Sigma sells a USB dock that lets you update and customize their lens firmware. The (free) program used with the dock is called Sigma Optimization Pro. I have an article on it here: .
Sigma has been providing firmware updates for my 150-600mm Contemporary (and also for the Sports version). The first update (1.01) improves the auto-focus speed (they claim up to 50%). The second update (1.02) fixes focus issues with the Nikon D500 used with a teleconverter.
I bought the USB dock to enable in-lens focus fine-tune. This style of focus fine-tune goes way beyond any other lens manufacturers; it lets you fine-tune at 4 focal lengths and 4 distances per focal length, giving you a total of 16 fine-tune settings. This feature totally transformed my lens resolution from mediocre to stellar. Nikon’s (and Canon’s) focus calibration only lets you perform a simple global focus shift; this just doesn’t cut it for focus calibration. It is handy, though, when you mount the Sigma on another camera body, where the camera’s focus fine tune gets applied in addition to the Sigma in-lens focus calibration.
My focus calibration fine-tune settings
Auto-focus Firmware Changes
I tried their auto-focus customization options (fast “Fast AF Priority”, medium “Standard AF”, or precise (slow)) when I first got the lens, but found the ‘fast’ algorithm wasn’t very accurate. I settled on the default “Standard AF” auto-focus speed, since I’m not willing to sacrifice resolution for speed. I didn’t notice any precision improvement trying their “precise” setting.
It took me a long time, but I eventually got around to testing the new focus algorithms that were provided with the 1.01 version of the software. I noticed when I first loaded the new firmware that the default speed (Standard AF) was more responsive than it used to be, and have been happy shooting with that setting.
It never occurred to me to re-try the “fast” auto-focus setting; big mistake. It’s great. Accuracy is now essentially the same as the medium “Standard AF” setting, and it is simply faster. It’s like I just got a new lens, but for free.
C1 switch settings: focus speed, focus limits, viewfinder stabilization ‘effect’
C2 switch settings: focus speed, focus limits, viewfinder stabilization ‘effect’
Accuracy Comparison: High-Speed Auto-focus vs. Standard Auto-focus
I used the MTF Mapper software to evaluate auto-focus accuracy. This test is a bit ‘statistical’ in nature, because it’s based upon a moving target. I lean on a tripod while hand-holding the lens at 600mm. This technique lets me get more reliable framing of my resolution target, but the lens is still “wiggling” quite a bit. I use back-button auto-focus and “AF-C” continuous focus. I also re-focus by pointing away from and then back onto the resolution target while AF is active.
Note that the following MTF results aren’t as good as a firmly-mounted lens on a tripod and remote shutter release. With a long lens, even 1/2000 will have a tiny amount of motion blur when hand-holding.
1) MTF50 maximum results with “Standard” AF Speed, 600mm 1/2000s f/6.3 hand-held:
28, 28, 26, 28, 28, 26, 30, 32, 26, 24, 24, 30, 28, 28, 26, 26, 26, 28, 30
Average MTF50 maximum: 27.47 lp/mm
2) MTF50 maximum results with “Fast AF Priority” Speed, 600mm f/6.3 hand-held:
28, 30, 23, 24, 28, 22, 28, 26, 32
Average MTF50 maximum: 26.78 lp/mm
There is no real focus accuracy difference using the “fast” auto-focus algorithm versus the “medium” auto-focus algorithm using the 1.01 or 1.02 firmware. So why wouldn’t you just leave it on “fast”? Sigma didn’t advertise that their accuracy got better with the new firmware, but I’m seeing a definite improvement in both speed and accuracy.
Vibration Reduction “Optical Stabilization” Firmware Changes?
The good news doesn’t end there. When I first got the lens, I experimented with using their vibration reduction (they call it “optical stabilization” or OS). They provide the usual ‘OS1’ for general hand-held use, and ‘OS2’ for panning use. I tested the lens using OS1 and shutter speeds beyond the normal VR upper-limit of 1/500. I found that the resolution was reduced when I tried 1/1000 by about 9%. As a result, I would turn off VR (OS) at high shutter speeds, just as I was taught to do for all lenses with VR.
Using the new firmware (1.02) I’m not noticing any measurable degradation in resolution at high shutter speeds (all the way up to 1/8000)! This is just fantastic. I’ve always hated having to remember to turn VR on and off to accommodate my shutter speed changes. Now, I can just leave VR on and forget it.
I’m going to have to re-test my other lenses to see if they really require me to turn VR off with higher shutter speeds or not.
The moral of the story is don’t blindly believe the urban legend about always turning VR off at high shutter speeds. Test it first!
VR Testing at High Shutter Speed Sample
These tests were performed at 600mm f/6.3 using the “fast” auto-focus setting, hand-held, AF-C “back-button” focus. Shutter speed was 1/2000 throughout. Sigma lens Firmware version 1.02. Again, these MTF50 numbers are lower than when using a tripod with a remote shutter release; even high shutter speeds with a big lens aren’t as effective as a tripod for static subjects.
MTF50 maximum: 28, 30, 23, 24, 28, 22, 28, 26, 32. MTF50 Average: 26.78 lp/mm
MTF50 maximum: 28, 26, 28, 28, 30, 22, 26, 24, 22. MTF50 Average: 26.0 lp/mm
Conclusion: There is essentially no difference with stabilization active or not at this high shutter speed. I tried tests such as these all the way to 1/8000 shutter, without significant changes to MTF50 resolution when leaving vibration reduction active.
Isn’t this great that Sigma comes out with these firmware updates? If only Nikon and Canon could catch up to these guys in making smarter lenses.