# Say What? The 5DS, f/11 and Confusing Circles



## Canon Rumors Guy (Apr 20, 2015)

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I enjoy reading things that make my head hurt, it usually means I’m learning something. Roger at <a href="http://www.lensrentals.com" target="_blank">LensRentals.com</a> is always good at it, I’m now going to have to pay attention to Alex Cooke at F-Stoppers. He has written a great article about diffraction the how it pertains to the resolution of the upcoming Canon EOS 5DS and EOS 5DS R.</p>
<p>From Alex:</p>
<blockquote><p>On a 5D Mark III, the size of the Airy Disk begins to exceed the size of the circle of confusion just after f/11. This means the 5D Mark III reaches its <strong>diffraction limit</strong> at that point, the point at which diffraction begins to become visible when viewing an image at 100% at a typical viewing distance. This is different from the <strong>diffraction cutoff frequency</strong>, the point at which airy disks completely merge and no amount of stopping down will improve resolution. Think of the space between the diffraction limit and the cutoff frequency as the space of diminishing returns. On the other hand, the 5DS reaches its diffraction limit just before f/8, slightly over a full stop sooner than the 5D Mark III. This might have landscape photographers and those who rely on having a large depth of field worried.</p></blockquote>
<p><strong><a href="https://fstoppers.com/education/5ds-f11-and-confusing-circles-68177" target="_blank">Read the full story</a> | Canon EOS 5DS $3699: <a href="http://adorama.evyy.net/c/60085/51926/1036?u=http://www.adorama.com/results/canonnewfeb" target="_blank">Adorama</a> | <a href="http://www.bhphotovideo.com/c/product/1119026-REG/canon_0581c002_eos_5ds_dslr_camera.html/BI/2466/KBID/3296" target="_blank">B&H Photo</a> | <a href="http://www.amazon.com/gp/product/B00T3ERPT8/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00T3ERPT8&linkCode=as2&tag=canorumo-20&linkId=C3LAZKJCU4IRBJUF" target="_blank">Amazon</a></strong></p>
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## dolina (Apr 20, 2015)

So this will make the camera lousy for landscapes? Can you do landscapes at f/11? I normally shoot wide open unless I am panning or want "to be there".


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## NancyP (Apr 20, 2015)

Naah. Those that don't have the TS-E 24 will want one. I want one.


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## quod (Apr 20, 2015)

dolina said:


> So this will make the camera lousy for landscapes? Can you do landscapes at f/11? I normally shoot wide open unless I am panning or want "to be there".


Landscapes on full-frame and APS--C are generally shot from f/8 to f/16. It looks like 5DS folks will need to work on their focus stacking technique.


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## TeT (Apr 20, 2015)

quod said:


> dolina said:
> 
> 
> > So this will make the camera lousy for landscapes? Can you do landscapes at f/11? I normally shoot wide open unless I am panning or want "to be there".
> ...



read the article ppl... your comments make it obvious that you did not...


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## mb66energy (Apr 20, 2015)

quod said:


> dolina said:
> 
> 
> > So this will make the camera lousy for landscapes? Can you do landscapes at f/11? I normally shoot wide open unless I am panning or want "to be there".
> ...



One more reason I bought two second hand 5D classic. A very limited but capable camera - if you learn to master it. Still learning.
Another reason: The lenses I own are good but might resolve 20 MPix with 5Ds(R) bodies - while resolving 11-12 MPix on the 5D classic.
Third reason: I like to shoot with two identical bodies with two lenses, e.g. 2.8 24 and 2.0 100 or 2.8 100 Macro and 5.6 400. The price of 5Ds made it 7 times more expensive and 7.2 Euro is close to a Pentax 645Z with the 120mm Macro.
Fourth reason: Decision between 5Ds and 5DsR is not easy - at least for me.
Fifth reason: Need for IS or tripod. Just the 5D classic is very challenging compared to the little bit mushy IQ of 40D and 600D which hided camera shake.

But: The 5Ds(R) are shurely great cameras for those who go to the limits - e.g. with OTUS lenses or yet to be released Canon lenses ...


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## quod (Apr 20, 2015)

TeT said:


> quod said:
> 
> 
> > dolina said:
> ...


Perhaps you should read my response carefully, or better yet, answer it yourself. I stand by my response to the question presented.


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## candc (Apr 20, 2015)

another thing to consider is that the blurring from diffraction can it be sharpened in post with good results. motion blur, oof blur, etc. is more problematic.


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## msm (Apr 20, 2015)

I do not fully understand why resolution is said to be so important for landscape shooters. Having shot a A7R with 36mpixels for a year I find it quite hard to realize this resolution from corner to corner, I almost always end up with a trade off between foreground in focus, background in focus or diffraction. I usually choose the latter, a little diffraction blur sharpens up nicely in post. Lens curvature does not exactly help in this matter either.

