# What is the "sweetspot" for the 100mm f/2.8L IS Macro & the 70-200mm f/4L USM



## jdramirez (Aug 25, 2012)

I bought two lenses and I prefer to take most of my shots near or on the mythical sweetspot in regards to aperture. With the presumption of sufficient light, for my 50mm f/1.4 I try to stay between 2.8 and 4.0. For my 24-105mm f/4 I make an effort to approach f/8, but that isn't always an option.

So that raises the aforementioned question. What aperture range is the 100mm and the 70-200 the sharpest? And don't hesitate to tell me that I was wrong about the 50 and 24-105... if indeed I'm way off.

Thanks a bunch.


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## bdunbar79 (Aug 25, 2012)

jdramirez said:


> I bought two lenses and I prefer to take most of my shots near or on the mythical sweetspot in regards to aperture. With the presumption of sufficient light, for my 50mm f/1.4 I try to stay between 2.8 and 4.0. For my 24-105mm f/4 I make an effort to approach f/8, but that isn't always an option.
> 
> So that raises the aforementioned question. What aperture range is the 100mm and the 70-200 the sharpest? And don't hesitate to tell me that I was wrong about the 50 and 24-105... if indeed I'm way off.
> 
> Thanks a bunch.



Pretty much all of my lenses are sharpest around f/8. That doesn't mean that lenses aren't sharp at other apertures. That's just where they are _sharpest_.


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## jdramirez (Aug 25, 2012)

bdunbar79 said:


> Pretty much all of my lenses are sharpest around f/8. That doesn't mean that lenses aren't sharp at other apertures. That's just where they are _sharpest_.



Which lenses do you have?


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## bdunbar79 (Aug 25, 2012)

jdramirez said:


> bdunbar79 said:
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> > Pretty much all of my lenses are sharpest around f/8. That doesn't mean that lenses aren't sharp at other apertures. That's just where they are _sharpest_.
> ...



All of the ones in my signature file.


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## jdramirez (Aug 25, 2012)

bdunbar79 said:


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Silly me. I guess signatures actually do serve a purpose. Thanks.


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## bdunbar79 (Aug 25, 2012)

jdramirez said:


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Haha! Hey no big deal!


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## pdirestajr (Aug 25, 2012)

Can I ask why you would want to buy / use a lens that has an adjustable aperture at only the "mythical sweet spot"? Aren't you limiting your creative control?


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## Viggo (Aug 25, 2012)

I don't absolutely agree that f8 is the sharpest.

I ran a "aperture sharpness test" in focal with all my lenses and the:

24 L II= sharpest at f2,5

35 L II= f3,5

50 L= better at 1,8 than 2,2, sharpest at f5

85 L= f5 (huge drop from f2 to 1,2)

135= f7.1

All lenses showed a fair amount of loss of sharpness any smaller aperture. 

I use my lenses at the needed aperture, but I must admit, I use 2,5 with the 24 more now (instead of 1,8-2.0), and the 50 at 1,8


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## candyman (Aug 25, 2012)

Viggo said:


> I don't absolutely agree that f8 is the sharpest.
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> I ran a "aperture sharpness test" in focal with all my lenses and the:
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Just curious; does that also mean that you now have set the in-camera sharpness setting to "0" (zero) ?


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## sheedoe (Aug 25, 2012)

Viggo said:


> 35 L II= f3,5


I guess this lens is no longer a rumor then


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## Viggo (Aug 25, 2012)

sheedoe said:


> Viggo said:
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LOL, yeah sorry about that!


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## Viggo (Aug 25, 2012)

candyman said:


> Viggo said:
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The software sets up the camera with it's own settings, so I'm not sure. But if you sharpen +3 or -3, the difference between apertures would be the same, all would be softer or sharper.


