Attachment A - AIC Guide.pdf

american institute for conservation of historic and artistic works wa s h i n g to n , d c

Jeffrey Warda (editor)

Franziska Frey

Dawn Heller

Dan Kushel

Timothy Vitale

Gawain Weaver dig i tal

The AIC Guide to photography and conservation documentation third edition

The AIC Guide to Digital Photography and Conservation Documentation is published and distributed by the American Institute for Conservation of Historic and Artistic Works.

Copyright © 2011, 2017 the American Institute for Conservation of Historic and Artistic Works

(AIC) and the individual authors. Contact AIC for specific details regarding copyright restrictions.

Notice of Rights

All rights reserved. No part of this book may be reproduced or transmitted in any form by any means without the prior written permission of the publisher. For information on getting permission for reprints and excerpts, contact info@conservation-us.org.

Disclaimer

The information in this book is distributed on an “As Is” basis, without warranty. While every precaution has been taken in the preparation of the book, neither the authors nor AIC shall have any liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the instructions contained in this book or by the computer software and hardware products described in it.

American Institute for Conservation

1156 15th Street NW, Suite 320

Washington, DC 20005

Third Edition

ISBN: 978–0–9978679–1–6

Library of Congress Control Number: 2011907498

Designed by Amber Hares

Typeset in Twentieth Century MT

CONTENTS

Preface to the first edition

Preface to the second edition

Acknowledgements for the first edition

Acknowledgements for the second edition

Introduction

1.0 WORKFLOW 17

1.1 Photography setup

1.2 Image capture

1.3 Image processing

1.4 Image management

1.5 Output

1.6 Sample flowchart – beginner

1.7 Sample flowchart – advanced

2.0 EQUIPMENT 21

2.1 Cameras

2.1.1 Sensors

2.1.2 Digital single-lens reflex (DSLR) cameras

2.1.3 Point-and-shoot cameras

2.1.4 Medium format digital cameras

2.1.5 Large format scanning back cameras

2.1.6 Issues unique to digital cameras

2.2 Camera memory cards

2.3 Lenses

2.3.1 Focal length multiplier (FLM)

2.3.2 Prime lens recommendations

2.3.3 Zoom lens recommendations

2.3.4 Lens speed, aperture, and f-number

2.3.5 Wide-angle lens distortion

2.4 Lighting

2.4.1 Lighting options

2.5 Grayscale and color targets

2.5.1 Target recommendations

2.6 Monitors

2.6.1 LCD monitor recommendations

2.6.2 CRT monitors

2.6.3 Viewing conditions

2.7 Printing

2.7.1 Inkjet print recommendations

2.7.2 Color laser printer recommendations

2.7.3 Photo finishing service recommendations

2.8 Software

2.8.1 Capture software

2.8.2 RAW processing software

2.8.3 Image editing software

2.8.4 DNG conversion software

3.0 CAMERA SETTINGS 61

3.1 Format

3.1.1 Capture format recommendations

3.2 White balance

3.2.1 White balance recommendations

3.2.2 White balance camera settings – pre-capture

3.2.3 White balance adjustments – post-capture

3.3 ISO

3.3.1 Copy stand or tripod work

3.3.2 Handheld photography (without a tripod)

3.4 Exposure

3.4.1 Exposure recommendations

4.0 IMAGE PROCESSING 73

4.1 Image size and resolution

4.1.1 Image size

4.1.2 Spatial resolution

4.1.3 Pixel count (camera or sensor resolution)

4.1.4 Printer resolution

4.1.5 Monitor or projector display resolution

4.1.6 Full resolution onscreen viewing

4.1.7 Determining resolution for scanners

4.2 Bit depth

4.2.1 Bit depth recommendations

4.3 File size

4.4 Color space

4.4.1 Adobe RGB (1998)

4.4.2 sRGB

4.4.3 ProPhoto RGB

4.4.4 eciRGBv2

4.5 Sharpening

4.5.1 Sharpening recommendations

4.6 File formats

4.6.1 RAW

4.6.2 DNG

4.6.3 TIFF

4.6.4 JPEG

4.6.5 JPEG2000

4.6.6 PDF and PDF/A

4.7 File naming

4.7.1 File naming recommendations

4.8 Metadata

4.8.1 Metadata templates and keywords

4.9 Color management

4.9.1 Monitor calibration and profiling

4.9.2 Color space settings

4.9.3 Printing and color management

4.9.4 Camera profiles

5.0 STORAGE AND BACKUP OF ELECTRONIC RECORDS 97

5.1 Five steps for long-term data preservation

5.2 Examples of backup strategies

5.3 Strategies for storage of electronic records

5.3.1 File formats

5.3.2 Hardware

5.3.3 Media

5.3.4 Software

5.3.5 Metadata

5.3.6 Policies

5.3.7 Responsibilities

5.3.8 Education

5.3.9 Budget

5.3.10 Storage and network capacity (scaling)

5.4 Risk management for storing digital files

5.5 Digital asset management software

5.6 Revisions to the Commentaries to the Guidelines for Practice of the AIC

6.0 PHOTOGRAPHIC TECHNIQUES FOR CONSERVATION 109

6.1 Introduction

6.1.1 Handling recommendations

6.1.2 Light safety recommendations

6.1.3 Photographic support system recommendations

6.2 Visible light photography

6.2.1 Normal illumination

6.2.2 Raking illumination

6.2.3 Specular illumination

6.2.4 Transmitted illumination

6.2.5 Darkfield and edge illumination

6.2.6 Reflectance transformation imaging (RTI)

6.3 Close-up photography, photomacrography, and photomicrography

6.3.1 Terminology

6.3.2 Close-up photography recommendations

6.4 Infrared photography

6.4.1 History

6.4.2 Infrared regions and sensitivity of cameras and imagers

6.4.3 Terminology

6.4.4 Infrared camera and imager options

6.4.5 Reflected infrared photography

6.4.6 Transmitted infrared photography

6.4.7 False-color infrared digital photography (FCIR)

6.4.8 Visible-induced infrared luminescence

6.5 Ultraviolet photography

