OpticalLimits reviews the Canon EOS RF 16mm F2.8 STM

[LogicExtremist]

You are saying that a certain resolution threshold separates 'good' lenses from 'bad' lenses. Any way you look at it, that's value judgement. Period. Full stop.

No, it's a categorisation, as both you and I know from science. Assigning descriptors to a range of values, much like: highly acidic, moderately acidic, weakly acidic, neutral, slightly alkaline, moderately alkaline, strongly alkaline for 0 -> 7-> 14

If you look at the test results in the reviews that utilise Imatest, certain ranges are defined as poor, good, excellent, exceptional. A value judgement is eyeing an image and calling it from that, but the corner crop photos in the TDP review leave little to subjectivity, those are blurred AF!

 

[neuroanatomist]

My point is simple, different applications often require different lenses, there is no universal good or bad, and as you just pointed out, price is not necessarily an indication that a lens is going to perform better at every possible application.

I think few, if any, Canon lenses are really good for astrophotography. Canon doesn't seem to prioritize reducing coma or astigmatism in their designs. I was actually surprised that the EF-M 55-200 has very little coma and almost no astigmatism...but with the focal range and slow aperture, it's not especially useful for astro anyway.

The RF 28-70/2 is pretty good in that regard, similar corner star performance to my Samyang 14/2.8 (but more expensive, much heavier, and even in terms of exposure length vs. aperture in terms of avoiding star trails).

 

[neuroanatomist]

No, it's a categorisation, as both you and I know from science. Assigning descriptors to a range of values, much like: highly acidic, moderately acidic, weakly acidic, neutral, slightly alkaline, moderately alkaline, strongly alkaline for 0 -> 7-> 14

If you look at the test results in the reviews that utilise Imatest, certain ranges are defined as poor, good, excellent, exceptional. A value judgement is eyeing an image and calling it from that, but the corner crop photos in the TDP review leave little to subjectivity, those are blurred AF!

Oh, I see. Corner resolution is what defines good lenses vs. bad lenses. You're right, that's not a value judgement at all. Not even a little bit.

 

[Del Paso]

I see, some Canon lenses have "bigly" alkaline corners...

 

[Johnw]

I see, some Canon lenses have "bigly" alkaline corners...

Well yeah, we Astro people get that “the corners are not that great” seems like a totally irrational response to 99% of people as a response to Frodo’s image.

 

[Johnw]

For hiking and traveling, small is a real bonus.

This is also a great point, a great image that might be just a bit off in the corners is still superior to an image that does not exist because you couldn’t carry the lens needed to produce it to the location.

 

[LogicExtremist]

Oh, I see. Corner resolution is what defines good lenses vs. bad lenses. You're right, that's not a value judgement at all. Not even a little bit.

Not what I was talking about, I was discussing objective and measurable values from test results as a measure of poor, good, excellent, etc, a topic you brought up mind you!

Now that you bring up the criteria of corner sharpness, for landscape, architecture, real estate, astro, the majority of genres where UW lenses are used, corner sharpness matters, and lenses that don't render corner details well would be less desirable for those uses.

For vlogging and casual travel photos, which the RF 16mm f/2.8 seems suited for, it doesn't matter that much at all.

Canon may have decided to sacrifice image quality for size/weight on its new range of cheaper lenses, and of course those who prefer those criteria would love them, those who don't plainly wont. I think a major stumbling block for some is understanding that some people's needs may be different from their own, but that's not my thing to fix.

Trying to point out the inherent limitations of lens on this forum sometimes is like trying to explain to someone why their two-seater sports car is not the ideal vehicle to transport a ton of construction sand lol!

Let's just pretend that the subject of this thread, the Optical Limits review (did we forget about that) doesn't exist, and what it says doesn't matter, sounds like a great approach!!! Wow!

 

[AlanF]

Not what I was talking about, I was discussing objective and measurable values from test results as a measure of poor, good, excellent, etc, a topic you brought up mind you!

Now that you bring up the criteria of corner sharpness, for landscape, architecture, real estate, astro, the majority of genres where UW lenses are used, corner sharpness matters, and lenses that don't render corner details well would be less desirable for those uses.

For vlogging and casual travel photos, which the RF 16mm f/2.8 seems suited for, it doesn't matter that much at all.

Canon may have decided to sacrifice image quality for size/weight on its new range of cheaper lenses, and of course those who prefer those criteria would love them, those who don't plainly wont. I think a major stumbling block for some is understanding that some people's needs may be different from their own, but that's not my thing to fix.

Trying to point out the inherent limitations of lens on this forum sometimes is like trying to explain to someone why their two-seater sports car is not the ideal vehicle to transport a ton of construction sand lol!

Let's just pretend that the subject of this thread, the Optical Limits review (did we forget about that) doesn't exist, and what it says doesn't matter, sounds like a great approach!!! Wow!

I can't imagine your avatar using emojis.

 

[neuroanatomist]

Not what I was talking about, I was discussing objective and measurable values from test results as a measure of poor, good, excellent, etc, a topic you brought up mind you!

Ok, then. Let's discuss the Optical Limits review of the Canon EF 50mm f/1.2L. Wide open and even closed 1-2 stops, the corner resolution remains below 1500 lp/mm. It falls in the MTF50 range that Optical Limits categorizes as poor (for the 5DII tests). By comparison, the EF 50mm f/1.8 II, a lens costing less than 1/10 of the 50/1.2, resolves >2300 lp/mm ('fair' MTF50) in the wide open corners.

By your logic, which you stated as a 'fact' for the RF 16/2.8, the EF 50mm f/1.2 L is a not a good lens.

Trying to point out the inherent limitations of lens on this forum sometimes is like trying to explain to someone why their two-seater sports car is not the ideal vehicle to transport a ton of construction sand lol!

That's obvious, but has no real relationship to your statement that launched this tangent. As linked above, you stated, "Fact is, the RF 16mm f/2.8 is not a good lens..." To extend your above analogy, you are claiming that a two-seater sports car is not a good car.

My point was and remains that a statement like 'the RF 16mm f/2.8 is not a good lens' is a value judgement. Apparently you'd rather just pretend that such a statement doesn't exist. Unfortunately for you, the internet doesn't forget.

 

[LogicExtremist]

I can't imagine your avatar using emojis.

Did Vulcans use emojis, who knows!

 

[LogicExtremist]

Ok, then. Let's discuss the Optical Limits review of the Canon EF 50mm f/1.2L. Wide open and even closed 1-2 stops, the corner resolution remains below 1500 lp/mm. It falls in the MTF50 range that Optical Limits categorizes as poor (for the 5DII tests). By comparison, the EF 50mm f/1.8 II, a lens costing less than 1/10 of the 50/1.2, resolves >2300 lp/mm ('fair' MTF50) in the wide open corners.

By your logic, which you stated as a 'fact' for the RF 16/2.8, the EF 50mm f/1.2 L is a not a good lens.


That's obvious, but has no real relationship to your statement that launched this tangent. As linked above, you stated, "Fact is, the RF 16mm f/2.8 is not a good lens..." To extend your above analogy, you are claiming that a two-seater sports car is not a good car.

My point was and remains that a statement like 'the RF 16mm f/2.8 is not a good lens' is a value judgement. Apparently you'd rather just pretend that such an asinine statement doesn't exist. Unfortunately for you, the internet doesn't forget.

If you can't see that the RF 16mm f/2.8 is not a very good lens, and has considerable limitations, and the overall opinions of the review sites out there seem to tally up, then there's not much I can do about that, and there's no need to either!

Perhaps you can tell me which UW prime is the worst that Canon has ever produced for their digital full-frame cameras, and where the RF 16mm f/2.8 ranks in that list of those lenses? Is it in the top 5? Perhaps top 3? Is it number 1? I'll defer this matter to those you have much more experience than me, and I'm curious as to what the answer might be. Can this site do a poll perhaps?

 

[AlanF]

If you can't see that the RF 16mm f/2.8 is not a very good lens, and has considerable limitations, and the overall opinions of the review sites out there seem to tally up, then there's not much I can do about that, and there's no need to either!

Perhaps you can tell me which UW prime is the worst that Canon has ever produced for their digital full-frame cameras, and where the RF 16mm f/2.8 ranks in that list of those lenses? Is it in the top 5? Perhaps top 3? Is it number 1? I'll defer this matter to those you have much more experience than me, and I'm curious as to what the answer might be. Can this site do a poll perhaps?

For chrissake give up. Loads of happy users have posted here. If you don't like the lens then don't buy it but stop this tedious dissing of those who do.

 

[neuroanatomist]

Perhaps you can tell me which UW prime is the worst that Canon has ever produced for their digital full-frame cameras, and where the RF 16mm f/2.8 ranks in that list of those lenses? Is it in the top 5? Perhaps top 3? Is it number 1? I'll defer this matter to those you have much more experience than me, and I'm curious as to what the answer might be. Can this site do a poll perhaps?

Here is the list of ultrawide prime lenses that Canon has launched since the release of their first FF digital camera (the 1Ds) in 2002:

• EF 14mm f/2.8L II USM (2007)
• RF 16mm f/2.8 STM (2021)

It's a short list, but the RF 16/2.8 ranks in the top 2.

Do you think it's fair to compare an L lens costing $2100 with a consumer-grade lens costing $300? Well, just for fun let's check out DxO's measurements, throwing in a Zeiss 15/2.8 (a 2012 lens that launched at nearly $3000) for kicks:



Now, DxOMark's Scores are bogus (because they're based as much on the sensor as the lens) but their measurements (Metric Scores) are robust and generally reliable. Looking at those, the RF 16/2.8 is better than the 14/2.8L II on sharpness and transmission, matching the Zeiss lens costing 10x as much.

Bryan/TDP's ISO 12233-type testing (with the caveat that it's n=1 lens copies) shows that the RF 16/2.8 and the EF 14/2.8L II are pretty similar, with the 16/2.8 having a slight edge on center sharpness.

Canon RF 16mm F2.8 STM Lens Image Quality

View the image quality delivered by the Canon RF 16mm F2.8 STM Lens using ISO 12233 Resolution Chart lab test results. Compare the image quality of this lens with other lenses.

www.the-digital-picture.com

I'm guessing these comparisons do not align with your intended point, maybe you'll pretend they doesn't exist – you seem to be pretty good at that!

 

[Johnw]

I think a major stumbling block for some is understanding that some people's needs may be different from their own

Oh yeah, I agree completely.

 

[LogicExtremist]

For chrissake give up. Loads of happy users have posted here. If you don't like the lens then don't buy it but stop this tedious dissing of those who do.

Alan, I'm not dissing people, just the shoddy logic and reasoning used to justify or downplay the shortcomings of a lens.

I've already mentioned many times that there can be no argument against anyone stating that they like a lens, that's a statement of fact about a personal preference, and I respect people's likes and dislikes. If someone says they dislike a lens I own, I'm curious and ask why? That can only help me learn more about my lens. I won't personalise it, defend Canon, or deny the limitations and shortcomings of the lens. What would that achieve?

Similarly, I have no problems with cheap lenses that have shortcomings, I like my RF 50mm f/1.8 'nifty fifty' for what it is. I've have detailed its limitations and strengths in an example to illustrate that by knowing this information, we can play to the lens's strength. I've stated that if a cheap lens suits my needs, I'd buy it, and if it doesn't, as in this case, I won't.

When people downplay or deny the limitations of a lens, it may help assuage an owner's feeling if they're feeling a tinge of buyer's remorse, but is generally unhelpful for people making buying decisions, and for those who own it to enable them to get the best out of their RF 16mm.

I suppose some people come to forums to learn things, while others may possibly come to them to validate preconceived notions, beliefs and feelings, which may or may not be valid. Perhaps missing that point is the mistake on my part, as I'm only interested in the latter, and my flaw in reasoning is that others come here for the same reason I do, which would be a logical fallacy...

 

[LogicExtremist]

Here is the list of ultrawide prime lenses that Canon has launched since the release of their first FF digital camera (the 1Ds) in 2002:

• EF 14mm f/2.8L II USM (2007)
• RF 16mm f/2.8 STM (2021)

It's a short list, but the RF 16/2.8 ranks in the top 2.

Do you think it's fair to compare an L lens costing $2100 with a consumer-grade lens costing $300? Well, just for fun let's check out DxO's measurements, throwing in a Zeiss 15/2.8 (a 2012 lens that launched at nearly $3000) for kicks:

View attachment 205726

Now, DxOMark's Scores are bogus (because they're based as much on the sensor as the lens) but their measurements (Metric Scores) are robust and generally reliable. Looking at those, the RF 16/2.8 is better than the 14/2.8L II on sharpness and transmission, matching the Zeiss lens costing 10x as much.

Bryan/TDP's ISO 12233-type testing (with the caveat that it's n=1 lens copies) shows that the RF 16/2.8 and the EF 14/2.8L II are pretty similar, with the 16/2.8 having a slight edge on center sharpness.

Canon RF 16mm F2.8 STM Lens Image Quality

View the image quality delivered by the Canon RF 16mm F2.8 STM Lens using ISO 12233 Resolution Chart lab test results. Compare the image quality of this lens with other lenses.

www.the-digital-picture.com

I'm guessing these comparisons do not align with your intended point, maybe you'll pretend they doesn't exist – you seem to be pretty good at that!

No neuro, despite your gratuitous ad-hominem attack at the end (couldn't help yourself could you lol!) this is EXACTLY what I was asking for, so thanks for supplying this useful information.

This clearly points out what the reviews all stated, that a 16mm prime is a very niche lens, even amongst UWs, and that focal length on a crop sensor providing 25.6mm equivalent makes for a more useful 24mm focal length substitute.

The fact that only three UW primes around this focal length have been released in the last 20 years, with one from a third party both highlights Canon's reading of the market and the very niche nature of the prime focal length, which has been expanded with the need for lightweight vlogging lenses, which may have been the impetus to release the RF 16mm, and maybe their need for lightweight lenses on the RF-S platform if they've been planning on dropping the M-series. An R10 with a RF 16mm f/2.8 is a lightweight 24mm equiv travel/hiking setup that crops away the less sharp periphery.

These three lenses sit so far apart in their market tiers and prices that a like-for-like comparison is not really possible, but as we see, the cheaper RF lens is the worst in class, with:

• almost 10x more distortion (4.7% vs 0.4% and 0.5%)
• around 2x more vignetting (-3.8EV vs -2Ev or -2.1EV)
• over 1.5x more chromatic aberration (27um vs 16um or 7um)

So, it looks like nobody has really cared much about this class of lenses, the pickings are slim, and Canon's doing the marketing thing creating demand while playing catchup in growing vlogging market that boosted their sales of high-end compacts and then the M50 I and II series APSC bodies, a demographic of mainly younger people, and a market that Sony is all over now with dedicated cameras and lenses for this specific video genre.

Looking back at the Optical Limits review, we see that the limitations are constantly raised, offset against the consideration of price.

Distortion:
"...The lens produces a native barrel distortion of almost 10%! This is excessive, making it basically unsuitable for use without digital correction. The latter does an excellent job by reducing the issue to essentially zero. While this is commendable, there is a price to pay for this because the image is stretched substantially, thus reducing resolution in the outer image field."

Vignetting:
"...The vignetting is still heavy at f/2.8 but not terrible when stopped down, considering the ultra-wide nature of the lens. With full correction enabled, the results are quite good even at f/2.8 because the light falloff is very gradual from the center to the corners. Needless to say but the signal boost comes at the cost of increased image noise in the outer image field."

MTF (resolution) at 45 megapixels (EOS R5):
"...The Canon RF 16mm f/2.8 STM is just not designed for being used without correction. The resolution characteristic is fairly predictable from here. The broader center quality has no issues whatsoever. The lens is tack sharp here, especially when stopped down a little bit. The borders and corners are an entirely different story, though. The borders are Okayish at f/2.8, but the corners are a pixel soup at this setting. Stopping down lifts the borders to reasonable levels, but the corner softness improves only marginally. This is all a bit tragic because, unsurprisingly, the lens appears to be much sharper without distortion correction."

MTF (resolution) at 30 megapixels (EOS R):
"...As you can see below, the general theme remains similar - although the reduced megapixels are boosting the outer image quality (on pixel level) quite a bit. While there's still some softness at f/2.8, the results are actually decent at medium aperture settings."

The verdict sums it up perfectly - "...The Canon RF 16mm f/2.8 STM is a lens with many facets. It comes down to where you come from and what you want."

"...From a technical standpoint, the RF 16mm f/2.8 STM offers poor quality on a high megapixel camera. The broader center is perfectly sharp but the quality is falling apart in the corners. And that's with auto-correction. The lens is basically unusable in pure RAW mode with excessive barrel distortion, extreme vignetting and high lateral CAs. It's about as underdesigned as it gets and relies heavily on digital correction to lift it back from the imaging abyss."

Optical Quality: 1.5/5 stars (@45 megapixel)
Optical Quality: 2.5/5 stars (@30 megapixel)
Mechanical Quality: 3.5/5 stars
Price/Performance: 5/5 stars

from: https://www.opticallimits.com/canon_eos_ff/1136-canonrf16f28


Who is this lens for?

"All and all, the RF 16mm F2.8 STM is easy to recommend to Canon R system owners who want to add a wide angle to the mix. It's a strong option for hobbyists getting started with an EOS RP, and more serious shutterbugs with an R6 or R5 can look to it as a lightweight option for travel and walks about town."

Canon RF 16mm F2.8 STM

A slim, affordable prime with a wide angle view

au.pcmag.com

"Buy it if...
You’re on a budget
There's no doubt about it – at this price, this is a bargain for a capable, full-frame-ready lens. You won't do better than this in the RF system at this price point.

You like to hike to your photographic locations
Thanks to its 165g weight, you’ll barely know this lens is on your camera or in your bag. On long landscape trips, that's a big advantage over alternative lenses.

You like to go wide
This lens' 16mm view is a very practical, go-anywhere focal length and also handy for video, too.

Don't buy it if...
You don’t like image editing
It's by no means bad, but this lens' image quality is nonetheless a good example of the compromises you make when you shop at this end of the lens market.

You don’t like moving your feet
Feeling a bit lazy? Buy something that zooms, like the RF 15-35mm f/2.8L IS USM, or the rather cheaper and wider RF 14-35mm f/4L IS USM."

Canon RF 16mm f/2.8 STM review

Basically weightless, ultra-wide and very practical

www.techradar.com

The limitations are stated time and again in every review, and the point is made that these compromises are expected in a lens of this price.
No, it's not a good lens technically or optically, as the reviews all clearly indicate.
Is it a lens worth buying? The reviews say yes, what it offers for the price is great, and it may be the lens for you, as the Optical Limits review, the subject of this thread states, " It comes down to where you come from and what you want", and that's the critical decision-making factor for potential buyers.

Are we really arguing against less-than favorable or mixed praise-criticism product reviews? I can't see what we're actually arguing here. Liking a lens and finding it works well for a person's needs doesn't invalidate the review test results, or tell us anything much about the lens, it just indicates that the lens's limitations don't significantly impact the person's intended use. Hooray!

 

[AlanF]

Alan, I'm not dissing people, just the shoddy logic and reasoning used to justify or downplay the shortcomings of a lens.
..
I suppose some people come to forums to learn things, while others may possibly come to them to validate preconceived notions, beliefs and feelings, which may or may not be valid. Perhaps missing that point is the mistake on my part, as I'm only interested in the latter, and my flaw in reasoning is that others come here for the same reason I do, which would be a logical fallacy...

You have fallen into your own trap. You are trying to justify your preconceived notions about not buying a lens of which it appears you do not have deep hands-on experience. The logical facts are that the pros of the lens outweigh the cons to the extent that enough people enjoy it and find it very convenient and affordable, and that's all that matters. By rabbiting on and on to prove it's not a good lens, you are dissing their judgement and possessions. If you don't realise that, then you need to add some EQ to your IQ.

If you can't see that the RF 16mm f/2.8 is not a very good lens, and has considerable limitations, and the overall opinions of the review sites out there seem to tally up, then there's not much I can do about that, and there's no need to either!

 

[LogicExtremist]

You have fallen into your own trap. You are trying to justify your preconceived notions about not buying a lens of which it appears you do not have deep hands-on experience. The logical facts are that the pros of the lens outweigh the cons to the extent that enough people enjoy it and find it very convenient and affordable, and that's all that matters. By rabbiting on and on to prove it's the worst lens out there, you are dissing them. If you don't realise that, then you need to add some EQ to your IQ.

I already own the RF 35mm f/1.8 and the Rf 50mm f/1.8, and reviews place the 35mm above the 50mm in IQ. In this series of lenses, the RF 85mm f/2 is rated as having the highest IQ, with the RF 16mm f/2.8 having the lowest. The 50mm is borderline for my uses, so the 16mm won't cut it and I don't have a use for a 16mm prime anyway, which is why I won't buy it.

