Wednesday, July 2, 2014

Persistence Pays Off


Once in a while, when you are ready to resign things to being just the way they are and give up, the planets align, the clouds part, and the gods smile down, making everything right again.  Well, perhaps I’m exaggerating a bit.  However, my initial testing of the new firmware Version 1.01 for the Canon mount Sigma 120-300 f2.8 “Sports” lens is complete and things are looking good.

To briefly recap, my issue with the lens and original Version 1.00 firmware was basically two-fold.  First, despite all sixteen adjustable focus points available in the Sigma Optimization Pro software being perfectly calibrated using the USB dock, on the 1D Mark III and Mark IV the lens would badly front-focus in between the 200mm and 300mm settings.  Second, the lens required completely different Optimization Pro focus parameter settings for the 1D Mark III and 1D Mark IV compared to Canon’s other bodies like the 7D, 5D Mark II and 50D.  This meant my lens was either “set up” to work with my 1D bodies, or my other bodies, but never ALL my camera bodies at once.  I began my testing with a very methodical approach.  I needed to find out first if the new firmware fixed the issue of the different parameter requirements for the different bodies.  I also wanted to get a baseline to see how different my new Optimization Pro setting would be from my old ones, and I wanted to do it for all my different camera models. 

One of the programs I discovered in my search for the “perfect” focus calibration tool (which btw, doesn’t exist on its own in my opinion) was Reikan FoCal Pro.  This software works by tethering the camera to the computer with a USB cable, and pointing the lens at Reikan’s special focus calibration target.  The software takes control of the camera, firing off a series of “in-focus” frames of the target while adjusting the camera’s internal auto-focus manual adjustment (AFMA) setting for each frame.  The software compares the “sharpness” of the target image from one frame to another, finding the AFMA value that produces the image with the best focus (ingenious).  It works very well, but can be time consuming as each “test” can take five minutes or longer depending on the accuracy and consistency of the camera/lens combination.  Considering the sixteen focus settings for the 120-300 in the Optimization Pro software, and the five different camera bodies I wanted to test the lens on, this adds up to a lot of time. 

Since it is not physically possible to print a Reikan target large enough to test a telephoto lens at infinity (or even reasonably close to it), I stuck with testing for the three closer distance settings.  These are 10 meters, plus the lens’ minimum focus distance which I labeled as “Min”, plus the distance in between the two, which is marked only by a line on the lens distance scale (no numbers) which I labeled as “Mid”.  I ran a full battery of tests at the three distances, with the lens set to 120mm, 150mm, 200mm, 235mm and 300mm, using the 1D Mark IV, 1D mark III, 5D Mark II, 7D and 50D (3 x 5 x 5 = 75).  At around 5 minutes each, that’s over 6 hours of just watching the software and camera do its thing (in case you were wondering why it has taken me so long to get this post up).

Below is a screenshot of the Excel document I created containing all the results.

At each focal length and distance I had Excel average the determined AFMA setting for the cameras together, thus generating a full set of values representing the average AFMA settings for all five models (note that on my 7D at the minimum focus distance for 300mm, 235mm, 200mm and 150mm, the software found the required AFMA value to be more than +20, which is the camera’s limit, so I had no choice but to just ignore those values).  Armed with these numbers, I proceeded to plug them into the corresponding values in the Optimization Pro software (screenshot below).  My experience with the older firmware was that the adjustment parameters for the infinity settings were close, if not identical, to the parameters for 10 meters, so I just copied them over.  Also, there is no adjustment setting for 235mm, I added that value because in between 200mm and 300mm was where the issue was on the 1D cameras, and 235mm is physically right in between the motion of the zoom ring for 200mm and 300mm.  I wanted to confirm that the new firmware was addressing this.

Being labeled with the “S” designation, the new Sigma 120-300 f2.8 is the first lens in the “Sports” category of Sigma’s “Global Vision” series of lenses.  This is a true sports lens, and that is what I use it for 90% of the time.  Unfortunately the end of June is not the best time of year to do practical testing on a sports lens, since not a lot of different sports are being played.  Baseball is not ideal because there is not a lot of focus tracking being done from far to near distances like football or soccer.  Luckily, there is an Ultimate Disk league that plays regularly at a park near my home, and is just what I needed to test the lens after plugging in the new values. 

Below are samples of frames from each camera, all taken at f2.8 and various distances and focal lengths.  The focus for all the frames is spot-on.

