There is no lens I love more than my Sigma 35mm 1.4 ART. If I had to choose one lens to live with for the rest of my life, it would undoubtedly be my Sigma 35mm 1.4. Unfortunately, now and again this lens starts to miss focus. This is a lament I hear frequently around the photography community. Further, many 35mm lovers like me enjoy shooting with the lens wide open, so a slight discrepancy in how the lens is focusing can result in images that are significantly different from what you intended.
Fortunately, Sigma offers a USB Calibration Doc to help you fine tune the focus of your lens. Priced at around $65, the USB calibration doc is relatively inexpensive (especially in comparison to what you pay for the lens itself!), and all it takes it a little set-up and a few tweaks to get your focus exactly where you want it.
After purchasing the calibration doc, the first thing you will want to do is download the Sigma Optimization Pro calibration software to your computer (click HERE for the link to the software). Once you have done that, simply follow the steps below and your focus will be as tack-sharp as ever!
Step 1: Set Up Your Test Scene
It is helpful to pick an object with a relatively easy focus point and set it up in high contrast light with very little noise. You will want to make sure there were no light issues distracting from the way the lens is focusing. Once you have that set up, place a tape measure alongside the object starting about 2 feet behind the object and extending at least 4 feet in front of it.
Step 2: Take 4 Test Photos
In taking the test photos you will want to open your lens pretty wide. By creating a very shallow depth of field you can really zero in one how accurate the focus is. This is key for those of us who like shooting f/2.8 or wider. You will then take a test photo at less than 1 foot from the subject, another at 2 feet, then at 6 feet and one beyond 6 feet. After taking each photo, using the tape measure as a guide, review the results to see what part of the image is the sharpest.
Step 3: Connect Your Lens To Your Computer
Once you have taken your test photos connect your lens to the computer using the Sigma USB calibration dock.
Step 4: Check The Firmware
Click on “Firmware Update” so that the software can check to see if you lens needs updating. Most often the answer will be no. After that click on “Customization.”
Step 5: Review Your Test Photos & Make Adjustments
After clicking on “Customization”, click on “Focus Setting”
This will bring you to the screen at which you fine tune your focus point at varying distances. To do this, you will want to review each of the images you took as test shots and note if you lens is front or back focusing at any of the distances.
For example, the image above was taken at a distance of 2 feet. When I reviewed it I noticed that the tape measure 1 inch in front of the subject was slightly more in focus than the eye of the pony.
I was much further off when I took an image at a distance of 8 feet. This is the issue I could really notice when using my camera that prompted me to run the calibration software. When reviewing it, I noticed that the area several inches in front of the pony was the most in focus. (Please note on this one, that I had a previous adjustment of +12 already on the firmware, so when making adjustments I was working from a starting point of +12 so I bumped it back to a +7)
Type your adjustments into the screen below and click “Rewriting”.
Step 6: Retake Your 4 Test Photos
You will now want to re-take your test photos from the same exact positions to ensure you focus is spot on. After re-taking your test shots repeat Step 5. It may take several tries to get it just right so go a little at a time until you know your focus is right where you want it.
And that’s it! I usually go through this process every few months, or before a very important photo shoot, to ensure my lens is at optimal performance when I have it opened wide.
The Sigma 35mm 1.4 ART is a gorgeous lens – so fast and sharp. All it takes is a little tweaking now and then and this lens will continue to be the workhorse you want it to be.
This is great to know!!! Thank you :)!
Sure thing 🙂 I love love love this lens!! But the only downside is that calibration is a MUST!
This has been by far the least complicated and most helpful tutorial I have found for calibrating my Sigma 35mm 1.4. Maybe it was the My Little Pony that made it relatable to this momma of 2 girls. 😉
Haha – thank you! Glad you found it helpful 🙂
great tutorial! I’ve just bought this lens. Does the lens need calibration before use?
Not necessarily. Some work great right out of the box and so are off right away. Run some test shots and see what you think and then go from there! You will love this lens!!
I just calibrated according to your demo and it is fantastic! my sigma 35 was back focusing at longer distance…..now sharp! Thank you for your tutorial!
Thank you for the information 🙂 I’ll try to caliberate my 35/50/135. They are all still under warranty do you think I should send me lenses and camera (D750 New) to the sigma service center for them to do this hard work?
If you are still under warranty you may want to consider sending it back. However, once you calibrate your lens once or twice it becomes a pretty quick and easy process. Now it’s something I check each month and only take about 15 minutes.
I am having so much trouble calibrating my lens with the last two settings. When I try to shoot infinity, my lens is way off. Even right before it as well. The only sharp shots I can get are right in front of my camera. Do you have any other tips or suggestions on how to get this lens perfect?
I do find shooting at Infinity to be the hardest to get sharp, so I’m with you here. It just takes me a little trial and error to get focus right. This lens definitely shines when you are up close with your subjects!
thank you for this tutorial. I had my sigma art 35mm calibrated by a professional about 4 months ago and it was working great. Now I am starting to have issues again where there are times it wont let me release the shutter as I focus. Do you think i need to have it recalibrated again? The guy at the camera shop told me as long as I use this lens with the same camera I should not have to have it recalibrated but I am thinking that is not true?
Do you have the doc so that you can calibrate it yourself? This is a lens that does need to be calibrated from time to time, even when using the same camera. During busy season I calibrate mine once a month using the doc. Off-season probably every few months. But either way calibrating it regularly is the key to maintaining that incredible Sigma sharpness that we love so much!
I Have the dock and tried calibrating it on my own using youtube videos and Thought i fixed the problem but then it WOULDN’T let me focus at certain lengths during a SESSION AND i was PANICKING… so when i got home i docked if and put all my setting back to zero. Ill DEFINITELY try this and hope it helps…
Hope this helped!!
Does this particular calibration system work well with other lens’s?
Thanks!
No it is Sigma specific.
Hi Jen. I am currently trying to use the doc to calibrate. Do you ever set the AF microadjustment for lenses in you canon menu? I noticed mine was set for this lens. Should I set it back to zero since i’m using the doc now? Thank you
Personally I don’t do any adjustments in camera for this lens as I prefer to do them all in the doc, but it would be a good experiment to see how the test runs with the in-camera adjustments and without!
Thank you for this! I just bought a used lenS Anand thought it was going to be OK but I am having some issues at certain distances. The same seller also has a doc so I am going to buy it since you are saying it needs to be done occasionally
I think the doc is a great investment. It really doesn’t cost much at all and it allows you to maintain full control over the sharpness of your lens.