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Ansel Adams and Depth of Field


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That image looked in focus from front to back, but what about zooming in, as if I were printing much bigger than just a 4 x

6.

 

Now, here is a 100% pixel detail from the spot I focused on, at various f-stops. You can clearly see here how diffraction

starts to set in at f22 (much better than some other lenses I have, which seem to start to suffer at f16), and how it is

noticeably softening the image at f32. No doubt, if I were printing big, this would create a problem for me.<div>00QwCG-72725584.thumb.jpg.97192d5bed55a78977ba47c71093c749.jpg</div>

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It occurs to me that the reason that ignorance and stubborness are so commonly found together is that people will

simply not allow themselves to learn anything. You are obviously connected to the internet, so you obviously

have access to the largest free library of information ever assembled by man, and getting larger every day. But

instead of looking it up yourself, you ask the question on a forum and then attack the people who give you the

correct answer, simply because you refuse to hear the correct answer.

 

Diffraction is not like Murphy's Law or the Rule of Thirds or the Rules of Etiquette. It is not an arbitrary law

that was made up just to make some people mad. It's physics. Light acts as a wave. When a wave of light passes

through a small hole and strikes a surface, the pattern of the wave can become visible. This is what diffraction

is... the appearance of an image being out of focus because of the pattern of waves striking the surface are not

organized.

 

The size of the hole, the distance from the hole to the surface, and the relative size of the image to the

wavelength of the light are the determining factors in whether or not the waves will be disorganized and create

diffraction. It just so happens that the size of the hole and the distance from the hole to the surface is

contained within the ratio called the f-stop. The f-stop is the focal length of the lens divided by the diameter

of the aperture opening. Because f-stop contains the focal length of the lens in it's calculation, lenses of

different focal lengths on the same format do not act differently in terms of diffraction. A 12mm lens has the

same diffraction limit as a 600mm lens, but the difference will be in the amount of DOF in relation to the

subject distance. The relative size of the image to the wavelength is expressed though the format of the film or

sensor and it's resolution. The smaller the sensor is, the more magnification is required to view the image, and

the greater the resolution of the sensor, the more magnification is possible.

 

Adams shot on an 8x10 view camera. An 8x10 negative has over 100 times the area of a 35mm negative, which means

it has over 200 times the area of an APS-C sensor. That means that even at the diffraction limit for 8x10, one

of his negatives could be blown up 200 times larger than an image from an APS-C sensor before showing softness

from diffraction. (Film resolution vs. pixel resolution not withstanding).

 

Another case is that a 6MP APS-C sensor will not resolve diffraction until it becomes very bad simply because the

sensor sites are larger than the disorganized light waves. But a 12MP APS-C sensor will resolve more diffraction

at a lower aperture. This means that small-sensor digital cameras have a resolution limit imposed by diffraction.

 

Here's a rule of thumb, see how it works for you... if the best sharpness for 8x10 is at f/64, then for 4x5 it's

probably f/45, for larger medium format it's probably f/32, for 645 it's probably f/22, for 35mm it's around

f/16, for APS-C or half-frame 35mm it's f/11, for 4/3's it's about f/8. You will notice that most camera

designers don't want you to use your camera beyond it's diffraction limitations, so lenses are usually limited to

1 or 2 stops past the best resolution. The problem is that if you are using a Canon or Nikon dSLR with a lens

designed for a film or full-frame sensor, it might have settings 3 or even 4 stops beyond the sharpest setting...

because it is designed for a different format with a different diffraction limit.

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Jerry,

 

Again, I showed you, based on what I've learned about that lens, a best case scenario. f32 is clearly "ok" but not "best".

Therefore, i would not choose f32 for my image if I wanted the best image. Ansel and his buddies in the f64 club were

looking for what was best, not what was ok.

 

Here's another example, my Tokina 11-16, which goes from f2.8 only to f22 (wisely, they don't bother letting this very

wide lens step down further than that. You can, again, see the diffraction set in past f11. I have learned that best results

with this lens are found at f5.6 or f8, and at the wide end, there's so much in focus that those f-stops work great. I have

only gone to f16 a couple times, and probably didn't need to.<div>00QwEW-72739584.thumb.jpg.c378955296abfaf26725cbe6f2690d09.jpg</div>

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Thank you peter. I'm satisfied with OK as long as other look at say "It's OK." I do not think I've ever managed the best in anything.

 

Part of my career was over 15 years in quality assurance. OK is what we always worked for. Best is phenomenally expensive like the Ford's three million dollar Superchief pick-up truck. And still people said it was not the best.

 

The F2 club still need to see that F2 (or there abouts) picture of your PEZ car not just a crop.

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btw, Jerry,

 

I just noticed you've been asking similar questions for months, now. Have you invested in any of the better books on

photography yet? They would be quite helpful! "Understanding Exposure" is great, and I think "The Camera" by Ansel

Adams will explain a lot of the questions you've asked, too.

 

Good luck!

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"I didn't need to use trial and error to know that firing at unbreakable targets was a waste of lead."

 

Would you have changed your choke if you had not seen the other shooters fail to break? Would you have done it if you had been first and had not seen where the clay appeared?

