Photographer Joe has been using his 85mm "portrait" lens on his 1.6x crop factor camera. He likes the results, but he hears that FF cameras will give him less DOF, allowing him to isolate his subject more.
So, photographer Joe rents or buys a shiny FF camera. He wants to see how his portraits are going to look, so he goes out to the park with his kid and his 85mm "portrait" lens on his new camera.
He gets home and cannot believe his eyes. "Wow! look how shallow the DOF is!" His conclusion is that the DOF is shallower on his new camera.
We all know what really happened (don't we?).
He framed his subjects as he always did. His style has not changed, after all. In order to maintain the same shots that he did before, he moved closer.
Now, IMO, it doesn't really matter whether this DOF difference is due to the camera or due to the photographer. In fact, I think it doesn't even really matter if photographer Joe is aware that he is the cause of the reduced DOF.
Unlike Joe, Jim likes zoom lenses and he likes to shoot animals at the zoo. From the fence at the monkey cage, he often uses a setting of about 85mm on his 24-135mm lens to capture the monkeys with is 1.6x crop camera.
Again, he hears "somewhere" that FF will reduce his DOF and create a more blurred background.
So he gets a FF camera, slaps on his trusty zoom, and off the zoo he goes.
He shoots the monkeys as he always does (he really like monkeys), goes home and is amazed. "Wow!...."
But we all know what really happened, right?
He zoomed (changed the focal length) to 135mm, to maintain the same framing of his beloved monkeys. The focal length change directly affects the DOF.
Again, it was the photographer's reaction to the new format that changed the DOF, but that is irrelevant. The DOF changed.
No, not a great example in my opinion. Apples to oranges...50mm to 85mm. Those lenses are going to have different characteristics. Compare with the same lens on each camera, "zooming with your feet" to maintain the same field of view. Then compare shots from the same distance with the FF image cropped to the same FOV digitally.
Disagree. Using different lenses is fine. F/stop behavior doesn't change with the lens. In other words, f/4 is the same on a 70-200 f/4 as it is on an 85 f/1.2. The only thing that matters is that the same f/stop is used for the same field of view. Lens is irrelevant.
Mike Mahoney wrote:
Exactly .. in the hands of a skilled photographer with an adequate assortment of lenses DOF can be created pretty much the same regardless of the sensor size.
And the shooters style is often ignored in these discussions .. some prefer to be closer to their subjects while shooting but still maintain a shallow DOF.
The spirit of what you say is correct but you bump into lens limitations. For example, you cannot replicate the dof on a ff camera of an 85mm lens at f/1.2 on a crop camera. There just isn't a lens fast enough with that field of view to do that.
ghozer wrote:
The spirit of what you say is correct but you bump into lens limitations. For example, you cannot replicate the dof on a ff camera of an 85mm lens at f/1.2 on a crop camera. There just isn't a lens fast enough with that field of view to do that.
cogitech wrote:
Regardless of how skilled a photographer is, they have a style (good or bad).
It really is as simple as that and that is why everyone immediately notices a difference when they buy a FF camera.
The merits of using different sensor sizes for different applications are significant and as you point out the difference is obvious. Having extensively used formats from 4X5 to medium format and both full frame & cropped digital the differences are not lost on me. But that is a different discussion.
But until some common misconceptions about DOF are cleared up it's hard to move forward with that type of discussion. So it bears repeating ... sensor size has no effect on depth of field.
Now if someone wants to ask the question "what would the best focal length and sensor size combination to produce the narrowest depth of field at 5 feet subject distance like I see in some of the cool wedding shots posted on the wedding forum" then we can have that discussion as well.
It's just that the OP's original question along with the usual incorrect answers & comparison photos followed by mass confusion shows that many do not have the basic understanding of depth of field. So starting with the basics may be a good idea.
Mike Mahoney wrote:
The merits of using different sensor sizes for different applications are significant and as you point out the difference is obvious. Having extensively used formats from 4X5 to medium format and both full frame & cropped digital the differences are not lost on me. But that is a different discussion.
