On 7/1/2010 9:39 AM, Ken Norton wrote:
> I'm sorry if I came across a little snippy to Chuck. But let me explain my
> thinking...
>
> 1. The bokeh effect with the partially blurred gate is part of what I was
> attempting to achieve here.
I've been biting my tongue for days. Now yet another of my favorite
correspondents on the list seems to me to be misusing or
misunderstanding the term bokeh. I see what seems to me to be a
conflation three quite distinct effects, DOF blur, grain and bokeh.
Look at this, rather nice, image closely. Look at the left side, where
post and leaves are in focus. That is GRAIN. Grain is a feature of the
film, and thus is the same in all parts of an image, regardless of focus.
Now look at the background. Doesn't look the same, does it? It's
composed of lots of tiny circles with bright edges and dark centers.
They are larger and of different character than the actual grain. They
have largely obscured the actual grain. The character of these OOF
circles is BOKEH.
> By having the gate gradually get softer the way it does,
That is DOF BLUR.
To quote Ken N's new hero, Ken R.:
"Bokeh describes the rendition of out-of-focus points of light.
Bokeh is different from sharpness. Sharpness is what happens at the
point of best focus. Bokeh is what happens away from the point of best
focus.
Bokeh describes the appearance, or "feel," of out-of-focus areas. Bokeh
is /not/ how far something is out-of-focus, bokeh is the character of
whatever blur is there."
Now go here to read the rest of his brief, cogent description, with
visuals of the different kinds of bokeh.
<http://www.kenrockwell.com/tech/bokeh.htm>
There have been several instances here lately of comments on posted
images praising the bokeh, when what I believe they mean to praise is
the good use of DOF to separate foreground subject from background.
Either that or their preference in bokeh is for what Ken R. (and I) call
bad bokeh.
Good, recent examples are Jim N's day lily shots with the 35/3.5 Macro.
The latest is a great subject, nicely composed and using DOF to isolate
the subject. However, it has classic, dark center with hard, bright edge
bokeh, which I find less appealing than bokeh can be. A little blur goes
a long ways toward softening those edges.
<http://www.moosemystic.net/Gallery/Others/Nichols/Last_Yellow_Lily.htm>
Unfortunately, blur, and I've tried a lot of variations, can only
alleviate the issue, achieving something like what Ken R. calls Neutral
Bokeh. I've tried several approaches, but haven't yet managed to herd
the brightness back from edge to center. Giving the subject a little
more 'pop' with LCE does at least pull the eye away from the background
a bit more.
> it draws the eye back to the left and towards the post again. The eye gets ...
>
Yup, no argument from me. Not what I would have done, but a perfectly
cogent plan and execution. It may be simply that my 'eye' like the rest
of me, doesn't like being told what to do. :-)
> 2. Everybody has their own opinions about grain/noise, but as the image is
> substantially blurry, but contains a tremendous amount of visual information
> in the blurred area, the eyes are screaming for
> something to focus on. By providing texture through grain, the eyes are able
> to establish a distance point-of-reference. However, not without a twist...
>
> Grain, dots, noise, etc., in an image such as this, or an impressionist
> painting trigger a very interesting visual trait. The human eyes will rarely
> focus on the exact same "dot" in the picture.
> In fact, the left and right eyes relocate to different "dots" pretty much
> every time you blink or move your head. This causes a slight focus shift as
> well as a slight positional shift. The end result is a
> very slight 3D effect as the background in the scene takes on a movement
> shimmer. Our visual processing nullifies most of this shimmer, but the effect
> is there. This is why many impressionist paintings look 3D. Everybody has a
> dominant eye, for close-up and the other eye is usually dominant for
> distance. In a picture such as this, the human brain will be switching back
> and forth between the eyes as dominant. This also contributes to the 3D
> characteristic as well as implied movement within the picture.
>
Again, a well thought out and presented argument. The problem is that
you refer to grain as the operative factor here, whereas the 'bad', hard
edged, busy, edgy bokeh is what's creating the effect.
As a matter of personal reaction, all that eye-brain stuff detracts from
the image for me. What should, to me, be a relaxing image of bucolic
landscape isn't. It provokes anxiety, instead.
I tend to think I might find your idea and it's execution pleasing if
executed using a lens with good bokeh, so that the film grain could be
seen throughout, not masked by busy bokeh. I've tried a very rough
approximation of what that might look like by blurring the background
bokeh, then adding artificial grain.
<http://www.moosemystic.net/Gallery/Others/AG/Grain_Bokeh.htm>
To get anything like as strong an effect as the bokeh has, I did a
second, higher level of "grain". I have to say, though, that even the
lower level seems to me slightly stronger than the actual film grain, as
seen in the objects in focus in the foreground.
Most 50 mm, 'normal' symmetrical double Gauss lens designs seem to have
the same problem with relatively close subject focus and distant
background. I've noted this same effect with the Mij 50/1.8
<http://www.moosemystic.net/Gallery/MPhotos/Home/5018bokeh.htm>
> Paintings almost always have a "tooth" to the surface. Either through the
> underlying canvas or the brushstrokes themselves. This tooth is what provides
> a focus point for the human eye. On a noiseless/grainless photograph printed
> on smooth-glossy paper, the picture lacks any surface reference point for the
> eyes. We end up seeing the glass or reflections in the surface. Same with
> computer monitors, unless you have a nasty monitor (like the one I use at
> the office), the transparancy is such that you end up looking through the
> image if there is large areas of blurriness.
>
I understand the argument. Obviously, our visual systems and/or our
tastes differ somewhat. I tend to find such textural "visual aids"
distracting, both in photographic and painted/drawn images, and prefer
them subtler than they often are. As with some other visual things, my
unusually acute vision may mean I see the detail of the texture/whatever
more clearly.
Moose
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