Understanding Camera Histograms in Photography

It took me a while after switching to digital photography, to fully understand the histogram. Now, for me, it’s an essential tool in determining proper exposure in my photography.

Most all cameras today can display a histogram. From the least expensive and simplest point and shoot to the most sophisticated professional camera, they all have the capability to display a histogram after you’ve taken the picture. Some cameras with electronic viewfinders will display the histogram live, even before you press the shutter.

Professional cameras will even display a histogram showing the three color channels, red, green and blue, (RGB), in addition to the luminance histogram showing the brightness of all the color channels together.

So what is the value of viewing a histogram? To me, it is everything. It is how I determine the proper exposure of every picture I take. But I’m a serious professional photographer.

Most serious amateurs, if they understand it, will take advantage of their histogram. But do those of you who simply want to have fun taking pictures of their friends, families and vacations need to consult the histogram? Not really. Modern-day point and shoot cameras and consumer level digital single lens reflex cameras, DSLR’s, do a great job producing good exposures and beautiful photos. But it never hurts to have a little understanding of such a deceptively simple yet potentially confusing camera function.

As I said above, it took me a while to understand the thing. There was nothing even remotely resembling it on film cameras and it was not something that anybody taught. My switch to digital would have gone much smoother had I understood it from the beginning.

So here it is, in all it’s simplicity.

Essentially, the histogram is my light meter. Because of it, a lightmeter is one piece of equipment I don’t no longer have to carry. Now that is heresy to some, but so be it. My life is simpler without having to take a lightmeter reading of every photograph I’m about to take.

Here is an example of what a good histogram looks like:

Here is an underexposed histogram:

And here an overexposed histogram:

That’s it, that’s all you need to know.

But then, of course, there’s more to it. Fundamentally, you don’t want your histogram to be climbing the walls. That is to say, the left side of a histogram shows the blacks and shadows in the scene. The right side show the whites and highlights.

If your histogram is climbing the left wall as in the underexposed histogram above, then you’re blocking up your shadows, i.e. there will be no detail in your shadows. If it’s climbing the right wall like the overexposed example, your blasting out your highlights. Again, no detail. And with jpegs, no possibility of getting the details back.

Here are photographs to go with the above histogram examples.

Good exposure:

Underexposed:

Overexposed:

And what are all those peaks in the histogram? They simply say that at that particular brightness level, the camera sensor is picking up more pixels. In other words, the scene you’re shooting is made up more of a particular shadow or brightness or mid-tone than other brightness’s. 

But that’s confusing the issue. All you need to know is whether you have a fairly even distribution across the histogram without blocking up the shadows and/or blasting out the highlights.

Copyright 2013 Dennis Jones/Dreamcatcher Imaging

www.dreamcatcherimaging.com

Check out my travel blogs on my extensive world travels at:

www.dreamcatcherimaging.com/blog

Panorama Photography-Photographing and Merging Panoramic Photos

Gore Range Panorama, Vail Colorado

Time was when you had perhaps three choices for creating a panoramic photo: 

1) You could print only a narrow strip of the film or slide. This was okay if you were using a 4x5 or larger camera but 35mm or smaller, forget about it. Make anything larger than perhaps a 10” print and the loss of detail was very apparent. Older film point and shoot cameras gave you a panorama option but all it did was crop the 35mm frame just like above, and show a crop in the viewfinder accordingly.

2) You could also painstakingly merge several exposures in the darkroom. Very difficult. 

3) Or, you could use a specialized panoramic camera.

That was then, this is now. 

Lots of cameras now will even do it for you. Simply put it in panorama mode, take a few pictures while panning across the scene that capture what you want and the camera will stitch them together. Even the iPhone has a wonderful pano feature; put it in panorama mode and slowly pan across the scene. All the stitching is done automatically. Pretty amazing.

But for high quality panoramas, there’s a bit more involved. And really, it is only a bit but you do have to own some stitching software, some are free, some not. 

Here’s a link to Ken Rockwell’s site. He is an excellent on line resource for many things photographic. This is his article on stitching software which explains the software better than I.

http://www.kenrockwell.com/tech/panoramic-software.htm

I don’t know when it was written, but Photoshop’s Merge to Panorama has definitely improved with the past few iterations of PS and it is what I use.

Ideally, you should use a tripod. But it’s not necessary except at night or in dim light. What is most important is that you take your shots from left to right, (the software is designed to work this way), that you overlap each shot by about a third, and that you keep the horizon or you subject level and even across all your exposures.

This is easiest on a tripod where you can level both the tripod and the camera. You can even use a bubble level to level the camera between shots. Vello makes one for $15 that fits in the camera’s flash hot shoe. Now though, some high-end cameras come with a Virtual Horizon function.