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## bdunbar79 (Aug 25, 2012)

I agree that it depends on the lens, especially zoom lenses. But you have to sit and think about why. As you stop down, more and more of the center of the lens is actually being used, until you get so narrow that diffraction comes into play. As you use more and more of the center, the sharper the images, until diffraction. It is beyond me how something wider than f/3.2 can be the sharpest aperture on any lens. I know I explained that very roughly, but it's coffee time


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## skitron (Aug 25, 2012)

jdramirez said:


> What aperture range is the 100mm and the 70-200 the sharpest?



The 100L and 70-200 f4 don't have the sharpness fall-off that a fast prime would at max aperture. 

DxO (see Measurements>Resolution>Field Maps). 

And since DxO can be a can of worms at times (Neuro pointed to the 70-200 II which on DxO seems to have totally invalid results), also see TDP. Photozone.de also has these two lenses, with similar results.

I have a 100L and in practical terms it is no different for anything f11 and less. Unlike the two fast primes I have that definitely get sharper >= f2.8.


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## jrista (Aug 26, 2012)

You can certainly ask other people's opinions about such things, however maximum sharpness is a function of every component in an imaging system, including the sensor. For someone using, say, a Canon 1D IV or 1D X, where the maximum theoretical sensor spatial resolution is less than 100 lp/mm, their best aperture is likely to be higher than someone using say the Canon 7D, which has a maximum theoretical sensor spatial resolution of 116 lp/mm, and could realize better resolution at wider apertures.

Theoretically speaking, most lenses will peak in sharpness at around f/4-f/6, depending on the specific characteristics of the lens. Top-grade professional lenses, such the more expensive Canon L-series lenses, can potentially peak near their maximum aperture, with the top few supertelephoto L-series lenses released in the last few years doing just that (the 300mm, 400mm, 500mm, and 600mm Mark II L-series lenses are all nearly perfect, and most achieve maximum sharpness at their widest aperture, or within 1/3 to 2/3rds of a stop from it.)

If you want to figure out the "sweet spot" for any lens, you can use *Reikan FoCal Pro* (http://www.reikan.co.uk/focal/focal-pro.html) to do so. It has an Aperture Sharpness tool that takes photos at every aperture, from the narrowest to the widest, and evaluates IQ for each one. I recently ran an evaluation of aperture sharpness for my copy of the *100mm f/2.8 USM Macro* lens (after using FoCal Pro to do what I purchased it for...automatically tune AF micro focus adjustment for maximum performance). My test results, after several runs, indicate that f/4.5 is the optimal aperture for this lens (at least with the 7D's 18mp sensor). This should remain true with larger sensors that have lower spatial resolutions as well, such as the 1D X or 5D III.


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## LetTheRightLensIn (Aug 26, 2012)

bdunbar79 said:


> jdramirez said:
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> > I bought two lenses and I prefer to take most of my shots near or on the mythical sweetspot in regards to aperture. With the presumption of sufficient light, for my 50mm f/1.4 I try to stay between 2.8 and 4.0. For my 24-105mm f/4 I make an effort to approach f/8, but that isn't always an option.
> ...



you must have a bunch of very weird copies then


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## Jamesy (Aug 26, 2012)

Viggo said:


> I don't absolutely agree that f8 is the sharpest.


Agreed. I too thought F8 was the place to be until I ran the Focal Aperture Sharpness test on all my glass a few weeks back and here are me results:

24-105 = 4.5
85/1.8 = 4.5
135L = 5.0
70-200/F4/IS = 5.6

FWIW, my nifty-fifty reported 2.8 as the sharpest aperature.


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## pdirestajr (Aug 26, 2012)

This thread makes me sad. Why are you people running so many tests with your lenses to determine absurd things like sharpness? What does that even mean? And what is the point of it?


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## jdramirez (Aug 26, 2012)

pdirestajr said:


> This thread makes me sad. Why are you people running so many tests with your lenses to determine absurd things like sharpness? What does that even mean? And what is the point of it?



