Old 12-04-2007, 06:29 AM   #1
asis80
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Default Metering and Exposure

So I just bought Bryan Petersons "Understanding Exposure" and "Understanding Digital Photography", GREAT books. Problem is I don't have an SLR, but have a higher end P&S. The Canon PowerShot A640, it's not a bad camera, not the top of the line A series canon makes, but it's a decent camera. Got it on sale, so what the hey ya know, it's a good beginner camera to help me understand how to compose a shot, try to understand the technicalities and such. Do have a question tho, I understand how the metering is explained in the "understanding exposure" book by basically metering off the sky, use those settings to get a correct exposure (my camera will tell me -2, -1 2/3, -1 1/3, etc all the way up to +2). I usually like to expose for +1/3 or +2/3, I'd rather have a slightly over exposed shot. But the thing is, I haven't tried this method yet. I expose on the light hitting objects (the train, ballast, rails, tree's, everything). I just recently tried the method out in a room in my house. Pointed left or right of a light source (a ceiling fan light bulb) adjusted the aperture and shutter speed (F5.6 for 1/60) then pointed at something in the room, and took the shot. Theoretically, and from what the books tell me, the object should be well lit when the picture is taken. Not the case. The photo turned out VERY dark. Any ideas of what I am doing wrong? I shoot in manual mode, sometimes program. My eyes see a well lit room, but my cameras eyes see different lol. Any hints?
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Old 12-04-2007, 10:40 AM   #2
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Quote:
Originally Posted by asis80
My eyes see a well lit room, but my cameras eyes see different lol.
Exactly! That's not a joke!

In a room considerably better lit than with a ceiling fan bulb, I use something like ISO 800, f/2.8, 1/50. You just don't get an indoor shot without flash with a digicsam.
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Old 12-04-2007, 10:41 AM   #3
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Its kinda hard to follow your example, but it sounds like you are metering off a part of the room which is very close to the light source and then using those settings to shot a part of the room more distant from the light source?

If I understanding what your saying, your results are pretty much what I would expect. I don't remember the exact numbers for the luminosity of light but it goes something like this: every time you double the distance from a light source, the light is 1/4 as strong.

Thus if your metering off a wall 2 feet from the light source and then shoot a wall 10 feet away, the light is 5% as strong as it was at two feet. So, following that train of thought, obviously it would underexposed.
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Old 12-04-2007, 03:01 PM   #4
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should be easier outside then i suppose, thanks for the comments guys.
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Old 12-04-2007, 03:33 PM   #5
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Well, I think my camera's light sensor is just too smart for me, I think this metering concept (taking a meter off of the sky, expose for a correct reading, recompose, take the shot with the settings you just used to get a correct reading) won't work for point and shoots. I'll have to try my mom's fuji finepix. Here are 2 shots I just took.

1) Metered off of the sky above near sun before taking this shot; 1/800 for 5.6

Now mind you, you can't see it, but the sun was out for at least a few seconds when i captured this, but I think the light metered off of the clouds in the background, but theoretically I had the "correct" shutter speed.

2) Metered off of the objects in front of me; 1/400 for 5.6

I caught the sun just as it was about to leave behind the clouds, the light meter readings suggested that this was the correct exposure, which IMO, looks a lot better exposure wise than the first one


I think that the problem lies within the point and shoot, my point and shoot. I love the camera but I'm not liking the auto features you can't get around such as this. I'm not bitching, I'm not a bitching person and Januz, Rich, and many others can testify to that. I'm a nice guy who likes to help others, I'm just seeking your opinions on what I should do. Would my method of metering off of subjects rather than the sky do better in this case UNTIL i can afford an SLR to better help with equipment? Any help is appreciated and I do appreciate all the help you have given me with my short time here with RP.net, and plan on to be here for a while! Thank you guys!




EDIT: In case you were wondering, they aren't the same photo's. The 2nd shot was taken 7 seconds after I took the first one. thanks again
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Old 12-04-2007, 04:00 PM   #6
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Quote:
Originally Posted by asis80
I think that the problem lies within the point and shoot, my point and shoot. I love the camera but I'm not liking the auto features you can't get around such as this. I'm not bitching, I'm not a bitching person and Januz, Rich, and many others can testify to that. I'm a nice guy who likes to help others, I'm just seeking your opinions on what I should do. Would my method of metering off of subjects rather than the sky do better in this case UNTIL i can afford an SLR to better help with equipment?
Remember that the camera, especially a P/S, is going to see that snow and that white overcast sky and it is going to think... GRAY! Cameras are set to take the dominant tone in a shot and make it neutral/average in brightness. For the same reason, people use "18% gray" cards in setting exposure manually.

So you have to have the ability to adjust for snow. Had all that been grass instead, the camera would have thought "dark green - I better increase exposure". Cameras do not generally make snow white, they make it gray. BTW, do you have a snow setting of some sort - it might help.

