Digital camera image files contain Exif data (Exif is Exchangeable image file format). This data describes the format of the image data. The camera is the source, and the value to camera users is that the camera settings are also recorded in the Exif data. Exif data can be in JPEG, TIFF, and raw image files, and also sound data files. Image formats PNG, GIF and JPEG2000 do not include Exif data. The current revision 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 proper to pronounce the letters E X I F, like say UFO or USA or FBI or IRS or BBC.
There are several Exif viewers, but the problem is, the Exif data contains a standard area and a larger Makers area (camera Manufacturers area). If you only want to see f/stop, shutter speed, and ISO, then any viewer surely works. But if you want to see the real deal, you need better viewer tools that can decipher the Manufacturers section. Not many viewers are recently updated, which omits newest cameras.
The Adobe File - Save For Web option saves as JPG, but specifically omits all Exif data.
The problem for 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 is another popular viewer, last updated in 2008. These are obsolete now, they no longer work for the Makers data in many newer cameras. If your Exif Viewer is older than your camera, be very suspicious. You need something more current.
But there is a fantastic solution. Phil Harvey's ExifTool is the ultimate, and is often updated a couple of times a month (adding new cameras and fixes, etc). It is the good stuff! All for free. It is a command line viewer, however don't get excited by that. It can also work as a useful Windows program. At least for Windows, sorry, I'm not aware of a Mac version. I can only discuss the Windows version.
The link is http://www.sno.phy.queensu.ca/~phil/exiftool/. 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:
It is a command line tool, and has many options. However, the ExiftoolGUI spawns exiftool, and filters out that part, and presents a normal Windows interface. 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.
If you directly click the exiftool.exe, you see:
And typing Return to answer More shows several more pages. Or CTRL C will terminate it before the end.
BUT, ExiftoolGUI offers the Windows app shown just before this.
To make sure you understand what you may be missing, here's a sample of what is there. It does take some careful reading, it can be confusing. You can output a text file (shown below, output From ExifToolGUI), 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). For example, Commander Group A mode (TTL or Manual) is there, along with manual power level or TTL compensation. And in this case, the Commander in the hot shoe flash is also shown. But these are just the current settings in the menus. Note both of these say the Commander Mode is Off, not in use. This is true of all settings, like Self Timer: 2 seconds, even if not used, or Vivid, even if shooting Raw that contains no settings. It does take some attention. Many interesting things, some of which I marked below, with comments 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 file, straight out of camera.
---- ExifTool ---- ExifTool Version Number : 10.27 9/23/2016 version ---- File ---- File Name : 801_2222.NEF A raw file Directory : . File Size : 36 MB File Modification Date/Time : 2016:07:25 10:44:42-05:00 File Access Date/Time : 2016:08:03 14:48:03-05:00 File Creation Date/Time : 2016:08:03 14:48:03-05:00 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 TIF image Image Width : 160 Image Height : 120 Bits Per Sample : 8 8 8 Compression : Uncompressed Photometric Interpretation : RGB Make : NIKON CORPORATION Camera Model Name : NIKON D800 Camera model Strip Offsets : 120068 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 : 2016:07:25 10:44:41 Artist : 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 : 1059328 Jpg From Raw Length : 3966257 Y Cb Cr Positioning : Co-sited Subfile Type : Full-resolution Image The raw image Image Width : 7424 Image Height : 4924 Bits Per Sample : 12 Compression : Nikon NEF Compressed Photometric Interpretation : Color Filter Array Strip Offsets : 5025792 Samples Per Pixel : 1 Rows Per Strip : 4924 Strip Byte Counts : 32670659 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 Subfile Type : Reduced-resolution image ? Dunno, guessing for B&W histogram maybe? Compression : JPEG (old-style) X Resolution : 300 Y Resolution : 300 Resolution Unit : inches Other Image Start : 178176 Other Image Length : 881083 Y Cb Cr Positioning : Co-sited Reference Black White : 0 255 0 255 0 255 Copyright : Exposure Time : 1/60 The basic Exif section, most viewers show some of this F Number : 5.0 Exposure Program : Aperture-priority AE ISO : 100 Sensitivity Type : Recommended Exposure Index Date/Time Original : 2016:07:25 10:44:41 Create Date : 2016:07:25 10:44:41 Exposure Compensation : 0 Max Aperture Value : 2.8 Metering Mode : Center-weighted average Light Source : Unknown This was hot shoe bounce flash under shaded patio Flash : On, Return detected Focal Length : 48.0 mm User Comment : Sub Sec Time : 50 Sub Sec Time Original : 50 Sub Sec Time Digitized : 50 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 : Auto White Balance : Auto Raw is not affected by settings, but embedded JPG shows them on rear LCD and histogram Digital Zoom Ratio : 1 Focal Length In 35mm Format : 48 mm Scene Capture Type : Standard Gain Control : None Contrast : Normal Saturation : Normal Sharpness : Normal Subject Distance Range : Unknown See Focus Distance in Maker