That's like saying, what is bokeh. Why does the bokeh of the 135mm f/2L blow away that of the 18-135mm? It just does. And sharpness is an easier concept to confirm that why a bokeh is pleasing. You put your equipment in the best position to reach it's maximum potential. Anything less and it raises the question of why bother getting L series glass in the first place.


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## jdramirez (Aug 26, 2012)

Jamesy said:


> Viggo said:
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> > I don't absolutely agree that f8 is the sharpest.
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I saw an article that compared 50mm lenses and I was blown away by the fact that the Canon 50mm f/1.4 actually was better or equal to the 50mm f/1.2L between 1.4 through 4. Having said that, their findings is that the f/1.4 was sharpest between 2.8 with slight improvements around 4.0. 

and I'm actually surprised to hear that your 24-105 is sharpest at 4.5. I just thought it was accepted that f/8 is where it shines. But f/8 is all but useless indoors... I find it interesting.... maybe I should start taking some photos of black and white lines.


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## jdramirez (Aug 26, 2012)

pdirestajr said:


> Can I ask why you would want to buy / use a lens that has an adjustable aperture at only the "mythical sweet spot"? Aren't you limiting your creative control?



I think of the sweetspot as a bell curve. And at f/5.6 (let's say) is where the lens is at its sharpest. So if I'm outdoors with plenty of light, I'll stay @ 5.6, but if I'm indoors I'll try and stay closer if I can to 5.6. I like having more information than simply guessing.


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## bdunbar79 (Aug 26, 2012)

LetTheRightLensIn said:


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Cool.


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## jrista (Aug 26, 2012)

pdirestajr said:


> This thread makes me sad. Why are you people running so many tests with your lenses to determine absurd things like sharpness? What does that even mean? And what is the point of it?



Tell me this...do you literally spend every waking moment, every minute of every hour of every day, every day of the year, taking useful photographs of interesting subjects? Do you never take a moment to evaluate where your technique is limited, or where your technological understanding is incorrect, in an effort to _improve yourself_, and _expand the horizon of your skill_?

Personally, I don't have the ability to shoot every waking moment. Once the sun has set and my primary light source is gone, I go home, head indoors, and try to relax. Sometimes...every so often...I'll spend time with my gear...cleaning, testing, learning. For what its worth, a FoCal Aperture Sharpness test takes about 10 minutes to do...once you set it up, its entirely automatic. I evaluated all of my lenses in about an hour. A single hour...doing "absurd" tests. I also used FoCal to automatically test each lens I own and set the correct Auto-Focus Microfocus Adjustment (AFMA) in my 7D for each and every lens. So, for all the time I "wasted" running "pointless & absurd" tests...here is what I've gained:

[list type=decimal]
An assurance that when I use autofocus on any of my lenses, the results will be superb, as I'm confident every single lens is focusing at optimum efficiency.
Confirmation of my own suspicions based, previously, purely on math...that most of my lenses achieve maximum sharpness at apertures much wider than either the DLA of my sensor, or the much-vaunted "optimal f/8" that is so frequently repeated online and in magazines.
The freedom to shoot at wider apertures, when circumstances permit and when I don't need DOF, to realize improved sharpness in my photography.

If you thought my answers would include "bragging rights", guess again. I don't waste my time on worthless endeavors such as bragging rights. I could be a shmuck stuck at f/8 because I heard, somewhere, that it was the "optimal" aperture to use. In 1960 on your average contact-printable film, I'd probably be correct. In 2012, I'd be a good two stops lower than I could be, at two stops higher ISO, with visibly greater noise and noticeably less sharp than is likely possible. I'd rather not be.

