A telephoto zoom is seldom the first lens purchased for a kit, but it is often the second one. These lenses are extremely useful.
As a rule, longer focal lengths in a telephoto range mean increased lens size and weight. With their Di III lineup, Tamron has been breaking rules and does so again with the Tamron 70-300mm f/4.5-6.3 Di III RXD Lens. Let me introduce you to the world's smallest and lightest 300mm-capable full-frame mirrorless telephoto zoom lens.
It is one thing to break a record, but it is another thing to deliver an overall high-quality record-breaking lens at a very affordable price. Unsurprising to those who have been following the Di III reviews, Tamron has done that.
Telephoto zoom lenses are typically purchased to cover the focal lengths longer than one's general-purpose zoom lens, and the 70-300mm range fits that need perfectly. Many general-purpose zoom lenses feature a 50-55mm maximum focal length, and few will be concerned about the small amount of gap in coverage between 50 or 55mm and this lens's 70mm wide end. Many standard zoom lenses fully reach 70mm, leaving no gap between this lens's offering. Having an overlap in coverage (for example, a 24-105mm range paired with 70-300mm) should not cause concern as this overlap is often welcomed, reducing the need to change lenses.
The 70-300mm focal length range has a wide variety of uses. The wide end of this focal length range is especially excellent for portraits, and the mid-long focal lengths provide great perspective for even very tightly cropped headshot portraits. Wildlife photography, especially with relatively close medium-to-large-sized subjects, is another good use of this range. Parents will have a great time chasing their family around, especially outdoors, with a 70-300mm lens mounted — at the beach, at the park, at the swimming pool, or in the back yard. Many products can be ideally photographed with this lens.
The 70-300mm focal length range finds use at a broad array of sporting events, including baseball, soccer, track and field, tennis, swimming and diving, equestrian events, etc. Due to its narrow max aperture opening (discussed next), This lens will work best for outdoor (vs. indoor) sports. Are you planning to attend an air show? The 70-300mm focal length range is a good choice.
I usually want at least most of this focal length range covered when photographing landscapes.
Following is this focal length range demonstrated on a full-frame camera.
When used on an APS-C-format imaging sensor, the 1.5x angle of view will equate to a 105-450mm focal length range on a full-frame camera. This narrower angle of view provides considerably more reach, significantly improving the angle of view range for large field sports and wildlife photography.
The f/4.5-6.3 in the lens name refers to the lens's max aperture opening, the relationship of lens opening to focal length. The lower the number, the more light the lens will allow to reach the sensor, enabling shorter exposures and lower, less noisy ISO settings. Each "stop" in aperture change (examples: f/2.8, f/4.0, f/5.6, f/8, f/11) increases or reduces the amount of light reaching the sensor by a factor of 2x (a big deal).
Because aperture is the ratio of the lens opening to the focal length and because this lens's maximum opening does not increase enough with focal length increase to maintain the same ratio, this lens has a variable max aperture. As the focal length increases, the widest available aperture measurement decreases. Unless it is huge, heavy, and expensive, zoom lenses reaching beyond 200mm have this variable max aperture feature.
Here is a chart showing the specific focal length ranges reported to the camera at each 1/3 stop aperture step for a sampling of lenses.
|Canon EF 70-300mm f/4-5.6L IS USM Lens||70-103mm||104-154mm||155-228mm||229-300mm|
|Canon EF 70-300mm f/4-5.6 IS II USM Lens||70-76mm||77-105mm||106-175mm||176-300mm|
|Canon EF 70-300mm f/4.5-5.6 DO IS USM Lens||70-94mm||95-184mm||185-300mm|
|Sony FE 70-300mm f/4.5-5.6 G OSS Lens||70-82mm||83-156mm||157-300mm|
|Sony FE 100-400mm f/4.5-5.6 GM OSS Lens||100-115mm||116-161mm||162-400mm|
|Sony FE 200-600mm f/5.6-6.3 G OSS Lens||200-299mm||300-600mm|
|Tamron 70-300mm f/4.5-6.3 Di III RXD Lens||70-109mm||110-151mm||152-240mm||241-300mm|
|Tamron 70-300mm f/4-5.6 SP Di VC USD Lens||70-103mm||104-160mm||161-217mm||218-300mm|
While this lens's max apertures are relatively narrow, despite the small size and light weight of this lens relative to others in its class, the max aperture differences are generally not significant, mostly within 1/3 stop of the other lenses in the same class.
