histogram ??

[jann1033]

i know it should be edging to the right ( hehe) but not crammed up on either side and i think no big dips if possible, more hill shaped? however some of the snow photos i took were not over or under exposed (ie highlights and shadows ok) and the histogram was still very u shaped...is that due to the subject( high contrast) or should i be shooting it differently? even when i adjusted everything ( raw) it still was more u shaped than anything else

 

[DueyDooDah]

I just found this today - great minds think alike:

http://www.disboards.com/showthread.php?t=1256447&referrerid=&highlight=histogram

 

[jann1033]

well that answered that thanks for the link!

 

[tinksdad]

The histogram shape you are talking about is more likely from a shot with a high dynamic range to it. Dark shades below the 18% grey scale to the left and lighter shades to the right. As long as you're not clipping the scale off on either side the shot will be, more than likely exposed properly. I really watch the the right side, since digital is fatal with overexposed ranges.

 

[Lachesis00]

I love using the histogram when I am in PS! It is the bomb!! I can just do minor tweaking with it, but it is nice to see how close I was to being right on track.

 

[boBQuincy]

The scene is what it is, not much can change that. If you take a photo of an 18% gray card with nothing else in the frame, it will show a big spike at one point in the histogram, and not much else. This shows there is a predominance of that one brightness value.

If the scene contains a lot of dark values and a lot of light values the histogram will be two peaks on the ends and a wide valley in the middle. It's like photographing a piece of black paper next to a piece of white paper, the histogram should show spikes at each end and very little in the middle. It will probably also show our cameras can't capture that much range.

But the 3 generations-from-now Canon/Nikon maybe will! I need more range instead of more pixels, but range isn't as easy to market.

 

[Groucho]

Black and white film has significantly more dynamic range than color, that's one of the reasons that some photographers are hesitant to move to digital. I need to shoot about 4-5 more b/w photos and then I can get my WDW b/w photos developed and see how they turned out...

As for histograms, I do have my DSLR set to show the histogram on the quick review after you're taken a picture, gives me a good at-a-glance look at how the exposure was.

Although, I have found quite a few underexposed photos in my collection from the trip, I can only guess that it's from the spot metering picking up something. Better underexposed than overexposed... I can usually brighten up the RAW and you'd never know. (It doesn't help that there were a lot of overcast days.)

 

[gruZ]

The histogram is also invaluable when it comes to flash photography. The back camera LCD can be very misleading with flash - you think you have hit the proper exposure but in reality the frame is VERY underexposed. The histogram never lies, and has saved me several times!

 

[MarkBarbieri]

The histogram never lies,

Be careful, there is one time with the histogram sort of lies. If your histogram only shows one chart without breaking out the colors, it can sometimes mislead you. Let's say that you take a picture of someone in a bright red jacket. Some of the pixels may be blown out in the red channel but the average value for those pixels (when you factor in the green and blue channels) might not show up at the right edge of the histogram. If you shoot saturated colors, it's handy to have a histogram that shows the different color channels.

 

[Anewman]

Be careful, there is one time with the histogram sort of lies.

In addition to what Mark mentioned...

When shooting RAW the histogram reflects what a processed jpeg would look like with the current camera settings(parameters). If the camera settings are set too aggresively the histogram(in camera) can appear farther right(or even left) than what the baseline RAW file will show when opened with a converter.

 

[gruZ]

Very true about the channels, but I wasn't aware the camera "applied" in camera settings to the histogram even when shooting RAW - something I'll have to look into - thanks for the notification.

 

[jann1033]

a question due to posts #7 to here...my histogram is only one , not broken down into colors...so would i be better to shot with b& w mode in raw where i still get the actual color info in the file, just the lcd image would be b&w..would that make it more or less accurate ie... the histogram would be for b&w, wouldn't that make it pick up anything under or over exposed no matter what actual color channel it would be in the raw color file?

 

[MarkBarbieri]

know it should be edging to the right ( hehe) but not crammed up on either side and i think no big dips if possible, more hill shaped?

No, no, no...You and your camera don't control the shape of the historgram, just it's position. If what your are shooting has lots of bright stuff and lots of dark stuff and very little in the middle, that's what you've got. Nothing you can do (aside from adding or removing light to the scene) will change the histograms shape.

a question due to posts #7 to here...my histogram is only one , not broken down into colors...so would i be better to shot with b& w mode in raw where i still get the actual color info in the file, just the lcd image would be b&w..would that make it more or less accurate ie... the histogram would be for b&w, wouldn't that make it pick up anything under or over exposed no matter what actual color channel it would be in the raw color file?

I don't think that will help. When you get back to the color version, you still may find one of the color channels blown out. This is usually only a problem when shooting highly saturated colors. The safest thing would just be to leave yourself some margin for error and/or bracket shoot.

 

[MarkBarbieri]

It looks like Canon added RGB histograms on the Rebel line with the XTi model. I'm not sure whether the 20D or 30D have the feature.

Here's an example GIF from the DPReview of the XTi.

 

[gruZ]

The 20D does not. Don't know about the 30D.

 

[DueyDooDah]

Yes, the 30D has a brightness and a RGB histogram.