I _*spend*_ my time evaluating my lenses and cameras in order to maximize the potential of both my gear...as well as myself. I _*spend*_ my time performing tests to enlighten myself, and to ensure I head out into the field with the most accurate knowledge I can, backed up not only by theory and math, but also real-world confirmation the theory and math are correct. I _*spend*_ my time to be a better photographer...to be the _*best *photographer I can be_. That requires more than just field smarts and hands-on time.[/list]


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## bdunbar79 (Aug 26, 2012)

Who cares what the sharpest aperture is, really? Do you change aperture because of sharpness? Sharpness of what? I use aperture to control my DOF or flash exposure. If my lens is sharpest at f/4, I don't care because how does that have any real useful impact on your photography? 

Second reason I don't care is because just because my lens is sharpest at f/4, doesn't mean it's NOT sharp at other apertures. So again, I don't care.


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## jrista (Aug 26, 2012)

bdunbar79 said:


> LetTheRightLensIn said:
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Your experience might have had to do with the required depth of field. Sometimes you simply can't shoot at a wider aperture to get _*enough scene depth*_ in focus to meet your needs. It might simply be that you need f/8 rather than f/4 or f/3.5 to get your entire subject "sharp". A thin DOF might result in even sharper results for part of a subject, while leaving others entirely blurred, or at the very least, considerably softer than they could be.

I wouldn't necessarily say its your lenses that are "bad"...simply that your work probably requires f/8 to maximize sharpness of detail in a deeper field.


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## bdunbar79 (Aug 26, 2012)

jrista,

It's probably a technique issue. I'm terrible, I mean terrible, at thin DOF's! I come from a sports background and learning to shoot at f/1.2-f/2 has been difficult for me, but I'm trying


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## jrista (Aug 26, 2012)

bdunbar79 said:


> Who cares what the sharpest aperture is, really? Do you change aperture because of sharpness? Sharpness of what? I use aperture to control my DOF or flash exposure. If my lens is sharpest at f/4, I don't care because how does that have any real useful impact on your photography?
> 
> Second reason I don't care is because just because my lens is sharpest at f/4, doesn't mean it's NOT sharp at other apertures. So again, I don't care.



Sure I do. I shoot a lot of very high detail subjects (birds...loads and loads of fine detail). For me, its imperative to get as much light down the lens as possible while maximizing sharpness, and flash is rarely an option (more so because it takes too long to recharge, and I often have to fire off a string shots at 8fps to get a single keeper). Less light means more noise, more noise means more NR, more NR means less, often considerably less, fine detail. If I was using a sensor with larger pixels, the sharpness issue would be largely moot, since the pixel pitch would intrinsically limit maximum resolution anyway. I use a Canon 7D, however, which is about 1.6 times as dense as the 1D X or 1.45 times as dense as the 5D III. Those two max out at 72 and 80 lp/mm, respectively and can't resolve any more detail than you get at an f/8 aperture anyway. The 7D has a theoretical peak resolution of 116 lp/mm, allowing it to resolve most of the detail you can get from f/5.6. As such, I try to shoot around f/5.6 or slightly wider (which helps improve image crispness...or microcontrast...if the lens can resolve more detail than the sensor). I've found that f/4 is a great aperture for small passerines (song/perching birds)...gets me just enough DOF to capture an entire bird, maximizes light down the lens, nicely blurs out backgrounds...in other words, it maximizes the quality of my work. There IS an impact.

If f/8 offers you the same benefit, great! More power to you. But there isn't any need to go around dissing those of us who prefer to KNOW the technological capabilities of our gear so we can maximize the potential of our own work. Not everyone requires the use of f/8 to attain a deeper DOF.


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## Jamesy (Aug 26, 2012)

The reason the aperture test interests me is I want to know the limitations of my gear. Will it impact how I shoot -- possibly. For instance, if DoF is not relevant to a particular shot I might move to the maximum sharpness range.
It does not mean I will start shooting my 135L at F5.0 all the time - that would be silly. It also changes my previous notion that most lenses are sharpest at F8.0 and there were times, again when DoF was not relevant, that I shot at F8.0.


