CCD Imaging and Processing 0 .0 2 Aschen 3.1 Alan Chen CFAS St ar - PowerPoint PPT Presentation

CCD Imaging and Processing 0 .0 2 Aschen 3.1 Alan Chen CFAS St ar Part y 20 0 2 1

0 .0 2 CCD Imaging and Processing Aschen 3.1 � The camera � Mat ching scope wit h camera � Taking t he image � Processing t he image � Final result s 2

0 .0 2 The Camera Aschen 3.1 • Choosing t he camera � Many different opt ions t o st art imaging wit h � Digit al camera - easiest way t o st art Nikon CP9 9 5 � Olympus C-series � Full digit al SLR � � Webcam - excellent for planet s (check QCUIAG) True CCD version (not CMOS based) � » Philips Toucam Pro, Vest a Pro » Older Logit ech/Connect ix B&W Quickcam � Video camera - I.e. St ellaCam - semi-deepsky capable � True CCD camera for ast ro-imaging 3

0 .0 2 The Camera Aschen 3.1 • True CCD camera � Several major CCD camera vendors � SBIG - probably t he largest and most recognizable � Apogee - high end cameras � FLI - high end cameras � St arlight Express - great values � SAC - very inexpensive t o st art wit h - lacking soft ware support � All are good choices 4

0 .0 2 The Camera Aschen 3.1 • St arlight Express � MX7C - why is t his a good choice? � An excellent first camera Good for st art ers and advanced imagers � Relat ively simple t o operat e, especially for color images � � Affordable by CCD st andards 750 x58 2 resolut ion t ops in it s price range � � Small and compact - 2” dia � Light weight Balance kit not necessary for t he LX20 0 � Approximat ely t he weight of a good 2” eyepiece � � Primary SBIG equivalent considered - ST-7E 5

0 .0 2 The Camera Aschen 3.1 • St arlight Express � MX7C (cont .) � One shot camera - color mat rix filt ers - CMY Synt hesizes RGB from t he filt ered signals � Much less overall imaging t ime involved for color � » Color filt er wheel not required Probably not as accurat e a color balance as RGB imaging � � Self-guiding capabilit y wit h St ar20 0 0 int erface Uses t he same chip for imaging and guiding � Sensit ivit y reduced by 50 % as a result � Simple soft ware int erface t o self-guide � 6

0 .0 2 Mat ching Scope and Camera Aschen 3.1 • General guidelines � Sampling � Depends on seeing Good seeing (i.e. 1 are-sec) can t olerat e higher resolut ion � sampling rat es Sampling rat e (arc-sec/pixel) = 20 6 x (pixel size)/(focal � lengt h) » Pixel size is dependent on t he camera » FL can be varied by focal reducers and barlow lenses Scope and camera should provide a t ypical sampling rat e of � approximat ely 2 arc-sec/pixel » 1 2”LX20 0 @ f/3.3 = 1 .7 arc-sec/pixel (good mat ch!) » Rat es>2 is undersampling and rat es<2 is oversamplign 7

0 .0 2 Taking t he Image Aschen 3.1 • Imaging process � Set up t he opt ics/camera 8

0 .0 2 Taking t he Image Aschen 3.1 • Imaging process � Set up scope, camera, lapt op and align � No hot plugging - t urn everyt hing on aft er set up 9

0 .0 2 Taking t he Image Aschen 3.1 • Imaging process � Choose first object � Slew t o it using HPP � HPP t arget s a nearby bright st ar t o cent er � Use t his opport unit y t o focus CCD camera on st ar � Slew t o object Not e: Ast roart is referenced in t his present at ion Great support for St arlight cameras � Relat ively inexpensive (~$1 50 ) � » Handles bot h camera cont rol and image processing 1 0

0 .0 2 Taking t he Image Aschen 3.1 � Take a quick 5 t o 3 0 second image of t he object 1 1

0 .0 2 Taking t he Image Aschen 3.1 � Select a st ar anywhere on t he image t o fine focus 1 2

0 .0 2 Taking t he Image Aschen 3.1 • Select t he focus box - st ar is rough focused 1 3

4 1 • Good focus has been achieved Taking t he Image 0 .0 2 Aschen 3.1

0 .0 2 Taking t he Image Aschen 3.1 • Aut oguider set up � Example uses a video camera as t he guider � Mint ron 1 2V1 (0 .0 0 0 1 lux) � St ar20 0 0 equally effect ive � Scope set up � Correct ion speed � Correct ion range � Backlash 1 5

6 1 Taking t he Image • Taking t he image 0 .0 2 Aschen 3.1

0 .0 2 Taking t he Image Aschen 3.1 • To t ake t he image, select image or sequence � Image generat es a single image � Sequence allows mult iple images t o be t aken and saved 1 7

0 .0 2 Processing t he image Aschen 3.1 • Ast roart : bat ch processing menu • For t he MX7C camera, t he Ant i- aliasing set t ing can be increased t o minimize t he point source issue for one-shot cameras, eliminat ing t he occassional wild st ar color 1 8

0 .0 2 Processing t he image Aschen 3.1 • Bat ch processing: select ing t he images 1 9

0 .0 2 Processing t he image Aschen 3.1 • Bat ch processing: result s in LRGB separat ion 20

0 .0 2 Processing t he image Aschen 3.1 • Pre-processing: select ing st ars t o aut oalign 21

0 .0 2 Processing t he image Aschen 3.1 • Pre-processing: select files t o combine 22

0 .0 2 Processing t he image Aschen 3.1 • Pre-processing: 30 x2min. images combined 23

0 .0 2 Processing t he image Aschen 3.1 • DDP processing - compresses signal range 24

0 .0 2 Processing t he image Aschen 3.1 • DDP processing - result of ddp filt er 25

26 Processing t he image • Unsharp Mask filt ering 0 .0 2 Aschen 3.1

0 .0 2 Processing t he image Aschen 3.1 • Unsharp Mask filt ering � Sharpens t he fine nebulosit y and t ight ens t he st ar images 27

0 .0 2 Processing t he image Aschen 3.1 • St ret ching t he image wit h a hist ogram 28

0 .0 2 Processing t he image Aschen 3.1 • Color processing � Repeat t he procedure as in slide 22 t o combine all of t he R-frames t oget her, t hen t he G-frames and finally t he B-frames � Upon complet ion, t here should be one L, R, G and B frame (4 t ot al frames) 29

0 .0 2 Processing t he image Aschen 3.1 • Color processing � Trichromy command � We have color! 30

0 .0 2 Processing t he image Aschen 3.1 • Color processing � Tweaking colors � Sliders at t he far right t o adjust color int ensit y and balance � Hist ograms can also be employed for bet t er cont rol � Linear st ret ch preferred for color frames 31

0 .0 2 Processing t he image Aschen 3.1 • Color processing - final result : saved as a jpg 32

0 .0 2 Processing t he image Aschen 3.1 • Color processing - t weaking in Corel Phot opaint 33

0 .0 2 Processing t he image Aschen 3.1 • Corel Phot o - resampling t o square t he pixels 34

0 .0 2 Processing t he image Aschen 3.1 • Corel Phot o - Eliminat ing image defect s 35

0 .0 2 Processing t he image Aschen 3.1 • Corel Phot o - Using t he clone t ool 36

37 • Corel Phot o - Gaussian blur Processing t he image 0 .0 2 Aschen 3.1

0 .0 2 Processing t he image Aschen 3.1 • Corel Phot o - save wit h compression - Done! 38

39 M42: 8 0 mm St ellarvue 0 .0 2 Aschen 3.1