The variable aperture design's significant advantages are compact size and light weight, despite the long focal lengths being included. We can all appreciate that affordability comes with the small size. A downside to the variable aperture is that manually-set exposures utilizing an aperture wider than f/6.3 are not retained throughout the entire zoom range. In an auto-exposure mode, the camera will automatically account for this change.
Wide apertures are useful for creating a strong background blur, but the telephoto focal lengths in this lens can create a very strong background blur even without wide apertures. Following are examples of the maximum background blur this lens can produce at the referenced focal length:
At 70mm, the background blur is significant, and the background is rendered completely unrecognizable at 300mm.
Tamron leaves image stabilization to the camera. Omitting the optical stabilization system reduces the size, weight, and cost of a lens, but image stabilization is a very useful feature, especially at telephoto focal lengths.
Fortunately, Sony takes care of that omission with Steady Shot IBIS (In-Body Image Stabilization) in their mirrorless cameras. On a traditional DSLR with an optical viewfinder, IBIS results in an unstabilized view, meaning that stabilization was not helpful for composition or for providing a still subject to the camera's AF system. With EVFs being prevalent in Sony's compatible E-mount lineup, the viewfinder image is directly from the imaging sensor, which is stabilized. Therefore, the viewfinder image is nicely stabilized, and sensor-based AF takes advantage of the stabilized view for improved accuracy.
With no IS switch on the lens, the camera menu must be used to enable or disable IBIS, an additional step that is annoying when speed is essential such as when going from tripod to handheld.
For many of us, the image quality produced by a lens is paramount in our selection decision, and good sharpness, a combination of resolution and contrast, is at the top of our requirements list. The Tamron 70-300mm f/4.5-6.3 Di III RXD Lens price tag immediately raises suspicion in this regard. Could a lens this inexpensive be sharp?
Wide-open aperture center of the frame results range from excellent at 70mm and 100mm to slightly soft at 300mm, with the sharpness fall-off happening gradually at the longer half of the focal length range. In general, lenses are not as sharp at their wide-open apertures as they are when stopped down one or two stops. Stopped down approximately one stop produces minor improvement at 70mm and 100mm, focal lengths where improvements are not needed. At 200mm, the 1-stop narrower aperture makes a slight improvement, and at 300mm, where gain is needed, f/8 brings on a noticeable positive change. The 300mm f/8 results are nice, though still very slightly trailing the excellent 70mm f/4.5 results.
In general, lenses are not as sharp in the periphery where light rays must be bent more strongly than in the center. In the mid-frame region, wide-open results are slightly soft at the wider end of the focal length range and relatively sharp at the longer half. The deep periphery results do not change greatly from the mid-frame results, except at 100mm, where the review lens is relatively soft. Stopping down to f/8 realizes only slight improvement in peripheral results, with 100mm showing the most improvement.
Below you will find sets of 100% resolution center of the frame crops captured in uncompressed RAW format using a Sony a7R III. The images were processed in Capture One using the Natural Clarity method with the sharpening amount set to only "30" on a 0-1000 scale. Note that images from most cameras require some level of sharpening, but too-high sharpness settings are destructive to image details and hide the deficiencies of a lens.
Be sure to find details in the plane of sharp focus to base your opinions. Overall, these results look excellent. Increasing the sharpness setting by a modest amount would bring the 300mm results close to those from the other tested focal lengths.
In some lens designs, the plane of sharp focus can move forward or backward as a narrower aperture is selected. This effect is called focus shift (residual spherical aberration or RSA). It is seldom (never?) desired. I mostly did not see focus shift as a problem with this lens, but the 300mm white birch tree example above perhaps shows a slight shift forward.
