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Must watch video on full frame vs crop cameras. "Full frame look" covered.


KarimNassar
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Oh, one more thing (since I'm getting it all out of my system).

 

To those who agree with his assertion that camera manufacturers are somehow "ripping you off" because the F/2.8 works more like a 5.6:

 

Understand that wider apertures are more expensive to engineer and produce than smaller ones. The glass is larger and heavier and requires more quality control in the optics. Canon doesn't charge more based on the DOF you get by using it, they charge more because it is technically more complicated to produce a constant aperture zoom with that amount of sharpness and aperture.

But producing a f2.8 aperture for an m43 system is a lot cheaper than doing it for full frame. The material cost is way lower. In fact the barrel distortion that the 12-35 has in proper raw files shows just how much they are saving on quality and quantity of materials. Those  full frame lenses are expensive, but they also feel expensive. Even the price of the new Panasonic 42.5 f1.2 is ludicrous. It's the same price as the Canon 50mm f1.2L! and the Fuji 56mm f1.2 is also about a third cheaper

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But producing a f2.8 aperture for an m43 system is a lot cheaper than doing it for full frame. The material cost is way lower. In fact the barrel distortion that the 12-35 has in proper raw files shows just how much they are saving on quality and quantity of materials. Those  full frame lenses are expensive, but they also feel expensive. Even the price of the new Panasonic 42.5 f1.2 is ludicrous. It's the same price as the Canon 50mm f1.2L! and the Fuji 56mm f1.2 is also about a third cheaper

 

But for every one 42mm f1.2 lumix lens that gets sold, canon sells about fifty of their 50mm L lenses.  The development costs of both lenses will be very much the same.  The L lens maybe costs twice the manufacturing cost if both lenses were made in equal numbers but since Canon probably sell one 50mm f1.2 lens to just about every professional photographer the world over - or just about every 5d or 1d owner in the world, they can manufacture in incredible numbers and thus deal in very large, easy to organise manufacture and material supply and run very efficiently.  Also, the 50mm L lens is a normal focal length.  the 42mm lumix is a telephoto - again dictating numbers sold.

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I thought I'd throw another spanner in the works regarding sensor size.  What I wanted to discuss is the ramifications of needing to open your lens up wide in order to obtain shallow dof.  Something that few seem to consider - me included until I started doing tests, is the fact that though we have lots of fast lenses for smaller sensors, are they actually capable of resolving as much sharp 'in focus' detail as a longer lens closed down a bit.  

 

This vid shows the difference between a Noritar medium format 80mm f2 (at f2) on full frame versus a hasselblad 150mm f2.8 (at f4), shooting medium format (60mm x 34mm).  It clearly shows how much of a difference having a lens working away from its limits can deliver a sharper in focus subject and as such deliver overall a greater overall in and out of focus separation or what we like to call 3d pop. 

 

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I thought I'd throw another spanner in the works regarding sensor size.  What I wanted to discuss is the ramifications of needing to open your lens up wide in order to obtain shallow dof.  Something that few seem to consider - me included until I started doing tests, is the fact that though we have lots of fast lenses for smaller sensors, are they actually capable of resolving as much sharp 'in focus' detail as a longer lens closed down a bit.  

 

This vid shows the difference between a Noritar medium format 80mm f2 (at f2) on full frame versus a hasselblad 150mm f2.8 (at f4), shooting medium format (60mm x 34mm).  It clearly shows how much of a difference having a lens working away from its limits can deliver a sharper in focus subject and as such deliver overall a greater overall in and out of focus separation or what we like to call 3d pop. 

 

 

 

Obviously we're moving up a notch in sensor size comparing a full frame sensor to 70mm, but the theory is quite accurately shown here.

If one were to wish to obtain the same look on m43 they'd need a 40mm f1.2 and it's simply not possible to get a high performance lens of this type.  Taking the hasselblad lens to f2.8 maintains sharpness, and dof gets even shallower.  - you'd need a true 40mm f0.75 to match it with m43.

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Because an often ignored fact is, that DoF has another factor: CoC, introducing the pixel size as equally important as the sensor size, or in other words: The sensor size means nothing unless you don't know the pixel size on it. The same lens with the same aperture will have different DoFs at different ISOs. How is that? Because using higher than the sensor's native ISO results in lower resolution. The pixels with actual signals within the noise are being sampled over time (video of cause), but they effectively behave like bigger (and therefore less) pixels, increasing the depth of field.

