero that the Antares Elite 105/1500, 105/1300 and 105/1000 optics were made in China.

OK, I've been re-educated! :tonofbricks:

So how does the Antares Elite 105 f/13 compare with the Carton 100 f/13?

Is it worthwhile having Dan at Crawmach build a new cell for the Antares to utilize all 105mm?

#20 Astrojensen

Astrojensen

    Fly Me to the Moon

  • *****
  • Posts: 5369
  • Joined: 05 Oct 2008
  • Loc: Bornholm, Denmark

Posted 03 December 2012 - 05:14 PM

Is it worthwhile having Dan at Crawmach build a new cell for the Antares to utilize all 105mm?


Oh yeah! My Antares 105/1300 objective is extremely good. The OTA is cr*p. It stops the lens down to 94mm. Make him build a complete OTA while you're at it.

BTW, you can't use all the 105mm, as that's the total diameter, and you need a little to hold the lens in the cell. Go for 102mm, 4".


Clear skies!
Thomas, Denmark

#21 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20507
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 03 December 2012 - 05:51 PM

Good question.

The Antares "Vixen Spec" optics are really good. The only Carton optics I have to compare them to are 60mm optics. I'd say that the coatings (single layer MgFl on each surface) of the Vixen Spec lenses is better than the thin or nonexistent coatings used on some of the surfaces of the Cartons I have. In terms of figure quality, they're both very, very good.

"Worth it" is a very personal question, I think. The optics certainly are excellent. But how much is an extra 8mm of aperture "worth" in dollar terms? For me, I'd likely pass on a new cell and enjoy it vignetting and all. If I was going to invest in improving the OTA, I'd scrap the whole shebang and have a new OTA, cell and focuser built. But that would be a huge investment in what was a very cheap set of optics ($650 for the OTA when I bought).

Regards,

Jim

#22 Ain Soph Aur

Ain Soph Aur

    Viking 1

  • *****
  • Posts: 713
  • Joined: 10 Aug 2011
  • Loc: West Tennessee

Posted 03 December 2012 - 06:56 PM

The Faworski sourced Carton 100/1300 in my OTA is MgFl coated and the cell was provided with the lens. The next time I remove the dew shield I will measure clear aperture.

I use a 2" Crawmach 2-speed crayford, 2" Baader Click-Lock dielectric diagonal. With the ES 82* 30mm it can achieve a respectable crisp to edge ~1.9 degree FOV. Some day I will replace this EP with an ES 100* 25mm.

#23 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20507
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 03 December 2012 - 07:49 PM

The carton 60mm units I have are coated only on one surface (the outer surface) leaving 3 surfaces uncoated. You need to check clear aperture from the rear of the scope, not at the objective end. Look in through the focuser tube and see if you can see the lens edges and spacers. In an Antares scope, you cannot.

Regards,

Jim

#24 Ain Soph Aur

Ain Soph Aur

    Viking 1

  • *****
  • Posts: 713
  • Joined: 10 Aug 2011
  • Loc: West Tennessee

Posted 03 December 2012 - 08:17 PM

Just did a quick check from the focuser end and I can see spacers.

#25 Astrojensen

Astrojensen

    Fly Me to the Moon

  • *****
  • Posts: 5369
  • Joined: 05 Oct 2008
  • Loc: Bornholm, Denmark

Posted 04 December 2012 - 05:13 PM

I checked up on Galakuma's site of old Japanese catalogues and the ONLY two companies I can find that has sold a 102/1300 scope are... Vixen and Carton. The only mention of the Vixen version is in the 1981 catalogue and the Carton version is only shown in the 1985 catalogue. This of course doesn't mean that they can have sold them for several years afterwards. Vixen also offered a 102/1500 version in 1981. In 1985 and later, Vixen shows only the 102/1000 version, which is still being made to this day. Upon close scrutiny it is evident that the Vixen and Carton 102/1300mm OTAs look A LOT like one another, although they are not identical. There are some detail differences, but also strong similarities. They use, for example, the same accesory threads on the focuser! Most of the smaller accesories are completely identical. It is clearly evident that they have used the same supplier for accesories, so I consider it likely that this could also have been the case with the optics. All their 0.965" eyepieces seems to have come from the same supplier that made 0.965" eyepieces for Kokusai Kohki.

The mystery is where the refractor objectives came from. A subcontractor? Carton supplied them both? Vixen supplied them both? (the hints "from a Vixen supplier" on several homepages seem to rule this option out) Both made their own lenses? (unlikely, as mentioned)


Clear skies!
Thomas, Denmark






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics