24-70mm vs. 16-35mm Canon Lens

[Alis]

Quick question: How does 24mm on a lens like Canon 24-70mm L f/2.8 compare to the same focal length on an UWA lens, like Canon 16-35mm L f/2.8 lens, in terms of perspective and distortion you get?

[Dave Humphries]

Hi Sedali,

I'd expect perspective to be identical, as it's related to angle of view/focal length, but distortion might be better as it'll be mid range, rather than at an extreme.

Colin will hopefully give you something more precise with his experience a little later.

Cheers,

[Colin Southern]

Quick question: How does 24mm on a lens like Canon 24-70mm L f/2.8 compare to the same focal length on an UWA lens, like Canon 16-35mm L f/2.8 lens, in terms of perspective and distortion you get?

Hi Sedali,

I'm not sure I understand the question fully, but field of view is the same (which is possibly what you're asking?)

Perspective distortion is a function of how close you are to the subject, not the lens; wide-angle lenses let you get closer and thus allow more perspective distortion, but if you're comparing the two lenses at the same focal length then you won't see any difference there.

The two lenses will be subject to other optical characteristics ("Distortions"), but these are relatively minor, and not something you're likely to notice.

Does this help?

[Alis]

Thanks, Dave and Colin,

wide-angle lenses let you get closer and thus allow more perspective distortion,

I think this is the part I don't understand. What What is different between these two specific lenses that you can get closer with a UWA lens?

This original question was something some asked me when he saw me with both lenses and I did not know the answer to it. Then I realized I don't know what makes the UWA lens unique and different from the 24-70mm. Here my question is just about two lenses that Canon makes. At the same focal length, is there any differnece between the two? From your answer, Colin, I take it that there is no difference. Sort of...

[Colin Southern]

Thanks, Dave and Colin,



I think this is the part I don't understand. What What is different between these two specific lenses that you can get closer with a UWA lens?

Specifically, the 16 to 23mm bit

It's not so much the fact that it's a UWA lens as it is the fact that it's an ultra-wide angle. Set both to 24mm and they'll be the same - the difference is that the 24-70 can't go any wider and thus can't "enjoy" the characteristics of those wider widths.

Try setting yours to 16mm and see how close you have to get to something like writing in a book before it starts to look big (just be sure to have your UV filter on the lens because you'll end up only a few mm away).

[_GUI_]

Colin, I find the 24-70 to have a quite noticeable distortion, even on my APS-C camera, so it is even worse on a FF body.

My Canon 10-22 is far better geometrically corrected than the 24-70, which I think was never intended to be a very low geometrical distortion but designed to focus on other characteristics.

BR

[William W]

Hmm,

On other fora these types of questions can get quite volatile, [ can't they CS? ]

. . .

So, in the spirit of true camaraderie, I offer a few thoughts for you guys and gals to ponder . . .

Firstly, Perspective is determined by the Camera's Viewpoint - specifically the distance from the FOCAL PLANE to the SUBJECT (SD = Subject Distance). Camera Elevation also is a consideration. Also the Subject’s Placement relative to the: Foreground; Middle-ground; and Background have an optical effect.

The VIEW or Angle of View, is decided by the Focal length of the Lens, in concert with the Camera’s Format / Film Size.

What I mean is: the Focal Length of the lens does not affect “Perspective” - ask any Cinematographer – they will choose the Camera Viewpoint to determine the Perspective and then choose the FL / Lens to create the View required.


***

What I believe has happened, and in many areas, is that the Technical lexicon has taken on other more broad-ranging meanings (which often leads to heated debate), but nonetheless, is still IMO, additive to confusion – especially when we converse by the written word, (as here), I believe definitions (especially Technical Words) are still very important.


***


When we have a wide angle lens (like a 14mm on an APS-C body – Canon 20D or Nikon D80 // or a 24mm lens on a 135 format – Canon 5D), we can create a specific visual effect as we move in close to the (human) subject. We can also cerate a specific visual effect by looking up at or down upon the (human) subject.

The effect of the nearer anatomy appearing bigger than “real life” is an aspect of using that wide angle lens, – the opposite visual aspect is to use a telephoto lens.

If we imagine an head and shoulders shot, using a Canon 5D, a 200mm lens will give a “Flat” or “Compressed” view of the face, but, if we move up closer with a 24mm lens, we can create, sometimes very funny effects – this is a particular type of effect, is encompassed by the technical term: “Foreshortening”. And the effect can be exacerbated with any barrel distortion the Wide Lens might exhibit.

Foreshortening can make Subjects look quite strange, especially, as one example - when a Young Child is photographed with a wide angle lens, by an Adult standing over the child, looking up – the Child will have a really big head and little tiny feet and not much body at all.

