Sigma Optimization Pro and USB Dock

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"Commerce makes progress. Fortune passes everywhere." - Frank Herbert

A few years ago I was accused of being a Sigma hater. (For the record, I did hate their quality control and so-called repair service at that time, and I didn't hesitate to say so in this blog.) For the third or fourth time in the last year, I'm about to be accused of being a Sigma fanboy.

I'm pretty certain I haven't gone soft over the last 4 years. I am certain, though, that Sigma Photo, Inc. has changed a lot in that time. Truth is, they're making serious waves in the photo industry these last few years. They've improved their repair service and quality assurance. They've released some world-class lenses at way less than world-class prices lately. And now they've released their USB dock and Optimization Pro software.

I've spent the weekend playing with it. Partly because I really think this is a revolutionary product and I wanted to see how it worked. Partly because I desperately need a 'Honey, I've really got to do this for work' excuse or I'd have been restaining the deck.

My conclusion, as usual, first: if anything is going to get the attention of those who like to disable features in firmware, overprice lenses, and limit our ability to customize, this might be it. I did some adjustments this weekend, in about 10 minutes, which would have required a trip to factory service on a Canon or Nikon lens. And let me stop the Fanboy stuff before it starts: you may never have needed to make this adjustment on your 10 or 20 Canon or Nikon lenses, but I've sent dozens of them to factory service adjustments for exactly the issue I'm going to demonstrate today.

Quick Overview of the USB Dock and Optimization Pro software

The directions are pretty simple:

  • Make sure you buy the dock in the proper mount (Canon, Nikon, or Sigma).
  • Download the Optimization Pro Software HERE. It's about 3.4 Mb in a zip file, available for Windows or Mac.
  • Open the software, put the lens in the USB dock, and plug the USB port in your computer.

Once you hook things up the program the program opens to a nice, straightforward main page.


The firmware update button reads the lens' firmware and lets you know if you need a firmware update. Push yes and it updates in about 20 seconds.

Adjusting a Lens

First of all, there's a nice 10-minute video that Sigma made that shows you the use of the device very clearly HERE. If you're like me, though, you might prefer a 30 second blog read. It really is that simple. Actually, 10 minutes is more time than it took me to do my first adjustment on the 35mm f/1.4 (of course, without reading any manuals).

I should be clear, I don't do a full-ballistic, OCD, 600-shot microfocus adjustment. I'm too aware that phase detection AF is a shotgun, not a sniper's rifle. I'll take nearly perfect in 10 minutes rather than perfect in 4 hours every time. Plus, like I said, I've got a deck to stain. Unless I can put it off so long that my wife gets frustrated and does it herself.

I chose a lens that is perfect for this software. This copy of the 35mm f/1.4 is perfect on my Canon 6D at close and intermediate distances, but at long distances it backfocuses badly. I can do a microfocus adjustment to correct long-distance focus, but then the lens is frontfocusing at near distances. Without the Sigma dock and software, the only option was a trip to the factory service center to change the lens parameters.

Since I was at home instead of the office, I didn't have Focal, LensAlign charts, or any of the other things that seem to be considered necessary tools for autofocus adjustment these days. So I made do with a placemat and my back yard.

Since I plan on using this lens outdoors in daylight I wanted to adjust it in daylight (autofocus can change slightly in different lighting conditions, if you aren't aware). I started with a placemat set in front of a picture window.

Spot focusing on the tip of the green leaf, I took several shots each at minimum focusing distance, 3 feet, and 6 feet. They all showed focus was accurate, as in the samples below.


Focusing at longer distances, however, showed the lens backfocused quite dramatically. In this image the focus point was on the small yellow leaf in the foreground (I've cropped the image to show the area behind the focus point).

Opening up the Sigma adjustment window shows I can make adjustments at 4 distances. With the 35mm, 3 of those are close: roughly 0.3, 0.4 and 0.7 meters. The other is infinity.

I left the close adjustments at zero and gave infinity adjustment a -12. You just click on the area you want to adjust, move the slider the amount you want adjusted, and then click the "Rewriting" button. (The "Rewriting" button is the only part of the software that isn't totally intuitive; it isn't highlighted until after you click on it.)

A repeat shot outside showed -12 was way too much adjustment so I went back and reset the infinity adjustment to -8. That was spot on as shown in the image below. I rechecked AF at closer distances and it had not changed a bit.

Total elapsed time for firmware update, focus checks, focus adjustments, and final check was just about 10 minutes. Obviously a zoom lens, which can be adjusted both at different focal lengths for different focusing distances at each focal length, will take longer.


For the even slightly gear-head amongst us, this is an awesome tool, giving us the ability to fine-tune autofocus adjustment much more completely than simple camera microfocus adjustment. At $59, I consider it an amazing bargain for anyone who owns one of the Sigma Art, Contemporary, or Sports lenses (it does not work on older lenses).

I've already heard a couple of people complain that it should be included with the lenses but I disagree. First, the price is very reasonable and the software is free. Why would they include it with each lens (which probably means each lens costs $59 more) when you only need one for all of your lenses? Not to mention half the people who got it would never use it.

