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Question about aperture and DOF

  
 
im140.6
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p.1 #1 · p.1 #1 · Question about aperture and DOF


I'm venturing into OCF and did this quick shot. This was just messing around and testing my settings.

Canon R6, RF 50mm f/1.8
1/160 - f/8 - ISO 100

So my question is, at f/8, shouldn't the entire dog be in focus (front to back)? I understand opening up to f/1.8 creates a super-shallow DOF but I thought f/8 would be safe for several feet.

https://ibb.co/7VnZNvp



Jul 06, 2024 at 02:23 PM
jwpstl
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p.1 #2 · p.1 #2 · Question about aperture and DOF


What was your distance from the subject? That plays a key part. Use one of the online DOF calculators to find out what the focus range would be using those settings and the distance from the subject.

im140.6 wrote:
I'm venturing into OCF and did this quick shot. This was just messing around and testing my settings.

Canon R6, RF 50mm f/1.8
1/160 - f/8 - ISO 100

So my question is, at f/8, shouldn't the entire dog be in focus (front to back)? I understand opening up to f/1.8 creates a super-shallow DOF but I thought f/8 would be safe for several feet.

https://ibb.co/7VnZNvp




Jul 06, 2024 at 02:37 PM
im140.6
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p.1 #3 · p.1 #3 · Question about aperture and DOF


jwpstl wrote:
What was your distance from the subject? That plays a key part. Use one of the online DOF calculators to find out what the focus range would be using those settings and the distance from the subject.


~2 feet, definitely <3 feet. Thanks, I'll look up a DOF calculator.



Jul 06, 2024 at 02:44 PM
Alan Olander
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p.1 #4 · p.1 #4 · Question about aperture and DOF


"shouldn't the entire dog be in focus (front to back)?"

Not even close at that distance.

Edited on Jul 09, 2024 at 07:29 AM · View previous versions



Jul 06, 2024 at 05:44 PM
Flowernut
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p.1 #5 · p.1 #5 · Question about aperture and DOF


DOF is a function of magnification and f stop. The greater the magnification the less DOF. The larger the f stop number the greater the DOF. You need to take both into account when selecting a f stop to guarantee DOF coverage,


Jul 06, 2024 at 06:38 PM
Imagemaster
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p.1 #6 · p.1 #6 · Question about aperture and DOF


im140.6 wrote:
I'm venturing into OCF and did this quick shot. This was just messing around and testing my settings.

Canon R6, RF 50mm f/1.8
1/160 - f/8 - ISO 100

So my question is, at f/8, shouldn't the entire dog be in focus (front to back)? I understand opening up to f/1.8 creates a super-shallow DOF but I thought f/8 would be safe for several feet.

https://ibb.co/7VnZNvp


Your R6 will do focus-bracketing that will give you lots of DOF, and you can stack the bracketed images in post-processing.

If you had the R6 II, it would automatically stack them all in-camera. The subject has to stay still.



Jul 06, 2024 at 07:57 PM
AmbientMike
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p.1 #7 · p.1 #7 · Question about aperture and DOF




im140.6 wrote:
So my question is, at f/8, shouldn't the entire dog be in focus (front to back)?

https://ibb.co/7VnZNvp


No.

I've found the lens scales to be wildly optimistic. I'd assume the online calculators are the same. F/8 helps, but is still more limited than you might think



Jul 07, 2024 at 11:44 AM
Norm Shapiro
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p.1 #8 · p.1 #8 · Question about aperture and DOF


Sounds like you donít understand some basic facts. 1-depth of field is an area 1/3 in front of and 2/3 behind your focus point. The longer the lens the less depth of field. The smaller the aperature the more depth of field.

I forgot to mention that the closer you are to the subject the less depth of field you will have.

And all this applies to cameras that do not have lenses and backs that can be moved.

Edited on Jul 07, 2024 at 11:34 PM · View previous versions



Jul 07, 2024 at 10:11 PM
 


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Imagemaster
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p.1 #9 · p.1 #9 · Question about aperture and DOF


Many new photographers have no grasp of f-stops and DOF. They just buy the gear and start shooting.

God forbid they should ever take a course in basic photography.



Jul 07, 2024 at 10:59 PM
GroovyGeek
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p.1 #10 · p.1 #10 · Question about aperture and DOF


Flowernut wrote:
DOF is a function of magnification and f stop. The greater the magnification the less DOF. The larger the f stop number the greater the DOF. You need to take both into account when selecting a f stop to guarantee DOF coverage,


And focus distance, as already pointed out by others.

The available DOF is often under-utilized. In this image it looks like to focal point was on the nose of the dog, which resulted in sharp whiskers and teeth, but softening around the eyes and definite softening around the ears. 1/3 of the available DOF in front of the nose is completely wasted. Placing the focus point on or slightly behind the eyes would push the DOF further back towards the ears while still keeping the nose and teeth sharp.



