On Jun 23, 2008, at 11:10 AM, Christine Aguila wrote: > 1) I'm having a devil of a time with blown highlights, especially in > challenging lighting situations. I've been trying to teach myself > the Zone > System--and I think I've got the gist of it. But for street > photography, > things get a bit rushed, so, as I've learned, I should quickly spot > meter > for a mid-tone, lock in exposure, then reframe, focus & shoot.
Digital camera exposure is different from film exposure because the characteristic behavior of a digital sensor is fundamentally different from film. - Highlight values run into the hard wall of sensor saturation when the sensor runs out of numbers to quantize the incoming energy level ... there's no "shoulder" or slope involved, when the energy level received by a photosite in a 12bit sensor hits the integer 4095 after going through the A->D converter, there is no more energy it can report and it simply gives the maximum value. - The minimum exposure threshold boundary is soft: it's a matter of the actual analog DR of the sensor vs how much noise you find acceptable to set where you put the black point. Compared to film, it's a much "softer" slope because you can determine from frame to frame what you feel is important. That said, on average, correct exposure for both tends to be fairly close, what you need to be conscious of is the sensor's dynamic range given whether you are capturing in RAW vs JPEG mode, and at what ISO sensitivity setting. I measured the K10D's DR with my standard test (which has built into it various of my assumptions about what I consider a useable black point signal/noise ratio...) and found that it provides in RAW capture mode a range of 11 to 9 stops working range from ISO 100 to 1600. Yes, DR decreases as ISO increases and there's not much you can do about it. For this reason, the methodology I find most useful sith digital capture, considering Zone System, is to meter for the Zone IX highlights, not the Zone V midtones, and to consider what are the important highlights with the sensor's dynamic range in mind. Only at the lowest ISO settings can you cover a full 10 EV tonal range, so you have to be ready to pick your desired highlight level and lose the rest. For street photography, where keeping shutter speed up is desirable to reduce subject motion, you often need to raise ISO and live with the shorter DR. I don't expect that the K20D will be any different in principle although if it does have EDR capability, well, you have a bit more range to work with. Most of the time with street work, however, rather than spending time metering for every shot, I tend to put the camera in Av, pattern matrix mode and set the EV Compensation for +.3 to +.7 stops. I make liberal use of the AE Lock button and play around testing until I see the light correctly and remember what the settings and situations were. Then I go to work. Spot mode requires a bit more thought but is useful if you're in seriously hard, contrasty light. > ... What do you guys consider to be mid-tones in color? > > 2) I'm trying to train my eye to visualize, but it's slow going. > Any tips > for faster learning? That's very hard to articulate quickly. Depending upon your eyesight (red-green colorblindness can affect judging colors) and whether you're wearing sunglasses or polarizing sunglasses or not ... it all affects how you see. Some photographers carry around a deep sepia filter and use that to smash all the colors into something that resembles a typical B&W spectral response so they can see the tonal difference separate from the colors. I did that years ago. Now I just wing it ... I know how different colors affect my eye and judge accordingly. > 3) Also, I've been metering for highlights more, then using > Lightroom to > bump up the shadows, which seems to work, but does anyone have any > other > suggestions? > > 4) Also, virtually 99.9% of the time I have to bump up the > "Lights" in > Lightroom to anywhere from +10 - +39. No bid deal, but is there > something I > should be doing in-camera to avoid this. I wonder if the K20D, > with it's > EDR, eliminates this? Any thoughts. I'm actually thinking of > making a > develop preset to do the things I seem to do repeatedly when > processing in > Lightroom, but thought I'd touch base here 1st I rarely look very closely at the numbers in Lightroom. I have a couple of preferred starting point for my B&W rendering work that I put into presets. I apply one of them on import and see what it looks like, then poke the values around to see what I get out of it. Not very scientific, but it is based on what I've experimented with that worked, for me, and turns out to be very quick and easy to do. I only rarely have to switch presets or start from scratch. My goal in setting my camera's exposure is to obtain the most usable data for image processing I can. That makes it simple. How I push the values around once I have a capture with enough data in it to do the job is pretty free form. :-) Godfrey -- 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.