6.5.1 History

6.5.2 Ultraviolet region and sensitivity of cameras and imagers

6.5.3 Personal and object safety

6.5.4 Ultraviolet terminology

6.5.5 Ultraviolet lamps

6.5.6 Ultraviolet-induced visible fluorescence photography

6.5.7 Reflected ultraviolet photography

6.5.8 False-color reflected ultraviolet (FCUV)

6.6 Visible light photography with UV-VIS-IR modified digital cameras

6.7 Multispectral and hyperspectral imaging and imaging spectroscopy

6.7.1 History

6.7.2 Terminology

2.0 equipment

7.0 APPENDIX 173

7.1 Inkjet printing – Epson Stylus Pro 3800 (Mac)

7.2 Inkjet printing – Epson Stylus Pro 3800 (Windows)

7.3 Capture process – Nikon & Adobe Photoshop (Mac)

7.4 Capture process – Canon & Adobe Photoshop (Windows)

7.5 Capture process – Adobe Lightroom & Nikon (Mac)

7.6 Metadata templates and keywords (Mac)

Online digital imaging glossaries

Online resources

Bibliography

Figure credits

Index

Author bios

Digital Photographic Documentation Task Force (2007–2008)

AUTHORS

Jeffrey Warda Associate Conservator, Paper Solomon R. Guggenheim Museum New York, NY

Dr. Franziska Frey McGhee Professor School of Print Media Rochester Institute of Technology Rochester, NY

Dawn Heller Conservator in Private Practice Heller Conservation Services Goodlettsville, TN

Dan Kushel Distinguished Teaching Professor Art Conservation Department Buffalo State College Buffalo, NY

Timothy Vitale Conservator in Private Practice Vitale Art Conservation Oakland, CA

Gawain Weaver Conservator in Private Practice Gawain Weaver Art Conservation San Rafael, CA

Hannah Frost Media Preservation Librarian Stanford University Libraries Stanford, CA

Louis Meluso Manager, Imaging Services The Nelson-Atkins Museum of Art Kansas City, MO

Jane Merritt Special Assistant, Office of the Director National Park Service, Harpers Ferry Center Harpers Ferry, WV

Virginia Naudé President Norton Art Conservation, Inc.

Philadelphia, PA

Alan Newman Chief, Division of Imaging & Visual Services National Gallery of Art Washington, DC

Steve Puglia Preservation and Imaging Specialist National Archives and Records Administration Washington, DC

Yosi R-Pozeilov Senior Photographer, Conservation Center Los Angeles County Museum of Art Los Angeles, CA

Angela T. Spinazze Information Technology Specialist United States Holocaust Memorial Museum Washington, DC

Laura Wahl Library Conservator Hagley Museum and Library Wilmingon, DE

Don Williams Image Science Associates Williamson, NY

CORRESPONDING MEMBERS TO THE FIRST EDITION

1 1

PREFACE TO THE FIRST EDITION

The AIC Guide to Digital Photography and Conservation Documentation was authored by the Digital Photographic Documentation Task Force of the American Institute for Conservation of Historic and Artistic Works (AIC). The task force was charged by the AIC Board of Directors to develop recommendations for conservators in the use of digital photographic equipment for conservation documentation, while also addressing concerns about long-term accessibility and preservation of these electronic records. The work of the task force was reviewed by ten corresponding members who provided invaluable assistance through their review and recommendations.

It is hoped that this guide will serve to ease the transition to digital photographic documentation in the profession, and to aid in the development of standards, reflected in the Commentaries to the Guidelines for Practice of the American Institute for Conservation of Historic and Artistic Works,1 that will ensure the efficient creation of the highest quality and most permanent records possible. Although written primarily for the conservation profession, many parts of this guide are applicable to other disciplines in which digital photographic records are produced or managed.

In addition to this guide, readers are directed throughout the text to a task force web page that lists specific product information. Look for this web address under the Product Information headings, or go to http://cool.conservation-us.org/coolaic/sg/ emg/dtf. Since much of the product information is time-sensitive, it will be updated regularly to reflect changes in technology. This web page is generously maintained by the Electronic Media Specialty Group (EMG) of AIC. For more information on EMG, go to http://cool.conservation-us.org/coolaic/sg/emg.

PREFACE TO THE SECOND EDITION

Readers of the first edition of this guide will find a number of changes and major additions in this expanded second edition. Recent advances in technology have been addressed by updating those areas or by introducing new equipment and tools as needed. These types of changes are found primarily within Chapter 2, Equipment.

A number of areas have been expanded to provide more depth and guidance for readers. Recommendations on the use of Adobe Photoshop Lightroom have been greatly expanded, and Chapter 5, Storage and Backup of Electronic Records, has been completely rewritten to provide a more comprehensive approach to storage and backup. Chapter 5 now also includes a summary of the changes to the Commentaries to the Guidelines for Practice of the AIC that were developed by the Digital Photographic Documentation Task Force and adopted by the AIC Board of Directors in 2009.

Chapter 6, Photographic Techniques for Conservation, by Dan Kushel, has also been greatly expanded—principally in regard to Infrared and Ultraviolet Photography, although a number of other areas within this chapter have also been expanded.

