dealing with stray light from behind the subject

[ALGonquin Bob]

RAW files are linearly sampled which limits the maximum dynamic range to approximately one stop per bit. The largest number of bits that I am aware of in DSLRs is 14 bits, thus 14 stops. (The RAW file typically has the same number of bits per sample as the A/D converter.)

The sensor, optical, and electronics systems can be far more limiting: some measurements of several recent high-end digital cameras give a highest dynamic range of 11.7 stops. The same author gives the greatest theoretical range of a sensor (5D Mk II) of ~14.7 stops.
http://www.clarkvision.com/imagedetail/digital.sensor.performance.summary/#dynamic_range
http://www.clarkvision.com/imagedetail/index.html#sensor_analysis

JPEG uses an 8-bit per sample representation, so it is limited to 8 stops. 8 stops post processing (eg for printing or screen display) is fine, but can be inadequate before processing.

BTW, dynamic range in film and sensors is often (generally?) denoted in D (log base 10) rather than stops (log base 2). log10=.301*log2, so 11.7 stops is equal to a D of 3.5.


The human eye has a greater effective range because we, unlike a camera, can change the "exposure" as we look at different parts of a scene. (One could argue that this ability to adapt to different parts of a scene is similar to what one can do in post-processing of an image.)

Doug

I miss the days when photography involved photographs and not calculus.

 

[forestgnome]

OK, I'm really happy with this image. I know about this situation and I was thinking about the backlight being a curse and a blessing and decided to just enjoy the blessing. I like the rim of light around the subject very much. The stray light coming across has grown on me. It says " early morning light".

I appreciate all the commentary, both technical and artistic. It can help us all. I take from it what sinks in to my head.

happy trails

 

[DougPaul]

I miss the days when photography involved photographs and not calculus.

There was lots of math involved in film too. And chemistry with a choice of developers and recipies. And suspensions of emulsion particles in binders. And discussions of dynamic range with D-values etc.

The complexity was there, just less visible to users.

Most of the artistic stuff is similar--digital has some advantages and some disadvantages.


FWIW, I liked the image. W7xman's alterations were only visible to me when viewed side-by-side. Perhaps a slight improvment, but sufficiently subtle that I'm not sure they were worth the effort.

Doug

 

[kmorgan]

Photoshop: down and dirty

Hey guys, don't get around much lately, but still play a lot with photoshop.

First one is very easy. Used the Shadows/highlights filter set to 50% shadows, then did an auto-levels to color correct:

This second yielded pretty much the same results but with more work. First convert to LAB mode and in curves steepen the line 10% in the A and B channels, then adjust the Lightness curve for contrast, convert back to RGB to finish... I like the first better, more contrast.

Take it easy...
Kevin

 

[Paradox]

You guys are way beyond me! As a casual viewer who thinks any one could be in an issue of National Geographic, I'd have to say the original is my favorite. I like the color of his face the most and the muscles in his shoulders still show up nicely. It's quite clear he's in a swampy Northeastern wooded area that just isn't that important to me.

 

[NeoAkela]

Photoshop can be a blessing and a curse - sometimes I can come up with 10 different versions of a final print before wondering if the original was better after all!

I'd just be tickled to have a big moose sit still for me for a beautiful shot like this one (the original photo)!