 

EDIT: On the net, this correlation is frequently denied, stating that higher ISO allowed for smaller apertures and that this alone would then increase the DoF. I admit that CoC combined with ISO is not a very obvious factor. There should be tests executed by maintaining exposure exclusively with ISO and NDs to prove or refute the theory.

 

All this math to reliably compare just too many contributing factors is futile imo. 

I'm not sure that I understand what you are talking about here. Resolution effects DOF?? Since when?? 5D mark 1, 2 and 3 all have different sized pixels and resolution, yet a 50mm f/1.4 renders the same DOF on all of them. What basis would there be to assume otherwise?

 

If one were to wish to obtain the same look on m43 they'd need a 40mm f1.2 and it's simply not possible to get a high performance lens of this type.  

 

Not so fast. Nikon has a 55mm f/1.2, and you could throw that on a speedbooster to yield an effective 38.5mm f/0.9.

 

Many ways to skin a cat... ;)

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I'm not sure that I understand what you are talking about here. Resolution effects DOF?? Since when?? 5D mark 1, 2 and 3 all have different sized pixels and resolution, yet a 50mm f/1.4 renders the same DOF on all of them. What basis would there be to assume otherwise?

 

 

Not so fast. Nikon has a 55mm f/1.2, and you could throw that on a speedbooster to yield an effective 38.5mm f/0.9.

 

Many ways to skin a cat... ;)

 

55mm f1.2 nikon is not sharp enough wide open to compete with the hasselblad 150mm at f2.8.  It's a different ballpark all together.

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Perhaps- I'm thinking it isn't as impossible as you may say. We have a 25mm f/0.95 lens which is pretty sharp open- its actually easier to make one that covers a smaller sensor since you don't need as much glass (image circle can be made smaller). That's why you don't see many FF lenses less than 1.2 and medium format below 2, however they are popular and plentiful in the size under them.

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In this video, the guy constantly mixes up perceptive image differences (such as field of view) with technically objective physical measurements (f-stop, ISO). It's almost a piece of propaganda made to confuse photographers who use to make calculations based on perceptive differences ("50mm f2.8 on full frame is 25mm f1.4 on MFT") that can be practically helpful but have technically never been correct.

 

Like convincing people that a compact car doesn't really drive at 100mph like a sedan because its wheels are smaller - so they need to turn twice as fast, which means that the car needs to run at double speed to match the sedan; according to which the compact is really only half as fast as the sedan, and the 100mph of the compact "aren't really 100mph" - and manufacturers like Volkswagen or Toyota fool you when they say that their cars run 100mph. [By now, everyone is so utterly confused in their head through this pseudo-logic that they believe this complete bullshit.]

 

Just two measures to deflate this guy:

(1) Tell him to go do cinema DoPs and tell them that their light meter measurements (in ISO and f-stops) for smaller film formats like 16mm have been wrong because the f-numbers weren't really the same for 16mm film with its smaller frame size.

(2) Give him a Blackmagic Pocket camera with its 1" sensor and let him compare noise levels and dynamic range to a consumer MFT or APS-C compact. Maybe he'll learn that it's about size of photo sites, not sensor size. (And that doesn't even factor in technology such as back-illuminated sensors vs. conventional sensors.)

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I'm not sure that I understand what you are talking about here. Resolution effects DOF?? Since when?? 5D mark 1, 2 and 3 all have different sized pixels and resolution, yet a 50mm f/1.4 renders the same DOF on all of them. What basis would there be to assume otherwise?

 

I did'nt know you were not familiar with that. Of course resolution affects DoF. If a pixel on the sensor is very big, it swallowes a bigger circle of confusion, whereas if you have four times as many pixels on a identically sized sensor, it also needs a four times smaller CoC to render sharp outlines. 

 

It's not the size of the sensor alone that affects DoF, it's the size of the sensor relative to it's resolution. This video explains it (jump to about 4'30"):

 

What is more: 

One 50 mm f1.4 is not as sharp as any other lens with the same specs, meaning it may not be able to focus an equally small CoC. Would the comparison of a 21 MP sensor (M2) to a 22 MP sensor (M3) show significant differences in DoF? I doubt so. There is so much signal processing going on before you actually see the image, particularly with HD video.