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## jdramirez (Aug 26, 2012)

jrista said:


> bdunbar79 said:
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> > Who cares what the sharpest aperture is, really? Do you change aperture because of sharpness? Sharpness of what? I use aperture to control my DOF or flash exposure. If my lens is sharpest at f/4, I don't care because how does that have any real useful impact on your photography?
> ...



3rd gear in a Porsche will get you there, but to maximize your vehicle's potential, you have to get to the higher gears.


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## bdunbar79 (Aug 26, 2012)

jdramirez said:


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Sharpness is the ONLY route of maximizing potential? Secondly, nobody was dissing anyone. That's great if you know where your lens is sharpest for what you do and you can use that information to get photos you want, sure. Personally and for my work, it doesn't matter. I'm not going for the absolute sharpest shots I can possibly take, I'm going for the shots with the correct amount of lighting and correct amount of DOF. Sharpness is not a "higher gear." If I'm shooting portrait shots and want a great amount of bokeh, and my lens is sharpest at f/5.6, and I shoot there because it's sharpest there, I will be fired very quickly. That is why I personally don't need to know where it is sharpest. I just don't.


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## jrista (Aug 26, 2012)

bdunbar79 said:


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Thats great...for you. However, remember the original question was asking what aperture offered the best sharpness. I believe you were the first to answer with the canned "f/8 is best for all my lenses". Not only was that information anecdotal, its simply wrong...and the fact that it was wrong is why your getting flak. In light of the original question asked by @jdramirez, it doesn't really matter that f/8 is great "for you". The correct answer is that the maximum sharpness of a lens tends to be around 1 stop or so down from maximum aperture, and closer as lens build and glass quality goes up. For most lenses with normal aperturs...f/2.8-f/5.6, the "sweet spot" tends to fall around f/4.5 on average. For fast lenses, that sweet spot tends to fall around f/2.8 or so. At those apertures, a high resolution sensor (think Canon 18mp, Sony Exmor 36.3mp FF pr 24.2mp APS-C) is capable of resolving considerably more detail than is possible at f/8 (were talking some 240+ lp/mm at f/2.8, vs about 85 lp/mm at f/8).

Particularly in the case of macro photography, where the use of focus stacking is an option, an f/4 aperture could be used on the Canon EF 100mm f/2.8 Macro lens to maximize sharpness and get as much DOF as you want. Technically speaking, there is no reason you couldn't use a similar technique, such as the Brenizer Method, with the 70-200 to achieve a similar effect, mazimizing both sharpness and bokeh, for portraiture. 

Great, f/8 works for you...but its the wrong answer, factually and technically incorrect. For the sake of the OP, I think its important thats pointed out. Obviously, the artistic needs of the job reign supreme...if you need DOF or you need creamy bokeh, then do what you need to do. But if your goal is to maximize sharpness, having the knowledge to do so is valuable, regardless of what works for you personally.


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## bdunbar79 (Aug 26, 2012)

It was pointed out again, and again, and again, and again, and again..........

I just still don't understand what it even means though. The depth of field changes for each aperture. How can one aperture be "sharper" than another? At f/1.4, my background isn't sharp. What exactly are we talking about anyways? I can understand a portrait shot, say at f/1.8, vs. f/2.8. Is that what we mean? The face is sharper at 2.8? Shooting at the same focal plane? On the other hand, at f/11, my whole scene is sharp. It just doesn't make a whole lot of practical sense to me, unless we're talking a flat surface focal plane, at the same distance.


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## jrista (Aug 26, 2012)

bdunbar79 said:


> It was pointed out again, and again, and again, and again, and again..........
> 
> I just still don't understand what it even means though. The depth of field changes for each aperture. How can one aperture be "sharper" than another? At f/1.4, my background isn't sharp. What exactly are we talking about anyways? I can understand a portrait shot, say at f/1.8, vs. f/2.8. Is that what we mean? The face is sharper at 2.8? Shooting at the same focal plane? On the other hand, at f/11, my whole scene is sharp. It just doesn't make a whole lot of practical sense to me, unless we're talking a flat surface focal plane, at the same distance.



