Digital camera image files contain Exif data (Exif is Exchangeable image file format). Each camera image contains the Exif data which describes all the camera settings that took that picture. Exif data can be in JPEG, TIFF, and raw image files, and also video and sound files (however a video Exif cannot show exposure because there are normally many different shots in a video file). Image formats PNG, GIF and JPEG2000 do not include Exif data. The current revision of Exif itself is Exif 2.2, and here is the Exif 2.2 specification.
How is Exif pronounced? Some acronyms are said as a word, and I've heard some try to say it, like Exit but with an F. My own notion is that it's more usual and proper to pronounce each letter E X I F, like say UFO or USA or FBI or IRS or BBC.
An important factor is that to see all of the Exif (unless it is a Raw image file), any JPG image file likely must be the straight out of the camera original. Image editors like Adobe will leave out most of the Exif when they rewrite the image file, and you'll never see most of it after that. Photoshop Bridge has menus to select which few items of the Exif to retain in the JPG file, but its choices do not include leaving the Manufacturers data (this section is also called Makers Data, or MakerNotes, same thing, Manufacturers section). Several photo editors have options for leaving or removing Exif data. Just saying, consider archiving and preserving your original image files if you might ever need to go back to them.
Removing the Exif data may be desirable for images being shared, but those should be copies of the image (written into a new file name), and should Not overwrite your original file.
But regardless, if you have ever once overwritten the original JPG image file from the camera, most if not all of the Exif data will likely be gone — as well as the original version of the image data also will be permanently gone if you have edited and overwritten it. IMO, you do want to first archive the original image files, certainly for any important photos. However, Raw images (if you don't discard the original Raw files) do preserve the original version automatically (called lossless editing), but JPG does not.
The big problem for most Exif viewers is that the Makers data section is proprietary format, not standard, and manufacturers can and do change its format at will (adding things, which messes up viewer programs). I used to use PhotoME for my Exif viewer, and I liked it. It seemed to work fine on my D300 camera (2007). But then it failed to show the Makers data for my D800 (2012). Nikon had changed the format. But PhotoMe was last updated in 2009. Opanda was another popular viewer, last updated in 2008. These seem obsolete now, they may still show basic exposure data, but no longer work for the Makers data in all of the newer cameras. If your Exif Viewer is older than your camera, be very suspicious. You need something more current.
There are several Exif viewers available, but again the problem is, the camera's Exif data contains a standard area and a larger Makers area (camera Manufacturers area). If you only want to see the basic stuff, f/stop, shutter speed, and ISO, then any viewer probably works. But if you want to see the other real deal data, you need better viewer tools that can decipher the Manufacturers section. Manufacturers can change its format at any time, so you may need a newer updated Exif viewer version. However very few Exif viewers are recently updated, which then fails to see much data from newest cameras (the last several years). Most Exif viewer files are several years old, not accessing the Manufacturers Data section.
But there is a fantastic solution. Phil Harvey's ExifTool is the ultimate, and is often updated a time or two a month (adding new cameras and fixes, etc.) And you will likely need an updated version after you buy a new camera. Or if you want to see the Exif data when someone sends you an image file from a new camera model.
ExifTool is the good stuff! And all for free. It is a command line viewer, however don't get excited by that. It can also easily work as a useful Windows program. There is a Mac version of ExifTool, but I don't know of a Mac viewer app.
The link to ExifTool and its info is https://exiftool.org/. As you will see there, this is a Big Deal. Complete, and updated very frequently, and it receives great attention from the developer, and from techies too. There is a forum too, and if you want to read awhile there, you might become an Exif Expert.
There are instructions, but in short, for Windows use, just do this:
ExifTool is a command line tool, with many options, and is a very serious tool. However again, the free Windows program ExiftoolGUI spawns exiftool, and filters out that command line part, and presents a normal Windows interface, and makes it easy to use. If used in Windows, and if you click exiftoolgui.exe, then you see like this:
This is very easy to use. It has various features in its menu, GPS and modify date, and you can export the Exif data to a text file (in same folder with the image. Then you can text search it.) Best of all, it shows all of the data.
But the basic command line version alone looks like this:
And many do prefer that. Typing Return to answer More shows several more pages. Or CTRL C will terminate it.
BUT, ExiftoolGUI offers the Windows app shown just before this.