Quite often and, frankly more-so the last four years, I have noticed that in the High School classes with which I have contact, refer the “Perspective” as related to the FL of the lens – and thus the phrase “Perspective Distortion” has crept into the classroom, and the lexicon.

I don’t wish to debate a point of right and wrong – I just want to clarify what we are discussing and what we are meaning – because, as I have seen recently happen, at a visit to Fox Studios where the Director of Photography was giving some instruction and explaining a sequence of shots to some of the 16 / 17 year old students: not only were some of the students slightly confused, but two in particular, were quite embarrassed when substantially told in very colourful and theatrical language “the value of their wiki-learning” (direct quote – expletives removed).

So my approach now is to explain what I am / we are discussing.

I have also adopted the term “Perspective Distortion”, to refer to that special type of “Foreshortening” - and, in my dealings with other Photographers, including Experienced Architectural folk, (who tend to be clinical, BTW, they too are comfortable with that intercourse and the use of the words and the more generalized meanings.

However, I still play a straight bat, and use the word “Perspective” correctly, and refer to “Distortions” as Lens and Optical matters, when I am around the old School Directors of Photography – or when setting questions and marking exam papers.

***

To the lenses: 16 – 35 and 24 – 70.

I would argue that the 24 – 70 might have more distortion at 24mm than the 16 to 35 has at that same FL.

This is a theoretical point, and based upon the facts of lens design, not a practical test I have done. I have used a 24 – 70 very little and I do not own one. I would expect that if my suspicion is correct, it would be apparent when the lenses were A/B tested, both at F2.8

– Colin have you done an A/B with both lenses at 24mm / F2.8 on a FF Camera?

Secondly, note that there are two versions of the 16 to 35, and IMO the EF16 to35F2.8L MkII USM does have improvements relative to Distortion which I can see (I am not a lab rat) – and I do really use my lenses, usually wide open or near to . . . so my comments should be taken with that in mind.

Thirdly, if one has a passion for the trilogy of the F2.8L zooms (as I do), then one should consider the leverage of a dual format DSLR system, either: APS-C + 135 format or APS-H + 135 format.

Thinking this way, often the 24 – 70L becomes an un-necessary lens, as it has thus far, for me and my needs.

WW

[Colin Southern]

– Colin have you done an A/B with both lenses at 24mm / F2.8 on a FF Camera?

The latest about 10 minutes ago ... Coming up





Couple of notes ...

- Slight difference in exposure as we've got a bit of wind and a few clouds dancing about today

- No PP

- One is @ 25mm - had to guess as to the exact position of the zoom.

Be interested to hear any comments

[William W]

Hi Colin,

It is a tough call at a low res.

But IMO the bottom image is crisper - and I truely decided that before I looked at the EXIF data.

What is your opnion on viewing the Hi Res images?

regards,

Bill

[Colin Southern]

Hi Colin,

It is a tough call at a low res.

But IMO the bottom image is crisper - and I truely decided that before I looked at the EXIF data.

What is your opnion on viewing the Hi Res images?

regards,

Bill

Hi Bill,

Here's a couple of 400pixel (ish) 100% crops - only processing is capture sharpening (which I should have done for the first two, but forgot) - both saved at JPEG quallity = 12 (first 2 were at 9 which might account for some of the degradation).

At this end I'm seeing small contrast differences, but that's about it - to be honest, I don't even know which image is which out of these two.

[Bill44]

Well, to old eagle eye with his bi-focals I would have to say the the bottom photo is a poofteenth (note the highly technical term) sharper, at the cost of what may, or may not, be a couple of spots of CA on the right hand side of some of the houses.

However, considering the extreme pixel peeping dimensions, in reality the difference is 4/5 of bugger all. (another of those technical terms)

[Colin Southern]

Perhaps we could devise a new testing standard ... we could defing the difference in terms of the magnification needed to detect the difference when holding a magnifying glass in front of that portion of a 22 x 33" print!

Seriously, there could well be differences in "distortion" and sharpness etc between the two, but the point I was trying to make is that with L-Series optics they're really relegated to the "lab rat" realm - not anything that's significant in real-world shooting (well my type of shooting in anycase).

So I stand by my original opinion that a 16-35/2.8L @ 24 and a 24-70/2.8L @ 24 are pretty "much of a muchness" for all intents and purposes.

[Colin Southern]

IMO the above "Two Bill" technical analyses proves beyond any doubt that the 16 to 35 is sharper wide open at 24mm than the 24 to 70. . . but the 16 to 35 it has a little more CA.

I bet two-bob, Colin has the original 16 to 35 - the CA is fixed up a bit in the MkII.

WW (The other Bill)

I thought that two Bills cancelled each other out?