Assuming a "perfect" lens (one in which zero optical aberrations are present...that is CA, spherical aberration, field curvature, etc.), the only thing that limits resolution (which is the objective measure of acutance and microcontrast) is diffraction. As your aperture gets wider, the effects of diffraction become less and less. Sharpness (in the context I believe you are using) is a somewhat subjective measure of acutance and microcontrast...how harsh edges appear, how fine detail is discerned...and as such sharpness improves as resolution improves. Higher resolution also allows you to resolve finer details, and resolve larger details more sharply, vs. only being able to resolve larger details. At f/22, your limited, by diffraction, to only 30 lp/mm. If the detail you are interested in is larger than 30 lp/mm, your lens will resolve them, and the larger the detail the more clearly it will be resolved. At f/8 resolution jumps to 85 lp/mm, allowing you to resolve detail less than half the size as what you could resolve at f/22. By f/2.8, resolution increases to 245 lp/mm...again allowing you to resolve more fine detail, nearly 3x more detail than you could resolve at f/8. 

In the case of, say, a macro subject (such as an insect), or a bird, or furry animal...there is PLENTY of very fine detail. If we use birds as an example, every feather has a shaft, on either side of which is a vane, each vane of which contains barbs, and each barb of which contains interlocking barbules, each barbule containing multiple fine hooks that assist in that interlocking. At f/8 and a shooting distance comfortable to most birds, I can resolve a vane and its barbs, but the fine barbule detail is blurred away. The shaft and each barb may be sharp relative to each other, however there is a considerable amount of detail that can't be resolved at all at this resolution, or if it is, its rather blurry. At a bird-comfortable shooting distance, barbule detail can be over 100 lp/mm. At f/4, my resolving power increases to around 170 lp/mm, allowing me to resolve much more of that fine barbule detail than I could at f/8 (only limited by sensor resolution...which is where high res. APS-C sensors like Canon's 116 lp/mm (luminance) 18mp sensor or Sony's 129 lp/mm (luminance) 24mp sensor). Now, not only are the spine and barbs sharp...they are sharper than they would have been at f/8 due to the improved acutance and microcontrast offered by a wider diffraction-limited aperture, _and_ a finer level of detail is now resolving, adding even more to the impression of overall image sharpness.

The same rough effect would exhibit for any kind of photography that aims to expose fine detail. Insect macro photography definitely benefits, as insects contain even more fine detail than birds. When it comes to macro photography, due to _extension_, your effective aperture is often much smaller than indicated by your F-Number (in the case of the Canon MP-E 65mm Macro, at full extension the effective aperture can be f/96 or greater if you really stop down to maximize DOF.) Its for this very reason that focus stacking has become a popular mechanism for maximizing DOF and sharpness in macro photos...you can NEVER resolve as much fine detail as sharply at an effective f/96 as you can at say an effective f/22...diffraction simply won't allow it.) The same general rules would apply to portraiture as well...not quite as much fine detail, but still plenty to think about. Sharpness in hair, eye lashes, even iris detail (if your doing head shots) can all benefit from improved resolution at wider apertures...assuming other artistic goals don't override sharpness (which entirely depends on your style.) Many heat shot photographers resort to intriguing post-processing techniques to improve eye detail (many of which produce great results)...but there is no real substitute to finely resolved real, natural iris detail that you can achieve at f/5.6 on a high res (say D800) sensor IMHO.

One aperture can be sharper than another when it increases acutance and microcontrast, and when it resolves finer detail than another clearly...for the depth of field that is in focus (which, admittedly, may be very thin...but thats beside the point when talking purely about resolution...about sharpness.)