To make sure you understand what you may be missing in the Exif data, here's a sample of what is there. Many things are shown in Exif about how you took the picture. You can output a text file (shown below, output From ExifToolGUI , here with my added bold blue comments), and then a text search can be very helpful to find things (I wish Search were in the program, but you can output the text file as shown below). Even if features are shown as OFF, their unused menu settings may be shown. It does take some careful reading, it can be confusing. This is true of all settings, like Self Timer: 2 seconds, menu setting, even if not used, or Vivid menu setting, even if shooting Raw that contains no settings. It does take some attention. Many interesting things, some of which I marked below, with comments in blue to the right side.
Menu File - Save As - JPG does retain some, but menu File - Save For Web does not retain any Exif data.
So, you do want to look at the Exif in your original camera JPG file, straight out of camera.
Exiftoolgui.exe has menus to show the Exif (as above), and it also an Export menu which can show the complete metadata, like shown below. If you use the exiftool.exe, depending on what your camera shows, you might see:
---- ExifTool ---- I added some comments in blue ExifTool Version Number : 11.12 - an older version, but it is updated a time or two each month ---- File ---- File Name : DSF_7308.NEF - the file name, this one is a raw file Directory : . File Size : 11 MB File Modification Date/Time : 2017:12:16 22:45:23-06:00 File Access Date/Time : 2017:12:16 22:45:23-06:00 File Creation Date/Time : 2017:10:24 13:44:45-05:00 File Permissions : rw-rw-rw- File Type : NEF File Type Extension : nef MIME Type : image/x-nikon-nef Exif Byte Order : Big-endian (Motorola, MM) ---- EXIF ---- Subfile Type : Reduced-resolution image - Thumbnail image - is shown in Windows with the Microsoft Codex file Image Width : 160 Image Height : 120 Bits Per Sample : 8 8 8 Compression : Uncompressed Photometric Interpretation : RGB Make : NIKON CORPORATION Camera Model Name : NIKON D300 - The camera Strip Offsets : 120948 Orientation : Horizontal (normal) Samples Per Pixel : 3 Rows Per Strip : 120 Strip Byte Counts : 57600 X Resolution : 300 Y Resolution : 300 Planar Configuration : Chunky Resolution Unit : inches Software : Ver.1.10 Modify Date : 2017:10:24 13:43:08 Artist : WAYNE FULTON Subfile Type : Reduced-resolution image - Embedded JPG, for rear LCD and histogram Compression : JPEG (old-style) X Resolution : 300 Y Resolution : 300 Resolution Unit : inches Jpg From Raw Start : 178548 Jpg From Raw Length : 1662567 Y Cb Cr Positioning : Co-sited Subfile Type : Full-resolution Image - The raw image Image Width : 4352 Image Height : 2868 Bits Per Sample : 12 Compression : Nikon NEF Compressed Photometric Interpretation : Color Filter Array Strip Offsets : 1841116 Samples Per Pixel : 1 Rows Per Strip : 2868 Strip Byte Counts : 10028417 X Resolution : 300 Y Resolution : 300 Planar Configuration : Chunky Resolution Unit : inches CFA Repeat Pattern Dim : 2 2 CFA Pattern 2 : 0 1 1 2 Sensing Method : One-chip color area Reference Black White : 0 255 0 255 0 255 Copyright : 2015 Exposure Time : 1/160 - This is the basic Exif section, most viewers show the most basic of this F Number : 5.6 Exposure Program : Manual ISO : 400 Date/Time Original : 2017:10:24 13:43:08 Create Date : 2017:10:24 13:43:08 Exposure Compensation : 0 Max Aperture Value : 2.8 Metering Mode : Multi-segment Light Source : Flash Flash : On, Return detected Focal Length : 35.0 mm User Comment : C2012 WAYNE FULTON Any added comments Sub Sec Time : 68 Sub Sec Time Original : 00 Sub Sec Time Digitized : 00 Sensing Method : One-chip color area File Source : Digital Camera Scene Type : Directly photographed CFA Pattern : [Red,Green][Green,Blue] Custom Rendered : Normal Exposure Mode : Manual White Balance : Manual - Raw is not affected by settings, but the embedded JPG shows them on rear LCD and histogram Digital Zoom Ratio : 1 Focal Length In 35mm Format : 52 mm Scene Capture Type : Standard Gain Control : Low gain up Contrast : Normal Saturation : Normal Sharpness : Normal Subject Distance Range : Unknown Offset Schema : 882 GPS Version ID : 18.104.22.168 Date/Time Original : 2017:10:24 13:43:08 TIFF-EP Standard ID : 1 0 0 0 Jpg From Raw : (Binary data 1662567 bytes, use -b option to extract) Thumbnail TIFF : (Binary data 57816 bytes, use -b option to extract) ---- XMP ---- About : uuid:faf5bdd5-ba3d-11da-ad31-d33d75182f1b Create Date : 2017:10:24 13:43:08 Date Acquired : 2017:10:25 12:45:32 ---- MakerNotes ---- Some good stuff in here Maker Note Version : 2.10 ISO : 400 Quality : RAW White Balance : Flash Focus Mode : AF-C Flash Setting : Normal Flash Type : Optional,TTL - Hot shoe flash mode used, might say TTL BL or MAN White Balance Fine Tune : 0 0 WB RB Levels : 1.6875 1.15234375 1 1 - Temperature degrees K is not in Exif. These are multipliers for R & B & 2 G Bayer channels (RBGG) Program Shift : 0 Exposure Difference : -5.7 - Difference in actual and metered ambient exposure, usually zero outdoors, usually large indoors with flash Compression : JPEG (old-style) X Resolution : 300 Y Resolution : 300 Resolution Unit : inches Preview Image Start : 11378 Preview Image Length : 109470 Y Cb Cr Positioning : Co-sited Flash Exposure Compensation : 0 ISO Setting : 400 External Flash Exposure Comp: 0 Flash Exposure Bracket Value: 0.0 Exposure Bracket Value : 0 Crop Hi Speed : Off (4352x2868 cropped to 4352x2868 at pixel 0,0) Exposure Tuning : 0 Serial Number : 3018352 Color Space : sRGB VR Info Version : 0100 Vibration Reduction : Off VR Mode : Normal Image Authentication : Off Active D-Lighting : Off Picture Control Version : 0100 Picture Control Name : Standard Picture Control Base : Standard Picture Control Adjust : Default Settings Picture Control Quick Adjust: Normal Sharpness : 3 Contrast : Normal Brightness : Normal Saturation : Normal Hue Adjustment : None Filter Effect : n/a Toning Effect : n/a Toning Saturation : n/a Time Zone : -06:00 Daylight Savings : Yes Date Display Format : Y/M/D ISO : 400 ISO Expansion : Off ISO2 : 400 ISO Expansion 2 : Off Lens Type : G Lens : 24-70mm f/2.8 - Lens used Flash Mode : Fired, External Shooting Mode : Single-Frame Choice excludes Self Timer use in same menu Lens F Stops : 6.00 Contrast Curve : (Binary data 578 bytes, use -b option to extract) Shot Info Version : 0210 Firmware Version : 1.10B ISO2 : 400 Shutter Count : 37434 - ** Users ask about this, here it is AF Fine Tune Adj : Unknown (0xd0d) Custom Settings Bank : A Custom Settings All Default : No AF-C Priority Selection : Focus AF-S Priority Selection : Focus AF Point Selection : 11 Points Dynamic AF Area : 21 Points Focus Tracking Lock On : Short AF Activation : Shutter/AF-On Focus Point Wrap : No Wrap AF Point Illumination : Auto AF Assist : Off AF-On For MB-D10 : AF-On ISO Step Size : 1/3 EV Exposure Control Step Size : 1/3 EV Exposure Comp Step Size : 1/3 EV Easy Exposure Compensation : Off Center Weighted Area Size : 8 mm Fine Tune Opt Center Weighted : 0 Fine Tune Opt Matrix Metering : 0 Fine Tune Opt Spot Metering : 0 Multi Selector Shoot Mode : Select Center Focus Point Multi Selector Playback Mode: Thumbnail On/Off Initial Zoom Setting : Low Magnification Multi Selector : Do Nothing Exposure Delay Mode : Off CL Mode Shooting Speed : 4 fps Max Continuous Release : 100 Reverse Indicators : + 0 - File Number Sequence : On Battery Order : Camera Battery First MB-D10 Batteries : LR6 (AA alkaline) Beep : Low Shooting Info Display : Auto Grid Display : On Viewfinder Warning : On Func Button : FV Lock Func Button Plus Dials : None Preview Button : Preview Preview Button Plus Dials : None AE Lock Button : AE/AF