Exposure compensation

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Iraussie
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Joined: Mon Sep 22, 2008 11:33 pm
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Exposure compensation

Post by Iraussie » Wed Dec 30, 2009 7:14 pm

:D Hi, I am new to the fusion subject and am experimenting with tufuse. My question is about the number of stops for a well exposed image where you have a bright highlights and deep shadows. My approach has been to measure the number of stops between the brightest and darkest areas. I then set my camera (EOS 30D) to the closest I can to cover that range. ( say +1.5, 0, -1.5) and then set exposure compensation towards the darker end , so that the settings are now -2, -1, 1. I do this to try and save the highlights. Is this the correct procedure or should I just use the full range on my camera. (-2, 0, +2)
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maxlyons
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Re: Exposure compensation

Post by maxlyons » Wed Dec 30, 2009 11:16 pm

I'm not sure there is a right or wrong answer here.

In my experience, 2 images is usually (always?) enough to cover the full range of brightness in the subject I want to capture. In one of the images I try to make sure the shadows aren't black (or nearly black), and in the other I try to make sure the highlights aren't white (excluding, of course, objects like light bulbs, the sun in the middle of the day, etc.) The degree to which I change the exposure between shots varies depending on the subject matter, but it is usually about 3 or 4 stops.

I'm sure this isn't the only way to do this, but it is an approach that I have found works well for me.

Max

Iraussie
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Joined: Mon Sep 22, 2008 11:33 pm
Location: Australia

Post by Iraussie » Thu Dec 31, 2009 7:02 pm

Thanks Max. I appreciate an answer from a master.
I like to shoot pano's and have trouble with the exposure difference across the width of the final image. I take it from your answer that the important thing is to get "Correct" exposure for both the Highlights and Shadows.I'll experiment more.
I also notice that 2 exposures enhance the focus or contrast more and when 3 or more exposures are used the final result is muddy. Is this me or is it something in the settings of tufuse.
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dsjtecserv
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Post by dsjtecserv » Thu Dec 31, 2009 9:34 pm

I agree with Max in most respects. I find that when using fusion the precision of the exposures is less important than covering the range with two or more exposures.

Having said that, I think I get better results using auto bracketing with the center exposure being as close to a "normal" or "best" exposure as I can make it. (An added bonus, of course, is that with the series of "proper" exposures I can also make a decently-exposed pano without using fusion at all, just like in the old days!) I usually bracket the full two stops either side of "normal", although I might go down to 1 1/3 in some cases. (For 1 stop or less, I can do just as well by manipulating the Exposure and other settings in RAW.)

This 3-exposure, 4-stop bracket serves OK for most scenes. But for panos that will include very bright areas (compared to the darkest areas), such as those that include the sun (even at sunrise/sunset), I will also make another set of bracketed exposures for each frame. Typically I will move the center exposure down 3 stops and take another series 2 stops either side of center. Thus I end up with 6 exposures: +2, 0, -1, -2, -3, -5. The -5 is usually dark enough to show even an afternoon sun as a disk, perhaps with a little aura and some "rays". For sunset it will usually produce a nice, saturated disk.

I almost never use all 6 exposures; I can just throw out the ones that aren't needed. I haven't found that TuFuse is able to do a good job with a -5 exposure without messing up the tones of the rest of the scene. Therefore I most often do the fusion with only 3 or 4 of the more moderate exposures. I then manually blend portions of the darkest (e.g. -5) exposure into the fused image using a layer and masks in Photoshop.

Hope that gives you some more ideas to play with...

Dave

Iraussie
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Joined: Mon Sep 22, 2008 11:33 pm
Location: Australia

Post by Iraussie » Fri Jan 01, 2010 5:50 pm

Thanks Dave, Those ideas certainly give me some new ideas for bracketing the individual images in a pano. I have been trying to automate things as much as possible , BUT as with all things automatic , you get what is the average. I think my next approach will be to study the scene more closely and try to pick the elements that are important within each bracketed set and expose to ensure they are captured "Correctly". Also you have prompted me to think that I dont need the same munber of images in each "Tile" of the pano, and so as long as the blending operation works I should get a reasonable pano. Thanks again to you and Max for the inspiration. Your images on pbase are of excellent quality and I congratulate you on their capture and presentation.
John
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