 

What I am trying to say: Things are much more complicated in the real world, and the only rule that always applies is that a faster lens will bring you less noise and better control over DoF. 

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Perhaps- I'm thinking it isn't as impossible as you may say. We have a 25mm f/0.95 lens which is pretty sharp open- its actually easier to make one that covers a smaller sensor since you don't need as much glass (image circle can be made smaller). That's why you don't see many FF lenses less than 1.2 and medium format below 2, however they are popular and plentiful in the size under them.

Possibly part of it but then faster (than 1.4 or so) lenses have not really been needed with full frame.

 

A micro four thirds 25mm f1 lens has slightly MORE depth of field than a 50mm f2 full frame lens (for a similar shot).

 

I think a lot of the fast m43 lenses started appearing to give  depth of field approaching that of "normal" aperture lenses on larger sensors for stills.

There have been a few faster ones for FF though mostly expensive and of course there will shortly be the Mitakon 50 0.95 lens available in Sony FE mount for well under $1000.     

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Of course resolution affects DoF. If a pixel on the sensor is very big, it swallowes a bigger circle of confusion, whereas if you have four times as many pixels on a identically sized sensor, it also needs a four times smaller CoC to render sharp outlines.


No.

Depth-of-field (and circles-of-confusion) is a purely optical property, regardless of what is receiving the image at the focal plane.

Coarser resolution can make the sharply focused areas look softer (similar to the less sharply focused areas), but a given depth-of-field optically remains constant, regardless of sensor/film resolution.

 

It's not the size of the sensor alone that affects DoF, it's the size of the sensor relative to it's resolution. This video explains it (jump to about 4'30"):


No.

Depth-of-field is an optical property. The size and resolution of the film/sensor have nothing to do with the optical property of depth-of-field. The only exception to this rule occurs when the sensor corners creep into the optically inferior edge of the image circle.

 

What is more: 
One 50 mm f1.4 is not as sharp as any other lens with the same specs, meaning it may not be able to focus an equally small CoC.


Yes.  Some lenses resolve more sharply than others.

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Depth-of-field (and circles-of-confusion) is a purely optical property, regardless of what is receiving the image at the focal plane.

tupp, you didn't check the meaning of 'circle of confusion', did you? (Actually it is the *only* reason for shallowDoF, I just brought the resolution into the equation) You take for granted, that when you see a projection, there don't need to be reflective textures that are fine enough to define the individual picture element you recognize? This is, excuse me, a rather naive way of understanding optical laws.

Coarser resolution can make the sharply focused areas look softer (similar to the less sharply focused areas), but a given depth-of-field optically remains constant, regardless of sensor/film resolution.

Softer? You mix up resolution and sharpness. Low resolution images may look out of focus when scaled to the same size as a high resolution image.

I never wrote: The CoC-resolution-connection is the most important factor for DoF, but it is inseparable, and therefore your statement 'a given depth-of-field optically remains constant, regardless of sensor/film resolution.' is wrong, given, that there always has to be a medium that receives the light coming through the lens - be it dust or smear on a glas pane, chalk grain on a wall, silver nitrate crystals, pixel circuits, your retina's rod cells (by the way: our night vision has absolute depth of field, even though our irises are wide open) -optically, physically, whatever.

Instead of arguing, you could make a test of your own. Open the aperture, then film with your camera's highest ISO/gain. You will find a considerably bigger depth of field than with your lowest ISO.

It's not proportional to what would change with closing the aperture, but nobody said so.

Yes. Some lenses resolve more sharply than others.

I'm happy we agree. Then what can all the pseudo-scientific comparisons of crops and lenses by their sheer numbers be worth?
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tupp, you didn't check the meaning of 'circle of confusion', did you? You take for granted, that when you see a projection, there don't need to be reflective textures that are fine enough to define the individual picture element you recognize?

No.

I do not wish to get into a semantics argument, but the definitions of depth-of-field and circle-of-confusion involve basic, well-established optical properties that apply to imaging. The resolution of the sensor/film (and projector/monitor) is not a consideration, as depth-of-field is a purely optical characteristic.