Notes GPS Version ID : 18.104.22.168 Date/Time Original : 2016:07:25 10:44:41 TIFF-EP Standard ID : 1 0 0 0 ---- MakerNotes ---- The Good Stuff is in here Maker Note Version : 2.10 ISO : 100 Quality : RAW White Balance : Auto1 Focus Mode : AF-S Flash Setting : Normal Flash Type : Optional,TTL-BL This was a hot shoe flash White Balance Fine Tune : 0 0 WB RB Levels : 1.8984375 1.44140625 1 1 Temperature degrees K is not in Exif. These are multipliers for red and blue and two green Bayer channels (RBGG) Program Shift : 0 Exposure Difference : -0.3 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 : 25348 Preview Image Length : 94699 Y Cb Cr Positioning : Co-sited Flash Exposure Compensation : 0 ISO Setting : 100 External Flash Exposure Comp : 0 Flash Exposure Bracket Value : 0.0 Exposure Bracket Value : 0 Crop Hi Speed : Off (7424x4924 cropped to 7424x4924 at pixel 0,0) Exposure Tuning : 0 Serial Number : 3046677 Camera serial number Color Space : sRGB VR Info Version : 0100 Vibration Reduction : Off What you did, or maybe lens does not have it VR Mode : Normal Active D-Lighting : Off Picture Control Version : 0100 Picture Control Name : Standard JPG does this, seen in the rear LCD Preview, but raw NEF data is not affected Picture Control Base : Standard Picture Control Adjust : Full Control Picture Control Quick Adjust : Normal Sharpness : 4 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 : No Date Display Format : M/D/Y ISO : 100 ISO Expansion : Off ISO2 : 100 ISO Expansion 2 : Off Vignette Control : Normal Auto Distortion Control : Off Lens Type : G Lens : 24-70mm f/2.8 Flash Mode : Fired, External Shooting Mode : Single-Frame Lens F Stops : 6.00 Contrast Curve : (Binary data 578 bytes, use -b option to extract) Shot Info Version : 0222 Firmware Version : 1.10b Repeating Flash Output External : 1 Repeating Flash Count External : 1 Flash Exposure Comp 2 : 0 Sequence Number : 0 Shutter Count : 13537 ** Users ask about this, here it is Auto Bracketing Set : AE & Flash Auto Bracket Order : 0,-,+ Camera settings are not necessarily being used Auto Bracketing Mode : Flash/Speed Flash Sync Speed : 1/250 s Flash Shutter Speed : 1/60 s Flash Control Built-in : TTL Internal flash menu, even if door is closed. Commander Channel : 1 Commander Internal Flash : TTL These are the settings, but Commander is not used this time Commander Internal Manual Output: Full Commander Group A Mode : TTL Commander Group A Manual Output : 1/51 Commander Group B Mode : Manual Commander Group B Manual Output : 1/128 Modeling Flash : Off Commander Internal TTL Comp : +1.0 Commander Group A TTL-AA Comp : +2.0 Commander Group B TTL-AA Comp : +1.0 NEF Compression : Lossless Noise Reduction : Off NEF Linearization Table : (Binary data 46 bytes, use -b option to extract) WB GRBG Levels : 256 486 369 256 256 times the "WB RB Levels" multiplier above Lens Data Version : 0204 Exit Pupil Position : 97.5 mm AF Aperture : 2.9 Focus Position : 0x32 Focus Distance : 2.00 m D-lens report, but Nikon zoom lenses are often grossly wrong Focal Length : 47.6 mm Lens ID Number : 147 Lens F Stops : 6.00 Min Focal Length : 24.5 mm 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 : 3712 2462 Retouch History : None Shutter Count : 13537 Flash Info Version : 0105 iTTL version, third party too Flash Source : External External Flash Firmware : 2.01 (SB-800) Hot shoe flash used External Flash Flags : Fired, Bounce Flash Flash Commander Mode : Off I think this one is the Commander mode in hot shoe flash, internal Commander above Flash Control Mode : iTTL-BL Flash Compensation : 0 Repeating Flash Count : 1 Flash GN Distance : 2.0 m TTL BL can use this, even if zoom D-lenses can be quite inaccurate Flash Color Filter : None Flash Group A Control Mode : Off 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 External Flash Compensation : 0 Flash Exposure Comp 3 : 0 Flash Exposure Comp 4 : 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 : 2016:03:09 13:04:17 AF Info 2 Version : 0100 Contrast Detect AF : Off Live View off AF Area Mode : Single Area Phase Detect AF : On (51-point) Viewfinder used Primary AF Point : C6 (Center) AF Points Used : C6 Contrast Detect AF In Focus : No File Info Version : 0100 Memory Card Number : 0 Directory Number : 102 File Number : 2222 AF Fine Tune : Off AF Fine Tune Index : n/a AF Fine Tune Adj : 0 Retouch Info Version : 0200 Retouch NEF Processing : Off ---- Composite ---- Derived from other sections or values Aperture : 5.0 Auto Focus : On Blue Balance : 1.441406 CFA Pattern : [Red,Green][Green,Blue] Image Size : 7424x4924 Jpg From Raw : (Binary data 3966257 bytes, use -b option to extract) Lens ID : AF-S Zoom-Nikkor 24-70mm f/2.8G ED Lens : 24-70mm f/2.8 G Megapixels : 36.6 Other Image : (Binary data 881083 bytes, use -b option to extract) Preview Image : (Binary data 94699 bytes, use -b option to extract) Red Balance : 1.898438 Scale Factor To 35 mm Equivalent: 1.0 Crop factor Shutter Speed : 1/60 Create Date : 2016:07:25 10:44:41.50 Date/Time Original : 2016:07:25 10:44:41.50 Modify Date : 2016:07:25 10:44:41.50 Thumbnail TIFF : (Binary data 57816 bytes, use -b option to extract) Circle Of Confusion : 0.030 mm Depth Of Field : 0.51 m (1.77 - 2.29 m) A few properties revealed Field Of View : 40.2 deg (1.46 m) This appears to be horizontal width Focal Length : 48.0 mm (35 mm equivalent: 48.0 mm) Hyperfocal Distance : 15.34 m Light Value : 10.6 This is EV of settings at ISO 100 (this link computes it)
ExifTool seems awesome to me. And it's free. And updated frequently (and modern, keeps up with the new camera models)