Finally, this second edition includes color figures to illustrate concepts and to provide examples of equipment. The screenshot images found in the appendix have also been updated for newer versions of software or more recent camera models.

note

1. AIC, “Commentaries,” 27–62.

http://cool.conservation-us.org/coolaic/sg/emg/dtf http://cool.conservation-us.org/coolaic/sg/emg/dtf http://cool.conservation-us.org/coolaic/sg/emg

12 The AIC Guide to Digital Photography and Conservation Documentation

ACKNOWLEDGEMENTS FOR THE FIRST EDITION

The task force would like to thank those who assisted with the development of this guide, many of whom, in addition to the corresponding members listed on the facing page, reviewed versions of this document and provided guidance to the task force members. This list includes Robin Myers (Robin Myers Imaging, CA); Mike Collette (Better Light, Inc., CA); Joe LaBarca (Eastman Kodak Company, NY); Dr.

John Delaney, Ken Fleisher, Bob Grove, and Elizabeth Walmsley (National Gallery of Art, Washington, DC); Dr. Gregory Smith (Indianapolis Museum of Art, IN) and James Hamm (State University of New York, College at Buffalo, NY); John J. Lentini, CFEI, F-ABC (Scientific Fire Analysis, LLC); John Vitagliano (conservator in private practice, NY); and Julia Day (The Frick Collection, NY). The task force members acknowledge and are greatly thankful for the work of Paul Messier (Director, Communications and task force liaison to the AIC Board of Directors) and Eryl Wentworth (Executive Director of AIC) for their guidance, encouragement, and enthusiasm for this project. Brett Rodgers (former Communications Director of AIC) and Sloan Carroll (former Publications Manager) were both instrumental in seeing this project through the publication stage. The task force would also like to thank the Art Conservation Department of the University of Delaware, George Eastman House, and the Conservation Department of the Solomon R. Guggenheim Museum for additional funding to support task force meetings.

ACKNOWLEDGEMENTS FOR THE SECOND EDITION

The authors wish to thank those who formally reviewed the text to this second edition. They include Ken Fleisher and John Delaney (National Gallery of Art, Washington DC); Jiuan-Jiuan Chen (Paul Messier, LLC, MA); Scott Geffert (Center for Digital Imaging, NJ); and Nancie Ravenel (Shelburne Museum, VT). Other sections of the text were reviewed by Anthony Sigel (Harvard Art Museums, MA) and Steven Weintraub (Art Preservation Services, NY). Brian Gamm (MS in Color Science, Rochester Institute of Technology, NY) made contributions to the LED section on Lighting. The authors extend their thanks to Nancie Ravenel (Director, Communications, AIC) for her work as liaison to the AIC Board of Directors and to Eryl Wentworth (Executive Director of AIC) for her ongoing support of this publication. Morgan Gilpatrick (Communications Director of AIC) guided this second edition through to publication. The authors are grateful to Amber Hares for her excellent work designing both editions of this book. Frederic Fane Wolfer was instrumental in copy editing the text. The authors and AIC extend their thanks to the Solomon R. Guggenheim Museum, the Fine Arts Museums of San Francisco, and Harvard Art Museums for use of images of works in their collections. Special thanks to Marlin Lum of Cultural Heritage Imaging for RTI images.

Particular thanks goes to Stevens Brosnihan (System Administrator, School of the Art Institute of Chicago, IL) for his contributions to the text of Chapter 5, Storage and Backup of Electronic Records. Julia Day (The Frick Collection, NY) was instru-mental in editing and organizing many versions of the text through both editions.

1 3

INTRODUCTION

Documentation is basic to the ethical practice of conservation. The Code of Ethics and Guidelines for Practice of the American Institute for Conservation of Historic and Ar-tistic Works1 requires that the conservation professional “…document examination, scientific investigation, and treatment by creating permanent records and reports.”2

In recent years, technological developments have brought profound and fundamental changes to this critical aspect of conservation practice. While the use of computers has been integrated relatively smoothly into the creation and handling of written records over the past 25 years, the photographic aspects of documentation have undergone changes far more profound and precipitous. This is a result of the remarkably rapid introduction of the digital camera over the past decade, portending the end of film-based photography for documentation.

Digital photography brings to our work many advantages over film technology, such as the ability to:

·· Assess the quality of the documentation immediately after exposure ·· Control color accuracy with precision and consistency ·· Easily integrate the graphic record with the written record ·· View photographs at very high levels of magnification ·· Perform efficient ultraviolet and infrared photography ·· Create virtual restorations for discussion or treatment planning ·· Immediately share or access photographic images with the public and professional colleagues throughout the world ·· Easily use the photographs for a variety of purposes, such as formal reports, conference presentations, professional consultations, and public outreach ·· Organize documentation records for more efficient use and access ·· Readily create and store multiple copies of documentation records for enhanced long-term security

These advantages, however, do not come without additional concerns.

No doubt primary among these is the need for some readers of this guide to learn an entirely new technology in order to produce photographic records. This guide is specifically designed to help in this process. Readers should understand that this guide is intended to provide recommendations that can aid the conservator in adhering to the standards of ethical conservation practice as set forth in the Code of Ethics and Guidelines for Practice of the AIC3 and detailed in the Commentaries to the Guidelines for Practice of the AIC.4 It is also written to help the conservator take full advantage of the technology and work with it as effectively and efficiently as possible.

The authors have attempted to provide sufficient explanation for those with little or no experience with digital imaging, as well as information for those with more advanced knowledge. The guide encourages conservators to go beyond the simple point-and-shoot camera to develop photography and image-processing skills that will give them control over the accuracy and quality of images and, in the long run, provide them with the most efficient means of producing effective and high-quality documentation. These procedures will require some extra effort to master, but they

14 The AIC Guide to Digital Photography and Conservation Documentation should be able to be incorporated into the workflow of most conservation practices. It is hoped that many readers of this guide will adopt such procedures into their normal working practice.