To respond to your statement, I don't need to justify any preconceived notions about not buying a lens, that wouldn't make sense. If that were the case, I would need to a fuss about why I don't need every other RF lens that I have no use for. From a pragmatic perspective, I either need a lens or I don't, case closed.

You're correct in what you said but missed the most critical element - "The pros of any lens outweigh the cons to the extent that enough people enjoy it and find it very convenient and affordable, and it meets their photography needs, and that's all that matters. " There, I fixed it! Totally agree.

I'm not dissing people's choices, I would never do that. I've only been pointing out where the objective results of the review are being disputed by emotional arguments.

People are getting worked up emotionally by mistakenly thinking it's a zero-sum game here, that they can't enjoy a lens AND acknowledge the inherent limitations of the design that are dictated by the laws of physics. That's how it is for every other lens, always has been and always will be.

As we can all surmise, the 'best' or 'worst' ranking of anything bears no relation in reality to whether a particular product performs sufficiently, it just indicates a relative position in comparison to other items in a group. The RP is the lowest ranked Canon full frame, but that doesn't make it bad. The RF 600 and 800 f/11 lenses arguably rank lowest amongst Canon's supertelephoto lineup, but that doesn't make them bad either. Most can agree that APSC kit lenses, especially the old ones, can be regarded as bad because of various measurable deficiencies.

Whether something is good or bad depends on its own attributed relative to some defined standard of quality, which all objective optical tests have, and performance against specific tasks or functions. I intentionally raised the idea of ranking the worst UW prime lenses, because I realise that people DO make value judgements about such labels, and it got the emotional reaction I was expecting. That mindset is what drives 'gear snobs' on other forums, but there still seems to be an emotional stigma around the idea of owning the worst lens in a product range, even if it is sufficient for its purpose, and people are happy with it.

We humans are driven as much by emotion as by reason, otherwise marketing hype, which is designed to manipulate emotions, wouldn't work, and a plain spec sheet would be more than enough to motivate buyers! You mentioned EQ earlier. If I'm unintentionally short-circuiting people's validation that they obtain by immersing themselves in communities with predominately similar opinions that reinforce the ideas they already hold, then my apologies, that was not my intention.

 

[neuroanatomist]

Are we really arguing against less-than favorable or mixed praise-criticism product reviews? I can't see what we're actually arguing here.

I’m honestly not sure what you’re arguing about. Nor am I sure why you feel the need to copy/paste large swaths of text from sources that were previously linked. It reminds me of people who try to win an argument with verbal diarrhea, not letting others get a word in edgewise. Except that tactic doesn’t work well online (unless your goal is just to have people ignore your bloated posts).

As to what I’m arguing about, as I’ve said very clearly and several times now, it is your statement, “Fact is, the RF 16/2.8 is not a good lens.” That’s not a fact, it’s your personal value judgement on the lens as a whole. There is nothing objective or factual about it.

“Testing has shown the RF 16/2.8 has poor corner sharpness.” Objective statement, fact.

“The RF 16/2.8 has high levels of barrel distortion, and the required correction of that distortion has a deleterious effect on image quality.” Objective statement, fact.

“The RF 16/2.8 is a bad lens.” Value judgement, not fact.

Every time I have quoted your statement of the third example, you’ve responded with (excessively lengthy) arguments similar to the first two examples.

Perhaps if I frame the discussion in a different, completely hypothetical context. I've looked over LEroy's portfolio of images, and I have the following comments:

"The colors in his image of Ayers Rock are oversaturated."​

"The shutter speeds he used for the surfers at Lennox Point are too slow to freeze their motion."​

"Fact is, LEroy is not a good photographer."​

I can repeat the first two points with multiple posts and thousands of words of text, but my statement about LEroy's photography remains a value judgement, not an objective fact.

You have repeatedly ignored the point I raised. You can continue to pretend that my point does not exist, or you can finally acknowledge that your statement was your personal value judgment, not a fact as you originally labeled it. Either way, I see no point in discussing this issue further.

 

[Johnw]

the shoddy logic and reasoning used

Your projector might need a lens change, just fyi, the picture is coming across a bit distorted.