EOS R1, RF 70-200mm lens: Do UV filters Detract from Sharpness?

[Zhaopian]

Hi,

I shot the same thing: first with my UV filter and second without the filter. While I personally cannot tell the difference in sharpness, I can see a change in light, glare, reflection, or something. Does anyone believe UV filters can make images a little bit more soft/blurry?

Canon R1 and the RF 70-200mm lens. Filter is Nisi L395 SMC. Also did not have the lens hood on.

Honestly, it might be a bit sharper without.

With the UV filter.

Without the filter.

Thanks.

[Cantrell]

I was told by a professional photographer that a filter can cause some distortion of the picture and the aperture can be effected by 1 F stop. After that conversation I took all of the filters off of my lenses.

[Peter]

A UV filter will not improve image quality. That said, your box or camera may have moved.

[p4pictures]

When you add an additional layer of glass in front of the lens, then it will have some impact on the optical performance of the lens. This additional air / glass layer might result in less contrast, softness, more flare, colour changes and more. Any filter that softens the image may also make the AF less accurate since the camera is working with a softer less sharp image. 

UV filters are largely pointless since the sensor itself has a UV blocking layer as part of its design. Also many current lenses have a fluorine coating on the front / rear elements that makes them easier to clean finger prints and other marks off than older lenses.

Canon does offer a plain glass "protect" filter in a range of sizes. 

https://www.usa.canon.com/content/canon/en/search.html?q=protect+filter&r=product 

[jrhoffman75]

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@Cantrell wrote:

I was told by a professional photographer that a filter can cause some distortion of the picture and the aperture can be effected by 1 F stop. After that conversation I took all of the filters off of my lenses.

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I don't believe the 1 stop impact is correct, but there can be reflections off the lens front element that then reflect back from the filter that will impact sharpness. There are numerous threads about sharpness impact from filters. 

A few Canon lenses do require a filter for total weatherproofness (the instruction manual will state that). Otherwise a lens hood is probably better for lens protection from impact.

[Cantrell]

jrhoffman75,

Misinterpreted the comment about the f stop.

[ebiggs1]

"I don't believe the 1 stop impact is correct,..."

Neither do I and who ever told you it did is not a person I would go to for photography advice from.

"...many current lenses have a fluorine coating on the front / rear elements that makes them easier to clean finger prints ..."

Totally disagree with that, too. Yes, the coating may be better but it is not superman or impenetrable. It is. And what is better to clean  a cheaper filter or the very expensive front element.  Plus like commented above some lenses require a filter to complete weather resistance.

"A UV filter will not improve image quality."

Absolutely true but it may not hurt it either if the proper filter is chosen. I have never used the filter, Nisi L395 SMC, in question so I can not comment on its performance per say but top quality filters like B+W do a great job without introducing harmful attributes.

And believe it or not any filter, any at all, can be removed if the scene is being compromised by it. They screw off as easily as they screw on.

[ebiggs1]

"... a lens hood is probably better for lens protection from impact."

Obviously, you have not done young children shoots like kindergarten graduation parties? The dark hole is an irresistible dark place for tiny  grubby hands to explore. Or, been on severe storm jobs. Or, the very humid southeastern US in mud and swamp water.

[wq9nsc]

The UV filter may have changed the metering and resultant exposure settings if you are not shooting in full manual exposure with fixed ISO.  Your screenshots don't don't provide the EXIF data so no way to tell from them.

I keep a lens "filter" on all of my standard size lenses but only high quality optical glass with no UV or other filtering since UV filters aren't needed for standard digital cameras since they already have an optical low pass filter to avoid the sensor "seeing" light above its capable sampling frequency.  These clear glass pieces offer a little protection to the front element and because I shoot a lot of sports it means I can wipe them if necessary with whatever is handy during an event without worrying about damaging the coating on a several hundred (or thousand in some cases) dollar front element.

My big L series telephoto primes along with my L 200-400 f4 zoom with integrated extender have very large front elements so a front filter can't be used.  These lenses always have their lens hood in place when in use even though those are also somewhat expensive (my EF 800 f5.6 uses a carbon fiber hood to reduce weight) but far less expensive than a front element.  These large element front lenses have a different coating material than the smaller lenses designed to be more robust but they still must be cleaned with care.  But for a smaller lens, they get a quick cleaning with a dust blower and a front filter installed as soon as they come out of the box.

Rodger

[Waddizzle · Accepted solution]

“ I keep a lens "filter" on all of my standard size lenses but only high quality optical glass with no UV or other filtering since UV filters aren't needed for standard digital cameras since they already have an optical low pass filter to avoid the sensor "seeing" light above its capable sampling frequency. “

I agree with Rodger.  The use of a UV filter on a digital camera is unnecessary.  Performing an A/B test by photographing the sky or water is not going to make much of a difference.  Not like it would with a film camera.

I also use a Clear filter on all my lenses. I don’t use them for protection against impact. I use them to keep my front element clean.  A couple need one for weather sealing. 

However, your lens is particularly sensitive to the use of UV filters. When I first began using the lens for BIF, I noticed that the images were softer than my 70-200.  I finally figured out that the UV filter was the issue.  The only reason I used is because I didn’t have a Clear filter on hand.

I swapped filters, and now the 100-400 was tack sharp.

It seems coatings on the internal lens elements were having a negative effect on focusing  with UV filtered light.