1D Mark IV 300mm
1D Mark III 220mm
1D Mark III 300mm
7D 300mm
7D 161mm
50D 300mm
50D 269mm
The frame below is some proof that the new Version 1.01 firmware has fixed my first issue with the lens front-focusing in between 200mm and 300mm on the 1D cameras.  This frame is shot on a 1D Mark IV with the lens at 252mm, right in between, and is tack sharp.  This would not have happened easily with the old firmware.
1D Mark IV 252mm
Also of particular note is the frame below, shot on a 1D Mark IV at 120mm, but here the full early evening sun is blaring just out of the left side of the frame.  Another improvement listed with the new firmware is faster focus speed and accuracy in the lens’ “Speed-priority” focus mode (which I use almost exclusively).  I shot a heck of a lot with the 120-300 f2.8 Sports and the Version 1.00 firmware, and don’t think this image would have been in focus with the old firmware.  Of course I have no direct comparison of the same image made with the old firmware, but my gut is telling me from previous experience that it is so.
1D Mark IV 120mm
Since I purchased the Sigma 120-300 f2.8 Sports over a year ago I have felt very confused and conflicted over it.  It is in a class by itself for focal range and maximum aperture, and has outstanding image quality, making it the most ideally suited lens I have ever owned for shooting sports, both indoors and out.  For the longest time I felt like I was the only one experiencing, and making noise, about the issues the lens had on the 1D Mark III and Mark IV, despite my results being consistent and repeatable on several different lenses and cameras.  In my previous “My Trip to Sigma” post I posed the rhetorical question of whether the long trip to Ronkonkoma Long Island was worth it (BTW, I have actually made two trips out there in total).  I concluded then that it basically would depend on whether Sigma was listening to my problem, and willing to do something about it.  I think I can say with some real confidence now that the answer to that question is a resounding “YES!” 

My test images above prove that a single set of focus parameters will now work for all my camera bodies, and that on my 1D bodies I can get consistent accurate focus in between 200mm and 300mm.  I will likely end up “tweaking” the focus parameter settings a bit as I go, but I think these are pretty close (I will start splitting hairs from this point on).  I did not shoot tests using my Canon 1.4 x III converter because I wanted to concentrate on the 1D issue specifically.  Subsequent testing so far has shown no issues or problems using the converter as well.


In my haste to get this post finished I neglected some important information.  I made no mention of the camera’s built-in AFMA adjustment option.  In his comment below Fnurck asked “I wonder how its possible using the average adjustment and still all image are in focus with the different cameras without change the settings in between”. 

Doing all the testing and averaging with the Reikan software allowed me to come up with a set of values that compensate for the front or back focus “bias” the lens has for each of the parameters in the Optimization Pro software.  As important as the numbers are themselves, more important is their relation to one another.  For example, suppose you add +5 focus units to each of the software settings, then dial a -5 setting into the camera’s AFMA setting.  In theory you should end up with the equivalent overall adjustment. 

After programming the averaged values into the lens with Optimization Pro, I then used each camera body’s internal AFMA adjustment to “calibrate” the body to the lens (for this I used a LensAlign MkII with the optional long ruler).  So in short, the first round of hours and hours of testing and averaging with the Reikan software is to “set up” the lens to compensate for its own front/back focus biases at each focal length and distance value.  The second round (which I neglected to include originally) is to “set up” each camera with the pre-programmed lens to compensate for the combination of the two together.   That is how that single set of averaged values can work well on all the different cameras. 

I also wanted to comment on the difference between the Optimization Pro settings I found necessary between the Version 1.00 and 1.01 firmwares.  If you look at the screen shots from my first “Initial Rant” post, you will see that for the 1D Mark III and 1D Mark IV the Optimization Pro settings make some pretty wild swings from deep on the “plus” side to deep in the “minus“ side in the adjacent values going from 200mm to 300mm.  The settings I found for the 5D Mark II, 7D and 50D cameras even required +20 settings in some fields and -18 settings in others (though for these cameras the progression from “plus” to “minus“ was spread over several sets of fields).  In general, the required settings I found with the Version 1.01 firmware had a little less overall “spread”, and also follow a relatively smooth progression from “plus” to “minus“ without any wild swings in adjacent fields.

