Dof

[viramati]

I find it hard to believe the DOF scale that you see in the X100. Lets say I set I set the focus at 7ft at f8 it then shows the DOF to be from about 5'6" to 10". Now I have a great little programme that I use for calculation DOF and use it in conjunction with the M9 so if I enter 7' at f8 in that it says everything from 4.2'to 17 ft will be in focus for a 24mm lens (x100 is a 23mm lens) if I dial in a 35mm it gives me more or less the same readings as the X100. Strange that they have got a 23mm lens to behave optically like a 35 or is their scale wrong or am I missing something

 

[foolproof]

sorry, read it wrong

 

[Sparrow]

m9 is full frame, x100 is not so its lens is actually 35mm in 35m terms. Don't tell me you didn't know that 😱

Yes, but that's only true with regard to FOV not for DOF

 

[Pickett Wilson]

Even at that, you need to do some real world testing and see what works for you. Acceptable DOF is based on factors other than focal length. The ultimate size you plan to print makes a difference, as does the assumptions the manufacturer made when he calibrated that DOF scale.

 

[foolproof]

Yes, but that's only true with regard to FOV not for DOF

yeah i read it wrong 😱

 

[dc5]

Is it even true for FOV? You're just cropping the 35mm image from the center of the 23mm image... everything stays the same, just cropped. To get that same image with FF and 35mm lens, one would need to move to a different location and spacial relationships in the photo would be different.

 

[Sparrow]

yeah i read it wrong 😱

no problem, it gets confused easily round these parts 🙂

 

[Sparrow]

Is it even true for FOV? You're just cropping the 35mm image from the center of the 23mm image... everything stays the same, just cropped. To get that same image with FF and 35mm lens, one would need to move to a different location and spacial relationships in the photo would be different.

DOF decreases as;

focal length increases, film/sensor size increases or the aperture increases

from there it's pick-n-mix as you wish 🙂

 

[ferider]

DOF decreases as film/sensor size increases

Only correct for constant FOV. For constant focal length, DOF increases with increasing sensor size. 🙂

 

[Sparrow]

can we agree on

"DOF decreases as;

focal length increases or the aperture increases

from there it's pick-n-mix as you wish"

 

[ferider]

Yes we can 🙂

-------------------

Coming back to the OP's question:

The Fuji X100 @ f2 has similar DOF than the M9+35mm at f2.8.

Roland.

 

[antiquark]

I find it hard to believe the DOF scale that you see in the X100. Lets say I set I set the focus at 7ft at f8 it then shows the DOF to be from about 5'6" to 10".

They might be using a CoC (circle of confusion) of 0.01 mm, instead of 0.02. CoC tells you how blurry things will be at the outer limits of the depth of field. In your example above, objects at 7ft will be perfectly in focus, but at 5'6" and 10", they will be slightly out of focus.

Traditional DOF calculations are based on a certain print size. Maybe Fuji tightened up their DOF calculations to make the pixel-peepers happy?

 

[rxmd]

Is it even true for FOV? You're just cropping the 35mm image from the center of the 23mm image... everything stays the same, just cropped. To get that same image with FF and 35mm lens, one would need to move to a different location and spacial relationships in the photo would be different.

No, it's the same. Try it one day - put a 50 on your camera, shoot a scene, put a 90 on your camera, shoot the center of the same scene, and then crop the 50 shot to the angle of view of the 90. You'll find that the images look identical perspective-wise (ignoring other crop-related effects such as grain, different DOF etc.)

In other words, with a 23 on a crop sensor and a 35 on a full frame sensor you can shoot the same scene and get the same angle of view without moving anywhere, and spatial relations remain the same.

We've had several threads on that in the past and somewhere I even posted pictures illustrating it for a 15 and a 50.

 

[rxmd]

They might be using a CoC (circle of confusion) of 0.01 mm, instead of 0.02. CoC tells you how blurry things will be at the outer limits of the depth of field. In your example above, objects at 7ft will be perfectly in focus, but at 5'6" and 10", they will be slightly out of focus.

Traditional DOF calculations are based on a certain print size. Maybe Fuji tightened up their DOF calculations to make the pixel-peepers happy?

Most DOF calculators apply different CoC sizes for crop sensors and for film/FF sensors. This seems to have been the case with whichever online calculator the original poster had. For the M9, it used the values for full frame, with a larger allowable circle of confusion and consequently more DoF. Case closed, film at 11.

 

[Pickett Wilson]

My usual example (cropped to fit - originals were same size)

Top is a FF EOS 5D with 24mm lens at 2.8
Bottom is a Panasonic LX-3 24mm (FF equivalent) at 2.8

 

[tlitody]

http://www.bobwheeler.com/photo/Documents/DOFExpo2.pdf

 

[viramati]

What I wanted to say is that the X100 display shows almost the same readings as this DOF calculator shows when the lens is set to 35mm not 23mm which is the actual focal length



this I find somewhat strange

 

[Andy Kibber]

This is a dangerous road to go down. There have been some rather spectacular fights on RFF about DOF across different frame sizes.

The beauty of digital is that you can test to your heart's delight and decide for yourself what's acceptably sharp.

 

[foolproof]

What I wanted to say is that the X100 display shows almost the same readings as this DOF calculator shows when the lens is set to 35mm not 23mm which is the actual focal length

View attachment 85383

this I find somewhat strange

Mines the same. Seems there's only two things then, 1 - Fuji programmed it wrong and put in a true 35mm scale instead of 23mm equiv 🙁 or 2 - They didn't tell anyone and actually put in a full frame sensor as a little suprise 😱 😀

Would I be right to think that to compensate you could just use a stop up to roughly judge the zone. ie. f8 on the x100 in camera scale would actually show you what 5.6 would if scale were correct?

 

[tlitody]

I'd suggest you play with camera and lens and find out what results you get with it and its different apetures and dof scale. That way you can forget all the maths and theory and just use your own real world examples as your guide. i.e. Know your kit.