Next, we'll look at a comparison showing 100% extreme-top-left-corner crops captured and processed identically to the above center-of-the-frame images. The lens was manually focused in the corner of the frame to capture these images.
Samples taken from the outer extreme of the image circle, full-frame corners in this case, can be counted on to show the worst performance a lens is capable of. From a relative standpoint, especially considering this lens's price, this performance is very good.
Think about where the subjects you want to be rendered sharply are positioned in the frame. Corner sharpness does not always matter, but it does matter for some disciplines, including landscape photography. Videos captured at typical wide-aspect ratios avoid the use of corners.
When used on a camera that utilizes a lens's entire image circle, peripheral shading can be expected at the widest aperture settings. The over-two stops of shading in the wide-open aperture corners is noticeable but not strong. The rule is that to reduce peripheral shading, use a narrower aperture. At 70mm, the f/8 setting results in just under one-stop of shading in the corners. The f/8 aperture setting is less stopped down at the long focal lengths, and over the last half of the focal length range, f/8 shading increases to just over 1.5 stops. Shading amounts continue to decline at f/11, becoming a non-issue for most uses.
APS-C format cameras using lenses projecting a full-frame-sized image circle avoid most vignetting problems. In this case, the about-one stop of shading showing at 300mm f/6.3 may be visible in some images, especially those with a solid color (such as a blue sky) showing in the corners.
One-stop of shading is often used as the visibility number, though subject details provide a widely varying amount of vignetting discernibility. Vignetting is correctable during post-processing with increased noise in the brightened areas being the penalty, or it can be embraced, using the effect to draw the viewer's eye to the center of the frame. Study the pattern showing in our vignetting test tool to determine how your images will be affected.
The effect of different colors of the spectrum being magnified differently is referred to as lateral (or transverse) CA (Chromatic Aberration). Lateral CA shows as color fringing along lines of strong contrast running tangential (meridional, right angles to radii) with the mid and especially the periphery of the image circle showing the most significant amount as this is where the most significant difference in the magnification of wavelengths typically exists.
With the right lens profile and software, lateral CA is often easily correctable (often in the camera) by radially shifting the colors to coincide. However, it is always better not to have the problem in the first place. Any color misalignment present can easily be seen in the site's image quality tool, but let's also look at a set of worst-case examples. These are 100% crops from the extreme top left corner of ultra-high-resolution a7R III frames showing diagonal black and white lines.
There should only be black and white colors in these images, with the additional colors indicating the presence of lateral CA. Especially for a zoom lens, these results are good, with color separation being primarily visible at the 300mm end of the range.
A relatively common lens aberration is axial (longitudinal, bokeh) CA, which causes non-coinciding focal planes of the various wavelengths of light, or more simply, different colors of light are focused to different depths. Spherical aberration along with spherochromatism, or a change in the amount of spherical aberration with respect to color (looks quite similar to axial chromatic aberration but is hazier) are other common lens aberrations to observe. Axial CA remains at least somewhat persistent when stopping down, with the color misalignment effect increasing with defocusing. The spherical aberration color halo shows little size change as the lens is defocused, and stopping down one to two stops generally removes this aberration.
In the real world, lens defects do not exist in isolation, with spherical aberration and spherochromatism generally found, at least to some degree, along with axial CA. These combine to create a less sharp, hazy-appearing image quality at the widest apertures.
The examples below look at the defocused specular highlights' fringing colors in the foreground vs. the background. The lens has introduced any fringing color differences from the neutrally-colored subjects.
These results are rather colorful, indicating that these aberrations are present.
Bright light reflecting off of the surfaces of lens elements may cause flare and ghosting, resulting in reduced contrast and sometimes-interesting, usually destructive artifacts. The shape, intensity, and position of the flare in an image is variable and depends on the position and nature of the light source (or sources) and on the selected aperture, shape of the aperture blades, and quality of the lens elements and their coatings. "The application of BBAR (Broad-Band Anti-Reflection) Coating for suppressing reflections on lens element surfaces minimizes unwanted flare and ghosting to deliver sharp, crisp, high-contrast images." [Tamron] Our standard flare test with the sun in the corner of the frame produced relatively few flare effects from this lens even at narrow apertures, reflecting good performance.
