Tag: MTF

Sigma Global Vision: The Journey Continues

What a difference a couple of years makes!

Two years ago, we were gearing up for PhotoPlus, just days after the announcement of the Sigma Global Vision at photokina 2012. We were preparing ourselves for discussions and briefings to explain the philosophy behind the three new lines being offered.

At that time, many photographers and technical editors were confused as to what Art, Sports, and Contemporary was meant to convey in a lens name. We spent a lot of time that fall explaining the way that Sigma is rethinking lenses and how this relates to the three new lens markings.

The Sigma 150-600mm F5-6.3 DG OS HSM | Sports lens is one of the newest lenses in the Sigma line, announced at photokina 2014. This lens is designed for exceptional outdoor performance.

Shortly thereafter, though, the first of the new Sigma lenses, the 35mm F1.4 DG HSM | Art lens was released, and almost overnight, the conversations changed. Photographers and editors around the world were blown away by the build quality, and more importantly, the total image quality of this new Sigma, full-frame, fast-aperture wide prime. People realized that this new lens, the original Art lens, was something quite special. It defined the Art category and heralded a new era for Sigma under the guidance of new CEO Kazuto Yamaki. It was the perfect proof of the promise of the Sigma Global Vision. Continue reading Sigma Global Vision: The Journey Continues

SIGMA 24-105mm F4 DG OS HSM | Art: Photo Samples

The SIGMA 24-105mm F4.0 DG OS HSM | Art lens has been generating a lot of excitement since its announcement just before PhotoPlus Expo 2013 in late October. And now, the lens is shipping in Canon mount, with other available mounts to begin shipping soon. I’ve already talked about the build and feel of the lens based on one of the pre-production samples we were displaying at the show, and you can read this companion blog posting for my first impressions.

1/15 F5.6 ISO 100.
Mint Martini seen through the SIGMA 24-105mm F4 DG OS HSM | A on a classic 5D. Camera was on a tripod, with slow shutter speed to expose for background Christmas lights wrapped around the legs of a tall tripod. Very low-powered strobe with barndoors and grid was aimed at the rim of the glass. This is near the close-focusing distance and magnification at 105mm.

Here we’re going to focus primarily on the photos this lens can create when paired with both a full-frame and APS-C DSLR. For photographers looking for a one-lens workhorse covering wide angle to short tele, with Optical Stabilizer, this lens is all kinds of amazing.

1/200 F10 ISO 100.
Here we are zoomed in all the way to 105mm, but on a Canon EOS Rebel T3i, an APS-C DSLR. We bounced a shoe-mounted strobe off the ceiling for this shot and stopped down to F10 for increased depth of field.
4/10 sec F4 ISO 100 on a tripod.
To give a feel for the overall range, here’s a view of a town Christmas Tree at 24mm on the Rebel T3i.
Same settings as above 4/10 F4 ISO 100 on a tripod.
And here’s the same tree, zoomed almost all the way in, to 95mm on the Rebel T3i.
1/25 F4 ISO 100.
This shot is handheld, 1/25 second, at 95mm with Optical Stabilizer activated. It is perfectly sharp at two stops below the reciprocal of the focal length. Canon 5D classic.
1/200 F4 ISO 400.
At 105mm at F4, there’s still a nice big of background softening, even when focal distance isn’t right in front of the lens. Classic 5D.
4/10 F4 ISO 100 on tripod, Canon Rebel T3i.
Now, here we are close-focused at 105mm, about the same overall distance from that tree, zoomed in on lights wrapped around a streetlamp. Notice how abstract the background is rendered.
1 second exposure, F4, ISO 100, on a tripod, again with the Rebel T3i.
And here’s that same scene captured at 24mm, again close-focusing on the lights wrapped around a streetlamp. The background is a bit more recognizable, but still simply beautiful in its softness. Notice how wonderfully round all the circles of light are!
3.2 sec F4 ISO 100, tripod, obviously. Canon Rebel T3i.
At 24mm at F4, both the tree and the courthouse are in sharp focus in this image made from a distance to frame both nicely.
At 105mm the tree branches in front of the column are the exact focal point, and are nice and sharp, but the courthouse in the background is softened up a bit. Remember, depth of field gets shallower as focal length increases. Same settings as previous shot. Only variation is zooming in.
1/50 F4 ISO 400, OS activated.
Here, at 87mm, we are close-focusing on the edge of the mirrored red ornament a few inches in front of the camera, a full-frame 5D. The people walking are only about twenty feet in front of the camera, but are very nicely soft.
Here, at 80mm, we’re focused a bit farther away from the lens, and again, the background, even though it is farther away than the people in the last frame, is much less softened due to the overall focal distance. Sometimes a bit of softness just what is called for. But with a 4x zoom range from wide to short tele, there is a ton of compositional creativity and variations that can be applied to the scene in front of the 24-105mm F4!
1/100 F4, ISO 400.
Fancy chocolates in a display case at 105mm just a few inches from the lens. It’s very nice as the pattern repeats off the focal plane.
1/125 F4 ISO 200, classic 5D.
Now here’s a skewed angle to a repeating pattern that is much more distant from the lens at 105mm, and the brickwork shows the edge to edge sharpness of this lens, even wide open on a full-frame camera.