With the transition to digital photography, its facility for image manipulation has raised some concerns about the integrity of the photographic component of conservation records. These concerns are shared even more acutely by the forensic profession. The issue of image integrity, as well as many other working procedures and recommendations similar to those included in this guide, are thoroughly addressed by a series of papers produced by the Scientific Working Group on Imaging Technology (SWGIT) of the International Association for Identification (IAI), a major professional organiza-tion for the forensic sciences. The entire set of papers can be accessed through the IAI website.5 The recommendations given in this guide with respect to the maintenance of the integrity of the original capture file, the application of image enhancements only to copies of the master file, and the documentation of image-processing steps, are in keeping with recommendations in the IAI guidelines.

HOW TO USE THIS GUIDE

This guide is intended to be a general reference for the technical aspects of photographic documentation, as well as a manual for planning and implementing a system for digital photographic documentation and storage of electronic files.

Individual topics can be accessed via the table of contents or the index, but the entire guide is also organized to lead you step-by-step through the design, setup, and use of a digital photographic documentation system. Each chapter gives practical advice for the creation of high-quality photographic images and also explains the photographic and digital imaging principles that support each recommendation.

Below is a brief overview of how to use this guide:

REVIEW OVERALL WORKFLOW

Get an initial overview of a photographic documentation workflow and the basic steps by reading through Chapter 1.

UPGRADE OR ACQUIRE THE NECESSARY EQUIPMENT AND SOFTWARE

Review your requirements for camera equipment, lighting, and computer hardware and software by reading through Chap-ter 2, Equipment. For up-to-date recommendations on cameras, inkjet printers, lighting, monitors, and targets, see the AIC Electronic Media Group website at http://cool.conservation-us.org/coolaic/sg/emg/dtf, and for overall equipment needs and configurations for studio and copy stand photography see Chapter 6, Photographic Techniques for Conservation.

KNOW YOUR CAMERA SETTINGS

Once you are ready to start using your camera, consult Chapter 3 for guidelines on the four most important camera settings that you should always be aware of: Format Mode, White Balance, ISO, and Exposure.

LEARN ABOUT YOUR SOFTWARE AND FURTHER DETAILS OF YOUR EQUIPMENT

Read through Chapter 4, Image Processing, take some test exposures, and select the appropriate settings on your camera and image-editing software to conform to the best practices described in this guide. By the end of this chapter you will be shooting and processing documentation images to the highest standards for your equipment.

SAFEGUARD AND BACK UP YOUR DIGITAL IMAGES

Review the recommendations in Chapter 5, Storage and Backup of Electronic Records, to ensure the long-term preservation of your digital files. Even if the Information Technology (IT) department of your institution handles file archiving, you should understand the principles of digital preservation and how your files are preserved. If you do not have an IT department, these issues are even more important, as you must preserve the documentary record yourself!

1 5

EXPAND YOUR PHOTOGRAPHIC TECHNIQUES

Chapter 6, Photographic Techniques for Conservation, details the equipment setup and imaging techniques for both standard studio and copy stand photography. The chapter also details a variety of advanced imaging techniques, including reflectance transformation imaging, infrared photography, ultraviolet photography, and a brief overview of multispectral imaging.

USE THE HYPERLINKS (THIRD EDITION NOTE)

The AIC Guide to Digital Photography and Conservation Documents, Third Edition, has had all reference URLs checked and updated where possible. Any out-of-date or missing links have been left inactive or have been noted. This edition is available in electronic format only.

notes

1. AIC, “Code of Ethics,” 20–27.

2. Ibid., 22, 26.

3. Ibid.

4. AIC, “Commentaries,” 53–56, 58–62.

5. https://www.swgit.org/documents/Current%20Documents(accessed January 15, 2011).

http://www.theiai.org/guidelines/swgit/index.php https://www.swgit.org/documents/Current%20Documents

1.0 workflow 1 7

HOW TO USE THIS CHAPTER

This chapter provides an overview of the digital photographic documen-tation workflow that you follow to acquire, process, and manage digital images. Read it over now and refer back to it as you establish your own workflow based on the equipment, file formats, and other choices you make.

A workflow that includes best practices in photographic techniques, image processing, and electronic file management will save time and ensure the most consistent results.1

A standardized workflow is especially important when there are multiple users of the same equipment. It is highly recommended that you write up your own specific workflow so that your documentation is consistent over time and from user to user. The general workflow provided in this chapter and the more detailed screenshot instructions in the appendix in the back of this guide offer workflow models that can be adjusted to fit your specific equipment and practice.

Each of the different types of workflows can have many variations. It can be as simple or as detailed as needed; user abilities, budget constraints, and institutional limitations will all influence the workflow. Whichever way you proceed, there are five basic stages in the photodocumentation process described below that should be considered when developing your workflow.2 Examples of two different workflows are illustrated as flowcharts at the end of this section. In addition, see appendix sections 7.3–7.5 for detailed screenshots of the capture process for Nikon and Canon digital single-lens reflex cameras (DSLRs) for Macintosh computers and PCs that run Windows.

Note that many of the terms and concepts introduced in this chapter are explained in more detail later in this guide.

1.1 PHOTOGRAPHY SETUP

This part of the workflow will most likely resemble your film-based photog-raphy setup, with a few important additions specific to digital photography.

Some of these steps may need to be taken only once, while others will need to be repeated for every photo session.