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## bdunbar79 (Aug 26, 2012)

I see your point. It is clear. I guess I just wasn't thinking that way when I read the original question. I was thinking about working with a landscape or architecture photographer and me telling him I'm going to shoot at f/2 because that's the sharpest aperture for the lens, and then him taking my camera and lens away from me. I can agree that at a fixed focal length, and consistent, fixed focal plane, a lens can be sharper at f/2 vs. f/8, or what have you. I also interpreted as, ok, what aperture will make most of my scene sharpest? I guess there are several ways to think about and measure sharpness. I suppose if you picked a finite point in the landscape scene, let's say your focal point you chose, and shot at f/4 and then f/11, sure the whole scene would be in focus at f/11, but perhaps that point you focused on is sharper at f/4, than f/11.


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## jrista (Aug 26, 2012)

bdunbar79 said:


> I see your point. It is clear. I guess I just wasn't thinking that way when I read the original question. I was thinking about working with a landscape or architecture photographer and me telling him I'm going to shoot at f/2 because that's the sharpest aperture for the lens, and then him taking my camera and lens away from me. I can agree that at a fixed focal length, and consistent, fixed focal plane, a lens can be sharper at f/2 vs. f/8, or what have you. I also interpreted as, ok, what aperture will make most of my scene sharpest? I guess there are several ways to think about and measure sharpness. I suppose if you picked a finite point in the landscape scene, let's say your focal point you chose, and shot at f/4 and then f/11, sure the whole scene would be in focus at f/11, but perhaps that point you focused on is sharper at f/4, than f/11.



Aye, the artistic needs should certainly outweigh achieving maximum sharpness. When it comes to landscapes, I'd pick f/11 on any normal lens, or I'd use a tilt/shift lens and use tilt to maximize focus to infinity at a more ideal aperture like f/4 or f/5.6. For architecture, its roughly the same deal...not much in the way of very fine detail in architecture, and you could probably stop down to your hearts content if you wanted to. For portraiture, if you need to get your full subject within DOF, f/8 is certainly going to do a better job making your entire subject sharp vs. f/4. Even if it limits the amount of fine detail that can be resolved, using a wider aperture would be antithetical to your primary goals.


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## bdunbar79 (Aug 27, 2012)

jrista said:


> bdunbar79 said:
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> > I see your point. It is clear. I guess I just wasn't thinking that way when I read the original question. I was thinking about working with a landscape or architecture photographer and me telling him I'm going to shoot at f/2 because that's the sharpest aperture for the lens, and then him taking my camera and lens away from me. I can agree that at a fixed focal length, and consistent, fixed focal plane, a lens can be sharper at f/2 vs. f/8, or what have you. I also interpreted as, ok, what aperture will make most of my scene sharpest? I guess there are several ways to think about and measure sharpness. I suppose if you picked a finite point in the landscape scene, let's say your focal point you chose, and shot at f/4 and then f/11, sure the whole scene would be in focus at f/11, but perhaps that point you focused on is sharper at f/4, than f/11.
> ...



Thank you!


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## Mt Spokane Photography (Aug 27, 2012)

pdirestajr said:


> This thread makes me sad. Why are you people running so many tests with your lenses to determine absurd things like sharpness? What does that even mean? And what is the point of it?


Why does it bother you?
Why wouldn't someone want to understand and know how best to use their tools. Certainly there is a lot more than sharpness, but, if you do not understand your tools, then you are just taking what comes at random.


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## sfunglee (Apr 25, 2013)

WoW many useful SWEET SPOT from jrista


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## Mt Spokane Photography (Apr 25, 2013)

sfunglee said:


> WoW many useful SWEET SPOT from jrista


 
Yes, Last August! 

Welcome to Canon Rumors. You should learn to look at the dates of the original posts. Old posts may no loonger be relavent.

Feel free to post some useful information, even starting your own topic.


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## hamada (Apr 29, 2013)

pdirestajr said:


> Can I ask why you would want to buy / use a lens that has an adjustable aperture at only the "mythical sweet spot"? Aren't you limiting your creative control?