Flare effects can be embraced or avoided, or removal can be attempted. Removal is sometimes very challenging, and in some cases, flare effects can be quite destructive to image quality.
Two lens aberrations are particularly evident when shooting images of stars, mainly because bright points of light against a dark background make them easier to see. Coma occurs when light rays from a point of light spread out from that point instead of being refocused as a point on the sensor. Coma is absent in the center of the frame, gets worse toward the edges/corners, and generally appears as a comet-like or triangular tail of light which can be oriented either away from the center of the frame (external coma) or toward the center of the frame (internal coma). Coma clears as the aperture is narrowed. Astigmatism is seen as points of light spreading into a line, either sagittal (radiating from the center of the image) or meridional (tangential, perpendicular to sagittal). Lateral CA is another aberration apparent in the corners.
The images below are 100% crops taken from the top-left corner of a7R III frames.
The 70mm results are nicely rounded but not crisply small (the center of the frame stars are sharply focused). The 100mm stars look good, with slight rotation motion blur showing due to the exposure length. By 200mm, the stars are illuminating aberrations that get strong by 300mm.
With few exceptions, zoom lenses have geometric distortion. This lens has very slight pincushion distortion at 70mm. The pincushion distortion increases to relatively strong by 100mm and then changes little through 300mm.
Most modern lenses have lens correction profiles available, and distortion can easily be removed using these. Still, distortion correction is destructive at the pixel level as some portion of the image must be stretched or the overall dimensions reduced.
I shared the maximum amount of blur this lens can produce earlier in the review, and telephoto lenses are advantaged in this regard. Assessing the blur quality is considerably more challenging due to the infinite number of variables present among all available scenes. Here are some f/11 (for aperture blade interaction) examples.
The first set of examples shows defocused highlights that are relatively round, smoothly filled, and having plenty of concentric rings showing clearly at 300mm.
Except for a small number of specialty lenses, the wide aperture bokeh in the corner of the frame does not produce round defocused highlights, with these effects taking on a cat's eye shape due to a form of mechanical vignetting. If you look through a tube at an angle, similar to the light reaching the frame's corner, the shape is not round. That is the shape noticeably seen in the following examples.
As the aperture narrows, the entrance pupil size is reduced, and the mechanical vignetting absolves with the shapes becoming rounder.
With a 7-blade count aperture, point light sources captured with a narrow aperture setting and showing a sunstar effect will have 14 points. In general, the more a lens is stopped down, the larger and better-shaped the sunstars tend to be. A narrow max aperture lens does not afford much stopping down before reaching apertures where diffraction causes noticeable softening of details, and these lenses typically do not produce the biggest or best-shaped sunstars.
The sunstars this lens creates are relatively small, with good shape at the wide end ranging to poor shape at the long end.
The Tamron 70-300mm Di III Lens design is illustrated above. A single LD (Low Dispersion) element is featured.
While the Tamron 70-300mm f/4.5-6.3 Di III RXD Lens does not produce the greatest image quality we've seen, the image quality it produces is exceptional for its size, weight, and price class.
Highlighted in the product name is that the Tamron 28-200mm f/2.8-5.6 Di III RXD Lens gets an RXD (Rapid eXtra-silent stepping Drive) motor unit. "RXD uses an actuator to precisely control the rotational angle of the motor, allowing it to directly drive the focusing lens without passing through a reduction gear. A sensor that accurately detects the position of the lens enables high-speed and precise AF, which is ideal when shooting continually moving subjects or video" [Tamron USA]
The Tamron 70-300mm f/4.5-6.3 Di III RXD Lens autofocuses extremely quietly and quite fast. Keep in mind that the camera plays a role in the focusing speed. The Sony a7R III and a7R IV defocus the lens slightly before focusing on the subject in AF-S (single shot) focus mode, even if focusing at the same distance with the same subject, for an overall mediocre focus speed.
