On Jan 28, 2012, at 10:31 PM, Larry Colen wrote: > > > On 1/28/2012 7:07 PM, Paul Stenquist wrote: >> >> On Jan 28, 2012, at 9:49 PM, Larry Colen wrote: >> >>> >>> >>> On 1/28/2012 6:29 PM, Paul Stenquist wrote: >>>> You can "expose to the right" or anywhere you choose by using exposure >>>> comp in any metering mode. The metering isn't based on jpeg or RAW. It's >>>> based on the light and what's in front of the lens. No meter is smarter >>>> than a photographer who understands how meters work. >>> >>> I'm certain that if I'm wrong someone will correct me. The metering mode >>> in our cameras picks a spot to meter on, and sets the exposure for that >>> point at midpoint. This means that if you look at the histogram, you >>> usually get a bell curve right around the middle of the graph, expose to >>> the middle. This means that if you go direct from RAW to JPEG without any >>> compensation in post processing, most of the pixels in the photo will be >>> right around the midpoint of exposure. >> >> No. In multi mode, the meter uses a program to analyze the scene and tries >> to achieve a balance of highs and lows. If you don't like the histogram that >> results, you can move it right or left with exposure comp. You only get a >> bell curve in the middle when you have an average scene without extreme >> highs or lwows. > > Interesting. Then why is it that if you photograph something like a white > table, or snow, using normal metering, it comes out grey rather than white?
Because the meter is dumb. It figures that if there's just one color, then it's midrange. However, modern meters do a better job than the older ones. The K5 only misses by about a stop. The older center weighted meters or averaging meters missed by close to two stops. If I shoot a snow scene with the K-5, I usually give it about plus one stop of exposure comp. > > So, what you are telling me is that the metering in our cameras is optimized > to give the best performance when shooting in raw mode, rather than in jpeg? No, it's not optimized for either mode in particular. It's just a dumb meter. It measures light and tries to guess what the scene looks like based on its firmware. > > Or, that unlike in film where you'd meter differently for negatives and > slides, there is no difference in metering for getting the best exposure out > of jpegs and out of raw? You only meter a bit differently for negatives and slides because of the processing. A slightly overexposed negative can still be printed rather nicely with more exposure in the enlarger, but an overexposed slide is junk. When my processing was set up right, I usually exposed about the same for BW film and transparencies -- or slides if you wish. > > >> >>> >>> What it does not do is look at the pixels out at the tail end of that >>> graph. If a bunch of them are off to the right, and you expose for the >>> middle, then you end up clipping on a lot of your readings, in other words, >>> you'll lose highlight detail. >> >> Then you bring that back in by dialing in negative exposure comp. >>> >>> Alternatively, if most of the readings are to the left of the point that is >>> metered for, then exposing for the middle will leave you with either a lot >>> of pixels that are clipped black, or a lot of your shadow detail lost in >>> the noise. >> >> Then you dial in positive exposure comp. Simple. > > Why not have a mode in the camera that does it automatically? Give me the > source code for the K-5 and I could probably implement it in a week. You'd have to invent a meter that could tell the difference between gray and white. Today's meters just read light levels then compare them to firmware that tries to predict shat part of the scene is sky, what's grass, what's a face, etc. They don't really know what color things might be or how much light they are capable of reflecting. But the human brain and the human eye can make that call with precision. So determining how much exposure comp you need based on your own intelligence is the best way, and it will probably remain the best method for many years to come. > > >>> >>> The principle of exposing to the right has nothing to do with where you put >>> the peak of that bell curve, but that you expose the picture as much as you >>> can without clipping details in the highlights. In the first case, this >>> will reduce the exposure on the fat point of the graph, giving you a bit >>> more noise, but you won't lose information in the highlights. >>> >>> In the second case, you expose everything a bit more, then when you >>> compensate in post production, the noise gets reduced along with everything >>> else, improving your signal to noise ratio. Not entirely unlike how Dolby >>> noise reduction works, apart from Dolby being on an analog signal, and only >>> in certain frequency ranges, but still, amplify everything, signal and >>> noise, and then when you reduce everything, the noise is reduced. >>> >>> >>>> >>>> Perhaps, I'm missing something, butI don't know what you men by choosing >>>> 18 percent gray for shooting jpegs. You can use the spot meter and take >>>> gray card readings if you want a pure 18 percent gray exposure read. A >>>> histogram based on the raw might be nice, but it's not hard to interpret a >>>> jpeg histogram in terms of where you'll be with RAW. If you're edge to >>>> edge with jpeg, you're pretty much golden with RAW, and if necessary, you >>>> can push it beyond that a bit. >>>> >>>> Paul >>>> On Jan 28, 2012, at 8:58 PM, Larry Colen wrote: >>>> >>>>> Never mind raw on a point and shoot, I want my DSLR to properly support >>>>> shooting in raw. I want metering and histograms based on the raw data. >>>>> I want to choose metering modes so I can use "expose to the right" for >>>>> raw, and if I want to shoot jpeg I can choose 18% grey, or whatever they >>>>> call it. >>>>> >>>>> For doing landscape and studio work, I fantasize about a mode that will >>>>> take a test shot (or three), examine the raw data and set the exposure >>>>> for details in the highlights or the shadows, or the bracketing for an >>>>> HDR series of exposures that will cover the full tonal range. I want a >>>>> TAv mode for the green button in M, so that I can set the shutter speed >>>>> and aperture based on a critical element of the photo, have it set the >>>>> ISO, and then just leave it there. >>>>> >>>>> Everything about using my camera indicates that raw is an afterthought, >>>>> and the UI is optimized for people that want a $1,000 point and shoot >>>>> with interchangeable lenses. >>>>> >>>>> -- >>>>> Larry Colen [email protected] (from dos4est) >>>>> >>>>> -- >>>>> PDML Pentax-Discuss Mail List >>>>> [email protected] >>>>> http://pdml.net/mailman/listinfo/pdml_pdml.net >>>>> to UNSUBSCRIBE from the PDML, please visit the link directly above and >>>>> follow the directions. >>>> >>>> >>> >>> -- >>> Larry Colen [email protected] (from dos4est) >>> >>> -- >>> PDML Pentax-Discuss Mail List >>> [email protected] >>> http://pdml.net/mailman/listinfo/pdml_pdml.net >>> to UNSUBSCRIBE from the PDML, please visit the link directly above and >>> follow the directions. >> >> > > -- > Larry Colen [email protected] (from dos4est) > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
