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10-31-2011, 06:19 AM   #1
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Setting under exposure? Why?

I had a brief conversation with a photographer the other who said that he always sets his camera to under expose as a matter of course, unfortunately I didn't get the opportunity to ask why.

So why would he do this and why?

And... I have a K20, how would I do it??

Ta...

10-31-2011, 07:08 AM   #2
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Simply because in PP you can 'recover' lost highlight details from an underexposed shot, but you can't 'recover' lost shadow details from an overexposed shot.

K20D tends towards underexposure as a default.
10-31-2011, 09:00 AM   #3
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QuoteOriginally posted by Damian.T Quote

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And... I have a K20, how would I do it??

Ta...
Use the "+ Av" button on your camera.

One thing that you should be aware of in this respect: Lenses, due to coatings and other design differenses, do not transmit light equally efficient even though they are set at the same, nominal f-ratio. Thus, to my experience one specific lens will often benefit from having "its own" Av-adjustment.
10-31-2011, 11:39 AM   #4
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QuoteOriginally posted by Damian.T Quote
I had a brief conversation with a photographer the other who said that he always sets his camera to under expose as a matter of course, unfortunately I didn't get the opportunity to ask why.

So why would he do this and why?

And... I have a K20, how would I do it??

Ta...
this is used to protect highlights and when people shoot film especially kodachrome, it is done to increase color saturation. to do it you set the EV compensation to -x where x is the number of stops you want to under expose by. Typically to preserve highlights might need as much as -2, which results in images being pretty dark, and could result in high levels of noise in the shadow areas.

With respect to this type of "rule" inherited by discussing with another photographer, and not getting an explanation, I would recommend try it very carefully. Rules from others can be bad practice, it is better to learn proper exposure technique and evaluating exposure correctly

10-31-2011, 06:09 PM   #5
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QuoteOriginally posted by Damian.T Quote
I had a brief conversation with a photographer the other who said that he always sets his camera to under expose as a matter of course, unfortunately I didn't get the opportunity to ask why.

So why would he do this and why?

And... I have a K20, how would I do it??

Ta...
I thought for a moment I spoke to you, I am in an area near Bolton Hill and I prescribe to the theory that Blown/Burned Highlights are unforgivable... but I see you're from the UK and not Baltimore

I am "Left of Center" both in personal tastes and photographs. I try to keep my peaks to the left of center when viewing a histogram. I think the advice is good, but you need to find out from PP what you consider "under exposed"... I usually do not under expose more than 1/3 - 1/2 stop and/or the peak of the histogram is not hugging the left side. I will always try my best to save highlights by underexposing enough or just finding a different composition that works; and the only rule of thumb I follow, you cannot save them all...

However, when using high ISO's, I might do the opposite...

When using anything other that Manual mode on the K20D, using the +/- will work; when using Manual mode, make the shutter speed faster...
11-01-2011, 06:41 AM   #6
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Expose Right

For me ETTR tends to mean underexpose when in sunlight, but overexpose indoors. Nonetheless, ettr is superior to alway overexpose/underexpose because it maximizes the camera's dynamic range and minimizes noise while preserving highlights.
11-01-2011, 09:36 AM   #7
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When I'm taking flower photos, I lean towards underexposure. The red or blue channel is easy to overload when the meter thinks everything is wonderful. You won't see it on the histogram either, unless you look at the RGB histogram.

Snow and the beach are classic times for overexposure. The overall bright background fools the meter into a lower exposure.

In low light, I try to get an exposure histogram that's really close to the right side, to combat noise. Sometimes I'll overexpose bright highlights with detail that I don't care about, to get the main subject well exposed. Otherwise I try not to overexpose, but go right up to the edge.

If you're shooting in JPG mode, you have less flexibility in processing, so an extreme exposure is less useful. In RAW, I'm often shooting to capture something I can use, not something that looks great immediatly.
11-02-2011, 01:49 AM   #8
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Thank you everyone for your thoughts, I shall go out this weekend and have a play around with the settings and see what the results are. I'll also swap and change the Pentax / Sigma lenses.

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