Of course you can focus stack, but seeing as you also usually need to bracket it is more work than I bother. Stacking is also a process which can introduce ugly artefacts.

But all in all I think around 20mpix actually works great for landscape because I can usually use all this resolution while with higher resolutions I feel must often be downscaled to look good from corner to corner.


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## bedford (Apr 20, 2015)

I'm having difficulties understanding the reference to the aperture without any mention of the focal length. 

Based on my "gut understanding" of physics the amount of diffraction is a function of wavelength and the lenght-scale of the object at which diffraction takes place (this being also true for sound waves). 

So, when discussing this phenomenon in a meaningful way, the focal length should always be specified, as the diameter of the hole through which light has to pass is equal to focal-length divided by f-number.

Could someone with a more profound background in physics shed some light on the issue? ;-)

Oliver


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## scott_m (Apr 21, 2015)

bedford said:


> I'm having difficulties understanding the reference to the aperture without any mention of the focal length.
> 
> Based on my "gut understanding" of physics the amount of diffraction is a function of wavelength and the lenght-scale of the object at which diffraction takes place (this being also true for sound waves).
> 
> ...



Well I wouldn't go so far as to say "profound"  but yes you are quite correct. All other things being equal (and you know what *that* means) a larger aperture will out-resolve a smaller one, which is why astronomers build bigger telescopes - light-gathering power is only part of the equation. 

However... the Airy disk formula states resolution in terms of angular separation (useful for astronomy where everything is effectively at infinity) whereas for camera sensors it's a linear measurement (pixel spacing or line pairs per mm). The linear, rather than angular, diameter of the disk then depends on the focal length of the lens (trigonometry) so in this case, the focal length disappears from the formula and you end up back with the f-ratio. 

More detail here: http://en.wikipedia.org/wiki/Airy_disk

HTH,
Scott


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## sanj (Apr 21, 2015)

msm said:


> I do not fully understand why resolution is said to be so important for landscape shooters. Having shot a A7R with 36mpixels for a year I find it quite hard to realize this resolution from corner to corner, I almost always end up with a trade off between foreground in focus, background in focus or diffraction. I usually choose the latter, a little diffraction blur sharpens up nicely in post. Lens curvature does not exactly help in this matter either.
> 
> Of course you can focus stack, but seeing as you also usually need to bracket it is more work than I bother. Stacking is also a process which can introduce ugly artefacts.
> 
> But all in all I think around 20mpix actually works great for landscape because I can usually use all this resolution while with higher resolutions I feel must often be downscaled to look good from corner to corner.



i agree.


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## marcel (Apr 21, 2015)

mb66energy said:


> quod said:
> 
> 
> > dolina said:
> ...



I am using my 5d classic again. I think I've learned to appreciate how good the camera is. And is 10 years old....


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## Sporgon (Apr 21, 2015)

F/11 ? That's nothing. Wait until they start talking about the realities of using an f/1.2 or f/1.4 lens on a FF 50 mp sensor.


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## LDS (Apr 21, 2015)

scott_m said:


> More detail here: http://en.wikipedia.org/wiki/Airy_disk



Be aware that some semplifications in the formulaes are valid only within a given acceptable error. And spatial resolution depends on the distance of the subject (almost always infinity in astronomy, but not in photography), and also the sensor size.


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## Ivan Muller (Apr 21, 2015)

so what?

If you set focus of a FF 24mm lens at 2.4meters and f8, everything will be in focus from 1.17meters to infinity...

and at f5.6 everything will be in focus from 1.8m to infinity...

http://www.cambridgeincolour.com/tutorials/dof-calculator.htm

Its called Hyperfocal distance

And btw I regularly shoot at f22 etc and at A3/2 sizes even at 100% I have yet to be disappointed....and what if the image is just a touch less sharp?


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## charlesa (Apr 21, 2015)

I am confused... or not.


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## dolina (Apr 21, 2015)

For those who reserved what will you be using the 5DS or 5DS R for? Wildlife? Birds? Landscape? Studio?


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## 3kramd5 (Apr 22, 2015)

dolina said:


> So this will make the camera lousy for landscapes?



That has yet to be determined. I doubt it, but if it is lousy for landscapes, it is not because of its high resolution. Hitting the diffraction limit doesn't mean that suddenly your images go to garbage. A 50MP image shot past the diffraction limit will almost certainly outresolve a 20MP image shot wide open.


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## quod (Apr 22, 2015)

So, I should spend $4K on a body so that I hit the unglorious heights provided by hyperfocal focusing and diffraction? I can do this with my 5D3 and not spend an extra dime. If I spend $4K for a 50MP sensor, I am going to squeeze every little bit I can get out of that resolution. To each his own. I aspire for more.


