Three methods of composing images for better science

photography

Martin ValentNational museum – Prague – Czech Republic

Contents1. Introduction

2. Greater depth of field (stacking images in Z axis)

3. Panoramic picture (merging images in X and Y axes)

4. High dynamic range photography (HDR)

5. Summary

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1. IntroductionProblems with photos narrow depth of field low resolution narrow field of view insufficient dynamic range

Solution three ways of stacking images

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2. Greater depth of fieldProblem: narrow depth of field with high

magnification – close up photography or microscope photography.

Solution: stacking series of pictures with same exposure and varying depth of field.

Note: The depth of field shrinks with decreasing subject distance, decreasing aperture value (f-stop) and increasing focal length.

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2. Greater depth of fieldHow to do it

1. Use tripod or stand for exactly aligned images.

2. Maintain same exposure for all images (program

M - manual exposure setting on your camera is highly recommended).

3. Take series of pictures with overlapping depth of field.

4. Take the same series of images again, to be sure you have good source photos.

5. Use software like CombineZP to merge pictures into final image with full depth of field.

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2. Greater depth of fieldHow to do it – using freeware CombineZP.

1. New – select images to be merged.

2. Align and Balance Used Frames (Quick) – GO.

3. Select method of stacking – e.g. Do Stack – GO.

4. Save.

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2. Greater depth of fieldExample: 14 images

CombineZP

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3. Panoramic pictureProblem: low resolution of images and/or lens

causing too narrow field of view.

Solution: assembling set of pictures with same exposure and same focal length.

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3. Panoramic pictureHow to do it (part A)1. Choose a focal length with minimal optical

distortion (e.g. more than 35 mm).2. Focus on desired subject. After that, it is useful to

turn off automatic focusing (AF), by switching to manual focusing (MF).

3. Determine exposure, using the brightest part of the scene. Exposure values (exposure time, f-stop and ISO speed rating) are taken in any suitable automatic/semiautomatic exposure program (usually, the best program is A – aperture priority) and then set in manual exposure program M.

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3. Panoramic pictureHow to do it (part B)

4. Turn off the camera's automatic white balance and set it to any acceptable preset value.

5. Remove any filters (except UV) from the lens.

6. It is essential that the imaged areas overlap by about 20%.

7. It is possible to take pictures in several rows; the camera can be oriented horizontally or vertically (preferable).

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3. Panoramic pictureHow to do it (part C)

8. Take the same series of images again, to be sure you have good source photos.

9. Compose images in MS Image Composite Editor.

For best results and smaller crop, use tripod or stand, but it is possible to take pictures with

camera in your hands.

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3. Panoramic picture

resolution 124 MPx14 source images with resolution 18 MPx

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3. Panoramic picture

29 source images with resolution 24 MPx

resolution of raw panorama 458 MPxresolution of final panorama 189 MPx

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4. High dynamic range photography (HDR)Problem: insufficient dynamic range.

Solution: merging images with different exposures.

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How to do it1. For best results, use tripod or stand.2. Set camera to any program where you can control

exposure – the best programs are: A – aperture priority: use exposure compensation;M – manual exposure: vary shutter speed.

3. Take series of identical pictures with different exposures.

4. Take the same series of images again, to be sure you have good source photos.

5. Merge photos using appropriate software.

4. High dynamic range photography (HDR)

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Example: using free program Fusion F1

Images taken with Canon 6D and macro lens Canon 100/2.8 USM

4. High dynamic range photography (HDR)

0 EV +1 EV -1EV -2EV

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HDR image O EV

It is possible to combine all above described methods to create high resolution images with full depth of view and high dynamic range.Follow these steps: 1. Create set of pictures with different exposures, but

identical focus distance, focal length and f-stop.2. Change focus distance, and repeat step 1 with the

same exposure steps. 3. Move field of view, and repeat steps 1 and 2.

5. Summary

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4. Combine pictures with different exposures to make HDR slices with one depth of field.

5. Combine (stack) HDR images (step 4) to make one image with full depth of field.

6. Merge photos (step 5) into one panoramic picture.

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3 sequential field of views * 2 slices of depth of fields * 3 different exposures= 18 images stacked together

Final image

Download

You can download this presentation

www.jakfotit.info/mendoza.pptx

or contact me

martin_valent@nm.cz

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Links to freeware programs

CombineZP – stacking in Z axishttp://www.hadleyweb.pwp.blueyonder.co.uk/

MS Image Composite Editor – stacking in X and Y axeshttp://research.microsoft.com/en-us/um/redmond/groups/ivm/ice/

Fusion F1 – creating HDR imageshttp://fusion-hdr.com/

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Thank you for your attention! Supported by project of Ministry of Culture of the Czech Republic

(DKRVO 2014, National Museum, 00023272)

HDR image of Prague Castle