Lens focus test chart to test your lenses
Download my free focus test chart, it is free!!! Make sure that your lenses are focusing properly. Total cost is a piece of paper and some time. Whether you have a DSLR or mirrorless I recommend testing your lenses. This way you can trouble shoot BEFORE you have issues.
Sometimes it is something as simple as a camera setting, sometimes it is more.

Catch up time – Lens Focus Test
One of the great things about this time of the year, especially when it is a blizzard, is that I have time to catch up on projects.
I was doing a focus test on my lens and made a video about a way of checking the focus on your lenses (links below)
Now before I go any further let me say not all cameras can do what I am going to describe in that you can adjust the focus yourself. If the focus is really out and you do not have the ability to adjust the focus you will have to send your camera and lens away.
So what is a lens focus check? It is a way to check to see that when your camera says that the image is in focus, and thereby should be sharp, that it is actually in focus and sharp.
This way you know if you have a problem lens and as mentioned above some cameras have a menu that allows the photographer to make changes to the focus setting without sending the camera away. In the past we would have to bundle up the camera body and lens(es) and send them away to be adjusted.

Should you test your lenses?
I have always checked my lenses to know if they are working correctly. Now with the 70D’s and the 5DMkIV’s not only can I check the focus but I can adjust it.
You only need to adjust if your lenses are way out of focus. Focusing a little more to the back or the front is normal and all lenses are a little different.
Before the test chart I would do a simple in field test of focusing on something. Taking the image then looking at the image on the computer. From there seeing if what I focused on was sharp and if not what was in focus. Simple but it worked.
Now using this video and the focus chart below you can see exactly how good a lens is and if your lens is out what direction you need to adjust it.
Yesterday I did both tests (my old way and the new way). I have to say that I had the lenses close the old way but when I switched to the focus chart I was able to nail it.
It was so much faster. As an extra benefit with using the chart you can adjust your lens to rear focus if you want that. I know a number of people who like their lenses to rear focus a little. This will allow you to set that easily and precisely.
Focus Test Chart Links
So if you have some time and are curious here is the link to the video https://youtu.be/Mn_gwppNh
Here is a link to download a free focus test page http://www.firstchoicephoto.ca/FocusTestChart.pdf