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## Random Orbits (Apr 23, 2015)

quod said:


> So, I should spend $4K on a body so that I hit the unglorious heights provided by hyperfocal focusing and diffraction? I can do this with my 5D3 and not spend an extra dime. If I spend $4K for a 50MP sensor, I am going to squeeze every little bit I can get out of that resolution. To each his own. I aspire for more.



Diffraction is always there. Trading acceptable sharpness versus depth of field has always been the photographer's responsibility. Sometimes focus stacking can work, but other times it's preferable to use smaller apertures to extend the DOF.


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## quod (Apr 23, 2015)

Random Orbits said:


> Diffraction is always there. Trading acceptable sharpness versus depth of field has always been the photographer's responsibility. Sometimes focus stacking can work, but other times it's preferable to use smaller apertures to extend the DOF.


Another trick that I have used is my gigapan head, where I take shots (usually) at 135mm f/8 with the 70-200 f/2.8L II and mimic a wider field of view, so long as the compression does not detract from the shot. The detail is spectacular.


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## nc0b (Apr 26, 2015)

I find the hyperfocal markings to be too optimistic on my Zeiss 18mm Distagon lens from an "in focus" standpoint. I often zone focus that lens, but if I want the background to look sharp, I have to manually adjust the focus point as if I am shooting more wide open than the markings on the lens indicate.


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## chromophore (Apr 26, 2015)

The concern over the effects of diffraction for high resolution sensors is completely misplaced.

You don't lose sharpness to diffraction by increasing pixel density, because the size of the diffraction effect is strictly determined by the lens. To understand why, suppose you have two camera systems that are identical in every respect except that one has twice the linear pixel density than the other (i.e., every pixel in the low-resolution sensor is split into four pixels in a 2x2 arrangement in the high-resolution sensor). Ignoring the effect this has on noise (and noise on perceived resolution), it is true that, as an increasing function of f-number, the higher resolution sensor will be able to reveal the effect of diffraction sooner than the low-resolution sensor. But the reason for this is because the low-resolution sensor is unable to resolve that effect, not that the effect is stronger in the high-resolution sensor. The Airy disks are IDENTICAL in the two systems because the lens is identical.

Therefore, increasing sensor resolution does not confer any disadvantage with respect to diffraction. You always have something to gain, and you never do any worse than the low-resolution sensor. You might not gain as much as you theoretically could (i.e., a high-resolution sensor might not realize the full sharpness in the sharpest plane of focus at f/16 compared to when it is shot at with a near-ideal lens at f/2.8 ), but you won't do worse than a low-resolution sensor that couldn't SEE the diffraction at f/16 in the first place.

The hesitation to go with higher resolution because of fears of diffraction reveals a complete misunderstanding of the phenomenon. If you said "I don't want high resolution because I want better dynamic range," then I can be on board with that statement. But if you said "I don't want high resolution because I would be more severely diffraction-limited," I would tell you that you don't understand what you're talking about.


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## geekpower (Apr 29, 2015)

chromophore said:


> The concern over the effects of diffraction for high resolution sensors is completely misplaced.
> 
> You don't lose sharpness to diffraction by increasing pixel density, because the size of the diffraction effect is strictly determined by the lens. To understand why, suppose you have two camera systems that are identical in every respect except that one has twice the linear pixel density than the other (i.e., every pixel in the low-resolution sensor is split into four pixels in a 2x2 arrangement in the high-resolution sensor). Ignoring the effect this has on noise (and noise on perceived resolution), it is true that, as an increasing function of f-number, the higher resolution sensor will be able to reveal the effect of diffraction sooner than the low-resolution sensor. But the reason for this is because the low-resolution sensor is unable to resolve that effect, not that the effect is stronger in the high-resolution sensor. The Airy disks are IDENTICAL in the two systems because the lens is identical.
> 
> ...



QFT


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## Valvebounce (Apr 29, 2015)

QFT? Quantum Field Theory?



geekpower said:


> chromophore said:
> 
> 
> > The concern over the effects of diffraction for high resolution sensors is completely misplaced.
> ...


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## Eldar (Apr 29, 2015)

dolina said:


> For those who reserved what will you be using the 5DS or 5DS R for? Wildlife? Birds? Landscape? Studio?


Yes


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## gary samples (Apr 29, 2015)

Eldar said:


> dolina said:
> 
> 
> > For those who reserved what will you be using the 5DS or 5DS R for? Wildlife? Birds? Landscape? Studio?
> ...


+1


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## chromophore (Apr 29, 2015)

Valvebounce said:


> QFT? Quantum Field Theory?
> 
> 
> 
> ...



