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So I've searched this forum (and others) looking for a good explanation of what is actually happening when I use the 'exposure', 'recovery', and 'black point' sliders in Aperture 2 . . . . I used to push/pull film back in the day, and it wasn't 'free' - there was a quality difference - not necessarily bad, just a difference.

 

These days, I shoot with a Digilux 2, ISO 100, RAW, and use ambient light, so I have a tendency to intentionally underexpose my shots so I don't have to carry/set up a tripod. Normally, I plan on fixing it during processing, but I got to thinking . . . there's always a price to be paid, the software isn't magic (I don't think - but it does seem that way sometime.)

 

So, anyone actually know what's happening to the image? I get the feeling that a properly exposed image would be superior - but I shoot a lot of images, and I'm not carrying a tripod around, and I can't hand-hold for 2 seconds, so . . . . does anyone know if shifting the exposure negatively impact the image? Is there actually a significant difference between changing the EV on camera vs. upping the exposure off-camera? And just what happens when you peg that 'recovery' slider all the way to the right?

 

Thanks!

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I am no expert but I would say that you are correct - there is no free lunch.

 

If you learn about using the histogram you will start to understand it more.

 

So - for example, today I shot some things under a bright but overcast sky.

 

By metering the sky I had fantastic detail in the clouds but had to pick up the grass and scenery - I was losing 'headroom' in the shadows - compressing the dynamic range.

 

By metering the grass I had fantastic detail in the scenery but had to either accept a blown out sky or try to 'recover' the damage in the highlights. - the loss of dynamic range here was due to clipping of the sky.

 

The solution? Manual exposure at 'just right' level !! Once you get that on the computer you can see that very little work is needed unless you want 'an effect' and you have the dynamic range in a accross desirable brightness points.

 

As I say, I am absolutely no expert so please only use my post as a starting point for your research!

 

Good luck!

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Guest joewehry

An article in LFI once mentioned that the human eye has a better ability to discern a range of shadows compared with highlights and the M8 file (as I recall) computes shadow details differently than highlights.

 

If you need the widest range, I'd say expose for the shadow detail and if needed, compress any highlights post processing. (watch for totally blowing out the highlights or there will be nothing to recovery.)

 

But ultimately, expose for the type of image you want. If you think of Boza Ivanovic's photos in LFI 02/2009, his exposures turn the background black. ( So much for shadow detail!) But his images are outstanding.

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Thanks for the replies . . . I do understand the histogram (it's an excellent tool). In conventional film, the axiom is 'expose for the shadows', but in digital, it's reversed - I read somewhere that the upper end of a RAW file contains double the information of the darker end . . . so to me, that would seem like there's more information to capture by overexposing a bit and then pulling the exposure down in post-processing.

 

Unfortunately, this would exacerbate the problem I already have . . . anyone else got any ideas/information/reference suggestions? Surely there are some experts out there . . . . and the Leica forum seems to collect them :)

 

Thanks!

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Basically what you do when underexposing is to throw a way the righthand side of the histogram. The exposure slider will increase the amplification in such a way as to stretch it to the right, but you will have lost dynamic range.A better way to fix under or over exposed shots is to go into photoshop, make a layer and use screen or multiply respectively, and repeat as necessary. Nothing has changed since Ansel Adams: A proper exposure is the starting point of a good photograph.

Would it not be a better to use a higher ISO when shooting instead of underexposing?

Edited by jaapv
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Guest joewehry

LFI 02/2007 has a good article on how the M8 processes data, with 07/2007 giving suggestions and software tips on exposures.

 

Their take is to "expose to the right" of the histogram such that you get a good range without overexposure and losing data.

 

Turn on the clipping warning to help make those decisions.

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Press info and the overexposed areas turn red, if you have activated the feature in the menu (menu>histogram>RGB with clipping). The problem with the clipping warning in the M8 (and any other camera) is that it shows the clipping for in-camera jpg-s. In reality you have about one additional stop in DNG, or maybe a bit more if you use higlight recovery in you RAW converter. The histogram is more reliable.

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Thanks for the replies (even the attempted thread hijacking :), I'll do a bit more reading and see what I can turn up.

 

I generally avoid shooting about ISO 100 w/ the Digilux 2 (for obvious reasons - it doesn't do it well), and I generally try to expose to the right of the histogram, but I guess I was hoping for more of a technical "This is what Aperture is doing to the RAW data" type of reference, a deeper understanding of the digital development process . . .

 

Thanks!

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. . . there's always a price to be paid, the software isn't magic

 

Actually, I'm often surprised at just how magical the software can be with shadows. You should be able to fill and recover significant shadow detail. I guess it depends on how far to the left you are.

 

If you are are compensating for a handheld exposure that would otherwise take two seconds, that's not likely. But when the D2 came out there was a popular approach to addressing its high ISO limitations by deliberately underexposing 2 stops (as I recall) and recovering in post.

 

-- John

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