·· Check software and computer preferences

workflow

1.0

18 The AIC Guide to Digital Photography and Conservation Documentation

·· Prepare photography area ·· Set up camera equipment and lighting ·· Choose target(s)

See section 2.0 on Equipment for more information.

1.2 IMAGE CAPTURE

Prior to taking a digital photograph, you will need to make sure that your camera has the correct settings. This can be done through the camera menu system, or remotely if your camera is tethered to a computer. Always check these settings before using a digital camera:

·· Image format (RAW, TIFF, or JPEG mode) ·· ISO level (use the lowest ISO possible) ·· Exposure mode (manual or aperture priority is recom-mended) ·· White balance setting (custom or other setting depend-ing on situation) ·· Sharpening, saturation, contrast, and color space set-tings (for in-camera processing of TIFF and JPEG images)

See section 3.0 on Camera Settings for more information.

1.3 IMAGE PROCESSING

Image processing is carried out through image editing soft-ware, such as Adobe Photoshop or Lightroom, after the capture process. Whether your image was shot as a RAW, TIFF, or JPEG file will determine how it is most appropriately processed. For example, relatively large changes in white balance and exposure can be easily applied to an image shot in RAW mode, while these types of changes are much less successful when applied to an image shot in JPEG mode.

Image processing can include the following:

·· Adjust exposure and white balance in RAW files ·· Create or apply color profiles to RAW images for color critical applications ·· Apply additional sharpening, depending on need ·· Apply metadata and name files ·· Process RAW files to TIFF or JPEG ·· Convert proprietary RAW files to DNG, if applicable

See section 4.0 on Image Processing for more information.

1.4 IMAGE MANAGEMENT

Image management involves developing a system to store and access digital image files. A backup strategy is es-sential to proper image management. Long-term storage of electronic records is an active process that can range from relatively simple storage on multiple hard drives on a local computer to more-complex, multiple-user network solutions. Image management also involves the use of proper file naming conventions and metadata to describe digital assets. Digital asset management (DAM) software is often used to simplify the organization and retrieval of digital images. File browsing software programs that can display thumbnail images are also useful for organizing and accessing images.

For more information see the opening parts of Chapter 4, Image Processing, and Chapter 5, Storage and Backup of Electronic Records, as well as section 5.5 on Digital Asset Management Software.

1.5 OUTPUT

Knowing the final output for your image file will determine how it is processed. For instance, a relatively large file size is required for a hard-copy output of a digital image (e.g., an inkjet print), while a much smaller file size is adequate for the screen output of the same image (i.e., for display on a monitor). Making changes to images depending on their intended use often requires image editing software (e.g., Adobe Photoshop, Lightroom, or Elements) to change image size, sharpening, or color space. Output of a digi-tal image to an inkjet printer involves choosing the correct printer options and the choice of appropriate paper to achieve optimum image quality and stability.

See sections 2.7 on Printing, 4.1 on Image Size and Resolu-tion, and 4.9 on Color Management for more information.

1 9 1.0 workflow

1.6 S ample FLowchart — Beginner

This workflow is intended for beginners who will be photographing in JPEG or TIFF mode from a point-and-shoot digital camera or entry-level DSLR.

every time

• Set up camera equipment and lighting. Place object

• Choose target(s)

3. image processing

• Image procesing takes place in the camera

• Transfer the images to the computer

• Rename the image files

• Add metadata

4. management and output

• Have a local service provider create 4 x 6 prints of your images.

• Back up the image files if you decide to keep the electronic files.

• Check camera settings

• Reformat memory card

• Take the images

2. image capture

1. photography setup before capture one time setup

• Decision making for equipment, software, lighting, etc.

20 The AIC Guide to Digital Photography and Conservation Documentation

1.7 Sample FLowchart — advanced

This workflow assumes that you will be capturing RAW images with a DSLR.

2. image capture

3. image processing one time setup

• Decision making for equipment, software, lighting, etc.

• Software settings on computer

• Process images using RAW processing software

• Rename images

• Add metadata

• Save RAW images in the TIFF format every time

• Set up camera equipment and lighting. Place object

• Choose target(s)

1. photography setup before capture

• Decide on tethered or untethered capture

• Check camera and/or software settings

• Take images

• Transfer images to computer

• Decide on a folder structure for saving your archived files and preferred file format(s)

• Back up the image files

• Maintain the archive of image files using digital asset manage-ment software

• Develop a migration strategy optional (but recommended):

• Print images as contact sheets

• Store in the object file under stable environmental conditions

5. output4. image management

See appendix sections 7.3 and 7.4 for detailed screenshots of the capture process for Nikon and Canon DSLRs on a Mac and PC.

notes

1. See the Universal Photographic Digital Imaging Guidelines (UPDIG) at http://www.updig.org.

2. This section on workflow was developed with suggestions from Lou Meluso.

http://www.updig.org

2.0 equipment 2 1

2.0 equipment

HOW TO USE THIS CHAPTER

The purpose of this chapter is to provide general recommendations for cam-eras, memory cards, lenses, lighting, grayscale and color targets, monitors, printers, and software—all the equipment necessary for high-quality photo-graphic documentation. These recommendations are specifically tailored to the needs of conservators or custodians of works of art to address the types of issues they will encounter or should be aware of during photography of works of art and artifacts.

Read each section in detail as you make choices within each category (cameras, lighting, etc.) to be sure that the equipment you choose has the necessary features for high-quality photographic documentation and is the right fit for the workflow you are developing. Recommendations for specif-ic equipment models are not included in this chapter because they change frequently. However, up-to-date equipment recommendations from the AIC Digital Photographic Documentation Task Force are available on the AIC Electronic Media Group website at:

http://cool.conservation-us.org/coolaic/sg/emg/dtf

This website contains listings of cameras, inkjet printers, lighting, monitors, and targets that supplement the information presented in this chapter to simplify the selection process.

