The PhotoVision Calibration Target ...

[r_fredrick_smith]

On Glamour1, I have several times posted about using the PhotoVision Calibrastion target. It is one of the most helpful tools you can find in digital photography. The 14" seems to be about the ideal size.

What is is used for? It has two main purposes. One, to determine the exact highly accurate exposure information for a scene. And the best exposure for capturing the full tonal range of the scene. Two, to set Custom White Balance.

Here is a photo of Dee holding the target:



So as you can see, its just a collapsible reflector that has a White, Gray and Black strip on it. The material is non-reflective, which is exactly what you want when using such a target. In the Dee photo, I've added the Histogram snip so you could see what it might look like in the camera when you look at the histogram on the LCD. I've drawn little lines so you can see which strip equals which in the histogram.

When using the target, you must make sure to fill the frame with it during your test shots. So you either zoom in, or move closer to be sure that the target is all you can see in the viewfinder.

Once you make the initial test shot, you then check to see if you have three full spikes in the camera's histogram (see final notes below). If not, you adjust your exposure and shoot again. Once you have three full spikes, then it generally is better to see if you can make micro adjustments to the exposure to move the three spikes as far right as you can without clipping the right spike. By doing this you are allowing MORE shadow data to be collected. Once you have the calibration done, the last shot of the target you took can be used as the reference photo for Custom White Balance. When I apply these above two steps in studio work, I find that about 90% of my shots need no post processing relative to levels and curves. I do usually adjust WB to go a bit warmer.

Another important thing to keep in mind, is that you must calibrate your camera's histogram with the one you use in Photoshop. They are not always the same and depending on whether you shoot RAW, or JPG, you may need to be aware of two calibrations (one for RAW and one for JPG).

Essentially, get a shot of your target perfectly exposed with three spikes as far to the right as possible without clipping. Now bring the shot into Photoshop and look at the histogram. Now set the camera beside the computer and bring up the photo you are testing one the camera's LCD. Compare the histogram and mentally note any differences relative to the right spike's distance from the right in the two histograms. Suppose you find that the spike in the camera's histogram is at the right edge, but about 1/2 stop from the right in Photoshop. That lets you know that you could actually slightly clip the spike shown in the camera. So ultimately you are going to adjust your camera exposure to produce the optimum histogram in Photoshop (since it is more accurate than the camera). You must remember whether to push the histogram right or left depending on what you see in the above test.

Another important thing is to always put the white side of the target on the same side as the main light in your setup. This gives much better results.

If you buy a knock off of the target, then you get no real instructions. If you buy the card directly from PhotoVision then you get a 1 hour plus DVD with complete detailed how tos for many different light setups.

Note: This article appeared in a slightly different form on G1. I have edited and expanded it for use here.

Cheers,
rfs

[RSStory]

I also use and highly reccomend the calibration target from photovision. It is a great tool to have. When I shoot wedding if I dont have time to shoot the target prior to the shots then I just take one after the fact with the target in it and can then use that for white balancing later. As Roger said, it is ideal to fill the frame with the target, but in a pinch you can just shoot the target in the scene and then in post just crop in on the target. While this isnt ideal it can be better then nothing. You then just crop in on the target in your raw conversion to and make your adjustments and apply them to the rest of the shots. You do have to be a little more careful this way especially if the light isnt the same.

At any rate, this is a tool that is worth every penny.

Scott

[r_fredrick_smith]

Originally Posted by RSStory

I also use and highly reccomend the calibration target from photovision. It is a great tool to have. When I shoot wedding if I dont have time to shoot the target prior to the shots then I just take one after the fact with the target in it and can then use that for white balancing later. As Roger said, it is ideal to fill the frame with the target, but in a pinch you can just shoot the target in the scene and then in post just crop in on the target. While this isnt ideal it can be better then nothing. You then just crop in on the target in your raw conversion to and make your adjustments and apply them to the rest of the shots. You do have to be a little more careful this way especially if the light isnt the same.

At any rate, this is a tool that is worth every penny.

Scott

That's right. When you watch Ed Pierce demo the thing, he often doesn't fill the frame with it, but just includes it in the photo somewhere. Its sort of like the example in my original post that shows Dee holding the target. The selection marquee represents the zoomed in section and the histogram on that image is that of the zoomed in section. So as long as you understand what the thing does, then it will work very well this way to.

