# Very, very initial impressions on the Sigma 120-400 APO DG (OS) HSM



## Edwin Herdman (Dec 25, 2010)

Quick edit: I'm wishing I had followed my gut instinct and taken a picture of the Sony version. The rest of this post, as noted, is for the non-OS (Optical Stabilization) Sony version, which seemed very different from this lens in a number of respects - so much so that perhaps they can't even be called equivalent or close. Impressions about the Canon version are starting three posts down.

I'm going to say *very* initial because *no photographs through the lens are possible* at the moment - Amazon sent out the wrong version! I ordered the Canon version, got the Sony version (which, of the four versions, has no Optical Stabilization). There's a stock sticker on the side of the black box saying "APO DG OS HSM" but the box itself clearly says "For Sony" and "APO DG HSM," which is as expected because Sony Alpha bodies have stabilization in-camera - and so the lens I held today did not have Optical Stabilization. I put the confusion down to Sigma making four different variants of the lens (Sigma, Canon, Nikon, and Sony) but the actual box clearly states what it is - and the back lens cap states FOR SONY.

The contents of the box, in total: The lens, a hood, open bags around both, two straps (one is a Sigma-branded camera strap, the other I didn't check too closely) in bags, a big squarish black case, a manual for the APO DG OS HSM (I'm wondering if there is a hollow point inside this lens where the IS mechanism normally goes; it generally seems like it's considered the exact duplicate of the OS versions), and a warranty card slipped in between the two folding parts of the box and the back.

*No case needed?*
The case was the first big surprise. People have speculated about why this lens was not deemed an EX series lens (which signifies it being like Sigma's version of the Canon L series) despite its quality build, yet the case in the box has the EX emblem sewn on. The box does seem to have had a mild amount of shelf wear (scuffing) but it doesn't seem to have had its contents shuffled around or replaced. The case is also considerably bigger (mostly wider) than the Lowepro S&F Slim Lens Pouch 75AW, which should have fit the lens (according to the dimensions of both on Amazon there should be extra space between the lens and the case dimensions given) but which barely fits with the tripod ring on (as it is by default - I didn't play with the ring much just to keep it nice for whoever eventually gets the lens), and it will apparently not fit with the hood on, reversed or otherwise. I'll be checking the Sigma lens's size versus the Canon 100-400mm, which Sigma seems to recommend a 200 AW bag for. The fold-over cap of the Lowepro is stiff, which is good, but it barely will fold over into place when touching the velcro, and feels like it will easily come off, which is not good. A zipper would be better. I will likely return that as well, and this time remember to get a S&F compatible camera holster bag instead. There's a cutout in the top panel of the Sigma lens case for the bottom cap to fit into, to prevent the lens from sliding around. It looks more like a storage case than a case to use in the field.

*Lens handling impressions*
The lens didn't have the cold metal touch, but feels very solid and the finish was quite pleasing if not striking - it's black or very, very dark grey, but with faint diamond-like sparkling bits all over. The lens hood isn't quite as effective-looking as the third-party Adorama hood I bought in place of the ES-71II for the 50mm f/1.4, which has a surface inside which does not reflect light. Instead, the inside of the Sigma lens hood is made up of ridges, with most of the flat surface pointed toward the outside. It still seems to reflect some light, though - the amount of light is clearly less when looking out through the hood than looking into it, but it's not perfect and it seems like with flocking it would be less reflective.

The lens itself feels quite solid and at least assuringly heavy; though I assume it's made out of engineering-grade plastic, it doesn't feel flimsy at all.

The manual focus ring was smooth, though the zoom ring, straight out of the box, was very stiff, just as I've read, though it doesn't jerk when turned, but moves smoothly. I didn't notice any change in the positioning of any internal elements (front or back) when turning the focus ring - and yes, it was focusing since the reading in the distance window changed. It's possible to turn the focus ring past near focus or infinity focus, which it will do with slightly more resistance than usual (obviously I stopped when this happened). This is still less force than seems to be needed to change the focal length.

The lens extends (without rotation of course) when zooming, and I noticed that it will very slowly creep back at least slightly toward the 120mm setting if zoomed out even partially and then stood straight up so the lens mount is down. The reverse seems to be true as well. So that's where the focal length lock switch should come into play...