Jul 08, 2024 at 10:55 AM
Flowernut
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p.1 #11 · p.1 #11 · Question about aperture and DOF


alfred Baker Applied Depth of Field First Edition old but still informatinve. At a longer distance 1/3:2/3 rule works. It changes as you get closer. For macro it is closer to 50:50.

As to focal length, it is it's contribution to magnification not the focal length that effects DOF. Goes back as far a John Shaw's macro book for me but here is a recent you tube view.






Jul 08, 2024 at 12:20 PM
Jman13
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p.1 #12 · p.1 #12 · Question about aperture and DOF


Imagemaster wrote:
Many new photographers have no grasp of f-stops and DOF. They just buy the gear and start shooting.

God forbid they should ever take a course in basic photography.


Well, OP is asking the question in a quest to gain more knowledge....it's a perfectly valid question and I don't think making fun of them is the way to go about making sure they continue to seek knowledge. There are many sources of information. Articles, courses, and, yes, conversing online with more experienced photographers.



Jul 09, 2024 at 01:06 PM
Choderboy
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p.1 #13 · p.1 #13 · Question about aperture and DOF


Wiki: "The depth of field (DOF) is the distance between the nearest and the furthest objects that are in acceptably sharp focus in an image captured with a camera."

Acceptably sharp. Acceptable to who?

DOF, in reality, is never larger than a single plane, or a single point.
Stopping down, or using a small aperture, only allows us to perceive DOF as larger.

Using a DOF calculator, it's not like a few pixels before calculated limit are sharp and then blurry after it.

You can read about DOF and 'circle of confusion' will be mentioned, and things like 'assuming a print size of 8x10 viewed from xx distance etc', but are you going to use a print to judge?

Most important is to understand it's not a binary thing. Further, your own eyesight is a variable.










Jul 10, 2024 at 03:48 AM
Abbott Schindl
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p.1 #14 · p.1 #14 · Question about aperture and DOF


Choderboy wrote:
Wiki: "The depth of field (DOF) is the distance between the nearest and the furthest objects that are in acceptably sharp focus in an image captured with a camera."

Acceptably sharp. Acceptable to who?

DOF, in reality, is never larger than a single plane, or a single point.
Stopping down, or using a small aperture, only allows us to perceive DOF as larger.

Using a DOF calculator, it's not like a few pixels before calculated limit are sharp and then blurry after it.

You can read about DOF and 'circle of confusion' will be mentioned, and things like 'assuming a print size of
...Show more

To be a bit more precise, only one plane is in perfect focus for rectilinear lenses, which iencluds "most" lenses (I believe fisheyes may differ). BTW: same's true of our eyes, but the way the eye-brain system works, the eye is continuously moving and the brain instantaneously integrates all the views to give the illusion of everything being in focus. But if you look at a scene and are very careful not to move your eye or shift "focus" to something else in the scene, you'll notice that only the center of the scene is in focus and the rest is pretty blurry.

You hit it the reference for "acceptable sharpness" with "circle of confusion", which is the basis for describing sharpness. With a DoF calculator, you can vary the circle of confusion value, which in turn changes the perceived DoF in the image.

With all of that, though, I think it's really gotten to the point that the DoF captured in the image is less important than it used to be, because the illusion of "sharp" can be changed significantly in post-processing. Indeed, cellphones automagically produce very sharp images (at least, very high DoF) using their built-in algorithms, which get better all the time. And with all the AI features being incorporated into computer-based processing apps, it's going to get increasingly easier to create just about any sense of DoF one wants (assuming of course that you've got the appropriate software).

BTW: PhotoPills has a DoF calculator and many other useful "pills". The OP might find it useful to explore how DoF changes with lens focal length, distance to the main subject, and so on.



Jul 10, 2024 at 02:37 PM
Imagemaster
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p.1 #15 · p.1 #15 · Question about aperture and DOF


Jman13 wrote:
Well, OP is asking the question in a quest to gain more knowledge....it's a perfectly valid question and I don't think making fun of them is the way to go about making sure they continue to seek knowledge. There are many sources of information. Articles, courses, and, yes, conversing online with more experienced photographers.


Well maybe you shouldn't make assumptions. I made a general statement that applies to any person new to photography. I also gave helpful info in a previous post. Just like you, the OP can digest that advice or ignore it.

And in case you have not noticed, the OP has been an FM member for nearly 5 years. People that take a basic photography course when they first take up photography learn about DOF, etc. The OP had 5 years to converse with you.

You don't think the advice he has been given on this thread would have been more helpful to him 5 years ago



Jul 16, 2024 at 11:24 AM







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