2.1 cameraS

There are three main categories of cameras available to the conservator:

point-and-shoot, digital single-lens reflex (DSLR), and medium format and scanning back cameras. It is suggested that serious consideration be given to the highest-quality camera system your budget can accommodate. Keep in mind that image quality is determined largely by sensor resolution and size, as well as lens optics. The sections below outline the basic requirements for sensor resolution (also referred to as pixel count) and size. Minimum recommendations for DSLR and point-and-shoot cameras are provided.

Digital backs and large format scanning back cameras are also discussed.

See figures 1, 4, and 6–8 for images of different types of cameras.

22 The AIC Guide to Digital Photography and Conservation Documentation

2.1.1 S ensors

Before providing details on particular types of cameras, a few basic principles should be outlined regarding the sensors in digital cameras. While a full understanding of camera sensors is not required for conservation documen-tation, general knowledge of sensors and pixels is benefi-cial for understanding your camera system. It also informs decisions when considering the purchase of a new camera.

Camera Sensors

The sensor in a digital camera is typically a solid-state silicon chip with millions of light sensitive pixels (picture elements) on the surface. Most cameras use a CCD (charge-coupled device) or CMOS (complementary metal-oxide semiconductor) area array sensor.1 There were once significant pros and cons to each type, but advances in their design have made them equal in most respects for still photography.

Typical CCD and CMOS sensors have a colored filter over them that filters the light that reaches each pixel site to red, green, or blue. This is known as a color filter array. The most common arrangement of these filters is known as the Bayer pattern. The Bayer pattern has an established order for alternating the color filters, with each basic cluster containing two green, one red, and one blue filter to mimic the dominant green sensitivity of the human eye. When a photograph is taken, each pixel on the sensor records the intensity of only one of the primary colors (red, green, or blue). In order to assemble a final full-color image with red, green, and blue (RGB) data for each pixel, the other two primary colors are estimated based on the values of neighboring pixels. This is accomplished through software processing, referred to as color interpolation or demosaicking.

Sensors with a color filter array are prone to image artifacts known as aliasing, which can occur when photo-graphing subjects that contain very finely spaced regular patterns. Camera manufacturers usually address this issue by installing an anti-aliasing (blurring) filter over the sensor that reduces aliasing but also diminishes sharpness in the image. Anti-aliasing can also be addressed through soft-ware, as is found with cameras that lack an anti-aliasing filter. Aliasing is more fully explained in section 2.1.6. The color interpolation process and the anti-aliasing filter are reasons, among others, why digital camera images from typical CCD and CMOS sensors can be somewhat soft.

This effect can be diminished with increased pixel count.

The Foveon X3 sensor, currently available only in Sigma digital cameras, has a different, layered structure that en-ables each pixel to capture its own full RGB image data.2 Neither color interpolation of the image data nor the use of an anti-aliasing filter is required. This results in images that are sharper than traditional CCD or CMOS sensors;

Sigma cameras, however, currently lack other features such as tethering and live view.

Some professional medium format cameras have a multi-shot sensor shift feature that takes multiple images while shifting the sensor to allow it to capture RGB data for each pixel in the image. Color interpolation is not necessary when shooting in this mode. A BetterLight scanning back used in a 4 x 5 camera has a linear array sensor, similar to that found in a flat bed scanner, with red, green, and blue filtered pixel elements along the length of the array. RGB data is collected for each pixel site in the image with these cameras. Color interpolation and an anti-aliasing filter are not necessary.

Fig. 1. Nikon D200 (left) and D90 (right) DSLR cameras. The D200 is a 10 MP camera with an APS-C sensor and a pixel density of

2.7 MP/cm2. The D90 is a 12.3 MP camera with

the same sensor size but a higher pixel density of 3.2 MP/cm2.

2 3 2.0 equipment

Sensor Resolution or Pixel Count

The resolution (or pixel count) for area array camera sensors is based on the total number of pixels covering the sensor surface. A sensor with 3,000 pixels in the long dimension and 2,000 pixels in the short dimension has 6,000,000 pixels, or 6 megapixels (MP). Although commonly referred to as camera or sensor resolution, the number of pixels on a sensor is more accurately described as the pixel count. The term “resolution” implies the ability of a camera system to resolve fine detail, which takes into account the combined performance of both the sensor and the lens.

Sensor Size

Sensors can range widely in physical size, depending on the camera. Point-and-shoot cameras typically have very small sensors, DSLR cameras have larger sensors, and me-dium format and scanning back sensors are even larger.

The smallest sensors, used in point-and-shoot cameras, can range in size from approximately 5.7 x 4.2 mm to 7.9 x

5.8 mm.3 These are extremely small when compared with the size of traditional 35 mm film at 36 x 24 mm. The recently introduced Four Thirds sensor (Type 4/3”) measures 18 x 13.5 mm and is noticeably larger than most point-and-shoot camera sensors.

Many DSLR cameras have still larger sensors that are roughly 23 x 15 mm. This size is often referred to as APS-C, Type 1.8”, or simply a “cropped” sensor to indicate that they are smaller than 35 mm film. The APS-C name derives from the original, similar size, APS film format introduced in 1996. APS film had three format sizes: APS-C (classic), APS-H (high definition) and APS-P (panoramic). The C and H designations are now used to distinguish different size digital camera sensors, roughly similar in size to APS film.