In AF-C (continuous) focus mode, the defocus and focus routine goes away, and the lens's fast focus speed can be fully appreciated.
Of utmost importance is AF accuracy, and this lens delivered well in that regard. Thanks to the relatively narrow apertures, this lens is not a good choice for low light AF.
Focusing is internal, and FTM (Full Time Manual) focusing is supported in Sony's DMF (Direct Manual Focus) AF mode. This lens supports advanced AF features in compatible cameras, including Hybrid AF and Eye AF.
The focus ring positioned behind the zoom ring is seldom my preference, but this is an ideal location for the focus ring, making it easy to use, especially when handheld as the focus ring is at the fingertips while holding the mounted lens balanced in the left hand. This modestly-sized and only slightly grippy focus ring is nearly-flush-mounted and is not the easiest to find when wearing gloves. The focus ring has a modest resistance with no play.
With the focus ring being electronically-controlled (focus-by-wire), the focus adjustment rate can be made variable, based on the rotation speed of the focus ring and the focal length selected. This lens has that feature. How much rotation does the focus ring require for a full extents adjustment? At 70mm, a quick 80° turn gets that job done. Alternatively, turn slowly for 410°. At 300mm, a fast 120° turn or very slow 1620° (4.5 rotations) is required.
A minimal amount of change in subject size (focus breathing) is seen in a full-extent focus distance adjustment.
The reviewed lens shows near parfocal-like behavior over much of the focal length range. For the examples below, the lens was focused at 300mm and switched to MF to capture the rest of the samples.
Only the wider two tested focal length results appear to need refocusing for optimal sharpness.
This lens has a minimum focus distance of 31.5" (800mm) and generates a reasonable 0.20x maximum magnification spec.
|Canon EF 70-300mm f/4-5.6L IS USM Lens||47.2"||(1200mm)||0.21x|
|Canon EF 70-300mm f/4-5.6 IS II USM Lens||47.2"||(1200mm)||0.25x|
|Canon EF 70-300mm f/4.5-5.6 DO IS USM Lens||55.1"||(1400mm)||0.25x|
|Nikon 70-300mm f/4.5-5.6E AF-P VR Lens||47.2"||(1200mm)||0.25x|
|Sony FE 70-300mm f/4.5-5.6 G OSS Lens||35.4"||(900mm)||0.31x|
|Tamron 70-300mm f/4-5.6 Di VC USD Lens||55.1"||(1400mm)||0.25x|
|Tamron 70-300mm f/4.5-6.3 Di III RXD Lens||31.5"||(800mm)||0.20x|
|Tamron 70-300mm f/4-5.6 Di VC USD Lens||55.1"||(1400mm)||0.25x|
At 70mm, a subject measuring approximately 10.4 x 6.9" (264 x 176mm) fills the frame of a full-frame camera at the minimum focus distance. At 300mm, a subject measuring approximately 6.4 x 4.3" (163 x 109mm) does the same.
The evergreen bagworm moth cocoon in the image below measures just over 2" (51mm) and was photographed at 300mm at minimum focus distance.
Image quality at 70mm minimum focus distance suffers from strong field curvature but results from the 300mm end are better.
Need a shorter minimum focus distance and higher magnification? An extension tube mounted behind this lens should provide a very modest decrease and increase, respectively. Extension tubes are hollow lens barrels that shift a lens farther from the camera, which allows shorter focusing distances at the expense of long-distance focusing. Electronic connections in extension tubes permit the lens and camera to communicate and otherwise function as normal. Tamron does not publish extension tube specs, nor do they manufacture these items, but third-party Sony-mount extension tubes are available.
This lens is not compatible with Tamron teleconverters.
