What is the focal length equivalent for an iPhone? Or my Android phone?

That can change from one phone model to the next. The safest bet to get info about your phone is to open one of its photos in a tool that can read exif data.

For example, the iPhone 5 has "Focal length" 4.1 mm and "Focal length (35mm)" 33.0mm. That means that it is roughly as wide as your favourite 33mm prime lens on your FX camera. Or as wide as your 22mm on your DX camera.

A Galaxy S4 has "Focal length" 4.2mm and "Focal length (35mm)" 31mm.

An iPhone 6S plus has a "Focal length" 4.2mm and "Focal length (35mm)" 29mm. The reason the 35mm equivalent is different from the Galaxy S4 is certainly that it the size of the sensor is different.

To read exif data you can use for example:

• Adobe Photoshop
• Adobe Bridge
• Aperture
• Preview (Mac OS X)
• exiftool
• ... and many others.

The only snag is that not all exif-readers display the equivalent value for 35mm, and not all cameras actually store the 35mm equivalent. If it does not work for you, don't be too disappointed. Just make sure you try with at least one of the tools listed above. If you still have no luck, just buy a new phone. There is probably a new model on the market anyhow.

How do I extract an embedded JPEG from a RAW file?

Short answer:

exiftool -b -JpgFromRaw IMG0001.NEF > test.jpg

Long answer:

Most RAW files contain not only the raw data that was captured when the picture was taken, but also a jpeg file which can be used to quickly show the image before the RAW has been completely interpreted.

Some programs that pretend to handle RAW files actually just extract the jpeg and displays that one to the user.

There is rarely any reason to extract the jpeg manually, but if you want to, you can use the command tool above using exiftool which is a tool available for Windows, Mac OS and Unix/Linux.

Just replace "IMG0001.NEF" with the name of your RAW file and "test.jpg" with the name of the jpeg you want to create.

Update: The name of the preview is not the same for all RAW files. That's why Jener in the comment section succeeds with PreviewImage but not with JpgFromRaw. In general, if you have problems with the command, try the exiftool documentation page. 

Searching EXIF data with Mac OS X Spotlight

Using Mac OS X Spotlight, you can quickly search for certain camera metadata. A simple search would be "D300" (without quotation marks) entered in the field you get when you click on the magnifying glass in the upper right corner of your screen. That returns all images, both NEF and JPEG, that were taken with a Nikon D300 camera. By default you also get all other files that contain D300, like PDF files, word documents and old mails where you discussed the camera with friends. To limit the search to just images, go to "Show all in Finder". That will open a window with the title "Searching this Mac". Here you can click on a plus ⊕ symbol to get more search criteria. Click on it and select "Kind" as "Image", and you will only get image files.

If you instead of selecting Kind, select "Other", you get a vast number of search criteria to choose from, like ISO or EXIF version.

To really see all the criteria you can search from, you can use a Terminal window.

1. Open the Terminal from Applications > Utilities > Terminal.
2. Type "mdls " without quotation marks, but with the space after the last "s".
3. Go to the Finder and drag an image file onto the Terminal window. It should now contain text that looks something like "$ mdls /Users/myhome/Desktop/mypic.jpg"
4. Type "| less" after the file name and hit Enter.

What you now get is a list of searchable fields for the image, and their values:

kMDItemAcquisitionMake         = "NIKON CORPORATION"
kMDItemAcquisitionModel        = "NIKON D300"
kMDItemAlternateNames          = (
    "mypic.jpg"
)
kMDItemBitsPerSample           = 32
kMDItemColorSpace              = "RGB"

kMDItemExposureTimeSeconds     = 0.004
...

To move down to see more options, hit the Space Bar.
To move back up, type "B".
To leave the list, type "Q".

Now we can go back to Spotlight to use this information for an actual search.

1. Click on plus ⊕ again, and select "Other".
2. Select "Raw Query".
3. In the search field, type a field name from the Terminal and some appropriate value, like "kMDItemExposureTimeSeconds < 0.003"

This will display all photos with a kMDItemExposureTimeSeconds (shutter speed) that is faster than 0.003 seconds.

If you know you want to repeat the same query over and over, you can hit the "Save" button, and you will get a virtual folder for quick access, whenever you need it.

Everything that is written here actually applies to all kinds of files, not only images, but as this is a photo blog, all the examples come from the wonderful world of images.

Searching in Adobe Bridge

If you want to find all photos you ever took with, say ISO 200, you can easily do that in Adobe Bridge. You just select Edit > Find, select "ISO" as search criteria and "200" as value.

It is slightly more tricky if you want to search for all files with a particular shutter speed or aperture, as these fields do not appear as search criteria. What you can do is to search for Exposure, which is a field that contains both those values. E.g.: "1/30 s at f/2.8". This means that you have to enter the values as free form text.

Some fields, like ISO and Focal length, are numeric, so you can search for all photos where the Focal length is greater than 50mm. However, the Exposure field is a text field, so it is very difficult to collect all files with shutterspeed greater than 1/200.