Delivering Aesthetically-Pleasing DSLR Images

1. Delivering Aesthetically-Pleasing DSLR Images • Humayun Qureshi

2. Introduction • About Me • What I’m Going to Present • Software Listing

3. About Me • Technical • Creative

4. What I’m Going to Present • When Mark Approached Me... • Theory, in Practice (pre), and In Practice (post) • Disclaimer: Right or Wrong?

5. Software Listing • IRIS • Adobe Photoshop • Diffraction Limited MaxIm DL • Simulation Curriculum Starry Night Pro Plus • Canon EOS Utility & Digital Photo Professional

6. Theory • Composition

7. Composition • What is Composition?

8. What is Composition? • “The organisation or grouping of the different parts of a work of art so as to achieve a unified whole.”

9. What is Composition? • The pleasant arrangement of subject matter in a frame which has a powerful ability to attract the eye and keep it exploring the image for as long as possible.

10. The Rule of Thirds • Focal points in a composition should fall on lines of thirds. • Example: at least one eye in a portrait. • Example: the Sun or Moon or planets in a terrestrial image. • Example: bright stars or object of interest in an astrophotograph.

14. Framing • What is Framing?

15. What is Framing? • Framing is what you do with your camera, with regards to orientation. • The aim is to try and present the simplest and most balanced scene.

18. Cropping • The easiest way to frame your scene in a balanced and pleasing way is to crop your final image. • We’re often hesitant to throw away all that precious sensor space, but, thinking about the way some bright objects may appear in the frame with relation to the main subject matter, may assist in providing for a more pleasing composition.

19. Using Planetarium Software for Composition • Camera Orientation • Non-centred compositions work if other objects can be included to balance. • Harder for long focal length imaging due to guide star constraints, but, cropping the final image appropriately can help here.

22. In Practise (pre) • Capture • Calibrate • Register, Crop, Normalise, Stack and Stretch

23. Capture • Using Software to Gauge Exposure

24. Using Software to Gauge Exposure • Exposure Length • Histograms and Simulated Exposure Length • Highlight and Shadow Clipping

25. Exposure Length • Dark Skies vs Suburban Skies • ISO Limitations and Capabilities in Older and New Cameras • (ISO-400=300 seconds; ISO-800=150 seconds; ISO-1600=75 seconds)

26. Histograms and Simulated Exposure Length • Example: Digital Photo Professional show’s a good histogram at 30 seconds for a test exposure taken at ISO-6400. • ISO-6400=30 seconds; ISO-3200=60 seconds; ISO-1600=120 seconds. • Exploit RAW latitude to work out your optimum exposure.

29. Highlight and Shadow Clipping • Alt+M and Alt+N in DPP will show where clipping is occurring as a blue and red mask; adjust your exposure until clipping is minimised. • Inevitability of Highlight Clipping

30. Calibration • Dark Frames • Flat Frames (And, Associated Dark Frames)

31. Dark Frames • When and What to Capture • The Use of Dark Libraries

32. Flat Frames (And, Associated Dark Frames) • How and What to Capture • Software-Assisted Capture

33. How and What to Capture • The Use of Lightboxes, Light Panels and Computer Screens • Capture somewhere in the vicinity of 16-25 frames and median combine. • At lowest native ISO setting of your system.

34. Software-Assisted Capture • Use histogram displayed in DPP to fine tune your exposure.

36. Register, Crop, Normalise, Stack and Stretch • IRIS’ Powerful Registration Commands • Crop Redundant Areas • Normalise • Kappa-Sigma Stacking • Stretching

37. IRIS’ Powerful Registration Commands • coregister2 <input> <output> <numfiles> • coregister4

38. Crop Redundant Areas • For normalising and for the kappa-sigma stacking routine. • window2 <input> <output> x1 y1 x2 y2 <numfiles> • Ignore Black Pixels

40. Normalise • Normalising (or, offsetting) sets median value of the background in each image to 0. • This aids in increasing dynamic range and allows kappa-sigma stacking to work optimally. • noffset2 <input> <output> 0 <numfiles>

41. Kappa-Sigma Stacking • Ideal solution is the sum of all images (caveat: cosmic rays, satellite trails, aeroplane trails, outlying data). • Median is a better option, but, still not the best as it has low signal-to-noise compared to summation. • Kappa-sigma takes the best of both of the above algorithms. • composit command. • MaxIm DL SD Clip.

42. Stretching • arcsin hyperbolic stretching -- form of non-linear stretching. • asinh <alpha> <intensity> • Same result acheivable in MaxIm DL by using DDP but disabling the kernel filters. • Click background point and mid-level.

45. In Practise (post) • Levels • Curves • Vibrance and Saturation

46. Levels • Use levels adjustment layer to fix colour balance. • Select each individual channel, hold the Alt key down, and move the mouse in from the left to see where clipping starts to occur in the shadows. • Do the same from the right hand side of the levels dialog to see where highlights start to clip -- typically, stars will be clipped a bit.

47. Curves • Use curves adjustment layers to increase brightness. • Try using the built-in Photoshop default curves adjustments such as lighten, and also the linear contrast curves adjustments layers.

48. Vibrance and Saturation • Use the vibrance adjustment layer to handle vibrance and also saturation. • Increasing vibrance takes the dullest colours in the image and increases their saturation. • Take care not to overdo it as you will start to introduce artefacts in your image (I use a vibrance setting of 20<x<50 and saturation 10-20% of vibrance).