But until some common misconceptions about DOF are cleared up it's hard to move forward with that type of discussion. So it bears repeating ... sensor size has no effect on depth of field.
Now if someone wants to ask the question "what would the best focal length and sensor size combination to produce the narrowest depth of field at 5 feet subject distance like I see in some of the cool wedding shots posted on the wedding forum" then we can have that discussion as well.
It's just that the OP's original question along with the usual incorrect answers & comparison photos followed by mass confusion shows that many do not have the basic understanding of depth of field. So starting with the basics may be a good idea....Show more →
I think it bears repeating (over and over, I guess):
The size of the sensor indirectly affects the DOF because it determines the effective FOV. This causes the photographer (whether he/she is aware of it or not) to either move closer or use a longer focal length, both of which DIRECTLY affects the DOF in the shot.
Basics? Anyone who wants to know the basics ought to simply read my two scenarios a page back. They explain precisely why we experience less DOF on a FF sensor than a crop sensor. They illustrate why this happens in two very basic, real-world situations. They are also irrefutably true.
I'll say it one more time; FF cameras effectively do have less DOF than crop cameras, but it is only because there is human behind the camera. A human who responds to the FOV of a larger sensor by moving closer or increasing the focal length.
There is no need to understand it any better than photographer Joe or photographer Jim and the answer is the same regardless.
Mike Mahoney wrote:
DOF is determined by three things, and three things only:
1) Lens focal length
2) Aperture used
3) Distance to subject (focus distance)
Notice that sensor size is not included in the three DOF determinants.
Notice that sensor size is not included in the three DOF determinants.
Notice that sensor size is not included in the three DOF determinants.
and read until it sinks in. Notice that the sensor size IS included in the DOF calculations. But read the whole thing, please. Some people read only the last pages of "Anna Karenina" and then they are convinced it's a novel about a railroad accident.
Yes, I was waiting for the person who would point this out to me .. the sensor size is used there in the context of determining the circle of confusion.
Of which you know nothing about or else you would not have used it in an attempt to support your idea that sensor size effects DOF. So come back when you have a grasp on COF (circle of confusion) and we'll talk again.
Actually I'll withdraw my offer to talk again as this seems to be going nowhere
But do take a few minutes to understand circle of confusion .. it is a largely visual measurement originally used in printing, and established the size or COF required to see a print sharp at different viewing distances and print sizes.
Mike, now you start contradicting yourself. Previously you wrote:
Mike Mahoney wrote:
DOF is determined by three things, and three things only:
1) Lens focal length
2) Aperture used
3) Distance to subject (focus distance)
Now you are adding :
4) COC (what is COF?)
So it's not "three things, and three things only" is it? The COC depends (among other things as well) on the sensor size (via magnification, distance, etc). End of story.
gfiksel wrote:
Mike, now you start contradicting yourself.
Mike Mahoney wrote:
DOF is determined by three things, and three things only:
1) Lens focal length
2) Aperture used
3) Distance to subject (focus distance)
Now you are adding :
4) COC
So it's not "three things, and three things only" is it? The COC depends (among other things as well) on the sensor size (via magnification, distance, etc). End of story.
On top of that, he is refusing to acknowledge that the sensor size directly affects the FOV, and that the photographer reacts to FF FOV difference by changing one of the following:
1) Lens focal length
3) Distance to subject (focus distance)
Both of which he has admitted do directly affect the DOF.
Hard to imagine how anyones brain works who cannot see the obvious truth to this. Oh well. Hopefully at least the OP and some others can see this irrefutable truth.
"The term circle of least confusion is often used for the smallest optical spot a lens can make"
A measurement.
Now you are making up quotes ??
http://en.wikipedia.org/wiki/Circle_of_confusion
In photography, the circle of confusion diameter limit (“CoC”) is sometimes defined as the largest blur circle that will still be perceived by the human eye as a point when viewed at a distance of 25 cm
