RGB Histogram

[DigitalPhotography]

I was at my favorite camera store yesterday and handled the Canon EOS-1Ds Mark II. As I was viewing some of the shots I had taken, I came upon the RGB histogram feature. That is a nice feature to have. I wish my Nikon D70 had that feature.

How many of you use the RGB histogram?

[mikej]

I have used the histogram since I switched to digital with the D30. This is a great tool for getting proper exposure, both with ambiant light and flash. I've started using the RGB histogram since I've moved up to the 1DMKII.

Mike

[mikej]

I do still have it, Pavel, although a friend of my wife's is using it with the idea of buying it from me. When I bought my 10D a year and half or so ago, I had thought of selling it then, but my wife took it from me so fast, I never had a chance. She used it till I bought the 1DMKII and now has my 10D. I'd wised up this time and knew if I offered her my 10D it would make it easier to buy the 1DMKII. And it worked. She was so happy to get the 10D almost two months ago that she only just got around yesterday to asking me how much my new camera cost me. Luckily we were in public so she had to control her reaction and not kill me in front of witnesses. I did stress the $500 rebate I got.

Mike

[photosbymorgan2]

I have messed with the RGB histogram on my 1D but I guess I do not fully understand how it helps me over the regular histogram. I mean if the red looks to be a bit blown but the green and blue look to be under exposed and I adjust for the red to be not blown out, the green and blue look even more under exposed.

[hartcons]

Originally Posted by photosbymorgan2

I have messed with the RGB histogram on my 1D but I guess I do not fully understand how it helps me over the regular histogram. I mean if the red looks to be a bit blown but the green and blue look to be under exposed and I adjust for the red to be not blown out, the green and blue look even more under exposed.

Isn't there something about more of the data tending to be in the green channel?

[photosbymorgan2]

Originally Posted by hartcons

Isn't there something about more of the data tending to be in the green channel?

Probably so. I am no expert and was just throwing an example out there. I have seen where one color is more than the other 2 and I am not sure exactly how I am suppose to read it or adjust for it.

[hartcons]

Ok, got it but then my question becomes how do these tools (histogram whether you get one or four, blinking highlights) help you get better exposure vs. just eyeballing the picture on your LCD (assuming you can see much of anything on that little screen). Is there a general rule of thumb or is it really something that has to be considered on a picture-by-picture basis? It seems like the in-camera constrast setting might come into play as well (at least for JPEG shooting). My e-300 also has a gradation setting that's supposed to be for low-key and hi-key shots. And maybe some cameras are set up a little differently when you are relying on matrix/esp metering in terms of whether they'd prefer for you to block up shadows or blow highlights? Personally I like sparkling highlights and the other night I was looking at sample pics from the panasonic fz5 over at that other site and it seemed to be doing a good job of that. But then again I also like really black blacks (basically give me shadows and highlights and the heck with the boring mid-tones!)

So it would be great to have a rule (like the hand-held shutter speed rule) that said something like:

* adjust exposure and contrast to insure that the histogram is as wide as possible and if it doesn't go all the way across then at least have it touch the right side
* then use the shadow/highlight feature to brighten shadows and knock back bright spots as needed (kind of like salt and pepper)

but I have no idea if such a rule has any merit. I like having rules that can serve as a starting point and then as I get more experienced I can get more intuitive about these things (and develop some sense of personal taste about what I prefer as well). But maybe photography is more art than science anyway.

[mikej]

Your LCD is good for showing you got a picture and not a whole lot more. Your LCD screen is not color corrected and does not give you a good idea of exposure other than in a just rough way. You can use it to zoom in on a area and see if it's in focus, but even that will only be an indication since many of the images are soft looking in the camera anyway. The LCD shows a very compressed jpeg image, which is why it's hard to tell if what you see is what you are going to get. With the histogram you can tell if you are properly exposed or if you have clipped the highlights or if you are going to have a lot of noise because you underexposed too much.

Mike

[mikej]

To me, you over exposed the shot by too much. I would have looked at the histogram and dropped the exposure a third to a half stop, which would have put some more detail back into the white tee-shirt (it's a good stop over exposed though so there would still be a bit of blown out area), but still left enough detail in the shadows to bring out later in photoshop.

There are a lot of times I will shoot for the shadows though and not worry about highlights. I usually do this when I'm shooting fast action and the sun is such that there are shadows on the side I'm shooting. Then I meter and add a 3/4ths to a stop extra exposure compensation, checking the histogram regularly to make sure I'm not flowing out the areas I need.

But regardless of how we are exposing, the histogram does help get the part exposed that we need exposed.

Mike

[DigitalPhotography]

Don't assume that the blinking hightlight feature on your LCD means blowout of highlights. It is just a warning that you may have overexposed to the point of no details. Also, in cases of wide contrast, don't forget about ND filters. They are a big plus in those situtations.

[hartcons]

ThOt,

I like the mood of your shot. Could this be referred to as high-key or is that something else?

[mikej]

Originally Posted by th0t

Hi Mike,

You're probably a better photographer than me. I actually did have some shots that were not as overexposed but I didn't like them as much. I wanted the boy's face to be properly exposed. I liked having the mother partly overexposed because it added to the "spiritual" quality of the occasion and worked very well for the media in which it was used. It's as if the boy is welcomed by more than just his mother—he's welcomed into the "light".

Th0t, I might have a lot of experience and know a lot about photography, but that doesn't make me a better photographer than you. I'll be the first to admit that I'm missing the other key ingrediant to being a good photographer... talent. That's why I said "To me..." which means it's just how I look at it, not necessarily the right way or a better way.

While you are correct that taking a couple of different exposures of candids can be hard, I've gotten pretty good at it as long as there isn't a lot of movement for a second. I can take a picture and spin the exposure compensation dial and take another picture within seconds and without taking my eye off the subject. Sometimes I get a pair that can be conbined in Photoshop and sometimes I don't. But it is something I keep in mind in situations like this and I really want to try and get both highlights and shadows exposued properly.

Mike

[hartcons]

Originally Posted by th0t

As for the ND filters, I don't think they would help. They shouldn't change the dynamic range of the scene. They will darken everything uniformly so the dynamic range will remain the same and if it was too wide for your camera before, it will still be too wide after.

What about graduated ND filters and especially the square kind from Cokin that you can slide up and down as needed in a little holder that screws onto your lens?

[hartcons]

Originally Posted by th0t

Thanks. I've never heard the phrase "high-key" before so I can't say.

The photo books I read often refer to low-key and high-key. low-key scenes are mostly on the dark side and high-key scenes are mostly on the light side. the e-300 even has a gradation setting for low-key vs. high-key but I'm not exactly sure what it does.