Telescope War - Thomas Back Vs Maxivision

夸克星 註冊時間: 2003-10-09 文章: 2196

Dear Telescope Enthusiasts,

After waiting for such a long time we finally get a clear night with stability good enough to test the new Maxivision 5 inch APO. Frankly speaking I just couldn’t belief my eyes.

The new Maxivision 5 inch apochromatic triplet telescope just performs so good than I cannot belief my eyes. It could easily be pushed up to 100X per inch and it gives a contrast, resolution and color correction, according to my memory, still better than that of the AstroPhysics 130 EDT.

Memory is not reliable. So we carried out an AB comparison test on the spot. Target was the lunar surface.

It happened that we just had a Thomas Back 7 inch Apochromatic Triplet telescope by the side and so we AB compared the performance of the TMB and Maxivision. In a magnification of about 300X ( TMB 7 inch f/8 used a Pentax XL 5.2 mm eyepiece, gives 275X. Maxivision 5 inch f/7.5 : used a TeleVue 2.5 X barlow + Takahashi LE 7.5 mm eyepiece gives 318 X ) Except that the TMB is much brighter everything we saw are identical in both telescopes, with the Maxivsion slightly at a higher contrast, and slightly at a less color aberration. We could hardly detect any advantages ( except more brightness ) in the Thomas Back comparing with the smaller Maxivision.

Thomas back is already regarded as the top performer in triplet apochromatic refractor. So is it high time for us to think twice before spending money on a Takahashi TOA 130, AstroPhysic EDT130 or a TMB 5 inch ? Since at 1/3 the price you get a same performance ( or even better ) Maxivision 5 inch APO.

I didn't say that Thomas Back is not good. Indeed Thomas Back performed excellently. But the fact is, the Maxivison is just too good.

Best regards
Chan Yuk Lun

中子星 註冊時間: 2003-10-08 文章: 1417 來自: H.K

镜神，我英文唔好有翻译吗；嘿嘿！

中子星 註冊時間: 2003-07-15 文章: 1418 來自: HK

jj12667 寫到:

镜神，我英文唔好有翻译吗；嘿嘿！

試下用此來翻译http://translate.google.com/

白矮星 註冊時間: 2004-07-22 文章: 917

Any comment on the field flatness?

Thanks!
Andy

夸克星 註冊時間: 2003-10-09 文章: 2196

sn-10 寫到:

Any comment on the field flatness?

Thanks!
Andy

Daar Mr. Andy,

Both the Maxivision and TMB gave field flat to the very edge of the eyepiece. There was not the slightest bit of aberration of any kind detected in the entire field of view, in both telescopes .

Best regards
Chan Yuk Lun

中子星 註冊時間: 2003-07-11 文章: 1680 來自: Malaysia

視場亮度的不一樣，是否因鍍膜的問題？測試期間的天氣變化如何？

中子星 註冊時間: 2005-09-13 文章: 1495 來自: Hong Kong

Chanlunlun 寫到:

Dear Telescope Enthusiasts,

After waiting for such a long time we finally get a clear night with stability good enough to test the new Maxivision 5 inch APO. Frankly speaking I just couldn’t belief my eyes.

The new Maxivision 5 inch apochromatic triplet telescope just performs so good than I cannot belief my eyes. It could easily be pushed up to 100X per inch and it gives a contrast, resolution and color correction, according to my memory, still better than that of the AstroPhysics 130 EDT.

Memory is not reliable. So we carried out an AB comparison test on the spot. Target was the lunar surface.

It happened that we just had a Thomas Back 7 inch Apochromatic Triplet telescope by the side and so we AB compared the performance of the TMB and Maxivision. In a magnification of about 300X ( TMB 7 inch f/8 used a Pentax XL 5.2 mm eyepiece, gives 275X. Maxivision 5 inch f/7.5 : used a TeleVue 2.5 X barlow + Takahashi LE 7.5 mm eyepiece gives 318 X ) Except that the TMB is much brighter everything we saw are identical in both telescopes, with the Maxivsion slightly at a higher contrast, and slightly at a less color aberration. We could hardly detect any advantages ( except more brightness ) in the Thomas Back comparing with the smaller Maxivision.

Thomas back is already regarded as the top performer in triplet apochromatic refractor. So is it high time for us to think twice before spending money on a Takahashi TOA 130, AstroPhysic EDT130 or a TMB 5 inch ? Since at 1/3 the price you get a same performance ( or even better ) Maxivision 5 inch APO.

I didn't say that Thomas Back is not good. Indeed Thomas Back performed excellently. But the fact is, the Maxivison is just too good.

