I recently purchased a Canon 70-200mm f/2.8 L-series lens — the largest investment in a single lens that I’ve made to date — and I began wondering if I should protect the front element of the lens with a UV filter. I am usually pretty gentle with my equipment, but I concede that dust build-up, the accidental fingerprint, and other things will inevitably happen regardless of how careful one is with their gear. So the small investment in a high-quality UV filter is a small price to pay for a little bit of extra protection. Up to this point, I have always placed a UV filter on every lens I own, without thinking twice about it. However, having paid a hefty price for this new lens that’s capable of delivering superb image quality, I began wondering if the UV filter may contribute to some degradation in image quality. So I decided to test things out…

Details

• Camera Body: Canon 6D
• Lens: Canon EF 70-200mm f/2.8L IS II USM
• Filter: Hoya HMC/UV (77mm)
• ISO: 100
• Focal Length: 150mm
• Aperture: 2.8
• Shutter Speed: 1/100 sec
• Notes: Images were uploaded to and hosted by Flickr, so I am not sure what sort of file compression and/or image correction Flickr may have applied to them. This shouldn’t matter for the comparison because the same compression/image correction (if any) would have been applied to both images. These were artificial flowers, which is why there is a noticible repeating texture in the magnified images.

Full Images: Without Filter (top) and With Filter (bottom)

Without UV filter (above) | download full-res file

With UV filter (above) | download full-res file

100-Percent Crop Images

Without UV filter (above)

With UV filter (above)

Conclusions

As far as I can tell, there is no significant difference between the images shot with and without the UV filter. Overall image quality is identical. There is no loss of sharpness, no chromatic aberrations on edges, or any other discernable loss of quality when shooting through the UV filter. In fact, I think there may be a very slight increase in edge sharpness when using the UV filter. Of course, this was a very narrow test comparing only two images taken in a brightly lit test environment. I would like to compare other image types taken in various lighting conditions. When I have a chance to do some more testing, I’ll post the additional images here. In the mean time, download the high-resolution files, analyze them yourself and draw your own conclusions. I look forward to hearing your feedback in the comments section below.