For the in-camera AFMA values, the additional good news is that with all my different camera bodies, none require a setting greater than +/- 5 focus units with the pre-programmed lens.  This tells me Sigma did a good job in not only addressing the issue specific to the 1D cameras, they also did a good job of “tightening up” programming.  Bravo!
So unless I come across any unusual findings, or get reports of such from other users, I think this just may be the final post on this blog. I would like to offer my sincere thanks to the folks at Sigma U.S.A and Sigma Japan for listening, and releasing the Version 1.01 firmware update.  I will continue to be a big fan of Sigma lenses, and am anxious to see what they have coming down the pipeline. 

As a final note, I will be writing a post in the future on my methods for doing focus calibration on Sigma lenses with the USB Dock and Optimization Pro software, and other brand lenses.  That post will be on another upcoming site which I will provide a link for here.  Thanks to everyone who has read this blog, commented and contributed!

Thursday, June 26, 2014

Firmware V1.01 Update

Today I feel somewhat vindicated.  Sigma just released firmware Version 1.01 for the Canon mount 120-300 f2.8 Sports lens citing "improved the Auto Focus speed of “Standard” and “Speed-priority” modes" and (DRUM ROLL....) " improved the focus accuracy when it is mounted on Canon EOS-1D Mark III or Canon EOS-1D Mark IV".  WOOPIE!!!

I just finished updating the firmware in my lens and everything seems to have gone well.  When I plugged in the USB dock with the lens mounted and launched the Sigma Optimization Pro software I got the following screen:

Clicking on the "Detailed information" launched my web browser and displayed the following:

Funny that it only mentions the improved focus accuracy on the 1D Mark III and Mark IV though.  Clicking on "Yes" begins the update process that first displays the following "Caution" screen:

Clicking on "Agree" starts loading firmware update into the lens:

I didn't think to time the actual update process, but it only took about a minute or so.  When the update is finished the software lets you know:

Clicking on "Close" brings you to the main screen for the Optimization Pro software, where the "Lens Information" section should display the firmware as "Version 1.01":

So does it work?  My next post will have full details of my findings after I do a complete re-calibration of the focus, along with some field tests, so please check back soon.  However, here are my initial impressions.  Since I first got the USB dock I have been using the lens almost exclusively in the "Speed-priority" focus mode. As soon as I put my Mark IV up to my eye and activated the auto-focus I noticed immediately that the image "snapped" into focus faster than I am used to.  I can't put a quantitative figure on just how much faster it is, but it's enough that I took note of it immediately, that's for sure.  The lens also seems to be doing a lot less of the constant back-and-forth focus error-checking that it has always done when focusing on a static subject with the camera in "AI-Servo" focus mode.  It feels more like the Canon 300 f2.8 IS now in that regard, this is good.  As I said, I have not re-calibrated the focus or done any real testing yet, but with the zoom set in between 200mm and 300mm the focus does "appear" to be more accurate than before.

I'm keeping my fingers crossed that my extensive testing will prove that this firmware update is everything I need it to be, especially if the new firmware allows the same focus calibration settings for the 1D Mark III, Mark IV and all the other models too.   I do wish Sigma gave the option to save out the original firmware in case things do not go as expected, but I guess that's asking too much any more these days (how many of us wish we could roll our iPhones back to iOS 6 but can't?).  It's great that Sigma has released this update.  Too often camera and lens manufacturers claim to be "listening" to their customer's input, but never follow up on common complaints.  I have mentioned before about the fantastic service I have gotten from Sigma, and this just seems to fall in line with that.  Stay tuned...


Thursday, May 15, 2014

Where it Stands Now

When I used the word "saga" at the start of this blog I had no idea how appropriate that term would be.  It's been a long road and a lot has happened, but I was holding off on adding to my posts until I had a real definitive feel for the situation. 

Before I get into real details, I have to say that if not for the outstanding service and attention I have gotten from the folks at Sigma (USA and Japan), I would have given up on this lens a while ago.  There are still "issues" but I am working through them.

I continued to have problems with the tripod collar guide pin screws coming loose, despite the Sigma service department putting new ones in with LockTite.  I also started having chronic problems with the screws holding the lens hood locking assembly together coming loose.  I finally managed to get a set of pentalobe screwdrivers and was keeping things tightened when necessary.  That was until the lens hood locking assembly (the locking knob, and two screws holding the assembly to the hood) came loose to the point where the hood just fell off in the middle of a job (very embarrassing).  My final solution was to put all the screws in tight with a dab of Crazy Glue.  So far so good now.