I've heard others state that only Sigma lenses need such a device. I'll meet them part way: I think there is probably a more frequent need for such adjustment on third-party lenses, but I can absolutely guarantee you that the big-boy's lenses do indeed have this same kind of problem, at least occasionally.

Whether they need it more frequently or not, now Sigma DOES have such a device. Which means, for example (just pulling a random lens out of my hat), the Sigma 35mm f/1.4 is now not only sharper and less expensive, but also more accurately adjustable than the manufacturer's 35mm f/1.4. I wonder if anyone is hearing footsteps*?


Roger Cicala


June, 2013

* For my non U. S. readers, hearing footsteps is a term used to describe an American football player, who, thinking he is wide open and about to catch a pass, unexpectedly hears the footsteps of an unseen opposing player about to crush him.

64 Responses to “Sigma Optimization Pro and USB Dock”

Brian B said:

Reikan FoCal + Sigma dock.

Has anyone developed a workflow for use with the Sigma dock and Reikan FoCal? This seems like it could be a great combination.

Michael said:

Thanks for posting the review of the Sigma dock. I am having a terrible time with a new Sigma 24-105 art lens which won't produce a sharp image unless I manually focus. I've spent 3 days testing, micro adjusting, testing again and still don't have a good result. Then I heard about the dock that may solve my problem.

Sounds good based on your description but, you didn't mention the impractability of what is required to get the readings in the 1st place. You skipped the most labor intensive and time consuming part of the process! One must set up your gear, shoot, make notes of how it was shot, relocate to a desktop, download, adjust blindly, do it all again and again...all for only 1 shot! To set up all the scenarios one might use on a lens you will spend 3 days!

LensRentals Employee

Roger Cicala said:


I've never spent more than 20 minutes on a prime or 45 on a zoom. Ever. I think people sometimes approach this like they're zeroing in a sniper's rifle. Since phase detection AF is, at best, a shotgun pattern, spending hours agonizing over an exact number if a fool's errand. Ambient lighting changes (not just amount but color), AF sensor inaccuracy, AF sensor mark placement inaccuracy, and a host of other things mean the best AF is a scattergram of points around your center point.

I have an area in my front yard (grass makes a great background for finding where the sharpness is) with several good AF points at various distances. I go out, shoot the distances at the different zoom ranges, check to see where AF was front of backfocusing, adjust that on the dock, and recheck. Usually I have to make one or two fine-tunes on a zoom, sometimes 1 on a prime.


Karl Wendlinger said:


I am wondering, why you dont use the AF Adjustment of the camera to find the correct values for the 4 distances and apply them afterwards in the dock at once. There you can also adjust -20/+20. Like this you dont have to check if the adjustment in the dock works.

Or do you think that you cant use the MICRO-AF-values of the camera? Are they somehow different from what the dock does to the lens?

By the way: I am pretty dissapointed with both of my SIGMA art lenses. The 50 and the 35. AF is a big issue. Sometimes it nails it and sometimes it is way off. Although i have calibrated the heck out of them... Sometimes it works perfectly, sometimes not. The distances you can adjust wont help much for other distances and especially for different AF points.

In the 35 mm there is for example no setting for 2 to 3 meters. You have 0,3/0,4/0,6/infintiy... After calibrating best possible for the given distances i can calibrate in the dock it works nice at the given distances (of course only in the light i calibrated them, but not in other light situations and mostly also not in other AF poits) I get a horrible front focussing at a focus point that lies between the infinity setting and the 0,6 meters (for example 3 meters) with the 35 mm especially at outer AF points with my 1 DX.

These lenses are not usuable for any documentary work, like wedding photography. AF is just not working with them. Whatever Canon does to make these lenses fail. It works. I will have to bring both of them back. I hate it, because my 35L is no way near the image quality of the 35 art, but the IQ is useless for me, when the AF outcome is a lottery.

I dont care if SIGMA or CANON are to blame, but its a shame that this lenses are sold as AF lenses. And its a shame that you have this outstanding glass which you can only use in MF for perfect results. If i want a MF lens, i use a LEICA camera and lens.

I never had these kind of problems with any of my Canon glass. These lenses are brilliant for MF, but useless for AF. You state it yourself: AF performance can change at so many occasions. I never experienced so HORRIBLE differences in AF Performance with my Canon ölenses (even not with the cheaper ones) like i do with these SIGMA lenses. All this despite the fact, that the SIGMA art glass it probably is the best glass i had on my 1DX at the given focal lengths 35 and 50 mm.

LensRentals Employee

Roger Cicala said:


The camera can set the entire lens for front or backfocus, but can't adjust it at particular distances. With a lot of lenses (not just Sigma, but it does seem to affect Sigma primes, where with Canon it's mostly zooms) the lens my backfocus at one distance, front focus at another. The camera can't do anything about that, but the dock can.

That being said, we do sometimes set the variation in the dock (+4 at infinity, +2, at long distance, 0,0 at shorter distances for example) for the lens, then set MFA in each camera for overall adjustment. We generally only do that when one lens might be used on several cameras.

