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 Post subject: Overexpose...help
PostPosted: Sun May 11, 2008 10:17 pm 
Hello to everyone.

I bought my first DSLR 4 days ago and i realized that there is a problem(?) with it.

I own a Canon EOS 450D/Rebel XSi with the "multi purpose" lens 17-85 IS USM.


If you look at the photo you can see that there are some points overexposed and other normaly exposed. For example the road that you can see in the photo is too light and there are no details at all while the trees and the people are ok.
Image
How could i avoid this phenomenon? Is there any issue with my lens or its just because of my bad use of the camera?

How can i avoid it? Maybe with a filter? (i use allready a Hoya UV filter) Maybe by using a hood? Or just my settings wasn't correct?

I would appreciate it if you could give me some tips about this.

*Sorry about my english, i m trying to write as better as i can.


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 Post subject:
PostPosted: Sun May 11, 2008 10:45 pm 
A filter can not save whats going one in this photo. There is nothing wrong with the camera either.This phenomenon depends mostly on the metering setting of the camera. If you use partial metering or even spot metering(dont know if spot metering is even available with the 450D ) on the concrete (brightest part of this scene) you would get less overexposure in this photo.Read your manual....i'am sure you will find more info about the different metering modes. I presume you used another metering mode where the camera takes the whole scene into the exposure metering of the photo. When the exposure is set at 0 ev you get a scene that has an exposure at 18% grey. You need to underexpose to get a correct exposure in this photo. Matrix or evaluative metering tries to calculate the whole scene and corrects the exposure to 18%grey....this metering mode does not recognize the brightest or darkest spots in the photo. Use spotmetering or partial metering on the brightest parts of the scene and the camera will correct the exposure in a way that the metered part looks well exposed. Just use the different metering modes from your camera and you will find the right one for this scene by trial and error. Succes!!!


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 Post subject:
PostPosted: Mon May 12, 2008 1:16 am 
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Joined: Tue Nov 08, 2005 3:32 pm
Posts: 9975
Location: Queenstown, New Zealand
Hi Nightwolf, further to Peter's message, we have a workshop on deliberately darkening photos here:

http://www.dslrtips.com/workshops/How_t ... tion.shtml


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 Post subject:
PostPosted: Mon May 12, 2008 8:28 pm 
Thank you very much Peter and Gordon!!!
Very usefull tips.

I' ve been using wide metering mostly and sometimes local but never spot metering! I tried spot metering today and the results were excellent. Its usefull when you want to focus on something specific without over or under exposing it. For example a portrait.

Exposure compensation is also a useful tool.

:D :D :D :D


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 Post subject:
PostPosted: Mon May 12, 2008 8:38 pm 
Yes overexposed indeed. What was your shutter speed? has to be something like 1/125 or something? Weird that your camera decided to go for this settings. Yes a polarizing filter would have helped you here because it works as a "stopper" so to speak. It decreases the light in a very special way.

What i would recommend you doing when the weather is like it was during the time is to bring down the EV to something like -0.3 or -0.7 this will decrease the shutter speed of your camera automatically and will decrease the chances of you overexposing such a big area. This photo i would just have binned..Its not worth the time. Its going to take to long.

My motto is: "When in doubt, underexpose"

Check out my blog for some more phototips apart from Gordons


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 Post subject:
PostPosted: Sun May 18, 2008 4:55 pm 
Ok, agree with you but sometimes your moto doesnt work...


For example...
Image
*I used spot metering mode targeting on the bridge.
What would you do in this picture?
If i had underexposed the bridge and the trees would be dark.
In "auto" exposure, without exposure compensation you see that the rock on the right of the picture looks so bright that ruins my photo.Its because of the sun...of course!
:cry: :cry: :cry:


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 Post subject:
PostPosted: Sun May 18, 2008 5:21 pm 
My motto always works, trust me!

So what you did wrong is that you should have metered of the "white" rock that is clearly overexposed. And if you were to meter of the bridge you could have just toned down the EV by -0,7 and then adjust the levels in PS.

would have work great! do you want me to try to fix this shot?


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 Post subject:
PostPosted: Sun May 18, 2008 5:23 pm 
Hi Nightwolf,

you're facing one of the oldest challenges in photography. No matter what metering, the camera can only expose everything at the same level. If there is too wide a range between what is darkest and brightest, something is going to get over or under exposed, regardless.

Shooting in RAW usually gives you a wider range of manipulation-options with the shadows and highlights, but when there are extreme differences as in this latest ones, it's not really the answer as it can end up looking rather synthetic when you manipulate too much.

There's also HDR (High Dynamic Range) where a piece of software can stack and combine several different exposed, but identical, images into a whole that can look pretty good. Pushing that too far will also make it look at little artificial though.

That leaves composition, composition and composition..and a dose of patience..as your main tools for keeping the dynamic range of the image within manageable levels.

However, some images can be enhanced by a careful use of over-exposure, such as sunlight reflected in water, for example.

All photographers struggle with this delicate balancing act in one form or another.

Cheers :-)


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 Post subject:
PostPosted: Sun May 18, 2008 6:41 pm 
Yeah metering is quite hard at start, but you will get sued to it!