Since my last entry I have had in my possession two other 120-300 Sports lenses that were provided to me by Sigma.  The first was sent to me to test against my original lens to see if the focus issues were indeed a global issue or just my lens.  This lens had been specially "calibrated" in Japan on a 1D Mark IV.  The second was sent to me as a "replacement" (I will get to the specifics of that).  In short, all three lenses which I was able to test extensively, along with a fourth mentioned in the last post at Sigma in Ronkonkoma, showed exactly the same focus issues on three different 1D bodies.  So I think it is very safe to conclude that the problem is inherent in the programming of the lens.  I have since added to my collection of Sigma lenses (8-16, 10-20 f3.5 and 18-35 1.8) and the 120-300 is the only one of them that I'm having this problem (or any problem for that matter) with.

My Sigma 120-300mm F2.8 DG OS HSM Sports, Canon 1.4x III and 1D Mark IV

The second "replacement" lens came about after my original lens spontaneously stopped focusing at the start of a Jets game.  It was quite a sight to see me running out of the stadium back to my car in one of the far flung parking lots to retrieve my Canon 300 2.8 from the trunk of my car.  I missed the first half of the first quarter, but luckily nothing important happened.  I sent my lens in to Sigma USA and at that point they just sent me a replacement, which I was happy enough to accept. 

Unfortunately the replacement was not going to work out for me.  After trying to calibrate it through the Optimization Pro software it turned out that for my 1D Mark IV body (the one camera I really NEED the lens to work on), the widest focus adjusting parameters in both the camera and lens were not enough to achieve good consistent focus across the full range (I needed more than +20 and -20 in the lens settings).  So I inquired about the status of my original lens.  I was told it needed to be sent to Japan for repair, which would take at least a month.  That was fine since they allowed me to hold onto the replacement, despite the fact the focus was not great on the Mark IV (it was fine on my 7D, but as mentioned before that camera requires a completely different set of focus adjustment parameters). 

After two weeks I heard back that Sigma Japan was claiming "impact damage" on my original lens which was not covered under warranty (I don't remember dropping or severely banging it, but OK).  After all that had happened up to this point I was resigned to just keeping the replacement and letting the whole thing go.  Much to my surprise my contact at Sigma USA told me he cleared the lens to be repaired under warranty (see what I mean about service?).   It took almost another month, but I finally got word to send the replacement back, and then my original lens would be returned to me repaired at no charge. 

So now the word "saga" basically means I have gone full circle, several times, and am pretty much back where the whole thing started.  To no surprise, my repaired original lens still has the issue of front focusing in between 200mm and 300mm on the 1D Mark III and Mark IV, even though every setting in the Optimization Pro software is dead on. 

For those who have asked, for calibration I have used pretty much EVERY lens calibration system and method I could find up to this point.  The list includes Reikan FoCal, Agisoft,  Datacolor SpyderLENSCAL and the Michael Tapes LensAlign.  My favorite is the LensAlign with the added long lens ruler.  I have also been asked to make a post on how to do my calibration method, which I hope to eventually get to.  Right now I'm pretty much "calibrated out". 


I mentioned in my "Initial Rant" post that the Sigma 120-300 f2.8 Sports lens works fantastically with the Canon 1.4x model III converter.  This still holds very true.  You get a 160-420mm f4, with amazing quality, for a fraction of the cost of the Canon 200-400 f4 (or even the Nikon for that matter).  I  did discover a strange and pleasant surprise when I decided to confirm my lens calibration with the Canon converter attached.  To my amazement, there is NO front focus issue on the 1D cameras when the lens is set in between 200mm and 300mm (280mm to 420mm with the converter).  What could this mean?  Is the camera "happier" communicating with a piece of Canon equipment in between it and the lens?  I don't have a copy of the Sigma APO 1.4x converter to test and see if the same thing happens, but either way this at least makes me smile.  

The Devils Marek Zidlicky, 1D Mk IV + Canon 1.4x III - 308mm @ f4 6400 ISO

 100% Crop from above (the vertical banding effect is from the plastic visor)

So at this point my Canon 1.4x model III is pretty much permanently attached to the lens unless I am in need of the extra stop in low light situations.  I am very happy with the quality at f4 and 420mm, and even happier at f4.5 where the loss in quality is almost nil.  It is not a complete solution, but I will take it.  I have gotten used to turning the zoom back and forth between 200mm and 300mm when the converter isn't attached (skipping the in-between bits), which is working well enough so far.  The front focus issue is bad, but I do sometimes get in-focus action shots in between 200mm and 300mm (a function of focus inconsistency found in any lens when tracking motion).

