Might seem like a simple question but how can I keep my whites from looking chalky . Example would be Snowy Egret on a sunny day . Even though exposure appears corect and no blown highlights photos still lack good definition ?
In a 2D photo most of the clues to 3D shape come from the contrast pattern the lighting creates. One of the most difficult things to render is the 3D shape of a white object because there are very few shadow clues. Most of the clues come from the 255 specular highlights on the higher top sides of the 250 white object. http://super.nova.org/MP/Comp3.jpg http://super.nova.org/MP/Comp6.jpg
The exposure difference between rendering the solid white as 250 and blowing it out is only about 1/6th stop on most cameras, below the range of the 1/3 stop adjustment. So what I do when shooting is err on the side of underexposure using the clipping warning to keep everything except what I know to be specular reflections under clipping at capture. That may render the solid whites a bit underexposed at capture, but that's a trivial tweek in PP. I can't tweek more detail and the illusion of 3D shape into a white object captured at 255.
What many don't realize is that highlight exposure is equally critical on a black object for the same reason: shadows on the object are not seen and it's the placement and rendering of specular highlights and the halo gradients surrounding them which contain the clues about 3D shape:
Something else to keep in mind shooting feathered and furry critters is that the AA filter of the camera tends to turn the micro-specular reflections off the flat facets of feathers and fur that give it sparkle and the illusion of fluffy texture by eye into mush. So whereas on a human you'd want to keep the skin out of the sun or direct flash to avoid specular hot spots for feathers and fur direct sun and direct flash is ideal because it creates specular reflections. A PP trick I usually use for fur and feathers is to make two copies of the image and sharpen one normally, then over-sharpen the second with high amt. / small radius (500, .3-5,0) then selectively blend it in on the higher parts of the bird where in person you'd see the strongest specular highlights glinting off the body. That sparkle works both to define the 3D shape in on the front side, and make the texture look soft and fluffy vs. flat and matte, or as you say "chalky".
It's one of the more counter-intuitive aspects of perception and lighting. The softer the object is in real life, be it fur on a black or white cat, or slices of white and chocolate cake, the more you want your light sources to be direct and collimated (parallel rays) so they will create specular highlights to define the shape and texture. You need "hard" light to make the clues on the object look as soft as you know they are from your sense of touch and memories touching them.
Highlight exposure control is the critical process control variable at capture. Err on the side of underexposure if you want to render the 3D shape of objects in 2D.
Chuck's answer above is excellent, and is true for subjects other than egrets.
The subject reflects light to the camera. Therefore the nature of the subject is critical. A "chalky white" I presume has some less-than-white pixels scattered through it. What is the nature of the surface which does that, beside egret feathers?
Your question is good, but incomplete. Can you post an example image?
This could be less a lighting question and more a post processing question I think. The first issue looking at this example is colour cast. Looking at the histogram the highlights green and blue channels are well below max while red isn't so (assuming the bird is white) you have quite a colour cast causing the 'chalky' look. White balance it and it may look more to your liking.
You could probably also increase local contrast (clarity slider in lightroom) to bring out the detail a bit more and make it a bit more punchy.
As for lighting I'm guessing this was shot near mid day on a sunny day. Later in the day the sun will be at a lower angle giving some nicer directional light from a lower angle.
Here's a Egret I shot. I don't do any bird photography per se, I was just visiting a park in Panama City Beach and he was hanging out near the fish cleaning station near the boat ramp
The first challenge is the DR limit of the camera. In just ambient light alone the shaded side would be middle gray if he hadn't been within range of my flash, a 580ex I keep on a bracket when shooting outdoors. Look close and you'll see evidence of the flash use on the legs. The flash helped somewhat to create specularity on the feathers on the shaded side.
The rendering in the left is with the amount of USM I normally use for screen views of that size. In the version on the right I took that file, duped the background layer, applied 500, .4,0 USM then selectively blended it into the feathers with a mask and opacity adjustment on the layer. Because I was working from the small JPG it's a bit pixelated, but it should give you an idea of how you can enhance the illusion of texture / fluffy feathers that way. The aggressive USM puts back the micro texture the AA filter obliterates.
Using a flash with a Better Beemer to extend it's throw won't do much to lighten the shadows of a bird in the distance but it will help to create shape defining specular highlight and a catchlight in the eye.
One can quibble over a couple of points of white point but Kent has the right idea. I would not worry about slivers of highlight blowing out, as these birds are so white when you look at them in person. It just adds to the dynamics of the image but doesn't take from any meaningful detail. If you had an image of such resolution that you could actually resolve something like the gradation going across a single strand of feather, that might want a reconsideration of exact white point, but the overall point here has been made and shown in a couple of examples. Should be a good base of information to start to move forward on.
