PLEASE NOTE THAT THIS POST IS NO LONGER FULLY UP TO DATE. A new post was made on 18-August-2017 updating this blog with my latest lens calibration methods and techniques. It is best to go here to read the new post.
This is the second part and continuation of last week’s post on How To Calibrate Lenses With Your Camera Body (Part 1).
In this post I am going to take you step by step through the 20 step lens calibration process from start to finish using the LensAdjust tool. First though is a short workflow summary of how I carry out the process in practical terms.
I start by using two tripods. I place the LensAlign tool on one tripod and my camera on the other. Afterwards, I go to the LensAlign web site and click on the “Distance Tool” tab to check the correct distance needed between the camera and the LensAlign tool based on the aperture and focal length of the lens I plan to test.
Then I take a tape measure to set the correct distance apart between the two tripods. Next, I take the tape measure to measure the height of both tripods to make sure the height of the camera and the LensAlign are at the same height.
Then I take a spirit level, put it onto the hot shoe of the camera and level the camera. Next, I go back to the camera, select the center focusing point, and aim it over the center target hole on the LensAlign tool. I may need to adjust the camera slightly to get the center focusing point on the camera to be fixed onto the center hole on the target. Next, I go over to the LensAlign tool and look through the 2 holes of the LensAlign tool from the backside. I do this to make sure I can see the lens of my camera centered in the holes when I look through the back side holes of the LensALign tool. If I can’t see the lens in the wholes from the back of the LensALign tool I move the position of the LensAlign tool a bit.
Then I go back over to the camera. If I had moved the LensAlign tool a bit, I first double check the camera to make sure the center focusing point of the camera is still aimed at center target hole on the LensAlign tool. It should be.
Then I turn on live view and I zoom in as much as I can on the front hole of the target to see if I am able to see the red dots from the the rear holes appearing inside the front holes of the LensAlign tool. If there isn’t enough light to see the red dots then I shine a flashlight on the LensAlign tool to help me see the red dots inside the front target holes. Usually I am spot on and don’t need to move either the camera or the LensAlign tool any further. Then I take my first test shot using the camera. It is best to do these tests during the daytime in a room with a window where there is good, natural daylight light.
Following Are The 20 Steps:
1 – Attach the LensAlign tool to either a tripod or a studio light stand. The thread hole on the LensAlign tool is 1/4″. The standard screw size though on most tripod heads and light stands is 3/8″. So you may need to buy a special 1/4″ screw adapter for use with the LensAlign tool as I mentioned previously in Part 1 of this post.
2 – Attach your lens to your camera and remove any filters from the lens and then attach your camera to your tripod.
3 – Check the height of the camera and the height of the LensAlign tool to ensure the height of both the camera and the LensAlign tool are equal. You can either stand your camera and the LensAlign tool next to each to compare the height or use a tape measure to check the height of each one individually.
4 – Attach a remote shutter release cable to your camera or a wireless unit if you have one.
5 – Attach a spirit level to the hot shoe on your camera and then make sure your camera is level.
6 – Place the LensAlign tool on its tripod/lightstand in front of a window and open the curtains or blinds so that there is a strong amount of daylight hitting the LensAlign tool from the back. Now rotate the LensAlign tool so that the front of it is facing 35 degrees to either the right or left side of the window towards the wall on either side of the window. This way, when you look through the lens of your camera to focus on the LensAlign tool, you are looking towards the wall instead of trying to focus onto the LensAlign tool with backlight coming at your camera through the window.
7 – Figure out what distance your camera should be from the LensAlign tool based upon the focal length and the aperture of the lens you are testing according to the table on the Distance Tool tab here. Correctly set the distance between the LensAlign tool and the camera using a tape measure.
8 – Set your camera to shoot in JPG mode at the highest resolution and set your camera to either ISO 100 or 200 for sharpest looking test results.
9 – Set your lens to the widest aperture setting that the lens is capable of. Either F/2.8 or whatever that may be.
10 – If you are testing a zoom lens then zoom all the way in onto the LensAlign tool target so that the lens is fully zoomed.
11 – Adjust the position of your camera on the tripod so that the center focusing point on your camera falls onto the center hole on the target of the LensAlign tool.
12 – Now walk behind the LensAlign tool and look through the back center hole of the LensAlign tool looking through to the front hole. You should be able to see the lens of your camera centered in the front hole of the LensAlign tool.
13 – Return to your camera, look through the viewfinder again and take a test shot.
14 – Now zoom in on the test shot you just took as much as you can using the LCD preview screen on your DSLR camera and, if all things are lined up correctly, then you should be able to see a red dot inside the LensAlign tool’s center hole of your test shot. If you don’t see the red dot then you will need to adjust things again by repeating the setup steps listed above until you are able to see the red dot in the center hole of your test shot. If you don’t have strong enough ambient light available in the room where you are working in order to see the red dot clearly within the hole then shine a flashlight onto the front hole of the target of the LensAlign tool to help you to see where the red dot is.
15 – Now you are ready to take a test shot to actually test your lens’ focus alignment. Start by focusing on the target of the LensAlign tool using the center focus point on your camera (don’t try to focus on the ruler part). Then press the shutter down half way to auto-focus the lens. Now you are ready and you can take your first test shot.
16 – Remove the memory card from your camera and open up the test shot on your computer screen at 100% resolution.
17 – First look at the target and make sure it is in focus to ensure your lens focused correctly on the target. Now look at the ruler to see if the number “0” is sharply in focus or if the camera will require any micro-adjustments for this lens.
18 – If the focus is not sharp on the “0” on the ruler then figure out where the focus is the sharpest. This will also reveal if the lens is front focusing or back focusing either in front or behind the number “0” on the ruler.
19 – Next, a bit of trial and error is needed to figure out how much to adjust the micro-adjustment settings on the camera. The micro-adjustment on Canon cameras can go up to 20 increments, both forward and backward (meaning plus and minus). So a total of 40 increments all together. Now make an initial micro-adjustment and reshoot another test shot to see if the adjustment you made is correct.
20 – Once you have selected a number for the micro-adjustment put your memory card back in your camera and take another test shot. Usually taking anywhere from 2 to 4 test shots with changing the micro-adjustment setting each time in between will be needed. After a few tries you should get it right in terms of the correct micro-adjustment setting needed for that particular lens and you can move onto your next lens.
So there you have it. And after you calibrate a few lenses you will start to get a better idea of how much compensation you will need each time. It is pretty easy once you get the hang of it. I ended up adjusting anywhere from 1 increment all the way up to 17 increments (on my 135mm F/2 lens) which was way off. Hopefully you don’t have any lenses which are off by more than 20 increments. Most of my lenses were off no more than 5-10 increments.
As a reminder from Part 1 of this article, I am using the Michael Tapes LensAlign MkII Focus Calibration System, which sells online for $85 with free shipping here.
If you have any questions on this calibration process please feel free to post them below.