So that's pretty much the story as it stands right now.  I am using the lens almost daily, and hardly pull out the Canon 300mm f2.8 IS any more (though it is not for sale so don't ask, I still need a backup).  I'm getting used to the little quirks, and will continue with the CrazyGlue on the crews if I have to.  In all, I am very satisfied with the lens, and especially the service from Sigma.  If and when I get around to doing a post on lens calibration I will provide a link to it here. 

Lastly, I have gotten questions on how the 120-300 2.8 Sports lens works on Canon's newer cameras.  I don't own any bodies newer than the 5D Mark II and 1D Mark IV.  I briefly tried the lens on a 1Dx, but didn't really have enough time to come to a real conclusion on whether it shares the focus issue or not (none of my colleagues are willing to part with one long enough for me to really test it).  I can only guess that the 1Dx's ability to adjust the AFMA values independently on the long and short ends of the zoom range can only help.  I have not been able to try it on a 6D or 5D Mark III yet.  All I can say in answer to the question is that I really can't say.  At some point it would be great to be able to test the lens on these cameras. 

Saturday, November 9, 2013

My Trip to Sigma

Not having anything else to go on to solve my focus issues with the Sigma 120-300 f2.8 “Sports” lens and the Canon 1D, I decided to make the trip to Ronkonkoma Long Island. My hope was an in-person dialog with the service department as they looked over my lens would get to the bottom of things.

First off, they were able to un-stick the front filter, swapped my emergency replacement brass tripod collar screws with nice standard Phillips head screws, and assured me everything was fastened in with Loctite. Then it came down to making adjustments in the PCB ROM not available using the USB dock.

It was interesting to find out that the dock actually provides more control over the focus adjustment of the lens than the factory adjustment software. The factory software apparently allows + and – adjustments to just the outer focal lengths (120mm and 300mm). Based on my earlier findings they programmed some additional “+” into the 120 end and some “-” into the 300 end. The goal was hopefully to lessen the large gap in the settings from +17 at 200 and -16 at 300.

To make a long story short, it didn't work. The reprogramming had no real effect on the 300 side, and just shifted the required existing settings over a proportional amount on the 120 side. The main problem of not getting accurate focus with the 1D Mk IV (and Mk III) in between 200mm and 300mm was still the same. Next they brought out another new 120-300 “Sports” lens to compare with mine. The results were the same with the new lens, so that confirms it's not some anomaly with my cameras. With that the service manager said he would be sending an advisory to their headquarters in Japan to have them investigate it more.

So was it a wasted trip? I guess I will have to wait and see if I get an answer back from Sigma Japan. I also don't think just shipping my lens to them with the Mk IV (and being without both for a week or more) would have convinced them as easily that there really is something to all this. I will say that I was very satisfied with the service and reception I got while I was there, despite the outcome so far.   I'm keeping my fingers crossed.

Friday, October 25, 2013

News From PhotoPlus Expo

I spent the day today in Manhattan at the PhotoPlus Expo.  Naturally a good bit of my time there was at the Sigma booth trying to shed some light on my Canon 1D and 120-300 f2.8 Sports lens issue.  The first rep I spoke with (name withheld) blamed it all on Canon saying that I should already know about all the horrible focus issues the 1D series has been plagued with.  Really?  Aside from the well documented issue in bright sunlight with the early 1D Mk III bodies I am not aware of any "focus plagues", especially when it comes to the Mk IV.  Aside from the fact that, as I mentioned before, my 1D Mk III and Mk IV focus perfectly on all my other lenses (including others from Sigma).  The second rep I spoke with was more reasonable.  After hearing my plight he invited me to personally bring my lens and all my camera bodies to their facility in Ronkonkoma, to see if the service department could figure it out.  I may just have to make the drive and take them up on that in the near future.

Next I went to speak with the folks at Canon.  A rep I have known there for many years (name also withheld) was able to help out a little.  Though he of course can't comment directly on the Sigma lens, he did confirm for me that the focus systems in the 1D Mk III and Mk IV are completely different from the rest of their cameras, in that they have an additional processor devoted just to the focus.  He also said that 3rd party lens makers don't always ensure full compatibility with high end "pro" camera bodies since they make up such a small segment of the market.  He used the example that, even on their least expensive lenses Canon needs to make sure they all can close down to their minimum aperture (say f22) perfectly at 12 frames per second.  Now that has nothing to do with the problem I am having with the Sigma, but does at least make some sense.  It does seem plausible that Sigma either was not able, or didn't bother to, properly reverse engineer the different focus system in the 1D cameras.  Maybe I am finally getting somewhere?

