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Tips guna tripod murah utk astronomy… 31 Disember 2009

Posted by azmirul in Astronomy, Astrophotography, Photography.
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Maklumat ni mungkin dah tak relevent sebab sekarang aku dah guna equatorial tripod.. tapi skill guna tripod murah kira value-added heher.. kat bawah ni aku sediakan tip2 utk guna tripod murah utk astronomy observation terutamanya tripod yg kurang stable dan takder slow motion control… maklumat ni mungkin tak tepat tapi percaya atau tidak, ia amat berguna (paling tidak utk akuler… heher): (selanjutnya…)

Magnification, sensor size and crop factor 25 Disember 2009

Posted by azmirul in Astrophotography, Photography.
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setelah study dibuat, akhirnya berjaya juga aku memahami secara “kasar” macamner nak calculate magnification power bila guna webcam/camera bersama telescope. rupa2nya semuanya amat bergantung kpd sensor size yg akan menentukan crop factor dgn perbandingan dibuat berdasarkan format film 35mm.. patutler field of view (FOV) bila guna webcam semakin kecil berbanding bila guna DSLR.. ini disebabkan sensor webcam yg amat kecil iaitu dlm 4mm diagonal (utk SPC900NC) berbanding DSLR iaitu 26.7mm diagonal (EOS 350D).  So, utk full frame sensor yg hampir sama dgn standard film 35mm (43.3mm diagonal) akan memberikan FOV yg lebih besar. So, ada kemungkinan wide-angle lens utk 35mm camera menjadi normal lens utk DSLR camera!

Berikut adalah beberapa calculation yg aku buat.. ni berdasarkan apa yg fahamler.. kalo tak tepatpun, aku raser masih bleh digunakan utk buat perbandingan.

Magnifaction of Telescope Apex 90mm with Philips SPC900NC Webcam:

  • crop factor for Philips SPC900NC is 10.8
    ( 35mm diagonal/sensor diagonal = 43.3/4 = 10.8 )
  • 35mm equivalent telescope focal length when using spc900nc
    ( 1250mm focal length * 10.8 = 13500mm )
  • magnification calculation (divide by 50mm) is 270x
    ( 13500mm/50mm = 270x  )

Magnifaction of Telescope Apex 90mm with DSLR Canon EOS 350D:

  • crop factor for Canon APS-C sensor is 1.6
    ( 43.3/26.7 = 1.6 )
  • 35mm equivalent telescope focal length when using Canon EOS 350D
    ( 1250mm focal length * 1.6 = 2000mm )
  • magnification calculation (divide by 50mm) is 40x
    ( 2000mm/50mm = 40x )

Common crop factor:

  • 35mm film = Diagonal (43.3mm) = 36 x 24 mm ( Crop factor 1 ), 3:2 aspect ratio
  • DSLR with Canon APS-C sensor = Diagonal (26.7) = 22.2 x 14.8 mm ( Crop factor 1.6), 3:2 aspect ratio
    eg crop factor calculation = 43.3/26.7 = 1.6
  • Typical compact digital camera = 1/2.5″= 5.76 x 4.29 mm ( Crop factor 6.02 ), 4:3 aspect ratio
  • Common camera phone/ webcams/ digital camcorders = 1/6″ = 2.40 x 1.80 mm ( Crop factor 14.14 )
  • SPC900NC webcam = 35mm diagonal/webcam sensor diagonal = 43.3/4 ( Crop factor 10.8)

Reference: (selanjutnya…)

Gambar abstrak guna telescope dan webcam 21 Disember 2009

Posted by azmirul in Photography.
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Ni gambar yg aku ambil guna Orion Apex 90mm + Philips SPC900NC webcam… (for info, gambo ni dah photoshopped):

1. Strength:

2. Single:

3. Kemuncup:

Lens Magnification Comparison with Orion Apex 90mm 15 Disember 2009

Posted by azmirul in Astrophotography, Photography.
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Aku ada buat gambarajah utk compare magnification antara lens yg berbeza. Ketepatan gambarajah ni memang bleh diragui heher, tapi blehler roughly agak… aku sketch guna subject dish kat cell tower dari view telescope Apex (1250mm focal length):

Gambar bulan sabit guna webcam + telescope 10 Disember 2009

Posted by azmirul in Astronomy, Photography.
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Ni gambar bulan sabit pagi tadi guna Philips SPC900NC + telescope Orion Apex 90mm.. (masa ambil dlm pukul 6 – 7pagi)… sorry, gambar tak sharp tapi kira bolehler utk collection aku sebab sendiri yg ambil, sebelum ni asyik tgk gambar orang ajer… heher

