Depth of field (DOF) does NOT change with sensor size

[Ysarex]

your video you just posted proves what i sand and disproves what you said lol

I posted that video as another example of a blathering idiot making the same wrong claims and then some.

Here you go again. Proof that you're wrong. How about instead of just ranting nonsense you post a DOF calculator that supports your claim?

Joe

 

[Ysarex]

Technically speaking, maybe not, but visually yes. IMO photography is based on visuals, not charts and numbers.

Technically and visually, what i said was 100% correct how could the sensor size have anything to do with changing DOF Except for some one who would step a few feet back to get the same shot as they got with the full frame, while uing crop sensor. that is the only reason DOF changes has nothing to do with the sensor size..
Sensor size will not change anything..

Then explain why this DOF calculator proves you're wrong:

Joe

 

[greybeard]

Every so often one of these things come up and we go on for days with it. It's fun I know but, this is all about how we try to explain things and has nothing to do with anything that matters. If you have any experience with multiple formats you understand how focal lengths differ with perspectives and DoF when used between formats.

 

[n614cd]

@Ysarex @Braineack @Derrel @WayneF @Tim Tucker 2

I think that is everyone!
It all sort of makes sense. Not sure I can regurgitate it yet.
The only two things I do not get, one why is it called "Circle of Confusion"?
And secondly, it is stated as fact in multiple places the formula, and specific values for CoC. I am perfectly willing to accept 0.3mm for full frame and 0.2mm for a standard 1.5 crop sensor. Even reading the Wiki page for some reason I cannot wrap my head around this explanation. It intuitively makes sense to me, but I just do not follow the "official" definition.

Tim

 

[n614cd]

Every so often one of these things come up and we go on for days with it. It's fun I know but, this is all about how we try to explain things and has nothing to do with anything that matters. If you have any experience with multiple formats you understand how focal lengths differ with perspectives and DoF when used between formats.

Well, I am not a grey beard yet, just going bald
Anyway, as a hobby photographer I have the usual 35mm before I "got the bug". When I did get the bug it was in digital, and I started with a crop sensor, and then went full frame very early. So I do not have the multiple formats background. So for me, I enjoy learning on these threads. It helps me actually understand what I have found out via experience.

Tim

 

[n614cd]

Technically speaking, maybe not, but visually yes. IMO photography is based on visuals, not charts and numbers.

Technically and visually, what i said was 100% correct how could the sensor size have anything to do with changing DOF Except for some one who would step a few feet back to get the same shot as they got with the full frame, while uing crop sensor. that is the only reason DOF changes has nothing to do with the sensor size..
Sensor size will not change anything..

Donny,

What is DoF? Start with the fundamentals please.

Tim

 

[donny1963]

Technically speaking, maybe not, but visually yes. IMO photography is based on visuals, not charts and numbers.

Technically and visually, what i said was 100% correct how could the sensor size have anything to do with changing DOF Except for some one who would step a few feet back to get the same shot as they got with the full frame, while uing crop sensor. that is the only reason DOF changes has nothing to do with the sensor size..
Sensor size will not change anything..

Then explain why this DOF calculator proves you're wrong:

View attachment 166135

Joe

it's wrong because Sensor size would have nothing to do with changing the DOF NOTHING!!

 

[n614cd]

it's wrong because Sensor size would have nothing to do with changing the DOF NOTHING!!

Repeating the same thing, with exclamation points does not prove or make your case. Start with the basics, and answer my question in post #51

Tim

 

[Ysarex]

@Ysarex @Braineack @Derrel @WayneF @Tim Tucker 2

I think that is everyone!
It all sort of makes sense. Not sure I can regurgitate it yet.
The only two things I do not get, one why is it called "Circle of Confusion"?
And secondly, it is stated as fact in multiple places the formula, and specific values for CoC. I am perfectly willing to accept 0.3mm for full frame and 0.2mm for a standard 1.5 crop sensor. Even reading the Wiki page for some reason I cannot wrap my head around this explanation. It intuitively makes sense to me, but I just do not follow the "official" definition.

Tim

Don't worry about the name. The name I think derives from the most common description of what we're measuring. A lens is used to focus a sharp dot -- how about a pin head. What we want to know is at what point do you see the pin head as blurred versus still sharp.

It's really just an empirical measurement to account for the acuity of human sight. If we were creating DOF tables for eagles we'd need different CoC values. So all you really need to know is that it's an empirically derived control value that factors human visual acuity and a magnification factor for film/sensor size into the DOF equations.

Joe

 

[n614cd]

Don't worry about the name. The name I think derives from the most common description of what we're measuring. A lens is used to focus a sharp dot -- how about a pin head. What we want to know is at what point do you see the pin head as blurred versus still sharp.

It's really just an empirical measurement to account for the acuity of human sight. If we were creating DOF tables for eagles we'd need different CoC values. So all you really need to know is that it's an empirically derived control value that factors human visual acuity and a magnification factor for film/sensor size into the DOF equations.

Joe

lol, the number of times I have had a teacher tell me that in college.
I always ask why.... drove my parents crazy (still does), and also my teachers.

Tim

 

[Ysarex]

Don't worry about the name. The name I think derives from the most common description of what we're measuring. A lens is used to focus a sharp dot -- how about a pin head. What we want to know is at what point do you see the pin head as blurred versus still sharp.

