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What causes this

MGrayson

Subscriber and Workshop Member
What causes this fringe around the bird...........is it camera shake or something else. THis is a JPG of the un edited RAW file?
Thanks Neil
Neil,

I don't see it until I stare for a while. I think it may be after-image optical illusion. You move your eye a bit, and the dark bird afterimage produces a light "shadow". The lower body and tail are just outside of the sharp focus zone.

Nice bird!

Matt
 

pegelli

Well-known member
Since there's also a fringe around the leaves I think it's caused by how the lens renders out of focus edges. The eye and beak are pretty sharp so I don't think it's motion blur which might cause a similar effect (if just the tail and leaves were moving and the head was static).

But I agree with Matt, nice bird.
 

jdphoto

Active member
It's probably a combination of things such as; focal length, movement and a bit of a gentle breeze.
 

jsf

Active member
What causes this fringe around the bird...........is it camera shake or something else. THis is a JPG of the un edited RAW file?
Thanks Neil
It looks like when the light bends around a back-lit image. Each lens and in this case sensor design has to interpret that additional bit of photons somehow. There is always a bit of diffraction that occurs when the light bends around something, especially if the something is really sharp. The light is actinic in the source so it registers as blue, in particular I think because the algorithms have to assign it to something as a color. And it is a bluish light. The bokeh is pleasing there is nothing wrong with the bokeh. However, every lens has its own peculiarities. Some lenses tend to smear the light a bit more than other lenses in these kinds of backlit edge situations. Some lenses are more prone to crisp edge definitions and some are not. This is a highly nuanced thing. Lenses we say are contrasty, are simply lenses that enhance edge definition. There are pros and cons for the design intention. In digital, some algorithms enhance edge definition more than others. As a consequence, we get these little artifacts. There is also another problem we all face, unless this recording device (camera) is on a very stable platform and used with good technique the probability of a bit of camera motion is inevitable. It doesn't take much to ever so slightly smear an edge. These are my thoughts on the problem. Personally, I either live with it or retouch it out.
 

Shashin

Well-known member
It is an edge effect caused by the interaction of the size of the aperture and the distance from the plane of focus. You can actually create it with your eye by holding your finger close to it and looking at the background. You will see the same sort of defined shadow appear.
 

Jack

Sr. Administrator
Staff member
I have a different take. Firstly, EVERY hard edge in a light path generates diffraction; the light will naturally bend around it. Pixels are now small enough and lenses good enough where the combo can capture the visible effects. Next any sharpening, even the smallest amount, enhances contrast at edges further magnifying the effect. Adding "clarity" can magnify it further. Lastly, most jpeg engines as well as resizing engines often add both sharpening and clarity. Combined, it is my belief these factors make even the slightest fringe more visible. At least that's my story, and I'm sticking to it!
 
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