Photo Jottings

Here’s a brief look at the Sigma 105mm DG F/2.8 macro lens.  Scroll down for the review.

Box and contents.

Fully extended.

Deep front element, notice dirt look finish on lens.

Backside.

Sigma MTF screen grab, incomplete, but this is all they give.

X-ray view

The Sony A700 and A900 were used for this review.  For full frame results, go to the bottom of the page.  For a better understanding of my review methods and terminology, go here.

The Sigma 105mm F/2.8 DG macro lens (made in Japan) is very compact, but extends out another 2″ at full macro.  Its build quality is ok to good, but lots of plastic.  The finish is atrocious flat speckle black which looks like dirt all over the lens, I hate the look of this lens and the finish, it’s the ugliest mess I’ve ever seen.  Are you reading Sigma?  Filter size is 58mm.  The lens is multi-coated, with a very bright green look.  It has an 8 blade (straight) aperture as opposed to the circular 7 and 9 blades of the Sony macro lenses.

The lens has the focus distance window with standard markings for FT/M, and DOF marks at F/32.  It has magnification levels from 1:1 to 1:4 written on the extended lens barrel.  The magnification marks are different for AF and MF because of the sliding focus ring, which is also used to switch between MF and AF, back for manual, forward for auto focus.  This is weird as the focus ring will still turn when slid back to manual focus, you need to switch the camera to manual focus to stop it from turning.  The owners manual says you might screw up the focus motor in the camera if you don’t do this.  Another useful item is a focus limiter switch, full, for the full focusing range, and two limited ranges, close, which cuts the focus travel down to approximately 4.7″- 7.5″ (190mm-178mm) and about 8.5″ (216) to infinity at far range.  To set you just throw the switch while in the range you want.  This helps speed up focusing, but don’t use auto-focus for extreme close ups, use manual to get the subject in focus and then move the camera back and forth until your target is sharp.  The figures above are for end of lens barrel to subject distances.

The Sigma focuses a little slow, but seems accurate, though plan on using manual focus for super macros, read above.  It takes about a manual 3/4 turn from close-in to infinity focus. It has the usual loud focusing sound, nothing you can do about it, so don’t worry about it.  The Sigma 105mm macro has a short 4.7″ (119mm) distance from the front of the lens barrel to the subject at close macro.  That’s about 1.5″ (35mm) shorter than the Sony 100mm macro.  The extra distance is good to keep shadows out of the frame, but that’s at maximum macro, and not everyone will need to be that close.

Lens flare/ghosting.  Not much of a problem here.  Look for a green blob when the sun is out of center, and still in the image, with the sun centered, everything looks fine.  Additionally, the lens has plenty of recess for the front element from close focusing to infinity.   You don’t need to use the included metal hood with this lens unless super bright lights are near the camera front.  See samples below.

Color.  Looks the same as Sony lenses.

Filter size 58mm.  This is an odd-ball size in the Sony world, and Sony currently has no lenses that use it.

Color fringing control is excellent, and one of the very best I’ve tested.  There’s a hint of green color fringing if used at F/2.8 and infinity focused.  At close focus, there is nothing, see the macro “2006” below.   This particular shot usually brings out the worst in color fringing on macro lenses.

Bokeh.  Good, but octagons show up at F/4.

This lens has been discontinued by Sigma, and replaced by the Sigma 105mm F/2.8 macro OS in 2012.

The top shots show what I was talking about in the text above.  The green blob and arc are seen in the corner of the left shot.  The right shot shows no rings or ghosts with the sun centered in the image.  The bottom photos show bokeh.  F/2.8 is not bad, but the F/4 shots show signs of the eight straight aperture blades, and causes points of light to appear as octagons.  That’s no big deal though.  Both ghosting and veiling glare are controlled better on the Sigma than on Sony’s macro lenses.

Distortion.  Very good job.  If you like to look at your pictures with a grid overlay, you’ll see very slight pincushion distortion.  Again, very similar to other macro lenses.  See image below.

Minor pincushion distortion.

Light fall-off, (directly below) is very light at F/2.8, and clears up at F/4 focused at infinity.  At high magnifications (close) it effectively stops down, (see chart below) so no problems at all.

Light loss at high magnification.
Here are the approximate F-numbers you will get as you increase the magnification per owners manual.  These numbers will not be indicated on the camera, and will still read F/2.8 even at 1:1 magnification, but look at your shutter speeds and you’ll notice the loss.  I provide this information to those who wonder why they’re getting low shutter speeds at F/2.8 when using high magnification.  Don’t worry, your camera will adjust the exposure correctly for you, just shoot away.

 

Let’s see what this baby has to offer as a medium telephoto lens.

Here are some center crops for comparison.  Look below for an explanation.

This is the full shot, below are the center crops.

Judging by the crops, you won’t be using this lens for medium telephoto shots.  The crops above are from the center of the image, but they represent the whole image.  The Sigma 105mm F/2.8 DG macro is very soft at F/2.8.  It sharpens up a little at F/4, then maximum sharpness is around F/8.  Note; this lens doesn’t focus very well past about 300ft, or 100m even when set to the hard stop infinity focus mark.  I’m not sure if something is wrong or it’s normal.  When focused at infinity, things are very sharp around the 100 meter mark, even at F/2.8.  The homes above are around 300 meters away.

Requisite macro paragraph.  As with all 1:1 life size macros, sometimes it can be a little tough to focus, and a tripod is highly recommended, especially if you go full size.  Hand held use is limited to about 1:2 in my opinion, any closer and you’ll be filling up a 16GB card trying to get a decent shot.  At F/4 the depth of field is razor thin, at F/16 you lose your shutter speed, so some extra thought is required before your photo session begins.  I often have to bump up the ISO to get a sharp picture with hand-held shooting.  Even on a bright sunny day you’ll be surprised at how low your shutter speeds are, and with jittery hands it’s all the worse.  If you like to compare shots from other lenses and cameras, don’t be too critical about it at 100% screen size.  Getting a uniformly sharp image from a flat object like my stamp is very difficult, especially when it’s a full 1:1 macro.  I use the stamp so you will know about how big an area is covered, and get an idea of the sharpness.  Keep this in mind when viewing the stamp macros.

Macro shot.

Below, check out the sample and click the picture to see it (2.36mb, large file), it may have been slightly cropped or straightened to reduce size.  The sample shot was taken with the Sony A 700 12.2mp camera.  The subject is a standard US stamp, 1″x 3/4″ or 25.4mm x 19mm.  Also, note the macro shot was taken as close to the subject as focusing allowed; In this case, about 4.7″ or about 119mm, measured from the front of the lens barrel to the subject.

Full 1:1 macro shot 2.36mb F/8

 

Conclusion.

 

This copy of the Sigma 105mm F/2.8 DG macro lens may have some issues with long distance focusing, judging by the results above.  This is a macro lens and if you’re going to use it as a macro lens, you don’t need to worry about the infinity focus shots.  Knowing Sigma, your copy may produce different results(!).  This lens also has nearly no perceptible color fringing or light fall-off, that’s real good.  Also, in macro range, it’s very sharp from F/5.6-11, and will hold its own against other macros far more expensive.  I use this lens for product shots because of the sharpness and lack of color fringing.  If you like to take pictures of artwork, currency or jewelry etc, look no further.  This is a $350-$380 lens and is a steal for macro imaging.

 

Full frame results are basically the same as the APS-C coverage, which is great.  This lens is better all the way around than the Sony 100mm F/2.8 macro, except for the focusing issue, there always has to be a downer right?

 

Check out the newest version of this lens here.