Tuesday, October 15, 2013

Initial Rant

Let me start by saying that this is not an official review of the Sigma 120-300mm F2.8 DG OS HSM | S, also known as the “Sports” version. There are plenty of reviews to be found online by people much more qualified at reviewing lenses than I am. The purpose if this blog is to voice some concerns I have with this lens, specifically when used on the Canon 1D Mk III and 1D Mk IV, and hopefully find out if others are experiencing similar things.

Before I get to the details I want to say that on the whole I absolutely love this lens. If you haven't noticed yet what Sigma is up to with their new “Global Vision” lenses I suggest you take a look. There are some truly innovative designs in the series, which are not only optically outstanding but solidly built. In addition, the level of customization available with the new lenses using Sigma's USB Dock goes beyond what any other manufacturer in the industry is doing right now. So with that out of the way let's get to the nuts and bolts of why I'm writing this blog.

Anyone familiar with Canon's professional and semi-professional cameras (starting with the 50D) knows that they have a built-in ability to fine tune the auto focus of the camera body to specific lenses (called auto-focus manual adjustment or AFMA). If you find a particular lens is consistently front or back focusing, you can “dial in” that lens using the AFMA to get accurate focus (+ or - 20 focus units from the camera body default of 0). If you use multiple camera bodies like I do (50D, 7D, 5D Mk II, 1D Mk III and 1D Mk IV), you will generally find most bodies and lenses have a certain “bias” towards back or front focusing, and will need some AFMA adjustment to get the most accurate focus.

Beyond the camera's built-in AFMA, Sigma goes even further by allowing the user to separately fine tune the auto focus of their new lenses using their USB Dock and Optimization Pro software. In the case of the new 120-300 2.8 “Sports” you can also adjust the focus speed, customize the optical stabilization (OS) and set the focus limiter range. Unlike Canon's global AFMA setting, the Sigma software allows precise focus adjustment of the lens at different spots in the zoom range, and different focus distances within that range. Below is a screen shot of the focus calibration window to give you an idea of the possibilities.

As you can see, focus tuning is possible (+ or - 20 units) at four spots in the zoom range (120mm, 150mm, 200mm and 300mm) and at four distance ranges for each focal length (minimum focus distance to infinity), making a total of sixteen user adjustable focus point settings. So if you have the time and patience (or are also a geeky under the hood compulsive type like I am), you can get the 120-300 2.8 “Sports” focus settings nailed down really, really well.

I will stop here a moment and back up a little so as to add some background to my story. In September of 2012 I purchased the older version of the Sigma 120-300 2.8 known as the EX DG OS APO HSM (not to be confused with the even older EX DG). Out of the box I had issues with that model not focusing properly on my 1D series cameras. Even on static subjects, at the long end I was only getting about 30-40% of the frames in focus. This was not an AFMA issue as I had carefully calibrated the bodies to the lens multiple times. Oddly enough, on the 50D, 7D and 5D Mk II my percentage of in focus images, even for moving subjects, was more in the 90% range (where it should be). That is all well and good, but I shoot a lot of sports and rely on the 1D series camera's voice tagging feature to keep track of plays, which helps a lot with writing accurate captions later on (the 50D, 7D and 5D Mk II have no such feature, and writing notes during a game is a real pain anyway).

I sent the lens back to Sigma with specific instructions and sample images hoping it just needed some adjustment. Sigma sent the lens back, saying there was nothing wrong with it, and did not perform any calibration or repair. They also said it must be a problem with my 1D cameras, and to just use the lens on my other camera bodies (really?). Next I had the focus on my 1D Mk IV checked and calibrated by Canon in Jamesburg, NJ. I also borrowed another 1D Mk IV from a colleague to test on the Sigma and got the same results as my own 1D bodies. Mind you, I was not experiencing any focus issues with my cameras using the Canon 70-200 2.8 L II and 300 2.8 L IS (or any of my dozen or so other lenses). I complained again to Sigma who, much to my surprise, offered to replace the lens outright with a new one (thanks!). By this time the new improved “Sports” version of the 120-300 2.8 had been announced, so without ever using the replacement lens I put it up for sale and put the cash towards the sports version once it was released.