Best regards
Chan Yuk Lun

-----------------

粗略翻譯
致：各位天文望遠鏡狂熱人仕
在等待了很長時間，我們終於有一個足夠清晰與大氣穩定的晚上來測試此新的 Maxvision ”大有可觀” 5 英吋口徑複消色差折射鏡。我可以坦白地說我只是不能相信我的眼睛。
此新的”大有可觀” 5 英吋口徑複消色差折射鏡的表現是這麼好我不能相信我的眼睛。此鏡可以輕易地被推往放大率每英吋100x，而據我記憶所及此鏡的反差，解像力及色差修正是仍然較壹枝 Astro Physics 130EDT 優勝
記憶是不可靠的。所以我們進行了一次 A 與 B 的對比測試。目標是月球的表面。
我們剛剛有了一枝 Thomas Back TMB 7 英吋口徑 f/8 複消色差折射鏡在一起作此對比測試。在放大倍率約 300x （TMB 用賓得 XL5.2 毫米目鏡得出 275x ”大有可觀”用 TeleVue 2.5 × 增焦鏡加上高橋 7.5 毫米目鏡得出 318 x ）。除了 TMB 的影像有極為比較高的亮度，這 2 枝鏡的其他我們所見都是相同只就是”大有可觀”有些微較高的反差及些微不及的色差修正。
我們幾乎不能夠測出 TMB 與”大有可觀”在比較上有任何優勝（除却光亮度）。
TMB 已被認為是最佳表現的三片鏡片複消色差折射鏡。因此我們以後要三思而後才可花錢購買高橋 TOA130 ，Astro Physic EDT130 或 TMB 5 英吋？皆由於以 1/3 價錢的”大有可觀”你可以得到相同表現（或更佳）。
我並沒有說 TMB 是為不好。事實上 TMB 的表現是非常出色。但事實上”大有可觀”是太好。
謹致問侯
陳玉麟

夸克星 註冊時間: 2003-10-09 文章: 2196

universe24 寫到:

視場亮度的不一樣，是否因鍍膜的問題？測試期間的天氣變化如何？

Dear Mr Universe24,

The Thomas Back has a 7 inch aperture lens while the Maxivision has only a 5 inch lens. The Thomas Back has a light grasp about 200% that of a Maxivison.

The difference in brightness is due to the bigger aperture of the TMB. Coating may brings out a little difference, but not the main cause.

Best regards
Chan Yuk Lun

中子星 註冊時間: 2005-09-13 文章: 1495 來自: Hong Kong

我們不如來壹次來ED折射鏡大格鬥
例如Maxvision ”大有可觀” ED127 對 Takahashi “高橋” TSA102 .

夸克星 註冊時間: 2003-10-09 文章: 2196

TONGKW 寫到:

我們不如來壹次來ED折射鏡大格鬥
例如Maxvision ”大有可觀” ED127 對 Takahashi “高橋” TSA102 .

Dear Mr. Tong,

This is a very good suggestion. However all telescopes should be of equal aperture. Because my guess is that all 4 inch refractor could easily be outperformed by the Maxivision 5 inch APO.

So in terms of the telescopes that still exist in HK at the moment, the best arrangment, in my own opinion, should be AstroPhysics 130 EDT Vs Takahashi TOA130 Vs TEC 140 triplet APO Vs Maxivision 127 triplet APO.

This is what I call Telescope War of Century.

Best regards
Chan Yuk Lun

白矮星 註冊時間: 2004-07-22 文章: 917

Just feeling that comparing only the performance by watching the moon isn't quite convincing.

夸克星 註冊時間: 2003-10-09 文章: 2196

sn-10 寫到:

Just feeling that comparing only the performance by watching the moon isn't quite convincing.

Dear Mr. 10,

Totally agree.

Nevertheless there is no other object for comparision at the meoment. Jupiter is too low on the horizon, Saturn too late to rise and Mars too small to tell a tale.

So moon is the only sensible target. The lunar surface could tell quite a great deal of story - color correction, contrast, resolution , image break down.....etc.

Of course for a complete performance evaluation we need to target at various objects and compare. But such a test, I 'm afraid, is not feasible at the moment.

Best regards
Chan Yuk Lun

白矮星 註冊時間: 2004-07-22 文章: 917

It is feasible.

A simple 30s exposure testing with DSLR can already tell us how good their performance are in terms of two important factors for judging refractors:

1, CA tolerance
2, Coma tolerance

With such a test we don't even need AB comparison, human eyes sometimes cheat, but the CCD doesn't.

Regards,
Andy

夸克星 註冊時間: 2004-03-15 文章: 10341

sn-10 寫到:

human eyes sometimes cheat, but the CCD doesn't.

I can't agree anymore~ Very Happy

白矮星 註冊時間: 2004-07-22 文章: 917

Wah!! 寫到:

sn-10 寫到:

human eyes sometimes cheat, but the CCD doesn't.

I can't agree anymore~ Very Happy

Why not?

If I'm too excited or being a little bias to observe with my own scope, even if there's abberration I would tell myself it is still as good as a TOA130.

While the CCD records everything without any bias; the data is solid but human conception isn't. Smile