Since what I got isn't an OS lens, there are only two switches on the side - a lock-unlock switch nearer the front, and an AF/MF switch nearer the mount. The lock-unlock switch seems strange; on the focal length scale markings found on the outside of the lens (not the ones under the distance window - yes, there's two sets), to the left is a "LOCK" marking, followed by 120mm (the widest setting). At 120mm it locks easily. Anywhere to the right, pulling the switch upwards towards "lock" only moved the switch closer to the first "unlock" setting; it wouldn't go further (at least not with any amount of force I cared to try on it). It didn't seem like you could easily lock it in at a farther focal length. I dare not open the fold-out manual to check, but I don't think that putting the focal length lock up a bit will increase friction on the zoom. With the zoom ring being so stiff, however, I didn't think there was really a need for a zoom lock at longer lengths (though I've read people say the zoom ring loosens up with use, which is considered good) unless you were pointing it at extreme angles - in which case you probably will have to keep your hand on the focal length or else bring along some tape perhaps.

The front cap is my preferred Sony type, pinched about midway from the edges to the center. I hope this cap style will be used for the Canon variant I ordered, since the pinch-type is the only type you can realistically get on with a hood in place. I'm not sure I'd chance it, however; with this lens the outer edge of the front optical element is actually very close to the edge of the barrel, so it would be easier to hit that front element. It's Sigma-branded so I'm confident it's the part I'll see again. 

The front element isn't one obvious color from the front; tilted to a light source it seems to be mainly purple, with then green coming in from the part tilted away from you closest to the light. Gut feeling was that the surface is not going to be weather-resistant as much as the new Canon 70-300mm L series lens, and that I ought to avoid getting it wet or dirty.

Hopefully I'll have a replacement soon after the New Year - though it'll be another whole day before I can even send this out.


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## traveller (Dec 29, 2010)

Nice to have your very detailed thoughts on an interesting alternative to the 100-400L. 

Can we look forward to your thoughts on its performance when you finally receive an EF mount version?!


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## kubelik (Dec 29, 2010)

second that; as a frequent purchaser and advocate of Sigma lenses, I am very much looking forward to the real meat of your review to follow.

I will note right away that I'm highly disappointed to hear that the lens hood is of the same type and material as that used on the sigma 100-300 f/4. I've had really bad experiences with flaring due to light being reflected off that matte-yet-reflective plastic material they use with the ridges. I don't know how expensive or difficult to assemble flocking is, but I can't imagine it's so prohibitive. had an excellent shot of a running moose ruined due to flaring despite the sun being fairly well off to my right side.

hopefully you'll have a better experience with your 120-400 than that, I never noticed something like that happening with my sigma 150-500. good luck with the new lens!


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## Edwin Herdman (Dec 31, 2010)

Good on Amazon - the lens arrived today, much quicker than expected! The first thing I did was go outside, zoom it out to 400mm, and take a photo of a birdfeeder. Even from a very close distance, I discovered that 400mm simply isn't close enough to get anything like a full-frame image. Wide open at 400mm (f/5.6), I can definitely differentiate between different feathers, but the subtle patterns on those feathers aren't distinct. I didn't try stopping the lens down, however, and we are talking about an area that in the original frame is a tiny portion of the full frame - because birds are pretty small, especially the one I chose. Noise was a factor in the smallest portions of the image because the camera chose settings of 1/500 second and ISO 1000 sensitivity, but all the same there should have been more detail visible (shooting in RAW).

I just spent a few minutes with the lens on a table (supported by the tripod collar) and taking photos of some stacked teacups in a corner, alternating between Live View focusing and autofocus, then zooming in (and for a last set I set the lens to 400mm and stopped down in 1/3 stop increments, from f/5.6 to 6.3, 7.1, and 8). Once I review these images in more detail I'll be able to say more. Of course, it should be mentioned that I wasn't using perfect technique like a tripod, mirror lock-up, or a shutter release cable, and on top of that the camera was selecting shutter speeds around 1/30 to 1/15 - so some of the images are slightly motion blurred. But I'd say that, in the full frame, all of them are sharp enough to be pleasing in most circumstances - the motion blur is barely visible in the cases where it appeared.

