[stevebrot]

No need to go any further, other than to say you may wish to read up on how DOF works.

Examples please. Prove your point with photos.

I have posted examples in the distant past, but need to find them. In the mean time, perhaps you can beat me to it.


Steve

[Lowell Goudge]

DOF is a result of three physical properties; focal length, aperture and distance to subject. These are basic *physical* properties that cannot be changed without changing how the Universe is built and operates. (doing so would be *bad* )

Actually DOF is a function of Moore than 3 things. Enlargement from the capture medium to the print also counts. And I. That respect Crop sensors are better because you enlarge the image mode and therefore reduce the DOF.

It is a complicated process. As you indicated, and therefore as opposed to learning how to shoot with crop sensors people complain it is simply "better" with full frame.

[amoringello]

Some people here clearly understand what they are talking about, but I think some terms are being mixed or being used more generically than they should be in relation the the OP's initial question.

Are you talking about DOF in the final display/printed image as one might hang on a wall or view on-screen (perceived sharpness), or DOF on the recording media (sensor, film)?

It is clear that some of us are obviously not talking about the same DOF.
They are not the same beast, and confusing the two has become problematic. Arguing that they are the same shows a fair lack of understanding..

- One has many post-capture ingredients even including an individual's own ability to perceive sharpness (bad eyesight), crop, print media & resolution & size, and many, many others. a.k.a. . perceived sharpness

- The other is a measurable and constant effect generally based on a few physical properties. a.k.a DOF == DepthOfField

i.e. Display & print size has no comprehensible effect on what is collected on the sensor.
Trying to argue otherwise is pure ignorance and/or blatant trolling.

Of course, if anyone can explain exactly how printing a 50% crop on canvas at 20"x30" being seen by a presbyopic viewer at 8 feet *affects what is recorded on the sensor*, I would be duly impressed by your understanding of DOF!!

---------- Post added 03-31-14 at 08:59 AM ----------

Examples please. Prove your point with photos.
I have posted examples in the distant past, but need to find them. In the mean time, perhaps you can beat me to it.

I tried searching but cannot find them. I would love to see that if you have some idea how far back to search or roughly what the subject may have been?

I do recall that someone else posted something similar some time ago (not sure if it was this website) but the methods were so out of whack and showed a complete lack of understanding of what they were trying to show and even how to test. i.e. different / unrelated subjects, locations, some even being slightly out of focus.
It was a complete and utter total mess.

I would be truly interested in real world examples done by someone capable.

I'll also try to get hands on a full frame and get adequate examples.

[jsherman999]

Some people here clearly understand what they are talking about, but I think some terms are being mixed or being used more generically than they should be in relation the the OP's initial question.

I also think you may have lost sight of the OPs original question - how DOF 'control' is affected by changing sensor sizes. Your chosen parameters for how you choose to contain and truncate the definition of 'DOF' does not change the answer for the OP. (If you want to take it on a tangent that's OK, but you're not close to answering what the OP was asking.)

Are you talking about DOF in the final display/printed image as one might hang on a wall or view on-screen (perceived sharpness), or DOF on the recording media (sensor, film)?

I would assume everyone talking about DOF would be talking about as seen, displayed either on screen or in print. What would be the purpose of talking about it on the sensor except as a step toward display/view?

i.e. Display & print size has no comprehensible effect on what is collected on the sensor.

So what?

Trying to argue otherwise is pure ignorance and/or blatant trolling.

I don't see anyone arguing otherwise, unless I missed it. You yourself have to realize that what's happening on the sensor is not the final step - other things affect perceived DOF in the continuing pipeline. You're not looking at the complete picture, here, as it were.

I tried searching but cannot find them. I would love to see that if you have some idea how far back to search or roughly what the subject may have been?

What type of examples are you looking for specifically? I can't tell from the conversation exactly what's being asked for.

.

---------- Post added 03-31-14 at 08:32 AM ----------

What is one of the best reasons? It is good to know (in general, knowledge is good), but in practical terms when does it ever come up? Who is walking around with two kits of different format and "equivalent" lenses to match? I am WAY more interested in how the same lens (one that I've got in my bag) will perform on a different format...

This is a good point, and in reality knowing about equivalence isn't important unless you plan to buy into another format and want to know what to expect with your images - meaning for example, your new 45mm f/1.9 (or whatever) on your new mirrorless m/43 camera is not going to look or behave much like the 43ltd on the K5 in terms of FOV and DOF, despite the FL and max aperture being very similar.