I was very excited about the new “Sports” 120-300. It promised better construction, weather sealing, a focus limiter, and most importantly the USB dock. I want to put a gratuitous plug in here for Allen's Camera in Levittown, PA who, while others where still just taking pre-orders, got me one of the first of the new 120-300mm F2.8 DG OS HSM | S lenses that came into the U.S. (you are the best Allen). I was disappointed to find out however that the dock was not released at the same time, and was still another month out (by the way, not for nothin', but for the price of the lens they should throw in the $59 USB dock).

The first camera I mounted the new lens on was my 1D Mk IV (which had the focus calibrated by Canon a few months earlier). Right away I noticed that there was again an issue with the focus. No matter how I set the AFMA in the camera I could not get the lens to focus accurately through the whole zoom range. If I set the AFMA to focus accurately at 200mm, it would badly front focus at 120mm, and badly back focus at 300mm. I tried the lens on my 1D Mk III and got similar results. Then I tried it on my 7D and was able to find an AFMA setting that provided reasonably good focus through the whole zoom range (and the same with the 50D and 5D Mk II). Something is definitely up here. It seemed as though the one thing I was counting on being different with the new lens was exactly the same as the old one (UGHH!). So now I'm anxiously awaiting the release of the USB dock, telling myself that I will be able to get the 120-300 2.8 "Sports” dialed in to my 1D bodies perfectly, and all will be right with the world. Do I have to say “guess what”?

The dock finally arrived. Knowing 200mm and an AFMA on my 1D Mk IV of -10 was about the “middle” of the focus range, I began tweaking the focus of the new lens from both ends. I adjusted the front focus issue at 120mm back, and adjusted the the back focus issue at 300mm forward. After many hours of continuous testing I arrived at the following settings:

The good news is that the AFMA on the camera is right in the middle at “0” now. Here's the bad news. Notice that starting at 120mm and up to 200mm the focus adjustment follows a relatively straight progression from +3 to +9 to +17. Then, at 300mm it swings all the way in the opposite direction to -12 and -16. This explains why, at the default settings of “0” across the board, the lens was front focusing at 120mm and back focusing at 300mm. So what's the big deal you may ask? The lens is dialed in either way right? Unfortunately not. Despite each of those individual focus points being dead on, in between the focal lengths of 200mm and 300mm, on the 1D Mk IV the focus is way off (about 15 AFMA units off).

So I went through the same procedure with my 1D Mk III, and here are the settings that worked for that camera:

Notice they are very close to the 1D Mk IV with a similar wild swing from +20 at 200mm to -16 at 300mm. The big difference is the in-camera AFMA of -9, but the rest of my lenses on that camera body all need an AFMA in the “-” range, so that explains that. There is also the same issue with the focus being way off in between 200mm and 300mm. Now it gets interesting. It took me several days, but I went through the same testing on the 50D, 7D and 5D Mk II. Here is what I came up with:

 The in-lens focus calibration settings are in no way at all similar to the settings I found for the 1D cameras. In fact, they range from the + side at close distances for all focal lengths, to - settings at infinity for all focal lengths. Additionally, with AFMA settings between -6 and -10, the lens focuses extremely accurately on all three cameras, even in between 200mm and 300mm. With these settings on my 7D the lens performs so well, even at f2.8 with fast moving sports, I haven't used my Canon 300 2.8 L IS since getting the Sigma dialed in.

What's going on here? I had the same experience with two different models of the same lens. My 50D, 7D and 5D Mk II are no problem, but forget about using it on the 1D series cameras. Part of the reason may be explained in an excellent article written by Roger Cicala at When they disassembled both the “OS” version of the 120-300 and the “Sports” version of the120-300 side-by-side they found the circuit boards to be essentially the same. Does that mean it is a programming issue in the PCB?

Let me add some more interesting facts into the mix. Besides Sigma's 120-300 2.8 “Sports” lens, I also own their APO 50-150mm F2.8 EX DC OS HSM (perhaps one of the most under-rated lenses around). Though it is a “DC” series lens, meaning it is designed for APS-C size sensors, it also fully covers the larger APS-H size sensor of the 1D series cameras (not to mention it is an excellent compliment to the 120-300). On all my cameras (including the1D Mk III and 1D Mk IV) the 50-150 focuses extremely accurately all the way through the zoom range at all distances with just slight in-camera AFMA adjustments. Even though it does vignette badly on the 5D Mk II, it still focuses accurately. I also used to have Sigma's older EX DG 12-24mm f4.5-5.6, and EX 14mm f2.8 which focused fine on all my cameras.