Nine rounded aperture blades, Optical Stabilizer, 4x constant-aperture zoom for creativity and quick one-lens recompositing all add up to a rock-solid new member of the Sigma Art line of lenses. For photographers looking for a constant-aperture one-lens solution from wide to short tele, the new 24-105mm F4 DG OS HSM | A, this lens is a serious new player.    

Read Jack’s First Impressions posting for more on the in-the-hands experience with this great new lens!

Seeing the Light with the Sigma 17-70 F2.8-4.0 DC OS HSM | C

The Sigma 17-70 F2.8-4.0 DC OS HSM | C is the first lens in the Contemporary line originally announced last September. This fast aperture standard zoom is a serious step up from the bundled kit zoom that covers a similar focal length.

Here’s why:

The lightweight, compact 17-70mm F2.8-4.0 DC OS HSM | Contemporary lens came with me on a hike on the beach at Cape May Point. As we wandered the beach, I noticed this perfect alighment of a lifeguard rowboat, St. Mary’s of the Sea and the Cape May Lighthouse. I zoomed in to 30mm to emphasize the foreground while also stopping down to F/10 for great deep depth of field to keep the structures in the background sharp and recognizalbe. 1/320 F10 ISO 200 on the Canon Rebel T3i. The wide to short tele range of this lens is great for most everyday compositions.

This is a great grab-and-go lens, it truly is. Mounted on the APS-C cameras for which it is designed, it covers a range from about 27-110mm, wide angle to short tele, a very usable range for most everyday situations. A quick twist recomposes the scene to take in more of the surroundings, or to zoom in close on selected details. And between the faster apertures than the bundle kit competitors and the Optical Stabilizer switch, it’s a winner in lower-light situations. Continue reading Seeing the Light with the Sigma 17-70 F2.8-4.0 DC OS HSM | C

The Sigma 35mm F1.4 DG HSM | Art: Another Look at this Amazing Lens

It was just about a year ago that the Sigma 35mm F1.4 DG HSM | Art lens was announced at Photokina 2012 as part of the Sigma Global Vision. And what a year it has been for this amazing wide, fast prime!  This lens quickly won the hearts of both technical reviewers and creative photographers around the world for its amazing optical performance even wide open at F1.4, its design and build, and of course, its incredibly competitive street price.

Detail shot of the front element of the Sigma 35mm F1.4 DG HSM | Art lens.

Here’s a rundown of just some of the highlights of the first year of this lens

Recently, I headed to Sandy Hook, NJ well before dawn to catch both the sunrise, and moonset over the beach. Here, facing west, is Moonset, captured in morning twilight with the Sigma 35mm F1.4 DG HSM | Art lens on a classic 5D. Look very close on the horizon for the Sandy Hook Lighthouse, too! 1 second at F16, ISO 100, on a tripod, of course!

Continue reading The Sigma 35mm F1.4 DG HSM | Art: Another Look at this Amazing Lens

A1 MTF Testing for New Sigma Lenses

On the Sigma Global Vision site, you may read and learn about every aspect of the evolution of Sigma. In this occasional blog series, we discuss aspects of the Global Vision in greater depth.

The Global Vision explains:

There are three requirements for outstanding lenses: fine design, precise manufacturing and inspection that ensures compliance with all specifications. Sigma lenses are born of well-thought-out design concepts and sophisticated, advanced Japanese manufacturing technology: the final clincher is our lens performance evaluation.

We used to measure lens performance using conventional sensors. However, we’ve now developed our own A1 proprietary MTF (modulation transfer function) measuring system using 46-megapixel Foveon direct image sensors. Even previously undetectable high-frequency details are now within the scope of our quality control inspections. The lenses in our new lines will all be checked using this new system before they are shipped.

Thanks to our new sensors, with their extremely high resolution, you can expect our high-performance lenses to be better than ever.

At the heart of the A1 measurement system is the same Merrill Generation 46 Megapixel Foveon sensor in the Sigma SD1 Merrill, and the Merrill Generation DP cameras. The incredible resolution of this sensor makes it perfectly suited to this advanced scientific purpose. The lenses to be measured are hooked up to the  image capture device, and the special charts are captured and analyzed using new, proprietary algorithms designed to work in conjunction with the high-resolution sensor. This level of detail analysis is critical for creating lenses capable of meeting the demands of the most detailed image sensors in cameras such as the Sigma SD1 Merrill and the Nikon D800.

Continue reading A1 MTF Testing for New Sigma Lenses

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