+1

sharpness is overrated. 
but it´s nevertheless good to know where the sweet spot of a lens is.


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## hamada (Apr 29, 2013)

Mt Spokane Photography said:


> sfunglee said:
> 
> 
> > WoW many useful SWEET SPOT from jrista
> ...



if you don´t want old posts to pop up at the top... why not just close them after some time?
otherwise i don´t see a reason for such a reply.


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## shutterlag (Apr 29, 2013)

This is useful:

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=674&Camera=453&Sample=0&FLI=0&API=0&LensComp=104&CameraComp=453&SampleComp=0&FLIComp=2&APIComp=0



jdramirez said:


> I bought two lenses and I prefer to take most of my shots near or on the mythical sweetspot in regards to aperture. With the presumption of sufficient light, for my 50mm f/1.4 I try to stay between 2.8 and 4.0. For my 24-105mm f/4 I make an effort to approach f/8, but that isn't always an option.
> 
> So that raises the aforementioned question. What aperture range is the 100mm and the 70-200 the sharpest? And don't hesitate to tell me that I was wrong about the 50 and 24-105... if indeed I'm way off.
> 
> Thanks a bunch.


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## distant.star (Apr 29, 2013)

hamada said:


> Mt Spokane Photography said:
> 
> 
> > sfunglee said:
> ...



Good point. It's not like they're bread on a grocery store shelf.


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## Artifex (Apr 29, 2013)

From my personal experience with the 100mm f/2.8L, I would say f/5.6, though I have not done any formal testing on it. It is a really awesome lens BTW!


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## jdramirez (Apr 30, 2013)

3.5 to 5.6 per DP Review. 

http://www.dpreview.com/lensreviews/canon_100_2p8_is_usm_c16/4

The lens is sharp all the way through, from 2.8 through f/11... then it starts to hit the other side of the bell curve. 

I really love the lens... it is my favorite over my 50mm f/1.4, 24-105, and 8mm fisheye (but that is completely different). I did just get a 70-200mm f/2.8L IS mkii today... so it is possible that will become my new favorite. I was looking at the DP and comparing the two lenses, and the 70-200 is supposed to be nearly as sharp as my 100mm. I guess the proof will be in the pudding.


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## Mt Spokane Photography (Apr 30, 2013)

hamada said:


> Mt Spokane Photography said:
> 
> 
> > sfunglee said:
> ...


 
Do you understand that the OP was asking for help last August??


Do you think that answering now is going to help him??


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## jdramirez (Apr 30, 2013)

Mt Spokane Photography said:


> hamada said:
> 
> 
> 
> ...



I didn't get a good answer the last go round... so maybe (as I'm the OP). Having said that, I did find the answer.


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## jrista (Apr 30, 2013)

jdramirez said:


> Mt Spokane Photography said:
> 
> 
> > hamada said:
> ...



In all honesty, the quickest and relatively cheap way to answer that question is to buy Reikan FoCal, and run your lenses through the Aperture test. It will take a series of shots at each aperture, measure them (I believe it just does an L/PH evaluation, but it might be something more like SQF), and plot the results on a chart. At the end, it will strait up tell you which aperture produces the best quality on YOUR GEAR.


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## jdramirez (Apr 30, 2013)

jrista said:


> In all honesty, the quickest and relatively cheap way to answer that question is to buy Reikan FoCal, and run your lenses through the Aperture test. It will take a series of shots at each aperture, measure them (I believe it just does an L/PH evaluation, but it might be something more like SQF), and plot the results on a chart. At the end, it will strait up tell you which aperture produces the best quality on YOUR GEAR.



What I found is that the 100mm I have is a really nice lens... so I can shoot at 2.8 or 8, and I will be more than happy with the results. I think that is partly why I'm not willing to part with my 50mm f/1.4... because I'd much rather have a lens that is sharp with good results at any aperture rather than having to always stop down the 50 to f/2.8 to get decent results.


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