 

It took trial and error for these things to come to light. You just had a golden opportunity (and you took it) to learn from someone else's trial and error.

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Jerry, there's no conflict here. You started this thread by talking about how impressed you were with Ansel Adams. Adams wasn't about "good enough" on a low res web image. He was about images looking "stunning" on a 16x20 B&W print. As was the rest of the f64 group. Your f32 images on a crop sensor DSLR will not look good on a 16x20 print, or even an 8x10. They will look soft.

 

If you want to "be Ansel", you've got to take the kind of care that he did.There's an old saying: the enemy of "great" is not "poor". The enemy of "great" is "good enough".

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<P><i>Therefore, i would not choose f32 for my image if I wanted the best image.</i></P>

<P></P>

<P>What is "best" varies from image to image. Sometimes "best" means maximum DoF even if that means a bit of diffraction. </P>

<P></P>

<P>Attached are the f/5.6 and f/22 samples you made using your 11-16 with one change: USM was applied to the f/22 sample 120/1/0.</P>

<P></P>

<P>Yes I know USM can't add detail that is lost. Yes diffraction will in some cases cost fine detail that cannot be restored through USM. Never the less, too much is made of this "rule" about usable aperture range. Certainly it's good to know hyperfocal distances and use them to stay within optimum apertures where possible. But if you need the DoF, stop down and adjust your USM settings in post.</P><div>00QwSG-72807584.jpg.afeffcba4afd3a855ca656638ec7c061.jpg</div>

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*Joseph Wisniewski .

 

"I didn't need to use trial and error to know that firing at unbreakable targets was a waste of lead."

 

Would you have changed your choke if you had not seen the other shooters fail to break? Would you have done it if

you had been first and had not seen where the clay appeared? *

 

Fair question, I think that I used my technical knowledge to work out that the shot pattern with a skeet choke would

fail and didn't need to see that other people were failing to do so. It was obvious. The first person to shoot isn't at a

real disadvantage because the first shooter is 'shown a pair' from the shooting position. However, if I had been the

first to shoot I probably wouldn't have had (or taken) the time to do the sums. That problem doesn't obtain when

photographing a chess board, there's plenty of time to do the sums, work at the angles and apply the theory.

 

Theoretical knowledge isn't always a complete substitute for trial and error but I do believe that an understanding of

the process, and an understanding of the underlying physics, makes most trial and error redundant. Second hand

knowledge is rarely a good substitute for real understanding, as evidenced in both the original question and several of

the answers

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Daniel,

 

At last... a great, intelligent response. Yes, this is true, however with that particular lens, I have so much depth of field at f8 and

f11 (and at 11mm, f5.6) that I may as well use the "sweet spot" and get all I can in terms of detail so that USM has loads to deal

with. You are so right, it is a general rule and can be broken (indeed, with my micro I break it all the time), but the original post

was about Ansel's amazing clarity and depth of field, and presumably about how to emulate that (short of using a larger format). I

maintain that if you know you are going to print a big "art print" you should use the best setting on capture you possibly can.

 

If I was shooting with a 35mm or 55mm lens, I could definitely see a situation where I might very readily "break the rule" as you

say, but not with a wider lens.

 

Jerry writes "Joseph, The actual truth is that I was trying to placate Peter Hamm before I had to go in the attic and get my HP

2800 wide format printer and mail him a copy of a photo on 13 x 19 inch stock through the US postal service." Aha! Your true

colors are showing, Jerry. I'm wondering if you have actually learned anything here. Doesn't look like it to me. Oh, well... We

tried.

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Peter,

 

I think we're in agreement. I wanted to address this issue simply because some posts make it sound like one can never shoot smaller apertures. I've met people who treat this as a hard and fast rule which is never to be broken.

 

I didn't mean to pick on your posts in particular, but you had sample images I could use to illustrate my point :-)

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Jerry,

I used to photograph often on f/22, using slides 36x24mm. I found that it is good for the images of blue sky and clouds. F732 and F/36 might be good to get really deep blue sky but only when the sky is clean without a haze.

It's the same for the sunrise or sundown. The colors might be more saturated. In that way the diffraction might be invisible. The focus is on the colors and tones, not on the objects. So, you might try this.

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Jerry,

<p>

<i>Despite all your arguments and learnedness, it's evident that good photos can be achieved at higher F/stops. It’s insane, “LOOK AT THAT PHOTO. IT’S F32 AND OK. YOU OBVIOUSLY DID NOT LISTEN TO WHAT I SAID!”</i>

<p>

What a stunning example to prove your point. What is it, 500 pixels wide at 96 ppi? I was mislead into thinking we were talking about prints 16x24 inches and up at 300 ppi.

<p>

As Joseph said, the only reason to respond to this thread is for the edification of those who are curious and willing to learn. You will not be pursuaded and there's no point in trying. It's like wrestling with a pig - you get muddy and the pig loves it :-)

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Jerry is only looking for an "OK" image after all.

 

For those of you looking for OK 4 x 6, 5 x 7, or on-screen viewing, stop all the way down, you'll probably be happy.

 

For those of us looking for the best possible image... learn your lens(es) and shoot carefully... or... if you don't have time...

"f8 and be there."

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