Cheers,
rfs

[soupman]

I have not tried to manually customize the white balance for my camera (I believe it can be done). I like the idea of better linking my camera to my photo editing software. I will order this calibration target and try it out. But, don't expect a quick response as I have to learn how to do this with my camera AND how to do this with my software. But, I think I will learn something new.

Thanks!

[RSStory]

It is very well worth it once you learn it. Definately saves a ton of time in post when you are shooting RAW. And Ed's video is very well done and very informative as are all of his videos. I have several and watch the one about weddings every year about this time to prep for wedding season. They are also worth every penny.

[r_fredrick_smith]

Originally Posted by soupman

I have not tried to manually customize the white balance for my camera (I believe it can be done). I like the idea of better linking my camera to my photo editing software. I will order this calibration target and try it out. But, don't expect a quick response as I have to learn how to do this with my camera AND how to do this with my software. But, I think I will learn something new.

Thanks!

You say:

I like the idea of better linking my camera to my photo editing software.

What do you mean you want to do here? Are you suggesting shooting tethered or do you mean something else?

Custom White Balance has nothing to do with the post processing software. When the photo is loaded into the software, it will have whatever white balance you've set from the camera (if its RAW, then you have all the data, so you can choose the White Balance you like after the fact in the software). Now CWB will make it easier to do color balancing in the software and so its a valuable in camera tool (especially if you shoot JPG). But you may be meaning something else, so let us know.

Cheers,
rfs

[RSStory]

I think he means he wants more consistency between the camera and the post work. Like you mentioned about calibrating the camera's histogram to PS's histogram. Just a guess but that is what I took it to mean.

Scott

[soupman]

No, you nailed what I poorly stated. I just want to be able to better match the photograph I see on my monitor to what I saw in the studio. Sometimes I think that I can take photos one day and they have certain qualities about the. The a week later, I do basically the same photo shoot and get slightly different results. I wonder if the dark background affects the complection of my subject more than a white background.

I am probably not being very clear. Last week I took some photos. One is my grandson in front of a softbox. I think it came out pretty sharp. But the photo I took with the darker background came out with poor quality. Maybe because I took a full length shot and then blew the photo up and cropped it? Or maybe I just don't know what the hell I am doing with all the stuff I bought? Anyway, here are the two photos...



and...

[PhotosbyChuck]

Originally Posted by RSStory

I think he means he wants more consistency between the camera and the post work. Like you mentioned about calibrating the camera's histogram to PS's histogram. Just a guess but that is what I took it to mean.

Scott

I took it to mean there may be confusion about how to read the histogram. You might add a blurb on that to your tutorial, RFS. Most of us from G1 know that moving the white spike by changing exposure doesn't affect its balance. However, I can see how someone reading that without much of a background in using histograms might think that by moving the white spike, you're color balancing because they read too much into what you're saying.

[PhotosbyChuck]

Originally Posted by soupman

Last week I took some photos. One is my grandson in front of a softbox. I think it came out pretty sharp. But the photo I took with the darker background came out with poor quality. Maybe because I took a full length shot and then blew the photo up and cropped it?

First of all, kudos to you for that compression. You're down to 13k on the first shot. Unfortunately, that also means I can't tell very well how sharp the original is ... but to my eye, this photo looks softer than the darker one.

One thought for you is that if you're shooting directly into a softbox, you're going to get light wrapping around the subject (especially if the subject is close to the box). That will create "glow" which will lighten the skin tones, soften the complexion and at the extreme, create a hazy look. I think I see some haze at the edges in the top photo, but it could be a compression issue.

Your second shot is pretty good -- it's just unevenly lit. If you'd had as much light on the man's face as you did the woman's, you'd have a very good portrait. It looks to me like your main light was on the camera left and it probably was fairly close (not extremely so). You could correct for the falloff on your male subject by moving the light a bit further and then increasing your exposure to compensate. That will reduce the falloff ratio.

[Warning. Do not mention the inverse square law or it will begin a thread from hell. Just read the "grey or gray" for a taste of my techno-facination. You have been warned!]

Originally Posted by soupman

Or maybe I just don't know what the hell I am doing with all the stuff I bought? Anyway, here are the two photos...

Heh...I've been there!