It's also marginally useful when shooting a P&S - you should know going in that your P&S doesn't really have a zoom lens that starts at 5mm - (well, it technically does, but it's probably about the equivalent of a 24mm lens on 135mm in terms of FOV, something you may find useful to know .)

When it's really useful is when you plan to use two formats that can share the same physical lenses, like FF and aps-c.

.

[amoringello]

I would assume everyone talking about DOF would be talking about as seen, displayed either on screen or in print. What would be the purpose of talking about it on the sensor except as a step toward display/view?

Well, you certainly cannot argue logic like that.
Honestly, you are 100% correct... but you're also talking about a whole 'nother world of issues, far beyond and unrelated to the camera, lenses and sensor. So to that end, far from correct.
The OP was asking about FF v.s. mFT. There was nothing about post-capture; printing, display, quality of eyesight, viewing angle/distance, and the myriad of other affects regarding final output independent of captured data.
If you cannot see why that is a problem, I am at a loss of where the confusion lies.

>> Examples please. Prove your point with photos.
>> I have posted examples in the distant past, but need to find them. In the mean time, perhaps you can beat me to it.

> I tried searching but cannot find them. I would love to see that if you have some idea how far back to search or roughly what the subject may have been?

What type of examples are you looking for specifically? I can't tell from the conversation exactly what's being asked for.

Really? It is pretty darned clear from the quote.
Being so quick to criticize based on lack of information is not helpful and does not add confidence to any other arguments.
My guess is you take the same approach, with the lack of understanding, towards the rest of this thread.

[vonBaloney]

Well, you certainly cannot argue logic like that.
Honestly, you are 100% correct... but you're also talking about a whole 'nother world of issues, far beyond and unrelated to the camera, lenses and sensor. So to that end, far from correct.
The OP was asking about FF v.s. mFT. There was nothing about post-capture; printing, display, quality of eyesight, viewing angle/distance, and the myriad of other affects regarding final output independent of captured data.
If you cannot see why that is a problem, I am at a loss of where the confusion lies.

But all of those things ARE important when comparing different formats, and in fact those are built-into (as constants/standards) of what is considered "acceptable" DoF. (All of those things are considered for the DoF scale on the lens -- which also assumes an FF format -- a DoF scale on a lens for a smaller format would be different but they just don't put them on the lenses anymore so we haven't seen one). In other words, it is assumed that if you take a photo with an FF camera or an APS-C camera that you are planning to make an equal-sized print with both -- in general it is assumed that you aren't going to make prints that are proportionally smaller with smaller formats. (For "normal-sized" prints under 20x30 or whatever -- for big prints then a larger format will actually be needed to retain acceptable sharpness/resolution.) It is also assumed that as a print gets bigger, the viewing distance is also increased (effectively removing viewing distance from the equation), but nevertheless you are shooting for "a print viewed at 'normal' distance given the print size" (once you start using a loupe to view prints, you are back to zero DoF because only one point is ever actually in focus).

Yes it is true that these things don't affect what the sensor captures, and some people do make it sound like something magical happens when you switch formats (when they are really talking about not only switching formats but switching lenses), but I don't think anybody has argued that in this thread. But nevertheless it is true that the DoF in the end assumes a human viewer viewing an actual image at an actual size, etc -- it is not just (or even mostly) about sensor data as captured. Without all that human stuff at the end (and the myriad of "givens" along the way that are based on human eyesight, etc) the entire concept of DoF has no meaning. Seems to me that you are the one that should be using a narrower and more technical terms that are purely about the objective data -- airy disks, circles of confusion, etc...

[amoringello]

FYI, here is what I'm talking about.
Full Frame vs Crop Sensor Depth of field myth

Anyway, we're obviously on the same page, but only to a certain extent as far as it pertains to the OP.

[jsherman999]

Well, you certainly cannot argue logic like that.
Honestly, you are 100% correct... but you're also talking about a whole 'nother world of issues, far beyond and unrelated to the camera, lenses and sensor. So to that end, far from correct.
The OP was asking about FF v.s. mFT. There was nothing about post-capture; printing, display, quality of eyesight, viewing angle/distance, and the myriad of other affects regarding final output independent of captured data.

I'm pretty sure the OP implied that he would want to, somehow, see the DOF differences he was asking about.