So here are my ultimate questions. What is different about the auto focus system in the 1D models compared to Canon's other cameras? Why is this issue happening only with the Sigma120-300 2.8 and not other Sigma lenses (assuming they use the same reverse-engineering for everything)? Is this some secret ploy by Canon to make you only buy their lenses if you use their “professional” cameras? Would adding a focus adjustment setting at 250mm in the Sigma Optimization Pro software fix the problem? (probably not considering the vast difference in settings already between camera types) Why isn't there a setting for 250mm in the first place, when there are small jumps from 120 to 150 to 200, and a big jump from 200 to 300?

If you have had a similar experience with Canon cameras and Sigma lenses, or if you are able to shed any light at all on my dilemma (especially if you happen to work for Sigma or Canon), please leave a comment.


In addition to all of the above (which turned out to be way longer and more complicated than I initially wanted) there are a few more issues with the Sigma 120-300mm F2.8 DG OS HSM | S that I'd like to share. Though not a huge deal, they are things I think Sigma should be made aware of.

Tripod Collar:

In general the tripod collar is an improvement over the older version in that it has loops for a strap positioned at 5 o'clock and 7 o'clock, as opposed to a single loop at the back elbow of the collar (though I wish they had kept the beveled cut on the bottom like the old one which fit nicely in a Acra Swiss head without an adapter). About a week into owning the new lens I was using it on a monopod and went to turn the camera vertically. I heard a terrible scraping sound and the collar froze up. After several minutes of wrestling with it I managed to get the collar off and found one of the screws holding the collar guide pins had come out and scraped along the inside, badly scratching the lens barrel. 
 Scratched barrel and replacement brass screw

Though I was mad now that my brand new lens had a nice scratch on the barrel, I figured no problem since I would just screw it back in. Nope. Instead of a standard Phillips head screw Sigma used a five pointed Torx type screw (just like Apple uses on the MacBooks and iPhones, called a pentalobe). Well, I don't have a pentalobe set of screwdrivers, and neither does any hardware store I could find. When I checked the other screws under the tripod collar I found they were all backing out, and could be unscrewed completely with just my fingers. Since I couldn't get the proper screwdrivers I did the next best thing and replaced all the screws with brass slot-head types of the same thread size I found in a hobby store. I also used Locktite to put them in, but if they happen to back out at least I will have the screwdriver I need to tighten them again.

Front Filter:

The Sigma 120-300mm F2.8 DG OS HSM | S unfortunately does not have a drop-in filter slot like Canon's and Nikon's big lenses. I think this is mostly because the lens has so many elements moving around inside, and not a lot of real estate on the barrel because of the zoom ring, that there is no room for one (other big Sigma lenses do have drop-in slots). The front of the lens takes a 105mm screw in filter. Sigma makes filters in many sizes, including 105mm, and they are not only excellent, they are a real bargain compared to the price of other high quality filters. I purchased their 105mm UV to protect the front and put it on as soon as the lens came out of the box.

The other day I noticed a few specks of dust behind the filter (and being the already aforementioned compulsive type I wanted to blow them out). I started unscrewing the filter (which I made a point of not initially screwing in too hard) and ended up removing the entire front element assembly along with it. Under the assembly are a bunch of brass shims which I had a bit of a time getting back into place before screwing everything back in. Now, of course, I have a few specks of dust inside the lens as well as behind the filter (which is now good and jammed on, and won't come off).

Some Good Things To Say:

I said at the top of this long rant that I really do love this lens, and there are many good things to say about it. So here is a simple list:

  • It's SHARP!!!
(if the Canon 300 2.8 L is a 10, the Sigma is a solid 9 and has a zoom)

Uncropped 7D frame of the Jets Nick Mangold
 100% crop (shot at f2.8)

  • It's built like a tank
  • The focus and zoom rings are nice and smooth
(and go the same direction as Canon's lenses do)
  • It works really well with the Canon 1.4x III (despite what Sigma says)
  • The OS is REALLY good, at least a stop better than Canon's
  • It's cheaper than Canon's 300 2.8 L by a mile (and has a zoom)
  • The customization options are very cool 
Understand that I'm not trying to discourage anyone from going out and buying the Sigma 120-300mm F2.8 DG OS HSM | S. Since I haven't been able to find anyone else complaining of the same Canon 1D focus issue, I'm wondering if my lens is just an anomaly (despite the similar problems I had with the first one).

As I get any more information, or maybe even a solution, I will post it here.