The Wikipedia page on depth-of-field addresses this very point (note limitation #6).

 

This is, excuse me, a rather naive way of understanding optical laws.

No need to get personal, but you would be mistaken if you considered sensor/film resolution as an optical property.
 
 

Softer? You mix up resolution and sharpness. Low resolution images may look out of focus when scaled to the same size as a high resolution image.

The term "Softer" is generic. It can apply to the properties of both resolution and sharpness.
 
 

I never wrote: CoC is the most important factor for DoF, but it is inseparable,

I never stated that you wrote so.

 

and therefore your statement 'a given depth-of-field optically remains constant, regardless of sensor/film resolution.'  is wrong, given, that there always has to be a medium that receives the light coming through the lens - be it dust or smear on a glas pane, chalk grain on a wall, silver nitrate crystals, pixel circuits, your retina's rod cells

The focal plane/surface is part of the optical system, but the resolution of the medium at the focal plane/surface has nothing to do with optics.

 

Instead of arguing, you could make a test of your own. Open the aperture, then film with your camera's highest ISO/gain. You will find a considerably bigger depth of field than with your lowest ISO.

It's not proportional to what would change with closing the aperture, but nobody said so.

Huh?

I am not sure what you are proposing, but it appears that you are suggesting that the depth-of-field will change if I merely vary the ISO setting on my camera while the lens and its aperture remain the same.

Is that what you are saying?

If so, would you be interested in a little wager?
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I do not wish to get into a semantics argument, but the definitions of depth-of-field and circle-of-confusion involve basic, well-established optical properties that apply to imaging. The resolution of the sensor/film (and projector/monitor) is not a consideration, as depth-of-field is a purely optical characteristic.

The Wikipedia page on depth-of-field addresses this very point (note limitation #6)

 

I also don't wish to argue. My point was, that there are influences on DoF in real world conditions that add up to the "Full Frame Look" in such a way as making the comparison of 5D (that's it, more or less) to cameras with smaller sensors futile. 

 

Your Wiki-links states:

Most DOF formulas, including those discussed in this article, employ

several simplifications

:

 

 

Among them demosaicing, sharpening and image noise reductions. Not mentioned was pixel binning, all methods that inherently reduce resolution.

 

I'm not saying this applies only to full frame cameras, I just ask if it's unreasonable to assume that it affects their look to a different degree.

 

The resolutions of the imaging medium and the display medium are ignored. If the resolution of either medium is of the same order of magnitude as the optical resolution, the sharpness of the final image is reduced, and optical blurring is harder to detect.

 

 

But not alone harder to detect. Lenses generally are calculated to produce the smallest possible CoCs, in order to focus a point within the physical borders of the pixel. The bigger the area of the pixel, the greater the hyperfocal distance, the bigger the DoF, that is in the real world a matter relative to resolution.

 

Precise focus is possible at only one distance; at that distance, a point object will produce a point image.[1] At any other distance, a point object is defocused, and will produce a blur spot shaped like the aperture, which for the purpose of analysis is usually assumed to be circular. When this circular spot is sufficiently small, it is indistinguishable from a point, and appears to be in focus; it is rendered as “acceptably sharpâ€. The diameter of the circle increases with distance from the point of focus; the largest circle that is indistinguishable from a point is known as the acceptable circle of confusion, or informally, simply as the circle of confusion. The acceptable circle of confusion is influenced by visual acuity, viewing conditions, and the amount by which the image is enlarged (Ray 2000, 52–53). The increase of the circle diameter with defocus is gradual, so the limits of depth of field are not hard boundaries between sharp and unsharp.

 

 

The amount by which the image is enlarged. Exactly. Relative size is all about resolution. 

 

For my argument I didn't perform an own test. Note also, that many sources on the net contradict me (highlighted red in my first post), like you, but only by ignoring the physics.

 

When we had 16 mm analog film we just knew there would be a noticable increase of DoF if we shot on TriX (ISO 400, as compared to ISO 100), even though we shot wide open.

 

When we had the first HD camcorders that had the same sensor size of 1/3" as our SD camcorders, we didn't expect a difference as far as DoF was concerned. But there was, not dramatically, not enough to let us pass 35 mm adapters ('DoF machines', proof that the 'big sensor' factor mattered the most).

