Depth of Field questions..

[photoguy99]

This is so delicious.

 

[Village Idiot]

You can also see how a full frame camera with the same lens on it will give you a wider depth of field at the same focal length.

I think you are confusing DOF with FOV.

Village Idiot; the question was about depth of field, not the field of view.

If you adopt a more easily-understood terminology, yoiu would see that your answer confounds the original question and leads one down the wrong path.

Instead of using a term like WIDER to describe the DOF, use either DEEP or SHALLOW to describe the DOF. That way, the issue of lens focal length and sensor size will not enter the conversation needlessly.

But the sensor size, focal length, and FOV all contribute to the DOF size. WIDER DOF = DEEPER DOF and SHALLOWER DOF = NARROWER DOF.

 

[wfooshee]

There's a basic logic flaw in you're example. When you crop the image from the FF camera to compare it with the crop sensor camera then you're comparing a crop sensor camera with a crop sensor camera. To make an appropriate comparison you have to take the same photo with the two different format cameras. When you do that you'll discover that the format size does factor into the equation.

It makes no sense to compare two different photographs and then claim they share a characteristic nor does it make any sense to alter the function of one of the cameras (making them the same) and then claim they're the same.

To take the "same photograph" with two different format cameras you must use both cameras from the exact same position so that perspective remains the same. You should then equalize the FOV between the two systems and this will require using different lens focal lengths. At the same f/stop then the smaller format camera will produce more DOF.

The smaller the recording format gets the more DOF the system will produce as a general rule and vice versa.

The easiest way to look at that mathematically is to look at the formula for hyperfocal distance.

...........f ^ 2
H = ----------
...........NC

(H)hyperfocal distance = (f)focal length squared / N(f/stop) * C(circle of confusion). The value for circle of confusion is variable with the recording format. As the sensor or film size decreases the CoC decreases and that formula produces a different result moving the hyperfocal distance closer to the camera -- more DOF.

Joe

Where I was going with that is the fact that cropping the picture from the FF camera, shot with the same lens used on both cameras, and printed to the same scale, does in fact yield the same image from the same lens. It would be the same effect as masking the sensor on the FF camera.

The difference would be the possible resolution difference, because if the FF sensor was not significantly higher overall resolution than the smaller sensor than it would be a lower-resolution image, using effectively larger pixels for the same image area, which brings in the CoC issue, which I've not been able to grasp. pgriz's post set off some light bulbs in my head, I think.

 

[Designer]

So which gives the wider DOF, FF or crop?????

Instead of asking about WIDER DOF, why not say "DEEPER"? That term is more in keeping with the physical manifestation of DOF, being as it is farther from or closer to the camera.

Now to rephrase your question: "So which gives the DEEPER DOF, FF or crop?????

(answer) Use the DOF calculator to find out for yourself. (Not that I don't want to do it, but your doing it yourself will show you better than anyone here can explain and you will see exactly how much it affects the DOF for a given lens focal length and distance.)

 

[Village Idiot]

Told you...can of worms.

 

[Designer]

You can also see how a full frame camera with the same lens on it will give you a wider depth of field at the same focal length.

I think you are confusing DOF with FOV.

Village Idiot; the question was about depth of field, not the field of view.

If you adopt a more easily-understood terminology, yoiu would see that your answer confounds the original question and leads one down the wrong path.

Instead of using a term like WIDER to describe the DOF, use either DEEP or SHALLOW to describe the DOF. That way, the issue of lens focal length and sensor size will not enter the conversation needlessly.

But the sensor size, focal length, and FOV all contribute to the DOF size. WIDER DOF = DEEPER DOF and SHALLOWER DOF = NARROWER DOF.

Yes, but that is not what he asked.

 

[Designer]

Told you...can of worms.

And it wasn't necessary, and served only to confound the issue.

How about just answering his question, as I did.

 

[Village Idiot]

So which gives the wider DOF, FF or crop?????

Instead of asking about WIDER DOF, why not say "DEEPER"? That term is more in keeping with the physical manifestation of DOF, being as it is farther from or closer to the camera.

