If you read my recent post about moving up to full-frame, you’ll know that I purchased a Sigma 24-70mm f2.8 art lens earlier this year prior to purchasing my D850. The Sigma 24-70mm f2.8 art lens was the last piece in my full-frame lens lineup before purchasing a full-frame camera.

I was planning on using the 24-70mm on my D500 body while I decided when and who to purchase my D850 from. I purchased the 24-70mm lens from Wex in January of this year and immediately dropped it on to my D500 as a replacement for my 16-85mm f3.5 to use as my everyday walkaround lens.

My first trip out to test the lens was later that month when I needed to take a trip up to our archery practice range to check on the state of the course. I threw my D500 with the 24-70mm attached and my 100-400mm Sigma lens into my bag and headed out with Teyah (our furry four-legged pooch). I figured she would make a good subject if the wildlife wasn’t going to be cooperative. Teyah loves running backwards and forwards when she’s in the woods and off the lead, so I decided to try and get some images of her running back towards the camera.

I figured this would be a good test of the speed and accuracy of the autofocus. After a few attempts, I was starting to feel a little frustrated. When examining the images on the LCD, they were not as sharp as I hoped. The 24-70mm f2.8 lens from Sigma is a £1000+ piece of glass and I was hoping for so much more from it. I persisted a little while longer, wondering if it was just the focus speed that was lacking or my technique. I tried increasing the ISO to give me a faster shutter speed, I tried prefocussing on a spot and releasing the shutter when she passed that spot. None of it worked. I switched lenses to the 100-400mm f5.6-6.3 lens to see if this was giving the same results. Nope, that lens gave me images that were tack sharp.

Upon returning home, I took a few test shots in the garden. First focusing through the view finder using auto focus, then using live view for auto focus. The results confirmed my suspicions, the images using the viewfinder autofocus were not sharp while the ones focussed in live view were tack sharp. The lens had some issues with what turned out to be back focus. I should’ve seen the warning signs when I took some of the first sample images around the house. When zoomed in to 70mm and focussing fairly close, the camera was hunting back and forth for focus lock.

Not a big issue I thought, I’ve done AFMA (autofocus micro adjustment) before and usually do it on all the lens and body combinations I use. As an added bonus, I have the Sigma USB dock which this lens is compatible with and lets me get even more granular with my adjustments rather than just the single adjustment possible in camera. I normally start doing the automatic adjustment in camera then move on to adjusting the different focal lengths using the dock. That gave me another warning sign, both my D850 and my D500 bodies were unable to carry out the AFMA automatic adjustment.

I broke out the lens calibration chart and set about tuning the lens manually using the Sigma dock. This all went well until we go to the infinity setting. For those of you who don’t know, when fine-tuning focus using the Sigma dock, you make adjustments at four different focal lengths and four docus distances. Below is a screenshot from the Sigma software which hopefully makes the above sentence make more sense.

The value in each cell indicates the amount of adjustment applied at each focal length and each focus distance. A negative value indicates the lens is back focusing, a positive value indicates the lens is front focusing. The value can range from -20 to +20.

As you can see from the above image, I applied a -20 adjustment at 70mm while focussed to infinity and the lens was still back focusing. The only way I could get it close to accurate focus was to apply a -10 adjustment manually on the camera body and then calibrate it in the Sigma Optimisation software. I have no idea what each step equates to, but a -30 adjustment on focus seems a lot to me.

After spending most of the day trying different adjustments, I still wasn’t 100% happy with this lens. For £1000+, I want something that works without this amount of adjustment. I appreciate all lenses need some adjustment, and I have no issue with that, but this lens was a long way from working as I expected out of the box.

I contacted Sigma Support in the UK to ask about returning the lens to them for a re-calibration. They responded that the issues I described above did indicate that the lens needed recalibration and I should fill out the online service request and return it to them along with the camera body I was most likely to use the lens on. I wasn’t thrilled by this response, I wasn’t happy at all about returning a £1000 + lens along with a £2500 camera body to a workshop. After all, I didn’t take my camera body to the shop when I purchased the lens to make sure it worked, and to my mind, Sigma should have specific tolerances when calibrating the lens before it leaves the factory.

I have since returned the lens to Sigma without my camera and I am expecting to hear back from them in the next few days. I am hoping they are able to recalibrate it back to factory tolerances without needing my camera. If not, then it looks like the lens will be going back to WEX for replacement.

I have since reached out to other photographers on Facebook via the Master Photography Podcast group to see if anyone else has had a similar request from Sigma when asking for a lens to be recalibrated. The general consensus seems to be that this is standard practice. I am still not thrilled about it if I’m honest. I’ll wait and see what Sigma have to say. Expect to see another post shortly detailing the outcome.

I hope you found this post useful and informative if you find yourself in a similar situation. I could find nothing online to indicate if it’s normal to have to send your camera away with the lens when it needed calibration. If you have had similar issues and resolved them an alternate way, please let me know.

Thanks for stopping by. Have a good one.