Lock AE Lock Button Plus Dials : None Command Dials Reverse Rotation : No Command Dials Change Main Sub : Off Command Dials Aperture Setting : Sub-command Dial Command Dials Menu And Playback : Off LCD Illumination : Off Photo Info Playback : Info Up-down, Playback Left-right Shutter Release Button AE-L : On Release Button To Use Dial : No Self Timer Time : 2 s - But it was not used, set OFF by Shooting Mode : Single-Frame Monitor Off Time : 10 s Flash Sync Speed : 1/250 s (auto FP) Flash Shutter Speed : 1/60 s Auto Bracket Set : AE & Flash Auto Bracket Mode M : Flash/Speed Auto Bracket Order : 0,-,+ Modeling Flash : Off No Memory Card : Release Locked Metering Time : 6 s Internal Flash : TTL - Menu, but door was shut, so hot shoe flash was the Flash Source : External below NEF Compression : Lossy (type 2) Noise Reduction : Off NEF Linearization Table : (Binary data 624 bytes, use -b option to extract) WB GRBG Levels : 256 432 295 256 - 256 times the "WB RB Levels" multiplier above Lens Data Version : 0203 Exit Pupil Position : 107.8 mm AF Aperture : 2.9 Focus Position : 0x71 Focus Distance : 3.35 m - Lens report, but zoom lenses are often grossly wrong Focal Length : 35.6 mm Lens ID Number : 147 Lens F Stops : 6.00 Min Focal Length : 24.5 mm - 24-70 mm lens used is shown above Max Focal Length : 71.3 mm Max Aperture At Min Focal : 2.8 Max Aperture At Max Focal : 2.8 MCU Version : 149 Effective Max Aperture : 2.8 Raw Image Center : 2176 1434 Retouch History : None Shutter Count : 37434 Flash Info Version : 0103 - iTTL version in camera Flash Source : External External Flash Firmware : 1.01 (SB-800 or Metz 58 AF-1) - which was in hot shoe flash and used External Flash Flags : Fired, Bounce Flash Flash Commander Mode : Off - Flash Commander mode, was Off Flash Control Mode : iTTL Flash Compensation : 0 Flash Focal Length : 35 mm - Flash head zoom Repeating Flash Rate : 10 Hz - Setting is not used in iTTL mode Repeating Flash Count : 1 Flash GN Distance : Unknown (144) Flash Color Filter : None Flash Group A Control Mode : iTTL-BL - Flash mode, but Commander was Off this time (a few lines above) Flash Group B Control Mode : Off Flash Group C Control Mode : Off Flash Group A Compensation : 0 Flash Group B Compensation : 0 Flash Group C Compensation : 0 Multi Exposure Version : 0100 Multi Exposure Mode : Off Multi Exposure Shots : 0 Multi Exposure Auto Gain : Off High ISO Noise Reduction : Off Power Up Time : 2017:10:05 23:05:27 AF Info 2 Version : 0100 Contrast Detect AF : Off - Live View is off AF Area Mode : Dynamic Area (21 points) Phase Detect AF : On (51-point) - Viewfinder is used, Not Live View Primary AF Point : A5 AF Points Used : A5 Contrast Detect AF In Focus : No File Info Version : 0100 Memory Card Number : 0 Directory Number : 101 File Number : 7308 AF Fine Tune : Off AF Fine Tune Index : n/a AF Fine Tune Adj : 0 Preview Image : (Binary data 109470 bytes, use -b option to extract) ---- Composite ---- - Derived by ExifTool from other sections or values Aperture : 5.6 Auto Focus : On Blue Balance : 1.152344 CFA Pattern : [Red,Green][Green,Blue] Lens ID : AF-S Zoom-Nikkor 24-70mm f/2.8G ED Lens Spec : 24-70mm f/2.8 G Red Balance : 1.6875 Scale Factor To 35 mm Equivalent: 1.5 - Crop factor Shutter Speed : 1/160 Create Date : 2017:10:24 13:43:08.00 Date/Time Original : 2017:10:24 13:43:08.00 Modify Date : 2017:10:24 13:43:08.68 Circle Of Confusion : 0.020 mm Depth Of Field : 2.27 m (2.56 - 4.83 m) - Computed from lens focus distance, but zooms can be incorrect Field Of View : 37.8 deg (2.29 m) - Appears to be horizontal Focal Length : 35.0 mm (35 mm equivalent: 52.0 mm) Hyperfocal Distance : 10.82 m Image Size : 4352x2868 Light Value : 10.3 - EV of settings adjusted to ISO 100 (also computed here) Megapixels : 12.5
ExifTool seems awesome to me. It is an extremely major program. It is great, and well maintained, and it's free.