Using the Manual exposure setting, adjust your aperture and shutter speed, take a shot of the scene and make sure you have a good exposure by checking your histogram. (More on that in another post.) Once you’re satisfied with the histogram. Take an Auto-focus reading and then turn auto-focus off. You don’t want your camera to focus on something in the foreground in one of your shots and then something in the distance in another.

That being said, there’s no reason you can’t do it on full auto, both exposure and focus. You just have to be aware of the potential auto-focus problems and that your camera’s exposure metering system might see each shot slightly differently giving you varying exposures.

Line up your first, left-hand shot and then practice how you’re going to overlap each shot and keep the subject level in the viewfinder.

Once you’re got it, line up the first shot again and stick one finger in front of the lens and take a picture. This will tell you later that this is the beginning of a pano. Now, take your shots. After the last capture, stick two fingers in front of the lens and take another picture to mark the end of the pano. When you download everything, maybe days or weeks later, you’ll know that the frames between your fingers are for a panorama.

Open these in your stitching software, click Merge or whatever you’re supposed to click and ouila’, a beautiful panoramic photograph.

        Here are the four photographs I used to create the Gore Range Panorama Photo plus the photos with my fingers to mark the images to be used. The finished Pano is below as well as at the top of this post.

Copyright 2013 Dennis Jones/Dreamcatcher Imaging

www.dreamcatcherimaging.com

Check out my travel blogs on my extensive world travels at:

www.dreamcatcherimaging.com/blog

Focus Stacking in Photography-Creating Infinite Depth of Field

One of the biggest challenges in photography has always been maintaining sharp focus from the foreground to the background in an image. In the past, this required either using the smallest aperture possible like f22 on SLR’s or getting out the big 4x5 camera. 

With macro photography, the problem is multiplied because even at the smallest apertures, the plane of focus is so very narrow. The closer you get, the narrow it becomes, often just millimeters.

A 4x5’s ability to change the perspective by using swings, tilts and shifts of the front and rear standard in conjunction with f32, 45 or even f64, allowed photographers to keep everything in focus from a subject inches from the lens to mountains in the distance.

Once again, I say an emphatic Hallelujah! for digital photography. Lugging around a heavy 4x5 camera, the film holders and a big heavy tripod, not to mention the other accouterments, like light meter, dark cloth, loupe, lenses etc. was always a major ordeal. Sure the quality from a 4x5 inch piece of film was incredible, but hiking miles into the best spot was at best, a labor of love.

Ansel Adams, the great master, did it as did so many other great artists even up until today. They even started a movement called Group f64. 

You’ve seen the caricature of someone behind a big camera looking through the ground glass beneath a black cloth. Well, what you didn’t see is the person beneath the cloth first composing the faint upside down and backwards image on the rear ground glass and then using a magnifying loupe to carefully inspect the focus. Then of course, they had to make their shifts and tilts, re-compose, check the focus, etc. ad nauseum.

Been there, done that. And I can’t laud enough praise on today’s cameras that give me far greater ease of use along with extremely high quality. Not to mention weighing significantly less.

But still, the problem of keeping things in focus from front to back is still there. Sure, you can use the smallest apertures, but the sharpness gets degraded as you close down. Plus, every lens has a sweet spot where it’s sharpest. My 28-300 Nikon is sharpest between f9 and f11.

So what if I could use my sharpest aperture while keeping everything from front to back in focus? What if you can do that on the tiniest of subjects, in this case, the center of an iris.

Enter Focus Stacking. It has to be done on a tripod and using manual focus. Whether you’re shooting a landscape with a close foreground and distant mountains or a flower, simply take a series of exposures with varying planes of focus. First focus on what’s closest to the camera, then focus on something a little further back, focus farther still and finally take a shot of the most distant part of the composition. This can take two to however many shots, but usually 3-5 will suffice.

Make sure all the photos are shot at the same aperture otherwise things will get really screwed up. And of course, make sure the exposures are all the same, the camera and zoom don’t move and the wind isn’t blowing

After downloading the images. Open them in PhotoAcute, Helicon Focus, Picolay or Zerene. These programs do a reasonable job and prices vary from free to $149.

Photoshop also does a good job. With PS, which is what I used here, select the photos in Bridge and go to Tools/Photoshop/Load files into Photoshop layers. Photoshop opens the photos as layers. Select all the layers. Align the layers under Edit/Auto-align layers/Projection Auto. Then use Edit/Auto-blend layers/Stack images. Flatten the layers when photoshop is finished and prepare to be amazed.

Here are the four shots I used. You can see how narrow the planes of focus are in each. The finished shot is both at the top of the blog and below the others.

Copyright 2013 Dennis Jones/ Dreamcatcher Imaging

www.dreamcatcherimaging.com

Check out my many travel blogs at: 

www.dreamcatcherimaging.com/blog