> On Dec 18, 2017, at 6:35 PM, Larry Colen <l...@red4est.com> wrote: > > Eric Weir wrote: >>> On Dec 17, 2017, at 2:08 PM, Larry Colen<l...@red4est.com> wrote: >>> >>> Note that the greater the dynamic range a camera has, the less apparent >>> contrast there will be in the unedited file. >> >> You’re gonna have to explain that, Larry. To my naive, uninformed, ignorant >> mind it strikes me as counterintuitive. More than a little. But just my >> naive, uninformed, ignorant mind. > > By the way, a significant portion of my upper division classes in college > were on digital signal processing. A lot of my professional life has been in > computer controls, where we digitize real world data and work with that. As > such, there are a lot of things that I don't even have to think about like > converting number of bits to an equivalent analog range, so if I mention > something as if it is obvious, and it's not, don't hesitate to ask. > > In short.... > The K-5 dynamic range at base ISO is basically 14 stops (each bit or stop is > a power of two), that means that it has a range of 1 to 2^14, or about 16,000 > between the least amount that it can register and the brightest that it can > register (for each color channel). > > If you have a camera with only 10 stops of dynamic then that is only a ratio > of 1,024. > > JPEGs (for example) have 8 bits (coincidentally a bit and a stop each > represent a doubling, or power of two), which is a ratio of 1-256. What that > means is if you map the range of the sensor onto the JPEG, then it takes 16 > times as much change in brightness (contrast) with a 14 bit sensor to make > the same change in 8 bits as it does with a 10 bit sensor. > > If you do an HDR in lightroom with two images shot 6-8 stops apart of a scene > with a lot of dynamic range, and you process it without the auto exposure the > resultant image will look very flat and low contrast. > > It's something that kind of takes some playing around and experimentation to > get a good feel for. > > As to the raw conversion engine, it doesn't really matter what is running > under lightroom, the fact that you do your processing in lightroom is what I > was asking about. > > One nice thing about lightroom is that it doesn't make any changes to the raw > file. It stores a set of steps (a recipe, if you will) for the raw conversion > engine, to apply to the raw file to get your final product. When you make a > virtual copy, it just starts off with all of the settings at whatever point > you make the virtual copy and you can adjust them at that point. > > You could go to one of you photos that you've already processed in lightroom. > Press 'D' to get into the develop module, go to the history on the left, > click on "import photo", and that will have all of the settings zeroed out. > Then hit (command or control)-single quote to make your virtual copy, and > that virtual copy is starting out fresh.
Thanks, Larry. I’m gonna have to study this. I’ll get back to you—with appreciations or further questions. ------------------------------------------------------------------------------------------ Eric Weir Decatur, GA USA eew...@bellsouth.net "Imagining the other is a powerful antidote to fanaticism and hatred." - Amos Oz -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
