While the Tamron 28-300mm f/4-7.1 Di III VC VXD is not the sharpest lens in Tamron’s lineup, it delivers good overall image quality for an all-in-one superzoom. Let’s break down its performance in various aspects of image quality:

Sharpness

• Center Sharpness: At the wide end (28mm), the lens is sharp in the center even when wide open at f/4. As you zoom in, the sharpness remains relatively consistent, with noticeable improvement in overall clarity when stopped down slightly.
• Edge Sharpness: There is some softness towards the edges at the wide end, especially when shooting wide open. This softening becomes more pronounced at the longer focal lengths, especially around 200mm and beyond. However, stopping down to f/5.6 or f/8 helps improve sharpness across the frame.

Color and Contrast

• Color Accuracy: The Tamron 28-300mm produces accurate and vibrant colors, with good saturation, especially at the wide and middle focal lengths. Colors are generally true to life, with no major shift towards cooler or warmer tones.
• Contrast: Contrast is generally good, though it can be a bit lower at the long end of the zoom range. In well-lit scenes, contrast is strong, making images pop, but in very high-contrast situations (like backlit scenes), you may notice a bit of flare or loss of detail in highlights.

Flare and Ghosting

• Control of Flare: Thanks to the BBAR (Broad Band Anti-Reflection) coating, flare and ghosting are well controlled. However, there is still some noticeable flare when shooting directly into strong light sources like the sun, especially at wider focal lengths.
• Ghosting: Tamron’s coating also helps to minimize ghosting in backlit situations, so you’re less likely to see unwanted artifacts in your images, although very high-contrast scenes might still show some ghosting.

Bokeh

• Background Blur: The lens produces fairly decent bokeh, though it’s not as smooth or creamy as more expensive lenses with larger apertures. At the long end (200mm–300mm), the lens produces more noticeable background blur, but it’s still not as pronounced as lenses with f/2.8 or wider apertures.
• Smoothness: The bokeh is not distracting and is relatively smooth, although you might see a bit of roughness in the out-of-focus areas, particularly at wider apertures.

Optical Aberrations

• Chromatic Aberration: There’s some visible chromatic aberration, particularly at the longer focal lengths (200mm and 300mm), but it’s not excessive and can usually be corrected easily in post-processing.
• Distortion: The lens shows some barrel distortion at the wide end and slight pincushion distortion at the telephoto end. These issues are typical for superzoom lenses but can be easily corrected in-camera or during post-processing.
• Vignetting: Vignetting is noticeable at the widest focal lengths (28mm), but it’s not overwhelming and can be fixed by stopping down slightly or using post-processing tools.