As with the other Di III lenses, the light weight and polycarbonate exterior design are not reminisce of a rugged design, but still, this lens feels like a high-quality product. The tight tolerances on moving parts, including negligible play on the extended inner barrel, add some assurance that this lens has been carefully designed and that modern construction methods were utilized. The lens has a very nicely-smooth narrow shape, and the matte/satin black finish, along with the engraved white lettering with a modern, attractive font style, looks classy.
The nicely-sized, rubber-coated zoom ring rises very slightly from the barrel and is very smooth with no play. As I said before, I generally prefer the zoom ring to be located behind the focus ring, closer to the rear of the lens, but this lens's design works fine. As usual for a telephoto zoom lens reaching 300mm, this lens extends by 2.4" (60mm) when zoomed to 300mm.
There are no buttons or switches on this lens. A lock switch to hold the lens in the retracted state is not provided, but gravity zooming was not an issue on the reviewed lens. The AF/MF button is the switch I miss the most. Having to navigate a menu option (programmed to a custom button) for this commonly-used feature is inefficient. Those who do not use MF will find the lack of this switch to be an advantage, and the lack of switches should mean increased reliability and decreased chance for dirt and moisture penetration.
The 70-300 Di III has weather and dust-resistant seals.
The front lens element does not get the fluorine treatment that provides improved water- and oil-repellent qualities.
"The 70-300mm F4.5-6.3 zoom’s optical design was refined via thorough simulations utilizing the latest technologies. With high priority on reduced size and weight, Tamron selected the aperture of F6.3 for the telephoto end to achieve a slim lens barrel and outstanding lightness. Taking the weight savings even further, we used a specially treated, high-strength aluminum-magnesium alloy, the first time Tamron has used this material in the mount components of a lens for full-frame mirrorless cameras. The new design maintains excellent strength while successfully reducing weight to around 68% of previous mounts. Eliminating waste to the extreme degree, Tamron reduced weight while still achieving very high image quality in the 70-300mm F4.5-6.3." [Tamron]
Record-setting light weight and small size are extremely attractive features for a lens. Carry this lens in hand or in the pack all day with little effort exerted. Reduced fatigue results in improved realized image quality (and quantity).
|Model||Weight oz(g)||Dimensions w/o Hood "(mm)||Filter||Year|
|Canon EF 70-300mm f/4-5.6L IS USM Lens||37.1||(1050)||3.5 x 5.6||(89.0 x 143.0)||67||2010|
|Canon EF 70-300mm f/4-5.6 IS II USM Lens||25.1||(710)||3.1 x 5.7||(80.0 x 145.5)||67||2016|
|Canon EF 70-300mm f/4.5-5.6 DO IS USM Lens||25.4||(720)||3.2 x 3.9||(82.0 x 100.0)||58||2004|
|Nikon 70-300mm f/4.5-5.6E AF-P VR Lens||24.0||(680)||3.2 x 5.7||(80.5 x 146.0)||67||2017|
|Sony FE 70-300mm f/4.5-5.6 G OSS Lens||30.1||(854)||3.3 x 5.6||(84.0 x 143.5)||72||2016|
|Tamron 70-300mm f/4-5.6 Di VC USD Lens||27.0||(765)||3.2 x 5.6||(81.5 x 142.7)||62||2010|
|Tamron 70-300mm f/4.5-6.3 Di III RXD Lens||19.2||(545)||3.0 x 5.8||(77.0 x 148.0)||67||2020|
|Tamron 70-300mm f/4-5.6 Di VC USD Lens||27.0||(765)||3.2 x 5.6||(81.5 x 142.7)||62||2010|
For many more comparisons, review the complete Tamron 70-300mm f/4.5-6.3 Di III RXD Lens Specifications using the site's lens specifications tool.
As with most other Sony E-mount lenses, my knuckles uncomfortably press against the barrel of this lens when using the Sony a7R III and IV, though the rounded contour at the point of impact is helpful in that regard.
Here is a visual comparison:
Positioned above from left to right are the following lenses:
The same lenses are shown below with their hoods in place.
Use the site's product image comparison tool to visually compare the Tamron 70-300mm f/4.5-6.3 Di III RXD Lens to other lenses.
