Image Stabilization Greatly aiding a narrow max-aperture lens is image stabilization IS. Canon rates this IS implementation at a best-available at review time 4 stops. With perfect indoor conditions and standing unsupported, I handheld this lens at 24mm with a. These figures show IS giving me well over 3 and nearly 4 stops of assistance.

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Image Stabilization Greatly aiding a narrow max-aperture lens is image stabilization IS. Canon rates this IS implementation at a best-available at review time 4 stops. With perfect indoor conditions and standing unsupported, I handheld this lens at 24mm with a.

These figures show IS giving me well over 3 and nearly 4 stops of assistance. I have sharp images captured at much longer shutter speeds, but as expected, the keeper rate trails off as the exposure duration is increased. Here are two examples of successful ultra-long exposure examples: 2 seconds at 24mm. IS is not always the answer. There are times when image stabilization does not work so well, such as when the subject is in motion, but the versatility added to a lens by the IS feature has a lot of value.

Canon informed me that this lens does not have the "dynamic IS" implementation expanded IS range when walking , but the image is very stable even while actively moving the camera including while video recording.

It is also nearly silent. This makes subject framing easier and makes your photography a more pleasant experience. The STM features auto-panning a switch setting is not required for the lens to stabilize in one direction only and auto tripod detection IS may remain switched on during tripod use. Note that Canon recommends turning IS off when using a tripod to conserve a small amount battery life and they recommend leaving IS on when using a monopod to assist in stabilizing the image.

The solid lines show sagittal lines radiating from center to outer image circle results while the dashed lines show meridional lines perpendicular to the sagittal lines results.

The left side of the chart shows center-of-the-image-circle measurement and the right side shows peripheral measurement. The higher the lines, the better the lens performs. The difference in list price between the two above-compared lenses does not appear to be reflected in the MTF charts. Waiting for the lens to arrive is the next step and with lens in hand, the real answers become available.

Concisely describing the image quality of a variable max aperture lens with less-than-perfect image quality is often But, most of you are photographers and not lens critics, so a concise description is important to you. At 24mm, stopping down yields only little or no noticeable difference in center-of-the-frame image quality and little improvement is needed.

Expect the same improvement by using a one stop narrower than wide open aperture from 50mm through mm. The corners are never terrible complete mush , but in general, using a wide open aperture results in mildly soft corners from this lens. Overall and comparatively speaking, this lens performs nicely from an image sharpness perspective.

As a rule, especially good results are obtained by stopping down at least one stop. APS-C bodies will be far less affected by any corner image quality deficiencies. Noticeably impacting mm full frame corner image sharpness is CA Chromatic Aberration.

Typical for a lower-priced general purpose zoom lens is that CA is present and it is most easily seen at the extents of the focal length range. At 24mm, CA can be found deep into the frame with a modest amount showing in corners. Very little CA shows at 35mm and then increases in visibility to minor at 50mm, moderate at 70mm, moderately strong at 85mm an rather strong and deep-reaching by mm.

The magenta and cyan colors are not part of this scene. These colors show that different wavelengths of light are not being identically focused on the sensor. Vignetting is normal and also normal is for the strongest shading to be in the widest angle corners with a wide open aperture. The STM upholds normal with about 3. Corner shading decreases from a just-noticeable 1. Vignetting increases very slightly again at mm to a not usually noticed.

Stopping down the aperture 1 stop eliminates noticeable vignetting with 24mm being an exception. All that said, this lens performs well in this regard. The shading is primarily outside of the smaller image circle used by these cameras. While this lens is not completely flare-free, it produces nice results even with bright lights including the sun in the corner of the frame.

Varying is the amount of distortion and where the transition between the two types occurs. In this lens, there is a moderate amount of barrel distortion that appears as a bulge in the middle of the frame at 24mm.

Somewhat unusual is how quickly the distortion changes over to the pincushion type — at only a few mm beyond 24mm. With relatively narrow apertures and a focal length range that goes only slightly into the telephoto range, this is not the lens to pick if creating diffusely-blurred backgrounds is a primary goal.

While this lens can create a blurred background especially at mm with a very close subject and a distant background , the quality of the background blur bokeh is not a big strength either.

That this lens has an odd number of aperture blades vs. Even numbers of aperture blades create stars with the same number of points as there are blades from points of light in the frame such as street lights and Christmas tree lights. An odd number of aperture blades will create stars with twice as many points as there are blades. My preference is usually for the latter. In the example above, thanks to the 7 blade design, you see 14 point stars around the harbor street lights.

As usual, I have spent a good amount of time with this lens and have had it to locations including Baltimore, Maryland. I am very pleased with the outcome and have no regrets from using this lens for the capture. Even at full resolution, this image has high quality. STM AF advantages are usually nearly silent operation and very smooth focus distance changes. These advantages are especially helpful for video recording using Movie Servo AF.

According to Canon, this is the first full frame lens to incorporate a "lead screw-type stepping motor. If you ask auto focus to make a full extents focus distance change, you are not going to be greatly impressed by the speed in which the lens responds.

But, if your focus distance changes are relatively small which is more typical in real use , the lens gets the job done with nice speed. Most important is that this lens focuses very accurately.

The manual focus ring, in all STM designs to date, electronically controls the focus of the lens it is not a direct drive system. In AF mode, manual focusing is supported only while the shutter release is half-pressed. Also normal for STM lenses is that the lens goes through an initialization process during power-up that involves the lens racking focus by some amount in both directions. This process caused me grief when I had carefully setup a shot, waited for the right timing, woke up the camera and watched my scene go out of focus.

But, the focus change was only temporary. I soon determined that the focus was returning to my previously set distance and I no longer stress at the initialization process.

The STMs focus ring is nicely-sized and positioned ideally forward of the zoom ring. This is a rear-focusing AF system. The lens does not extend with focusing and the front filter threads do not rotate. Expect some modest subject size change in the frame when pulling focus using this lens.

There are no focus distance or DOF markings provided on this lens. I expect that to change. With a 0. Here is a comparison chart: Model.


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