I would also mention that the Sigma lenses tend to be camera specific, which is why I always recommend talking to people who shoot your exact camera type before deciding. It may do great on a 5DIII but be inaccurate on a 70D, for example.


Karl Wendlinger said:

Hi Roger,

thanx for your reply. I understodd this difference between MICRO AF in the camera and the dock. What i meant was shooting the different dock relevant distances and finding the right adjustmenst first only by using the micro AF for the different distances first in the camera. you select exactly the disctances you need for the dock and make your test shots while adjusting the micro AF in the camera for every distance until you get the best indiviual results. these values then you apply in the USB dock. thats what i did. and as i said, it works under the same light for the given distances, but it does not work at the distances between for example o,6 meters and infinity in the case of the 35 mm.

For example on the 35 mm:

Shooting at 0,3 meters with different micro AF values in the camera. finding the one that works best. then changing the distance of the object to 0,4 meters and again checking for the best in camera micro AF adjustment. after that for 0,6 and finally for infinity. after the procedure connect the lens to the dock and apply the different values.

in case of my 50 mm after this procedure i had the values:

0,4 = +12
0,7 = +12
1,5 = 17

these were the values at which the lens produced the best results when adjusting the micro AF in camera at different distances. i used the micro af adjustement like a screening tool after applying the values in the dock directly to the lens, i then set the in camera adjustment back to zero.

Am i not making the procedure clear enough or do you think that this does not work and i need to find the correct adjustments with micro AF set to zero in the camera and trial and error directly in the dock, like you did?

Perhaps my idea in fact does not work and i got only usable results just becasue the SIGMA lenses sometimes perform spot on? The nearer the distance, the better it worked.

Thanx for your support


Karl Wendlinger said:


If i understand you correctly you say, that the micro adjustment in the camera cannot produce different results at different distances?

is this correct?

Thanx, Karl

LensRentals Employee

Roger Cicala said:

Hi Kari,

I misunderstood your original comment. I've never tried to do what you're doing, so I can't say if it's a great idea or a bad one. I would guess adjusting with the dock is more accurate, but I'm not certain. My reason for thinking so is that a Sigma lens is accepting a Canon protocol and data array from the camera (probably one of the reasons Sigma lenses often identify themselves in EXIF data as a Canon lens), then the chips in the Sigma lens modify that protocol for the lens motors and feedback. I would assume that adjusting in the lens would be more accurate but that's just an assumption.

True confessions now: my microfocus protocol with Sigma lenses probably would just embarrass most people. I take the camera and lens outside where I have a gravel path with stepping stones. I focus and take a couple of shots at each focusing distance, go back in and look at the pictures, hook up the dock and make some rough adjustments, go back outside and shoot them again, check and make fine tuning adjustments if needed. It takes me maybe 15 minutes.

As you mention, though, light makes a big difference with certain cameras. Since I shoot 90% outdoors I adjust outdoors, but I have noticed that a distinctly different light can throw my MFA off.


John Paventi said:

Something I do not comprehend. What distances do the micro adjustments correspond to in the real shooting environment? When I adjust inside one of the four-section parameters, am I adjusting the lens to only be in focus within those limited measurements shown within the four-section chart? For example, within the section that shows 1.5 feet (0.4 meters), is that the distance I need to place my target from the sensor plane? And, if so, what shooting distance does that equate to? Or, is that the actual shooting distance (1.5 feet) that I am adjusting the focus for?

Harold U. said:

Excellent article Roger, along with the other ones regarding "Soft Lenses" from the past.

Recently got a Sigma 18-35mm Art, and have definitely seen it front focus by about an inch or so in typical phase detection. However it focuses spot on, tack sharp through live view (Canon 7D MKII & DPAF) at all distances and focal lengths.

Question, will straight out of the sensor auto-focus always be precise (ie: Live View & DPAF), even if I adjust the in-camera Microfocus adjustments for phase detection? Or even if I adjust the lens through the USB dock?

LensRentals Employee

Roger Cicala said:


If I understand the question correctly, yes it will. Microfiches adjust and the Sigma dock only work on the phase system. The contrast detection system does no calibrate differently with adjustment.


Arthur said:

Hi, is there any guide to estimates the value of adjustment for the 18-35 on a 550D? For a close range, both 18 and 35 are in focus, however the nightmare begins when I move 1m away. It has front focus.

Jimmy C. said:

My copy of the 35mm f1.4 also has focusing problem on longer focusing distance, and this device seems to be great. However I probably will use it for only once or twice, so I think it would be great if we can rent it. Will LensRental provide rental service for this in the near future? If so, I would love to get it and calibrate my lens at a lower cost.

David Arkin said:

I have been reading this thread about the dock. From the example above of BackFocusing you go to a negative side of the scale (-12) at the start.

When I read the manual:

When you adjust the value, click the ◄► buttons in the spin box, or drag the ▼ button of the slider (Shifting focusing towards the front requires “-“ side, while back focusing orientation requires “+” side).

I get confused by their syntax.

My question is if the camera/lens shows Backfocusing then you go to which side of the scale? If you place a number into the Dock program for lens then do you turn of the AF Fine Tune of my D-810?

Thanks for clarifying this.

David Arkin

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