Some impressions of the physical build: Much the same as the earlier Sony Alpha-mount version, but with some differences. The case for this lens has a rubber emblem sewn in with the Sigma logo, instead of the EX logo. The EX logo is nowhere to be seen. The lens hood is the same type that I described earlier, which uses flat surfaces pointed away from the lens to reflect most light, but some light still can come into the lens - a replacement lens hood might be a good idea. I didn't play around with it much, but it seems to me that you store the lens in the supplied case by putting the hood in upside down and then you put the lens on top of that (diagonally in a certain orientation so the rear lens cap fits into a little hole cut into the foam pad on the top cover of the lens case, same as the Sony version). I'll have another look at it but there didn't seem to be a way to reverse the cap on the lens, which would make storage much easier (and reduce the chance of parts rubbing together).

The same sparkly black finish as the Sony version is used here, although there seemed (to me) to be more flat black surfaces, and with the OS switches and extra text the lens seemed to have a different appearance, though similar enough to the non-OS Sony version to be confused with it, I bet. The tripod mount is the same.

A good feature of this lens compared to the Sony version is that when zooming out to 400mm and pointing the lens straight up I didn't notice the zoom slowly retracting back to a wider setting - instead it stayed at 400mm. That's good. The zoom and focus rings are stiff but with no play, which is decent as well, although with full-time manual focusing I was using the focus ring with the switch set to the AF position (remains to be seen if it makes any difference, but I doubt that).

OS is interesting - while it was effective at allowing sharp shots handheld at even 1/15 of a second, it wasn't all of them, and the keeper rate seemed to be in line with what I've read about Canon three- or four-stop IS systems - not bad. To activate OS, you half-press the shutter, which should cause no problems. The sound is a bit of a subtle click, much quieter than a shutter release or mirror flip. With the camera on a table, I gently played around with the OS system by pressing on tripod collar to move the lens barrel up or down slightly, and watching the image in Live View react. With OS set to Mode 1, when you activate OS, the image in the viewfinder stops jumping about from human jitters completely (as far as I could see, though I don't remember what magnification I used - 1x, 5x, or 10x), and when you move the lens barrel up or down slightly, the image in Live View moves smoothly to that new point, taking about a second for a small change, and starting to move slightly after you move the lens. I didn't try any snap focus changes, which would be a poor choice of time to keep the OS active in Mode 1 anyway (I believe Mode 2 is a panning mode).

I'm not preparing any Ken Rockwell-style smell or shake tests - in his defense he seems to do those things only when something jumps out at him about the handling. I didn't notice anything unusual, and the lens seemed pretty solid with nothing clunking about when handled normally.

Closest focus is 150cm, though a more helpful way of looking at is is 1.5m or 5 feet as provided on the close end of the distance scale. Since the lens is not an internally focusing model, focus changes somewhat as you zoom the lens, enough to be noticeable on Live View within a house room, so the old trick of zooming out to the longest setting and setting focus will not work. AF seems pretty good though, especially considering I had not chosen a solid portion of a teacup to focus on, but rather was focusing on a handle, the middle part of which was empty - the camera still seemed to be getting focus with the center point more or less correct, however - I'll have to look at those shots again to see if focus wasn't actually on another point.

Overall, I feel that if you can fit a subject into the viewfinder, this lens should provide the focal length you need with pretty decent quality. Sharpness at 400mm doesn't seem to be a jump down from other settings, like 300mm; it seems just the same, and perhaps just minor defects in the optical performance compared to some other lenses are being magnified here.


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## Admin US West (Dec 31, 2010)

I wouldn't be concerned about what you may see under difficult conditions, there can be any number of things stackiing up to make high resolution captures difficult. 

To determine the actual capability of the lens, you need good lighting conditions and a more stationary and frame filling target. You want to eliminate as many things that are not under your control as possible. 

Once you can determine the best possible image the lens can produce, and are happy with that, then determining how to achieve the goal of maximum IQ in the real world is a learning experience and takes a lot of expermentation.


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## match14 (Mar 1, 2011)

I have been thinking about this lens or the 150-500mm OS.


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