Tamiji Homma
Pooh-Bah
Reged: 02/24/07
Posts: 1081
Loc: California, USA
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Hi,
I just saw this news on Takahashi Japan web site. There is no
direct link so you need to click the entry of the news items.
Takahashi Japan news
It seems that FET 300 1 ED, 1 unknown(not specified flint?), 1 FL glass
triplet 300mm f/8, 150Kg, 2.9m long scope and improved
EM-3500, EM-3700 are about to ship to customer in Korea.
It must be awesome view through it 
Tammy
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jdownie
scholastic sledgehammer
Reged: 02/24/06
Posts: 759
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Here is a direct link.
Direct link to 300mm f/8 telescope.
By the way, to get these direct links, right click on the item and select "Properties". Copy the url out of the "Properties" field and paste it into a browser.
John
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ATM project - a terrible waste of good Pyrex.
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Daniel Mounsey
Vendor - Woodland Hils
Reged: 06/12/02
Posts: 3200
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Tamiji,
I'm guessing about a million dollar spread there. It's interesting you mention this scope. A customer just took delivery on one of these in Korea according to sources. I would expect this to be the finest refractor in the world period and at the limit of how big these kinds of scopes can be, due to spherical issues. About the closest I've gotten to this is with the 10" F-16 Ziess which houses a doublet up front and a 4" color corrector made by Roland Christen at the rear for a total of three elements. Saturn on a good night looks like a 50 cent piece but the 300 Tak here is in a completely different catigory using the latest technology like glass, coatings, design etc.
A scope as big as the 300 you presented here needs an observatory with a properly designed air conditioning system to keep the spherical correction in place, otherwise it will remain in a highly under corrected state. Just to put this matter into perspective, my friends 8" triplet TMB at sea level can take about two hours before it reaches perfect spherical correction and up to three hours at certain locations at higher altitudes. Just a tip for you. When you set up your 6" triplet, take the cover off the lens and remove the cap on the rear so the optical tube can settle down faster.
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Daniel Mounsey
Vendor - Woodland Hils
Reged: 06/12/02
Posts: 3200
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If I could have any telescope in the world, that would be it. Not only would images of planets be second to none, but the contrast on globulars would be breathtaking. I'm not the biggest light bucket fan because I'm not keen on fast scopes. BTW the 11x70 finder looks the size of most 6x30 finders on other large scopes 
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roadi
professor emeritus
Reged: 08/18/07
Posts: 531
Loc: Denmark
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Thats crazy.. 
But truely amazing!!
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Regards Rodi
60mm Polarex, Sky90, µ210, SKW150 Binoscope
Vixen GpDx, Astro5, LX200
Modified Baader/Celestron Binoviewer.
Panoptics, Tak LE's, Baader Ortho's, Antares Erfle's
Couple of diagonals..
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SkyscraperJim
professor emeritus
Reged: 07/29/07
Posts: 537
Loc: Providence, RI
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Interesting, but given the list prices I've seen for the 8" and 10" Tak "observatory class" refractors, I'd rather order one from APM. If I ever do own a refractor that big, it will most likely be a D&G achromat.
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Jim
TMB/APM 130/780 (#185) on G11
TMB/APM/Lomo 80/600
Tele Vue Pronto (#3533) on Half Hitch
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Tomvictor
professor emeritus
Reged: 08/09/04
Posts: 509
Loc: N.59.11.47. Norway
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I think the finder is a FSQ 
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Tom Victor
http://www.ccd-astrophoto.com/
Takahashi EM-200 - 10" LX200ACF - Artemis 4021M - Mini Borg 60ED - FLI CFW - DSI PRO II. Canon EF200L f/2.8 - 450D - Baader mod. 350D.
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dothead
super member
Reged: 08/13/08
Posts: 163
Loc: Heidelberg, Germany
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Daniel,
Interesting you mention Pons' scope. Maybe a Petzval type refractor would be the way to go to avoid thermal problems caused by too much glass (too many elements) in one place.