Seriously (for just a moment!) - for real-world work - I put the sharpness and CA performance of both in the "more than adequate" category - keeping in mind that any CA could almost certainly be improved in ACR (I just checked that AWB had chosen the same colour temp then clicked right through it with ZERO adjustments).

[William W]

Seriously (for just a moment!) - for real-world work - I put the sharpness and CA performance of both in the "more than adequate" category

Yes, I agree.



But Colin? . . . I have had a really close look - and you did not shoot these at F2.8, did you ?

So, what I believe is see, is that the 16 to 35 is "a bit crisper" - but at F11?

Note: that is why I deleted my last posting. . . .


You know I am an available light freak - anything stopped down more than F2.8 is way toooooo slow - hey, that's why I only own two zooms (see above, my logic)

WW

[Bill44]

Seriously, there could well be differences in "distortion" and sharpness etc between the two, but the point I was trying to make is that with L-Series optics they're really relegated to the "lab rat" realm - not anything that's significant in real-world shooting (well my type of shooting in anycase).

So I stand by my original opinion that a 16-35/2.8L @ 24 and a 24-70/2.8L @ 24 are pretty "much of a muchness" for all intents and purposes.

I totally agree, as my highly technical in depth analysis and report showed.

I would be proud to have either lens in my kit if I was ever corrupted enough to return to being a Canon (wash my mouth out) shooter.

[Colin Southern]

Hi Bill W,

I'm not sure I follow your thoughts on this one ...

The original question was along the lines of "how does a 16-35/2.8L @ 24mm compare to a 24-70/2.8L @24mm" - to which my opinion was "for all intents and purposes they're the same" (not sure if a landscape context was intended, but that's what I primarily do so that's the one I picked and ran with) ...

... so in a landscape-shooting scenario, F11 would be quite typical - and I'd like to think that (with all kidding aside) that overall geometry related distortions appear to be similar/neglegible (per the complete FF shots), and sharpness/CA etc also appears to be the same (per the 100% crops). Not sure what shooting at F2.8 would achieve in a landscape scenario; serving only to introduce OOF areas in the periphery due to the narrow DoF.

Or put another way - based on what I've shown here, if I needed to take a shot at 24mm and someone said "which is the best lens for the job" my answer would probably be either "toss a coin" or "whatever happens to be on the camera at the time" - I can't say I've seen anything here that would lead me to favour one over the other, with both being more than up to the task.

Have I missed something somewhere?

[William W]

Hi,

So here is how we do it tough, down under . . . a 24 wide open at F1.4 on a 5D, 1/8s, ISO1600 - HH - I can't afford a tripod either



WW

[Colin Southern]

*** Sigh *** I must get over that way again sometime with my camera!

[William W]

Hi Bill W,

I'm not sure I follow your thoughts on this one ... Have I missed something somewhere?

Hi Colin,

No you missed nothing at all. You love your landscapes, and I love my low light capture . . . I have fast lenses you have fast lenses too, but you use them differently to me (usually).


I think all that happened is I read the question:

“How does 24mm on a lens like Canon 24-70mm L f/2.8 compare to the same focal length on an UWA lens, like Canon 16-35mm L f/2.8 lens, in terms of perspective and distortion you get?”

And I immediately think: “gee, I bet the 16 to 35 is sharper wide open at 24mm” – because I use mine at F2.8 a lot . . . (that is when I am being lazy and not using a Prime - I guess I gotta use a zoom occasionally).

Whereas you most likely think – “well I shot the Lake with the 24 to70 and I shot that Gorge with the 16 to 35, and there is only 4/5ths of bugger all in it.” – but you would have been using the middle apertures.

One of my reasons for jumping in, was, in all seriousness, as an effort to “balance” the view / assumption that yes essentially WA lenses (generally both zooms and Primes) are bought to be used for Landscape, and similar capture. And that means they are generally / most frequently used at F 5.6 through to F11.

My balance to the forum was to show that there are uses for all the three variants of the Canon F2.8L zooms to be used at F2.8 – including the 16 to 35 zoom. . . and to answer the question fully we should look at distortion variations between the two lenses in question, at F2.8, for the times when that speed is required.

***

My post above (Woolloomooloo Wharf) was in jest – obviously I am proud of the shot because I could pull 1/8s hand held - and I bloody needed all of F1.4 to do that – if I were serious about it I would have dragged the tripod out – yes I do own one – somewhere –

***

Does that explain my posts better?

Cheers,

WW

[Colin Southern]

Does that explain my posts better?

For sure

Out of interest, I'll try the same test at F2.8 at some stage (it's cold & windy outside right now - and my pizza is ready to pick up - so I'm not going to do it right now!).