QFT = Quoted For Truth


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## mb66energy (May 2, 2015)

chromophore said:


> The concern over the effects of diffraction for high resolution sensors is completely misplaced.
> 
> You don't lose sharpness to diffraction by increasing pixel density, because the size of the diffraction effect is strictly determined by the lens. To understand why, suppose you have two camera systems that are identical in every respect except that one has twice the linear pixel density than the other (i.e., every pixel in the low-resolution sensor is split into four pixels in a 2x2 arrangement in the high-resolution sensor). Ignoring the effect this has on noise (and noise on perceived resolution), it is true that, as an increasing function of f-number, the higher resolution sensor will be able to reveal the effect of diffraction sooner than the low-resolution sensor. But the reason for this is because the low-resolution sensor is unable to resolve that effect, not that the effect is stronger in the high-resolution sensor. The Airy disks are IDENTICAL in the two systems because the lens is identical.
> 
> ...



I think it is a concern/hesitation due to "diminishing returns" by using higher sensor resolutions - as I
read the comments here.

With a 5D classic I see losses of detail from f/8 on while doing macro shots at 1:3 (I think it
is actually comparable to f/11). From that I extrapolate that the 5Ds can be used at a
max aperture of f/5.6 to use the lenses capabilities in similar situations. The lens used was
the near ideal EF 2.8 100mm Macro (non-L).
To use the full potential of the 5Ds you need stacking at least for macro but I think it will
be necessary for landscape and architecture as well.


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## Busted Knuckles (May 2, 2015)

Give me pixel density or give me death! or something like that.

I had an aha moment in the circles of confusion discussion. The concept creates an mental image of a few circles falling neatly onto a photosite. Depending on the diameter of the photosite either neatly contained within the microlens or horror if the photosite is too small overlapping onto the next.

My moment is that there is typically infinite airy disks and circles in every direction. So ever smaller photo sites will better resolve next infinitely close circle of confusion or airy disk 

I can't recall if I posted it before, but asked the rhetorical question, as we approach infinitely small photosites (excluding read noise) do not we not approach the equivalence of an analog sensor?

Lastly do the circles of confusion when infinitely evaluated look like the specular highlight bokeh circles for each lense? 

Its early and I am still enjoying the excessive consumption of fermented grain and fruit juices.


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## AlanF (May 3, 2015)

mb66energy said:


> chromophore said:
> 
> 
> > The concern over the effects of diffraction for high resolution sensors is completely misplaced.
> ...



Is that a valid extrapolation? Go to the slrgear site where they measure IQ at different apertures for both full frame and crop. For all the good lenses, there is minimal diffraction degradation at f/8, a tiny amount at f/11, and then more significant at f/16. It is exactly the same for FF and the 7D with 5Ds size pixels.


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## Busted Knuckles (May 3, 2015)

AlanF said:


> Is that a valid extrapolation? Go to the slrgear site where they measure IQ at different apertures for both full frame and crop. For all the good lenses, there is minimal diffraction degradation at f/8, a tiny amount at f/11, and then more significant at f/16. It is exactly the same for FF and the 7D with 5Ds size pixels.
> [/quote
> 
> Roger at lens rental posted as much in his blogs a couple months ago. An upside down "U" in max resolution w/ f8/f11 sometimes being better/worse than wide open depending on the starting point. f16 starting to tail off pretty quickly


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## mb66energy (May 3, 2015)

AlanF said:


> mb66energy said:
> 
> 
> > [...]
> ...



I think it is a valid extrapolation. Look at the plot of the resolution @ photozone
http://www.photozone.de/canon_eos_ff/508-zeiss100f2eosff?start=1
http://www.photozone.de/canon_eos_ff/847-canon35f2isff?start=1
http://www.photozone.de/canon_eos_ff/430-canon_135_2_5d?start=1
and
http://www.photozone.de/canon_eos_ff/489-canon_100_28_5d?start=1
The sharpness loss with higher f-numbers is less dramatic if you take the suppressed zero into account.

or compare the 2.8 100 L macro @ f/4 and f/16 with the 7D ii (you are right to use that camera as a good extrapolation basis for 5Ds):
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=674&Camera=963&Sample=0&FLI=0&API=2&LensComp=674&CameraComp=963&SampleComp=0&FLIComp=0&APIComp=6

Less pronounced with the 1Ds iii:
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=674&Camera=453&Sample=0&FLI=0&API=2&LensComp=674&CameraComp=453&SampleComp=0&FLIComp=0&APIComp=6


With very good lenses you can spot the decrease of center sharpness from f/4 on on a 20 MPix sensor consistently (in the graphs of photozone). The corner quality increases usually while closing one or two f-stops due to the minimization of lens errors.
With better sensors you will get more detailed images but if you stop down to f/16 you will loose a lot of this gain and I think it will start with f/5.6 or f/8 if "detailedness" is a strong concern.

And never underestimate the sensitivity of our eye-brain system which detects a 5% or 10% loss in detail easily - I do it very often too 

But I am open to update my understanding while the new data is coming in!


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