Now to rephrase your question: "So which gives the DEEPER DOF, FF or crop?????

(answer) Use the DOF calculator to find out for yourself. (Not that I don't want to do it, but your doing it yourself will show you better than anyone here can explain and you will see exactly how much it affects the DOF for a given lens focal length and distance.)

Told you...can of worms.

And it wasn't necessary, and served only to confound the issue.

How about just answering his question, as I did.

Because just answering a question can often lead to more questions. Forums are for discussion. Don't want to discuss a topic? Well then...

 

[Designer]

This is so delicious.

???

This thread got off track at least twice, and might have been only a couple of frames long if people would just answer the OP's question without trying to throw a monkey wrench into the works.

 

[wfooshee]

So which gives the wider DOF, FF or crop?????

Instead of asking about WIDER DOF, why not say "DEEPER"? That term is more in keeping with the physical manifestation of DOF, being as it is farther from or closer to the camera.

Look at the smiley on that question and lighten up, K? And look at the lines I quoted, where the same member stated two different answers to that question. It was a bit of a dig at him.

As for off-track for the thread, The question of how to get depth of field became how to calculate it using known or available parameters, and one of the factors turns out to be sensor size, which I clearly did not understand. That discussion still pertains to the OP's question.

I see your point about "deeper" and "shallower" for degrees of DoF, though, and will make the effort to use that terminology.

 

[photoguy99]

It is delicious for personal and private reasons. Suffice it to say I am enjoying watching certain people make asses of themselves.

 

[Designer]

.. one of the factors turns out to be sensor size, which I clearly did not understand. That discussion still pertains to the OP's question.

No, it doesn't. The OP asked if his lens could do that and how to make a shallow DOF. Given that he has a camera (no matter what size sensor) and he wasn't planning to change the camera to affect the DOF, the sensor size did not enter the equation, nor did it need to.

I answered the question that was asked based on existing conditions.

 

[Stormchase]

I think the OP read this and then sold his camera lol.

 

[photoguy99]

These explanations are always hilarious and worthless.

Go take a dozen photos.

Pick an object about four feet away. Take four photos of it. One with the aperture wide open. The next 3 or 4 clicks closed down. The next another 3 or 4 clicks. The last closed all the way down.

Pick an object about 10 feet away. Take the same four photos.

Pick an object 30 feet away. Again.

Now look at those dozen photos. Look at them. Really look.

Repeat for different focal lengths as necessary.

Now you know 1000x as much as any of these dumb threads will teach you.

Photography is about looking. It's not about calculating. It's not about using cool apps. It's not about following oft repeated rules and methods found on some god damned web site or in some ridiculous book.

LOOK shoot and LOOK.

 

[Ysarex86 80]

These explanations are always hilarious and worthless.

Go take a dozen photos.

Pick an object about four feet away. Take four photos of it. One with the aperture wide open. The next 3 or 4 clicks closed down. The next another 3 or 4 clicks. The last closed all the way down.

Pick an object about 10 feet away. Take the same four photos.

Pick an object 30 feet away. Again.

Now look at those dozen photos. Look at them. Really look.

Repeat for different focal lengths as necessary.

Now you know 1000x as much as any of these dumb threads will teach you.

Photography is about looking. It's not about calculating. It's not about using cool apps. It's not about following oft repeated rules and methods found on some god damned web site or in some ridiculous book.

LOOK shoot and LOOK.

Yep, wanting to understand why and how things work is for stupid people. And the idea that you could do both and take photos to see the results plus understand why and how it works is only an idea that would occur to the ignorant. Understanding how something works doesn't in any way enhance or improve the experience of actually using it. Like flying an airplane. Pilots have to learn how to operate the plane for sure and get in plenty of practice flying, but making them study and understand the principles of aerodynamics is really dumb. I mean none of us would want to fly with a pilot who had wasted time studying aerodynamics right? In fact we know that any time wasted learning to understand aerodynamics just confuses a pilot and makes them a worse pilot.