By the way, Daniel, have you ever heard of the 10 inch Petzval (2 front, 3 rear elements) APO made by the Colorado based EQUINOX INTERSCIENCE company (you can google their website). Looks like a truly professional scope (for instance, it sports an 8 inch focuser!); with a $90000 price tag for the OTA alone, it's certainly out of reach for all but the most affluent amateurs (talk about a dream scope!).
My dream refractor would be a 20 inch F/30 folded D&G achromat. To mount this thing, a AP El Capitan mount would surely be way too small! But Markus Ludes of APM Telescopes sells an equatorial mount which weighs 1000 lbs without counterweights (for Euro 24000) which should handle the OTA.
Together with a Zeiss 160 mm eyepiece (70 degres AFOV, 180 mm field stop, 8 inch barrel), which Markus also had on offer for quite some time (sold now), you could attain a TFOV of 41 arc minutes, despite the 600 inch focal length of the 20 inch - F/30 D&G. The color correction of this scope should be roughly equivalent to an 6 inch F/9 achromat (devide the f-ratio by the aperture (in this case, 30/20 or 9/6 and get 1,5. The old rule is that once you get over 5, achromats reach apochromatic colour correction. For instance, an 3 inch F/15 achromat (yes, the old Tascos! (Royal company objective lens) show almost no residual colour even at a magnification of 50x per inch)).
Cheers,
Ralph
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Dave Novoselsky
sage
Reged: 06/16/08
Posts: 462
Loc: SE Wisconsin/Chicago
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The news release also contains a discussion of the new ED version of the Extender, the Extender ED (catchy phrase, eh?) TNR just got them in early this week, according to Art. Should be a neat piece, which Art says will work well on any scope, not just a Tak, and works best on a fast refractor. Dave
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Time wounds all heels.
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dothead
super member
Reged: 08/13/08
Posts: 163
Loc: Heidelberg, Germany
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'scuse me, sir, but I don't understand the relevance of your post to those preceding. Could you please elaborate?
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ABC
sage
Reged: 10/22/06
Posts: 422
Loc: Heidelberg, Germany
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Quote:
Interesting, but given the list prices I've seen for the 8" and 10" Tak "observatory class" refractors, I'd rather order one from APM. If I ever do own a refractor that big, it will most likely be a D&G achromat.
Yes, there is a 12" TMB for sale, for a fraction of the price:
http://www.apm-telescopes.de/secondhand.php?action=showpic&id=321&picnr=2
To my knowledge, TMB has produced triplets up to 20", so a 12" Tak is not so much exciting...
However, I have to admit, a focal ratio of f/8 is very exciting for a 12" refractor (the TMB has f/12).
(would like to scan the Virgo cluster with this great instrument, using a 41mm PanO  )
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Kind regards, Christian
Meade 178 ED
Meade 152 ED
Intes Micro Alter M500
Bresser 70/700 Achromat
CGE
EQ-6
Edited by ABC (08/15/08 03:53 AM)
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dothead
super member
Reged: 08/13/08
Posts: 163
Loc: Heidelberg, Germany
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With the 3 inch 60 mm Pentax XL eyepiece (or for that matter, the 60 mm Siebert Obsercatory eyepiece), you'd get the same TFOV (and magnification) in the F/12 TMB as with the 41 Pan - F/8 - combination! (59x with 67 arcminutes TFOV)
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dothead
super member
Reged: 08/13/08
Posts: 163
Loc: Heidelberg, Germany
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Grüße an 'nen Sternfreund in unserer wunderschönen Stadt!
Ralph
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ABC
sage
Reged: 10/22/06
Posts: 422
Loc: Heidelberg, Germany
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You have PM 
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Kind regards, Christian
Meade 178 ED
Meade 152 ED
Intes Micro Alter M500
Bresser 70/700 Achromat
CGE
EQ-6
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Dave Novoselsky
sage
Reged: 06/16/08
Posts: 462
Loc: SE Wisconsin/Chicago
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Quote:
'scuse me, sir, but I don't understand the relevance of your post to those preceding. Could you please elaborate?
I was referring to the web link in the thread. That link also had some other Tak new releases, including the new version of their focal extender that had been discussed in other related Tak threads. Dave
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Time wounds all heels.