Note that on the second shot the small amount of blue sky looks sort of good, although of course it is hard to tell.
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Old 12-04-2007, 08:48 PM   #7
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I do have a snow selection, BUT, it's not in manual mode I guess 250 bucks for a PS wouldn't do too too bad in auto mode I suppose, I'll give her try. I'll also try it when all this snow melts which looks like it ain't gonna be a while, supposed to be a blizzard tonight. OOOOOOOOOOO how i hope santa.......and working double shifts at UPS ........brings me an SLR! Thanks Janusz!
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Old 12-04-2007, 08:49 PM   #8
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Hey Janusz, since I can't use that snow mode in manual, do you think a white balance adjustment might help along with a longer shutter speed? just a thought
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Old 12-04-2007, 08:53 PM   #9
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Quote:
Originally Posted by asis80
Hey Janusz, since I can't use that snow mode in manual, do you think a white balance adjustment might help along with a longer shutter speed? just a thought
Of course a longer shutter speed will help! You are underexposing!

Sorry, I guess I didn't follow your whole thread. Info overload. You need to increase exposure, whether you do it by changing some manual setting (do you have exposure compensation?) or some other means. Just shoot and learn, read your manual and make sure you are aware of all the features, and you are on your way.
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Old 12-04-2007, 09:03 PM   #10
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ill keep trying thanks again man!
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Old 12-04-2007, 11:35 PM   #11
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Quote:
Originally Posted by JRMDC
You just don't get an indoor shot without flash with a digicsam.
On the contrary. That's what a tripod is for.
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Old 12-04-2007, 11:43 PM   #12
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On the contrary. That's what a tripod is for.
So true, so true!
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Old 12-04-2007, 11:46 PM   #13
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And I only say that firmly because I photograph houses (interior and exterior) for a living.

asis80, I'm glad you got the UE book. I think it's excellent for a beginner.
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Old 12-05-2007, 05:02 AM   #14
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thank you jim and janusz! Greatly appreciated! Yea Jim, the book is great, wish I had an SLR to better understand the technical stuff but I'm beginning to "see" things as I would want to see them in the viewfinder. Even like driving to work or just to go get gas down the road, I see something and it clicks in my head "That would make a GREAT shot!" The Digital Photography book of Peterson's is also VERY nice.
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Old 12-06-2007, 01:17 AM   #15
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Look over the section on setting up your camera's meter. You can probably choose to set exposure as an average of the whole scene or a very narrow part of it. I meter on whatever needs the best exposure by putting the meter's spot on that. Then, while holding the shutter button half way down, I compose the shot and fire.

For some scenes you'll want the average of the whole shot and your meter is probably set for that.

Just when you're getting that hang of it some bozo is going to mention graduated neutral filters screw up everything!

Besides shooting in manual you might want to experiment with program mode. I'm learning to use it to control ISO.

The best answer is: Make More Photos! Experience helps!
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Old 12-08-2007, 01:34 PM   #16
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Just when you're getting that hang of it some bozo is going to mention graduated neutral filters screw up everything!
haha Grad filters can be great if you're shooting landscapes and parked trains. The idea of a grad filter is to be able to slow down the shutter speed to better expose dark areas, while controlling bright areas. I have used a CP filter on a parked train, but I haven't used one of my ND grad filter yet. Perhaps I'll give that a try one of these winter days when the clouds are bright and the train is dark. Oh wait, that would force me to use a higher ISO than 100 for a moving train. bah!

Quote:
Besides shooting in manual you might want to experiment with program mode. I'm learning to use it to control ISO.
I shoot in manual and I have NO idea what you mean by that. Why can't you learn to control ISO in manual?
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Old 12-10-2007, 07:09 PM   #17
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[quote=I shoot in manual and I have NO idea what you mean by that. Why can't you learn to control ISO in manual?[/QUOTE]

Program mode is sort of half way to manual. I'm assigning the ISO and letting the camera work out exposure. If I'm short on time to arrange the shot I can concentrate on composing.

When I was shooting 35mm I was all manual, so I guess I'm getting a little spoiled. Using program is part of the learning process, trying to change a limited number of variables at once. I've done some shooting in manual for motion when shutter speed was important.

I'm going to have to add a notebook to my gear because the metadata can't record filter changes, and can't always remember them.
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Old 12-11-2007, 12:37 AM   #18
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Quote:
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When I was shooting 35mm I was all manual, so I guess I'm getting a little spoiled.
I guess I don't understand why you'd want the camera to do the work when you already KNOW how to shoot in manual. Hmmm....
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Old 12-11-2007, 09:45 PM   #19
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Quote:
Originally Posted by JimThias
I guess I don't understand why you'd want the camera to do the work when you already KNOW how to shoot in manual. Hmmm....
Because it's a new camera and a new subject--trains--there's a lot of variables and potential that wasn't in my grasp with film. I try to evaluate the metadata after a shoot so can begin to understand what works best.

One of the disadvantages to shooting in RAW is that it's slower. One the advantages is also that it's slower, meaning I need to be more thoughtful about each shot instead of machine-gunning the subject with jpgs and hoping I get lucky. That is, I suppose, a subjective personal philosophy, but I think it will serve me well in the long run.

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Old 12-12-2007, 01:27 AM   #20
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Understandable. As someone who started out in auto and quickly forced myself to learn manual, I was just curious as to why someone with the knowledge of shooting in manual would not want to stick with it.
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