  

Gambar sambungan Philip SPC900NC webcam dgn Orion Apex 90mm 7 Disember 2009

Posted by azmirul in Astronomy, Photography.
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Ni gambar sambungan webcam ke telescope:

1. Philip SPC900NC webcam + adapter (front view)

2.  Philip SPC900NC webcam + adapter (side view)

3.  How to connect Orion Apex 90mm with webcam (close-up)

4. Complete setup image:

jenis2 sambungan yg dah try (ikut turutan object):

1st configuration:
(webcam + webcam adapter) + 45degere diagonal correction lens + telescope

2nd configuration with 2x barlow lens
(webcam + webcam adapter) + 45degere diagonal correction lens + 2x barlow lens + telescope

sambungan slr yg dah try:

1. Canon EOS 350D + telescope

sambungan yg blum try:

1. Canon EOS 350D + ( eyepiece + eyepiece adapter ) + telescope
2. (webcam + webcam adapter) + 45degere diagonal correction lens + ( eyepiece + eyepiece adapter ) + telescope

Webcam with telescope 7 Disember 2009

Posted by azmirul in Astronomy, Photography.
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masa beli telescope haritu, aku ader beli webcam adapter.. hari ni baru sempat try sambung webcam kat telescope Orion Apex 90mm. Aku guna webcam Philip SPC900C… webcam ni mula2 kena cabut focus ring dia baru bleh sambung dgn adpater (focus tak perlu sebab kita akan focus di telescope)… bleh refer link kat bawah macamner nak buat:

http://www.nightskyjournal.com/2008/10/24/from-webcam-to-astrocam-my-phillips-spc900nc-journey/

mula2 tadi panic sebab adapter aku takleh screw (tak sampai), aku tak pastiler apa salah kat mana.. tapi seperti biasa improvised solution, aku selotape ajer skit, janji bleh pakai… heher

seperti biasa subject focus adalah cell tower kat area rumah aku.. (refer post sebelum ni kalo nak tahu berapa jauh cell tower tu)… so, kat bawah ni sample gambar yg aku ambil:

1. Webcam + 1250mm telescope img1

2. Webcam + 1250mm telescope img2

3. Webcam + 1250mm telescope img3

4. Webcam + 1250mm telescope img4

5. Webcam + 1250mm with 2x barlow lens

aku tak pasti macamner nak kira magnification utk semua image kat atas… tapi kalo roughly samer macam slr, mungkin image #1-#4 bersamaan 25x magnification dan image #5 adalah 50x

Beza gambar guna SLR telephoto 200mm dgn telescope 1250mm 5 Disember 2009

Posted by azmirul in Astronomy, Photography.
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Kalo nak tahu beza result guna lens magnification/zoom yg berbeza, bleh tgk comparison gambar kat bawah (camera SLR tu abang aku punya, telescope tu guna aku punya Orion Maksutov-Cassegrain Apex 90mm):

Magnification=Focal length of the Objective/Focal length of the Eyepiece

kalo ikut formula kat atas dgn “andaian”[1] focal length eyepiece utk SLR adalah 50mm, telephoto lens 200mm* bersamaan dgn magnification sebanyak 320/50=6.4x dan gambar no dua guna 1250mm focal length telescope adalah 1250/50 = 25x

*35mm equivalent focal length adalah 320mm

update (8 Dec 2009):
utk makluman jarak antara cell tower dgn telescope dlm 0.52 km

1. Canon EOS 350D + 200mm telephoto lens (4x 6.4x magnification)

2. Canon EOSD 350 + telescope Apex1250mm (25x magnification)

3. Gambar cell tower yg sama without any zoom magnification guna iphone utk comparison

(sorry gambo gelap, masa captured berbeza dgn gambar1 dan 2 iaitu waktu petang semalam, gambo ni aku baru capture jam 7 lebih pagi tadi sebab tak sabo2 nak submit kat blog ni heher)

p/s: lepas ni, nak try ambil gambar guna telescope baru aku tu guna magnification eyepiece yg lagi power (>50x)

[1] ref:

http://photography-on-the.net/forum/showthread.php?t=29133
http://www.photography-forums.com/calculate-zoom-t4135.html
http://photography-on-the.net/forum/showthread.php?t=21278