How do you read a Histogram?

Raymond Lin · 2 Nov 2006 at 12:28

Since the LCD is small so its hard to tell if the shot is 100% exposed correctly and people use the histogram to check. The problem is I never used it, anyone wanna show me how to read it and what is a good curve and a bad curve?

dod · 2 Nov 2006 at 12:35

Have a looky here

http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml

Not really a good or bad histogram. Black subject will load the left, bright subject will load the right.

King_Boru · 2 Nov 2006 at 12:55

Dont always trust the histogram, depending on the scene your own judgement can sometimes be best.

ElDude · 2 Nov 2006 at 13:18

It's something you get used to. I don't really use it much, but then again I suck so I suppose that's one of the many reasons

Someone buy me a 30D

Mohain · 2 Nov 2006 at 13:21

King_Boru said:
Dont always trust the histogram, depending on the scene your own judgement can sometimes be best.

I think you can always trust the histogram. What you have to be careful with is only reading a brightness histogram which can look OK whilst some colours are overexposed. Luckly the 30D has RGB histograms.

Scam · 2 Nov 2006 at 17:48

I read an article on this in some random NZ magazine i bought. It mentioned that whilst exposing to the left (side of the histogram) was recommended for film, in digital you're best off exposing to the right. Do people agree with this? :confused:

SDK^ · 2 Nov 2006 at 18:02

Scam said:
I read an article on this in some random NZ magazine i bought. It mentioned that whilst exposing to the left (side of the histogram) was recommended for film, in digital you're best off exposing to the right. Do people agree with this?

Yup

Expose for the highlights and recover shadow detail in your image editor.

ranarama · 2 Nov 2006 at 18:14

SDK^ said:
Yup
Expose for the highlights and recover shadow detail in your image editor.

I've always agreed with that but thought this would be described as expose to the left.

Have I got this round the wrong way then as I thought exposing to the right was overexposing the shot. The reason I thought this is because when you overexpose you push the histogram to the right hand side and move the exposure compensation to the right into +ve numbers.

Scam · 2 Nov 2006 at 20:51

You're confusing yourself. You expose to the right, but not so much that you blow out the highlights. Meaning the graph shouldnt be clipped on the right edge, but it should be as far to the right as you can without clipping. This generally means you are exposing for the brightest parts of your shot. This might help: http://www.luminous-landscape.com/tutorials/expose-right.shtml

ranarama · 2 Nov 2006 at 21:07

Scam said:
You're confusing yourself. You expose to the right, but not so much that you blow out the highlights. Meaning the graph shouldnt be clipped on the right edge, but it should be as far to the right as you can without clipping. This generally means you are exposing for the brightest parts of your shot. This might help: http://www.luminous-landscape.com/tutorials/expose-right.shtml

Yeah I see now, thanks. I found that article shortly after I posted with a quick goolge but didn't have a chance to edit my post. You have, however, explained it better in one short paragraph rather than that whole page long article.

Raymond Lin · 2 Nov 2006 at 21:10

When it says blow the highlights, that means over exposed right?

ranarama · 2 Nov 2006 at 21:21

Raymond Lin said:
When it says blow the highlights, that means over exposed right?

yes

EDIT - To clarify when you blow the highlights they go completely white and you can't even recover any details even from the raw. I usually do that with clouds.

Scam · 2 Nov 2006 at 21:43

ranarama said:
You have, however, explained it better in one short paragraph rather than that whole page long article.

Raymond Lin said:
When it says blow the highlights, that means over exposed right?

Yep. And thats what you dont want.

Raymond Lin · 2 Nov 2006 at 21:47

Scam said:
This generally means you are exposing for the brightest parts of your shot.

Spot metering on the 30D for the win

Meter on the bright part - ie wedding dress and shoot !

ElDude · 2 Nov 2006 at 21:54

Spot metering is one of the main reasons I wanted the 30D