Since there would be no way to see the DOF differences if they were not displayed one way or the other, you're keeping the argument in an odd theoretical limbo state. You have to display the image in some way, and that introduces variables that affect the DOF. You simply can't get around that, and if you notice most DOF calculators themselves assume a certain distance and display size (if they're being complete.)

Really? It is pretty darned clear from the quote.

Really? Here's the series of quotes:

>>>> (you) No need to go any further, other than to say you may wish to read up on how DOF works.
>>> (steve) Examples please. Prove your point with photos.
>>> (steve) I have posted examples in the distant past, but need to find them. In the mean time, perhaps you can beat me to it.
>> (you) I tried searching but cannot find them. I would love to see that if you have some idea how far back to search or roughly what the subject may have been?
> (me) What type of examples are you looking for specifically? I can't tell from the conversation exactly what's being asked for.


I can't tell what Steve was originally asking you for, nor can I tell what you're really asking him for, other than some generic "DOF examples". Do you want to see examples of how cropping can change DOF when the cropped image is displayed at the same size? Here's an example Lee Jay showed a while back when someone else was confused about this:



See how the act of cropping and displaying the crop changes the DOF in the resulting image?

.

[vonBaloney]

FYI, here is what I'm talking about.
Full Frame vs Crop Sensor Depth of field myth

Anyway, we're obviously on the same page, but only to a certain extent as far as it pertains to the OP.

Yes, and for such confusion I place the blame on the equivalence people, who make lots of statements with a whole lot of assumptions behind them that they usually fail to mention, and then when you start asking questions they say things like, "OF COURSE we are talking about 'equivalent' systems [i.e. different lenses on different bodies capable of taking the 'same' image, even if only in theory] -- what POSSIBLE point could there be in discussing anything else?"

[jsherman999]

Yes, and for such confusion I place the blame on the equivalence people, who make lots of statements with a whole lot of assumptions behind them that they usually fail to mention, and then when you start asking questions they say things like, "OF COURSE we are talking about 'equivalent' systems [i.e. different lenses on different bodies capable of taking the 'same' image, even if only in theory] -- what POSSIBLE point could there be in discussing anything else?"

Those darn equivalence people! They always insist on bringing facts and physics into every discussion! Curse them!

[vonBaloney]

Those darn equivalence people! They always insist on bringing facts and physics into every discussion! Curse them!

It is not the facts I object to, but the fact that they almost never mention a whole host of "givens" (like that they are even talking about "equivalence"), and that they also argue that talking about anything other than equivalence when comparing things is not worth doing. So yes, curse them, they're jerks.

[amoringello]

See how the act of cropping and displaying the crop changes the DOF in the resulting image?

There are actually ZERO changes in DOF in your examples. DOF is roughly 22in to 23in in all examples.
Perceived sharpness may change as the ratio of in focus v.s. out of focus area becomes larger.
But actual DOF changing? Nope!

Many people falsely confuse this with a change in DOF, but it is NOT.

[jsherman999]

It is not the facts I object to, but the fact that they almost never mention a whole host of "givens" (like that they are even talking about "equivalence"), and that they also argue that talking about anything other than equivalence when comparing things is not worth doing. So yes, curse them, they're jerks.

They (which includes me) are not jerks, and understanding equivalence doesn't need to be something that makes you angry or defensive. Here's one of the best links you can bookmark - I suggest everyone keep it handy and refer to it from time to time, it's excellent and aside from a few language quibbles has held up as pretty much irrefutable:

The Mother of All Equivalence Links

You're welcome!

.

[amoringello]

Actually that link doesn't show anything that disputes anything anyone in this thread has said - he is shooting the same lens, same f-stop on two different-format cameras from the same position. When you do that, the DOF is the same, but the image is radically different, since it's a different FOV. No-one who actually knows what they're talking about ever says any different. (I'll paste his example below so we can see it in this thread.)

WTF? Field of view does not affect DOF in any way what-so-ever!
The rest of the statements do not even make sense without qualifying which parameters are staying the same or changing.
Simply including lens and sensor/body type is insufficient for any calculation and are completely meaningless on their own.

[vonBaloney]

They (which includes me) are not jerks, and understanding equivalence doesn't need to be something that makes you angry or defensive.

Then you are not who I'm talking about, and I have no argument with "understanding equivalence". I do have a problem when people are totally unclear about what they are talking about, belittle others for not making all the same (unstated) assumptions that they are, and try to shut down discussion of anything else other than what they want to talk about (or say that it has no value). And I've seen A LOT of that surrounding this topic.