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Dave Novoselsky
sage
Reged: 06/16/08
Posts: 462
Loc: SE Wisconsin/Chicago
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Quote:
Grüße an 'nen Sternfreund in unserer wunderschönen Stadt!
Ralph
Come on, Ralph, keep it clean. There are children who read these posts! Dave (Just kidding, and my high school German translated this as your greeting to an observing friend to your beautiful city. Did I get that right?)
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Time wounds all heels.
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Dave Novoselsky
sage
Reged: 06/16/08
Posts: 462
Loc: SE Wisconsin/Chicago
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I have to agree wholeheartedly with the comment about the price for the Tak versus the used (or even a new)APM. I owned an early iteration of the current design now used by APM in a TMB 203 f/9 and have had the privilege of viewing through a 10" APM version. Incredible views and incredible optics and mechanical features. The big Taks are priced at an astronomical level (sorry about that) and are built with an eye (stop it Dave) towards the goverment and college observing market. Those that are sold to private individuals, especially in light (okay, enough) of the cost with the mount, are few and far between. Wealthy amateurs who want a refractor beyond the 203 range are fortunate to have the APM option available as the only real choice. I'd also be surprised to see that much, if any, real difference in performance of the APM as contrasted (whoops, forgot) to the Taks. Given the inherent limits in seeing within our atmosphere, there should be nothing capable of detection by the eye. Dave
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Time wounds all heels.
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ABC
sage
Reged: 10/22/06
Posts: 422
Loc: Heidelberg, Germany
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Quote:
I I owned an early iteration of the current design now used by APM in a TMB 203 f/9 and have had the privilege of viewing through a 10" APM version. Incredible views and incredible optics and mechanical features.
Moreover, the 203 f/7 is still portable:
http://www.apm-telescopes.de/info_bilder.php?action=show&id=3221&artikel_id=72373
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Kind regards, Christian
Meade 178 ED
Meade 152 ED
Intes Micro Alter M500
Bresser 70/700 Achromat
CGE
EQ-6
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dothead
super member
Reged: 08/13/08
Posts: 163
Loc: Heidelberg, Germany
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Dave,
Immaculate translation (but please don't tell the kids!).
More seriously, I totally agree with the points you made on the big Takahashi/Pentax vs TMB/APM apos.
As Daniel Mounsey very rightly pointed out in his thoughtful first post in this thread, once you go to 10 inches or bigger with 3 element apos, the thermal/cooldown issues become the dominant/limiting factors.
Markus Ludes has put his 12 inch TMB for sale because he discovered that it didn't deliver the exquisite views he expected! Reason: The massive 12 inch 3 element lens just couldn't cool down fast enough to keep track with the often rapidly falling post-dusk temperatures here in Germany. So the sperical correction just almost never was good enough under the real life obseving conditions at his observatory. Such a scope would fare much better at a location in the tropics with minimal temperature changes. The TMB/APM 21 inch APO (elements) just isn't a practical telescope almost anywhere in the world!
A Petzval system with two front and two rear elements would come much nearer to solve the cooldown/sperical correction issues.
Just my two cents!
Ralph
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Dave Novoselsky
sage
Reged: 06/16/08
Posts: 462
Loc: SE Wisconsin/Chicago
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I agree. The 8" took a long time to cool down in relation to my 6" TMB but once there, it was fine, When we had extreme drops in temperature that same issue you describe above reared its head but never to the extreme you describe in your post.
Of course, I was dealing with a lot smaller volume of glass. I just ran the numbers on the overall difference in actual glass area between my 8" and Markus' 12" and the increase between these two optics is staggering, recognizing the the increase of 4" in diameter is not a true measure of the increase the size or ability of the optic. The superior light gathering ability is a result of a whooping increase in the surface area of the elements, which is more akin to a geometric increase. The vastly larger surface area is what, in theory, should give you much enhanced views. But those now huge triple elements are going to take a LOOOONNNNG time to settle down and I have no doubt Markus had a real beast on his hands in the conditions you describe. Dave
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Time wounds all heels.
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