Now i just did some quick cloning here from the other rock to the right rock to give it a rocky look and then i did some basics levels adjustments and added a digital polarizing filter to boost the contrast a bit, the adjust the hue/saturation a tad and wuala, you get that. In my opinion this image has POPED! compared to the one you shot, i dont mean that in a bad way you just need to learn and you have plenty of time ahead of you :)

Image


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 Post subject:
PostPosted: Sun May 18, 2008 6:53 pm 
Nightwolf wrote:
I used spot metering mode targeting on the bridge.
What would you do in this picture?
If i had underexposed the bridge and the trees would be dark.
In "auto" exposure, without exposure compensation you see that the rock on the right of the picture looks so bright that ruins my photo.Its because of the sun...of course!


You were right to use spot metering, but here if you were to follow the underexposure rule of thumb then you should have been metering on the most bright object in the frame. This would undoubtedly leave you the foreground lump of concrete. Recovering shadows is far more easy than highlights.

Alex - I like the way you've tried to clone the concrete back from using the far sided one as a clone source. However to the trained eye, it does look very obviously cloned in because of repetitive shapes and stroke patterns. You have tried to add some variation to reduce this, but still not quite enough for my eye. In the end it is a better image than the original, and an illustration that PP can be used to salvage images.


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 Post subject:
PostPosted: Sun May 18, 2008 7:41 pm 
Ed-I cannot agree more that looks obvious to the train eye's but i m going to be honest i m not going to spend time on a photo that isn't mine, what i did was to illustrate what can be done, i did quite shady job but i was a quick fix! Give me an 1h on that photo and i would use another rock from another picture instead :P

Honestly i hate fixing overexposed pictures because its a wast of time, its really hard to make them look perfect, that why i use that rule of thumb, of when in doubt underexpose


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 Post subject:
PostPosted: Sun May 18, 2008 8:21 pm 
Haha!! Its much better now!! I can't believe the difference!

If i didnt know that you tried to clone the rock i wouldn't even realize that its fixed or something. Except for the colour of the scenery that looks a little unatural, the rock is OK!

And as you said, i need to learn many things about photography, i ve been using a DSLR 1 month so far.

Your advice is really helpful for me as i am new yet. Thank you Alex, Photoj and LahLahSr !!


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 Post subject:
PostPosted: Sun May 18, 2008 8:33 pm 
No problem night, you gotta learn you way around the post work as well :)

now if you want more tips and have the time its worthwhile to sit back grab a pen and paper and read some tips of MY BLOG i bet you will learn something more then just now :)


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PostPosted: Sun May 18, 2008 8:51 pm 
Hi

You could try to use the camera's histogram to judge exposure too.....the histogram is a very easy to use tool in the field.

The scene where you took the original photo is not moving(or running of)....so you could take more than one photo to get the exposure correct.
I took the liberty of copying your photo an attach the histogram that comes with it.
A histogram is very easy to read. There are three zones in a histogram.
The shadows are at the left side, the higlights are at the right side...in between are the midtones. To get a good photo without overexposure in the highlights you must prevent that the black curve touches the right side of the histogram edge. If you take a look at the histogram of your photo you can see a high peak of black touching the right side of the histogram edge.....this means info is lost ....and overexposure is present.

Use the exposure compensation button to lower the exposure and take a new photo.....than check your histogram again. You must compensate the exposure so that the curve no longer touches the right side in the histogram.Keep the curve as close as possible to the edge at the right but without actually touching it. If you lower the exposure too much and there's a big gap at the right side your photo will be underexposed.

It may seem difficult at first...but it is the only way to get the exposure correct without having to use software to correct it afterwards.


Image


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 Post subject:
PostPosted: Mon May 19, 2008 2:42 am 
Wow that is totally blown out! :shock: good times
shooting RAW is great advice, if you have time to work out a correct exposure, just under expose it and fix it later.

But imho the solution lies in AE Lock:
(this is defined from photonotes.org/dictionary)

AE Lock (AEL).

Also “auto-exposure lock.” A common feature on many SLRs with automatic exposure which allows you to lock in the current exposure settings for a period of time, regardless of what happens to the incoming light levels in the viewfinder.

Let’s say you’re taking a photograph of a scene which contains one very bright light source in the corner. Normally this bright light will fool the automatic exposure system into thinking that the scene is brighter than it really is. What you really want is for the camera to meter the scene without the troublesome bright light being in there.

Now you could just turn off the light if it’s under your control. But that won’t help you if the bright light originates from the sun or from other source you can’t switch on or off at will.

So another way to do this is to move the camera slightly so that the bright light no longer appears in the viewfinder. When this happens we’ll assume that the scene now contains the light levels you really want to meter for. You can then press the AEL button (often marked with the * symbol on Canon cameras, for example) to lock in whatever the camera’s light meter believes are the correct settings.

Now when you move the camera back so that the bright light is visible once again the correct exposure settings are retained and you can take your photograph. This is a typical use for AEL.

Here are a couple fixes I did in Lightroom. With RAW you have even more control.

Image

Image


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