Canon’s APS-H sensor is the largest, measuring 28.7 x 19 mm; all other manufacturers’ APS-C sensors are smaller, ranging from 22.2 x 14.8 mm to 23.6 x 15.7 mm.

All of these cameras have sensors that are much smaller than a “full-frame” DSLR’s sensor, which is the same size as 35 mm film at 36 x 24 mm. Full-frame DSLR cameras have improved image quality compared with APS-C DSLRs, and in recent years they have become more affordable. Much more costly professional medium format digital cameras have significantly larger sensors. See figure 2 for an image of common sensor sizes in relation to 35 mm film and figure 3 for a comparison of sensor sizes ranging from point-and-shoot to large format cameras. For a more complete description of sensor sizes, see the Glossary section of the Digital Photography Review website.4

Pixel Size

As the physical size of a sensor increases, the physical size of individual pixels on that sensor can also increase proportionally. Sensors with larger pixels have greater sensitivity to light, wider dynamic range,5 and the potential to deliver sharper images with less noise than sensors with smaller pixels. This is primarily because smaller pixels have less surface area, which limits the amount of light each pixel can capture and store during exposure. This lower sensitivity can decrease dynamic range and increases noise. Many recent cameras provide noise reduction features, but this may undermine other aspects of image quality, such as sharpness. As megapixel counts continue to increase with new camera models, individual pixels will become smaller, resulting in diminished image quality.

This issue is particularly critical on point-and-shoot digital cameras because of their very small sensor size.

The relative size of individual pixels is commonly expressed by either “pixel pitch” or “pixel density.” Pixel pitch describes the distance between the centers of adjacent pixels on the sensor.6 This can range from roughly 5 to 8.5 µm on a full-frame sensor and 1.5 to 4.5 µm on point-and-shoot cameras. Pixel density expresses the total number of pixels divided by the area of the sensor. For example, the pixel density of a 12 MP full-frame DSLR camera is 1.4 MP/ cm2, while that of a typical 12 MP compact point-and-shoot camera is 43 MP/cm2. The point-and-shoot camera must squeeze the same number of pixels into a much smaller area than the full-frame DSLR camera. When checking review sites for cameras, remember that a larger “pixel pitch” number and a smaller “pixel density” number are indications of a larger sensor and typically improved image quality. Review websites such as Digital Photography Review list pixel density for camera models. When possible, choose a camera with a

Fig. 2. Illustration of a typical point-and-shoot camera sensor (1/1.8”) compared with APS-C and -H DSLR sensors and a full-frame DSLR sensor (equivalent to image area of 35 mm film). Actual size.

APS-C Nikon, Pentax, Sony

1/1.8”

35 mm film (Full-frame DSLR) 36 x 24 mm

APS-H Canon

24 The AIC Guide to Digital Photography and Conservation Documentation lower pixel density; it will have larger pixels with greater sensitivity, lower noise, and greater dynamic range.

How Many Megapixels?

Provided you are comparing cameras with reasonably large sensors (APS-C or larger), you should purchase a camera with the most megapixels (MP) possible within your budget. As noted below under minimum recommendations for DSLR cameras, the minimum camera resolution in the second edition of this guide has increased from 6 MP to 10–12 MP. This is currently the lowest resolution available for DSLR camera models.

The 6 MP camera has long been considered the mini-mum sensor resolution (or pixel count) requirement for conservation documentation. It was first recommended in 2002 by Kushel because it approximates the resolution of commonly used 35 mm medium-speed color slide film (e.g., Kodak Ektachrome 160T).7 It also provides the minimum res-olution required to print an image at 8 x 10 in. (20 x 25 cm), typically the largest print size for film-based conservation documentation photographs.

Having more than 6 MP may not make much of a dif-ference if images are only viewed as 8 x 10 inch prints.

But more typically, digital images are viewed on a com-puter monitor, and it is often necessary to zoom into the image to bring out as much detail as possible (one of the great advantages of digital photography). For this reason, higher camera resolution (pixel count) than 6 MP is usually very desirable.

Users of 6 MP cameras should not feel obligated to upgrade to a new camera if their current system is serving them well. When it is time to replace the camera, however, purchase one with the highest MP count that you can afford. New digital camera models are announced almost weekly, and as megapixels continue to increase, keep in mind that a 2 MP difference is generally not significant (e.g., between a 6 MP and an 8 MP camera). When comparing a 4 MP difference (e.g., between a 6 MP and a 10 MP camera), there is a noticeable increase in detail that can be obtained. Note that the increased pixel count of a 10, 14, 18 or 24 MP camera is especially useful when photographing large objects or objects with extremely fine detail (see Aliasing in section 2.1.6), but it is not as important when taking close-up images or photographing small objects. Do not forget that megapixels are only part of the equation when determining image quality.

Fig. 3. Comparison of different sensor sizes found in: (A) Point-and-shoot cameras (1/1.8” and Four- Thirds); (B) Cropped sensor DSLRs (APS and Foveon); (C) Full-frame DSLRs; (D) Medium format digital cameras; (E) Large format scanning back cameras; and (F) Large format 4 x 5 film. Actual sizes.

APS-C Nikon, Pentax, Sony, Foveon (SD1)

Full-Frame 36 x 24 mm (35 mm Film)

APS-H Canon

APS-C Canon

1/1.8”

Four-Thirds

Medium Format 36 x 48 mm

Medium Format 40 x 53.9 mm

Large Format 72 x 96 mm (BetterLight scanning back)

Large Format 96 x 120 mm (4 x 5 Film)

Foveon

A

B

C

D

E

F

2 5 2.0 equipment

2.1.2 D igital Single-Lens Reflex (DSLR) Cameras

A digital single-lens reflex camera is recommended for most conservation documentation applications as the best compromise between quality and price. The main reason for this recommendation is that DSLRs provide better image quality than point-and-shoot cameras (fig. 1).

