www.astrocafe.hk

Dear all,

Be prepared to move up larger aperture to 8inch plus for Ha solar and DSO Ha imaging. Yes, dual purpose scope.

A genius method to di-electrically coat the front corrector to achieve big ERF at 1/4 lambda.
At present the biggest ERFs are 180mm by Baader D-ERF (1/10 lamda) and up to rarely made 10 inch by Daystar (1/4 lambda).

http://www.airylab.fr/AirylabUS/index.p ... &Itemid=67

Not cheap and you have to add up Etalon and blocking filter.

Raymond

Raymond TSE 寫:Dear all,

Be prepared to move up larger aperture to 8inch plus for Ha solar and DSO Ha imaging. Yes, dual purpose scope.

A genius method to di-electrically coat the front corrector to achieve big ERF at 1/4 lambda.
At present the biggest ERFs are 180mm by Baader D-ERF (1/10 lamda) and up to rarely made 10 inch by Daystar (1/4 lambda).

http://www.airylab.fr/AirylabUS/index.p ... &Itemid=67

Not cheap and you have to add up Etalon and blocking filter.

Raymond

我看你是準備動手了...

This is only the 1st batch production with a few C8EdgeHDs being released.
Better not to be the guinea pig in their test run.

With the 33% central obstruction, C8 is only about 7 inch in effective clear aperture.
Not much jumping up from Lunt 152.

Waiting for C9 or C11 instead

But at least it is commercially viable for SCTs to be adapted for solar Ha.

This also re-enforces my belief that SCT is highly versatile as :-

1. giant spotting scope for bird/landscaper watching/photography;
2. planetary/Moon visual and imaging with 2-3x;
3. solar white light/Ha visual and imaging; and
4. DSO visual at F10 or F7; and imaging with 0.7x reducer or by Fastar at around F2.

Raymond

Raymond TSE 寫:This also re-enforces my belief that SCT is highly versatile as :-

1. giant spotting scope for bird/landscaper watching/photography;
2. planetary/Moon visual and imaging with 2-3x;
3. solar white light/Ha visual and imaging; and
4. DSO visual at F10 or F7; and imaging with 0.7x reducer or by Fastar at around F2.

Raymond

雖和而不同的觀點與討論，一些個人看法：

對第一項有些保留。

第二項用於攝影的優勢是共識了，但仍比DOB GOTO系統稍遜，目視上會比牛反差些。

第三項是值得探討與實踐

第四項我認為現成的方案仍有不少機械等問題待改善/解決

始終我認為施卡是一種妥協的產品，想面面俱圓，但結果沒有強項

我倒想花些時間弄一台為拍攝行星月面而優化的望遠鏡，當然是純反射光學系，很大機會牛頓，但會用在一套Celestron Ultima的义式赤道儀上，用Byer蝸輪，有PEC及自動導星口的，一顆9V電池可以用超過一晚。

SCT's relative strength is its planetary/moon imaging in compact size. The most notable eg is C14.
The other options and uses are just regarded as bonuses.

SCT could be placed near home window as surplus scope for quick & casual viewing on terrestial objects,
white light solar, Moon watching etc.

For serious viewing/imaging, go to dark site or Observatory using dedicated scopes.

Raymond

拍月面行星還是口徑說了算，我用Dob 16 GOTO可以一個人開車運出去一個人架起來用，

viewtopic.php?f=27&t=3151#p20487

viewtopic.php?f=27&t=3154#p20514

Meade 16 或C14不可能了，

viewtopic.php?f=12&t=368#p4459

小至150牛頓反射，就算是中學生自製的，拍月面深空也可以，C6不見得有特別優勢，

viewtopic.php?f=6&t=2938&start=40#p22922

viewtopic.php?f=6&t=2938&start=40#p22948

我曾擁有C8七年時間，當時也有自家天台可以做固定觀測，但就是發現這類施卡只是應對大眾化市場需求的妥協產物，並沒有獨特的長處，David那台也擱在一旁很多年沒用了。

若是地面用的，始終受視寧度影響，我會用LOMO 80 APO，因為那是實用上限，那是在同口徑下全球修正度最高的望遠鏡。

鳥攝我倒想稍後拿台RH200到濕地公園試試，600mm 焦距 f3光圈，42mm 直徑極高修正度良像圈，有機會可以跟什麼856鏡頭比比。

Dear Savio

"鳥攝我倒想稍後拿台RH200到濕地公園試試，600mm 焦距 f3光圈，42mm 直徑極高修正度良像圈，有機會可以跟什麼856鏡頭比比。"

May be we could go together for a shoot-out side-by-side to see the imaging abilities of RH200 and C925-EdgeHD.

Or erect-image binoviewering bird-watching at 120x close-up.

Raymond

Raymond TSE 寫:Dear Savio

"鳥攝我倒想稍後拿台RH200到濕地公園試試，600mm 焦距 f3光圈，42mm 直徑極高修正度良像圈，有機會可以跟什麼856鏡頭比比。"

May be we could go together for a shoot-out side-by-side to see the imaging abilities of RH200 and C925-EdgeHD.

Or erect-image binoviewering bird-watching at 120x close-up.

Raymond

我有興趣試，

RH200 vs C9.25 EdgeHD 鳥攝 (RH200 不能目視)

LOMO 80 APO + Baader Mark V bino vs C9.25 EdgeHD + Your Bino 目視 @120x (前者肯定較暗，但視寧度應已限制大口徑發揮，當然日間地面用，60x是較合適的倍率)