One of the questions I get asked the most is whether I’d use a tripod in a church to take an HDR photo but we won’t go there (sorry, I had to sneak that one in)

Anyway, what’s the difference between the Exposure slider and the Brightness slider (both in the Basic panel as well as the Adjustment Brush)? They both have the effect of brightening the photo right? The main difference I’ve found is that Exposure really targets the brightest parts of your photo and makes them brighter. Almost to the point of over-exposure. And it does so pretty quickly as you increase (or decrease) the slider. Brightness on the other hand still brightens the overall photo but does it more in the mid-tone (middle gray) area. Here’s a view of a simple gradient image I created in Photoshop (By the way – you can download it here if you want to try it out for yourself) with the Highlight warnings turned on. You can see the before/afters and how each slider affects the highlights.

(Click to see a larger version)

If it’s hard to visualize what it’ll do to a photo then check out the lighthouse from a photo of mine. On the left is the result of reducing the Exposure and on the right side is the result of reducing Brightness. Notice that reducing the Exposure almost immediately gets rid of that bright highlight on the very far left side of the lighthouse. Reducing Brightness makes it all darker but keeps the brighter highlight area better. This fits with the whole idea that Exposure attacks the really bright stuff harder than Brightness does.

(click to see larger)

It also has some affect on color. Another similar gradient that I’ve created shows how moving the Exposure slider and the Brightness slider all the way to the left changes the blues, the greens, and even the yellows but in a slightly different way. I usually see this the most when I’m working on the sky and it probably explains why I usually prefer the Brightness slider to darken a sky rather than the Exposure. Personally, I just find that the result looks better (remember, this is totally a personal-taste kinda thing). But they definitely do affect color in a different way.

(Click to see a larger version)

So what’s your take on it? Which one do you use the most and why? Oh yeah, if you want to download the sample gradient images I used then just click here.