 

Once again: I don't intend to question every single of Northrups statements, nor do I try to come up with a new theory. But for a "full frame look" (thread title, obviously referring to 5D) there are just too many of the 'several simplifications'.

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Is this what is going on, and does this help resolve it?

 

 

Depth of field and circles of confusion are optical properties, independent of sensor.

 

We should agree on this.

 

However,

 

The relevant circle of confusion changes depending on your sensor.

 

You want your lens to resolve well enough to get the best out of your sensor, but it doesn't need to be better. Larger photosites -> tolerance of larger circles of confusion. Lower resolution -> tolerance of larger circles of confusion.

 

Circles of confusion feed, mathematically, into depth of field calculations, because the depth of field is the region where things are acceptably in focus, as defined by your specified circle of confusion.

 

Next:

 

Other things affect resolution apart from megapixels - processing for instance. Noise reduction can reduce resolution. Higher ISOs have more aggressive noise reduction, so can have lower resolution.

 

So the argument is: Higher ISO -> more processing that lowers effective resolution -> larger acceptable circle of confusion -> deeper depth of field.

 

This isn't magic, it doesn't make any more of the scene be in focus. What it does is make more of the scene be equally just-out-of-focus, to put it one way, because the lower resolution is inherently less sharp and so more of the image will be "sharp enough."

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My point was, that there are influences on DoF in real world conditions that add up to the "Full Frame Look" in such a way as making the comparison of 5D (that's it, more or less) to cameras with smaller sensors futile.


When discussing depth-of-field in the "real world," the term applies only to real world optical systems.
 
 

Your Wiki-links states: "Most DOF formulas, including those discussed in this article, employ several simplifications:"

Among them demosaicing, sharpening and image noise reductions. Not mentioned was pixel binning, all methods that inherently reduce resolution.


No.

Re-read the "simplifications." All of those post-capture processes are ignored by the DOF formulas.

Depth-of-field is an optical property -- it has nothing to do with sharpening or softening an image after the image is received by the sensor/film.

Furthermore, not all of the methods that you mentioned change the resolution.

 

I'm not saying this applies only to full frame cameras, I just ask if it's unreasonable to assume that it affects their look to a different degree.


Full-frame, half-frame, 16mm, IMAX, 4"x5", 11"x14" -- the size of the medium at the focal plane really has nothing to do with the depth-of-field.

Depth-of-field and an image's "look" are two different things, but, certainly, DOF can affect the "look" of an image.

 

"The resolutions of the imaging medium and the display medium are ignored. If the resolution of either medium is of the same order of magnitude as the optical resolution, the sharpness of the final image is reduced, and optical blurring is harder to detect."


Well, this passage that you have quoted says it all: Resolution of the imaging medium is ignored.

When the resolution of the capture medium is similar (or greater than) the optical resolution, the captured image will seem more blurred throughout, making it more difficult to discern the depth-of-field. Nevertheless, the depth-of-field (an optical property) remains the same.

 

"The acceptable circle of confusion is influenced by visual acuity, viewing conditions, and the amount by which the image is enlarged (Ray 2000, 52–53)."

The amount by which the image is enlarged. Exactly. Relative size is all about resolution.


"Acceptable circle of confusion" and DOF are two different properties.

Magnification of the image at the film plane affects resolution, but not depth-of-field.

Cropping into and enlarging a captured digital image can lower the effective resolution, but manipulating a captured image has absolutely nothing to do with depth-of-field.

 

When we had 16 mm analog film we just knew there would be a noticable increase of DoF if we shot on TriX (ISO 400, as compared to ISO 100), even though we shot wide open.


I doubt that you would notice any difference in DOF with the same f-stop on the same lens, by merely changing film stocks.

Regardless, you weren't increasing the depth-of-field -- you might have been creating an image that had a coarser resolution overall, thus, making the overall image look softer and more homogeneously in the same focus.

 

When we had the first HD camcorders that had the same sensor size of 1/3" as our SD camcorders, we didn't expect a difference as far as DoF was concerned. But there was, not dramatically, not enough to let us pass 35 mm adapters ('DoF machines', proof that the 'big sensor' factor mattered the most).


Big sensors matter, but the size of the sensor doesn't change the DOF. Depth-of-field is an optical property.
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