DSLR Cameras—Recommendations

·· 10–12 megapixel (MP) (or greater) recommended na-tive sensor pixel count (resolution) (produces a 28–35 megabyte (MB), 8-bit/channel RGB file)

·· Ability to shoot RAW and/or TIFF formats, not only JPEG8

·· Accepts interchangeable lenses ·· Sensor size roughly 23 x 15 mm (APS-C or Type 1.8”) or greater, with an aspect ratio of 3:29

·· Ability to tether to a computer ·· Live view capability ·· Support for Adobe RGB (1998) color space, not only sRGB (when shooting in TIFF or JPEG mode)10

Full-Frame DSLRs

DSLR cameras with full-frame sensors are currently available from Canon, Nikon, and Sony (fig. 4). The sensors on these cameras are roughly twice the size of APS-C type sensors, providing increased sensitivity, less noise, and greater dynamic range.11 Many full-frame DSLR cameras have higher megapixel counts than most cropped sensor cameras. Another advantage is that lenses on a full-frame DSLR camera have the same large field of view as on a 35 mm film SLR camera. In contrast, when mounted on a cropped sensor DSLR, lenses will have a smaller field of view. In this regard, full-frame cameras can be more advantageous for copy stand photography or situations were the shooting distance is limited. This topic is discussed in greater detail within section 2.3.1 on Focal Length Multiplier.

Full-frame cameras tend to be professional-level cam-eras with larger bodies and more features than midrange or “prosumer” level cameras. For instance, full-frame DSLRs have larger and brighter optical viewfinders com-pared with cropped sensor DSLRs, a welcome feature when manual focusing is necessary. These cameras have long been considerably more expensive than cropped sensor DSLRs (primarily because of the larger sensor), but manufacturers have recently introduced more affordable models by balancing features such as speed (the number of frames a camera can capture per second) with overall megapixel count. As prices continue to come down, look for increasing numbers of affordable full-frame cameras in smaller camera bodies.

Tethered Shooting and Live View

Additional features available with most DSLRs are tethered shooting and live view. Tethered shooting allows captured images to be transferred directly to a computer and immedi-ately displayed on a computer monitor (fig. 5). This feature permits accurate assessment of images as they are taken— to check framing, focus, and exposure, for example. It also allows nearly every menu function on the camera to be con-veniently controlled through the computer, and it eliminates the additional step of having to manually transfer images from the camera’s memory card to the computer. Tethering software that provides both direct download and camera control is currently available only with select camera mod-els from Canon, Nikon, Sony, Fujifilm, and Leica. Cameras with this option are highly recommended for documentation photography. See section 2.8.1 on Capture Software for more information.

Live view permits a “live view” of the subject on the camera’s LCD screen instead of or in addition to the optical viewfinder. While this is the standard viewing method on point-and-shoot cameras, it is only recently that DSLR cameras with this capability have become available. This is a very desirable feature—especially when the camera is tethered to a computer, because it allows the user to check focus and framing directly on the computer monitor before taking an image. Live view can be a great convenience when working on a copy stand or when adjusting placement of reference plates or a subject in the studio. It is also an essential feature if one plans to modify a DSLR for infrared or reflected ultraviolet photography. Although many

Fig. 4. Nikon D3X DSLR. The D3X is a 24 MP camera with a full-frame sensor and a pixel density of 2.8 MP/cm2.

26 The AIC Guide to Digital Photography and Conservation Documentation manufactures offer live view through the camera’s LCD, not all offer capture software that will display a live view during tethered shooting.

2.1.3 P oint-and-Shoot Cameras

Point-and-shoot cameras are more appropriate for installa-tion, gallery, and working shots than for conservation doc-umentation (fig. 6). Setting aside recent developments in compact interchangeable lens cameras (see below), most typical point-and-shoot cameras do not offer the same high-level image quality as DSLRs, primarily because of their smaller sensor size and lower-quality lens construction.

Point-and-Shoot Cameras—Recommendations

·· 10–12 MP recommended native sensor resolution (pro-duces a 28–35 megabyte (MB), 8-bit/channel RGB file)

·· Four Thirds or APS-C sensors preferable to smaller sen-sor sizes

·· Minimum sensor dimensions no smaller than (roughly) 7 x 5 mm (Type 1/1.8”)12

·· Interchangeable lens camera preferable to non-inter-changeable lens camera, if used for conservation docu-mentation

·· Ability to capture images in RAW format, not only JPEG13

·· Support for Adobe RGB (1998) color space, not only sRGB14

Compact Interchangeable Lens Cameras

A number of manufacturers now offer compact cameras with interchangeable lenses and larger sensors, in an effort to produce better-quality images while maintaining the look and handling of a point-and-shoot camera. One class of these cameras manufactured primarily by Olympus and Panasonic is known as Four Thirds and Micro Four Thirds cameras, which is a reference to the 4/3” type sensor size introduced by Olympus in 2003.15 At 17.3 x 13 mm, Four Thirds sensors are quite a bit larger than sensors in most other point-and-shoot cameras. The Micro Four Thirds cameras have an even smaller camera body because they lack a mirror, pentaprism,16 and optical viewfinder, but the sensor is the same as found in their regular Four Thirds counterparts.

Fig. 5. Nikon Camera Control Pro tethering software (right) with live view window (left) from a Nikon D3X DSLR cam-era. Subject: Edouard Vuillard, By the Lake, 1900, Oil on cardboard, mounted on wood panel, Solomon R. Gug-genheim Museum, NY.

Fig. 6.