If you have been following Tamron's Di III lens lineup, the 67mm filter size was expected. This size is rather common overall, and within Tamron's Di III lineup, the standard. Traveling with a kit of Di III lenses? You likely need to pack on 67mm effects filters such as circular polarizer and neutral density filters.
The Tamron HA047 lens hood is included in the box. This is semi-rigid plastic round-shaped hood has a ribbed interior designed to avoid reflections. This hood offers significant physical protection to the front element and offers much protection from bright light, especially at wide focal lengths. An advantage of this hood shape that it enables the lens to stand on its hood, while the petal-shaped hoods are easier to align for installation (simply learn the small petal to the top installation orientation). A push-button release is not provided, but this hood rotates and clicks into place smoothly (as long as it is not angled slightly during the install).
No lens case is included in the box, but finding a case for a common lens form factor is not challenging. Consider a Lowepro Lens Case or Think Tank Photo Lens Case Duo for a quality, affordable single-lens storage, transport, and carry solution.
Tamron's Di III lenses are defined by great value, and the Tamron 70-300mm f/4.5-6.3 Di III RXD Lens, sporting a very low price, is that.
What does "Di III" mean? Tamron's Di III lenses are designed for use on mirrorless interchangeable lens cameras. The Tamron 70-300mm f/4.5-6.3 Di III RXD Lens is compatible with all Sony E-mount cameras, including both full-frame and APS-C sensor format models.
"This product is developed, manufactured and sold based on the specifications of E-mount which was disclosed by Sony Corporation under the license agreement with Sony Corporation." [Tamron] Tamron USA provides a reassuring 6-year limited warranty.
The reviewed Tamron 70-300mm f/4.5-6.3 Di III RXD Lens was online-retail sourced.
The camera manufacturer, Sony in this case, has a similarly-spec'd lens, so let's pick that model, the Sony FE 70-300mm f/4.5-5.6 G OSS Lens, for comparison.
In the image quality comparison with wide-open apertures, as a generalization, the Tamron lens is slightly sharper in the center of the frame, and the Sony lens is a slightly better performer in the periphery. Stopping down erases most of the center of the frame differences, but the Sony lens holds the peripheral image quality advantage. The Sony lens has less peripheral shading at wide apertures. The Tamron lens has less considerably less geometric distortion at 70mm but significantly more over the balance of the range.
Regarding specs and measurements, the Tamron 70-300mm f/4.5-6.3 Di III RXD Lens vs. Sony FE 70-300mm f/4.5-5.6 G OSS Lens comparison shows a substantial weight difference. The Tamron lens's smaller diameter is noticeable in hand, with slightly narrower filter threads being associated (67mm vs. 72mm).
The Tamron lens holds the reported f/4.5 aperture to a slightly longer focal length (109mm vs. 82mm), but the Sony lens remains f/5.6 through 300mm vs. until 241mm. The Sony lens has 9 aperture blades vs. 7, and it has a full complement of switches, including a focus distance range limiter. The Sony lens has Optical SteadyShot working in conjunction with IBIS vs. IBIS only. The Sony lens has a higher maximum magnification (0.31x vs. 0.20x) despite a longer minimum focus distance. Not surprising is that the Sony lens has a significantly higher price tag.
Use the site's comparison tools to create additional comparisons.
Due to their usefulness, a telephoto zoom lens is often the second lens added to a kit. The 70-300mm range made available in this lens has long been featured in manufacturer's lineups and is highly valued by those owning such a lens. The Tamron 70-300mm f/4.5-6.3 Di III RXD avails that range in a record-setting small and light lens.
Despite being a record-setting model, this lens remains a high performer with good image quality. As I mentioned earlier in the review, reduced fatigue results in improved image quality and quantity. A comfortable and attractive design along with a quiet and accurate AF system round out this lens's attributes.
It is easy to love Tamron USA's 6-year warranty, and the Tamron 70-300mm f/4.5-6.3 Di III RXD Lens's low-price makes it an excellent value and very attractive choice.
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