Here are some great examples of iris photos and instructions on how to take them correctly.
First, what you'll need is some type of light source. A pen light, a flash light, or a cell phone light are the best light sources I've found. Then you'll need any type of cell phone. You can also use a DLSR camera but I've personally found more success with a cell phone camera.
Its easiest to have someone else take your photos for you.
The most important part is getting close enough to the iris and also being able to keep the clarity. It takes a minute to find that sweet spot.
There is now an app that is really helpful called: EyeCos EYE selfie
You can get this app on both iPhone and Android. It's really helpful for those of us that have to take our iris photos alone. What I do to take the photos alone is stand in front of my bathroom mirror, I zoom in and use the back camera on my phone, (not the selfie camera) light up the iris with a flashlight or a pen light and take the photo.
I’m going to add some examples of what I’m looking for.
No eyelids in the way, up close so I can see the fibers and no reflection from windows.