It's really just an empirical measurement to account for the acuity of human sight. If we were creating DOF tables for eagles we'd need different CoC values. So all you really need to know is that it's an empirically derived control value that factors human visual acuity and a magnification factor for film/sensor size into the DOF equations.

Joe

lol, the number of times I have had a teacher tell me that in college.
I always ask why.... drove my parents crazy (still does), and also my teachers.

Tim

OK -- damn! I'm a college teacher. So here's a couple sentence from my class notes that I give my students:

Used in photography the size of the circle of confusion is a complex value dependent upon the viewing distance, degree of enlargement and therefore size of the camera sensor, and the size of the photographic print/display and must be adjusted to match all these variables. For an 8x10 photograph from a 35mm film negative a commonly agreed upon size for the circle of confusion is .03175mm. What we've done in the industry is make some assumptions about normal print size and then establish common circle of confusion values tied to the size of the camera sensor/film. For more detailed info: DOFMaster.

Here's another way to think about it: If we place a point before a lens in the plane of focus, the point will appear as a point on the film/sensor. As we move the point away from the plane of focus it's image on the film/sensor will blur into a disk. At the threshold beyond which we can see the difference between the focused point and the out of focus disk we find the diameter of the circle of confusion.

Joe

 

[n614cd]

My parents are retired college professors; so I get the struggle.

Anyway, between your notes and other pages. Is it safe to assume CoC was measured via empirical testing. The result of which formulas were defined to predict other values?
The part I was struggling with was going from nothing to formula to value...

Tim

Sent from my SM-J737T using Tapatalk

 

[Ysarex]

Technically speaking, maybe not, but visually yes. IMO photography is based on visuals, not charts and numbers.

Technically and visually, what i said was 100% correct how could the sensor size have anything to do with changing DOF Except for some one who would step a few feet back to get the same shot as they got with the full frame, while uing crop sensor. that is the only reason DOF changes has nothing to do with the sensor size..
Sensor size will not change anything..

Then explain why this DOF calculator proves you're wrong:

View attachment 166135

Joe

it's wrong because Sensor size would have nothing to do with changing the DOF NOTHING!!

So we've already proven that you're wrong. I've shown you the proof probably close to a dozen times now. My proof that your wrong is mathematically derived at DOF Master -- a recognized authority.

Further back in this thread are posts from Petrochemist and Wayne that explain why you're wrong. To calculate DOF we use a variable we call CoC and the value of that variable is in part predicated on sensor size. The common table of sensor size/CoC values was posted here in post #30 -- go look at it. If you change the value of a variable in an equation the equation produces a different result. Change sensor size and you change the value of CoC and the DOF changes.

Now that proves you're wrong. You've offered NOTHING to prove otherwise.

Standing in front of a mathematical proof that shows why you're wrong and just repeating your mistake is a pretty dumb thing to do.

Prove what you say -- here you'll find all the math that proves you're wrong: Depth of field - Wikipedia show us where that math is incorrect.

Joe

 

[Ysarex]

My parents are retired college professors; so I get the struggle.

Anyway, between your notes and other pages. Is it safe to assume CoC was measured via empirical testing.

BINGO. If you look at tech explanations you're going to see formulae used for CoC calculation but that's the real bottom line. It is an empirically derived value that reflects human eyesight acuity -- we add into it values to account for enlargement size print viewing distance.

Any good DOF calculator will allow you to enter your own CoC values which you can select to tailor results to your usage and liking.

Joe

The result of which formulas were defined to predict other values?
The part I was struggling with was going from nothing to formula to value...

Tim

Sent from my SM-J737T using Tapatalk

 

[AlanKlein]

Technically speaking, maybe not, but visually yes. IMO photography is based on visuals, not charts and numbers.

Technically and visually, what i said was 100% correct how could the sensor size have anything to do with changing DOF Except for some one who would step a few feet back to get the same shot as they got with the full frame, while uing crop sensor. that is the only reason DOF changes has nothing to do with the sensor size..
Sensor size will not change anything..

Then explain why this DOF calculator proves you're wrong:

View attachment 166135

Joe

it's wrong because Sensor size would have nothing to do with changing the DOF NOTHING!!

So we've already proven that you're wrong. I've shown you the proof probably close to a dozen times now. My proof that your wrong is mathematically derived at DOF Master -- a recognized authority.

View attachment 166136
Further back in this thread are posts from Petrochemist and Wayne that explain why you're wrong. To calculate DOF we use a variable we call CoC and the value of that variable is in part predicated on sensor size. The common table of sensor size/CoC values was posted here in post #30 -- go look at it. If you change the value of a variable in an equation the equation produces a different result. Change sensor size and you change the value of CoC and the DOF changes.

Now that proves you're wrong. You've offered NOTHING to prove otherwise.

Standing in front of a mathematical proof that shows why you're wrong and just repeating your mistake is a pretty dumb thing to do.

Prove what you say -- here you'll find all the math that proves you're wrong: Depth of field - Wikipedia show us where that math is incorrect.

Joe

Depth of field remains the same with the same lens and with different crop sensors. What's happening is the crop sensor is just capturing a portion (let's say 1.5x or 2x) of what a full frame sensor would capture. So when you blow it up to match the FF, the depth of field is reduced. It's like changing a normal lens to a telephoto lens shooting from the same distance. The DOF is reduced. See my earlier post. Depth of field (DOF) does NOT change with sensor size