Amen! On Fri, Mar 27, 2009 at 10:56 PM, Joseph McAllister <[email protected]> wrote: > Pay no attention to the man behind the curtain. > > I know enough to know what he is talking about - even see it in the data > Larry presented. > > But I just take my camera out and shoot, Can't be bothered at the techie > level anymore. > > You should not be either... > > > On Mar 27, 2009, at 16:43 , Nick Wright wrote: > >> If anyone wants to know why I don't really care for digital cameras, >> you just have to look at all that below!! ;;D >> >> In other words, woosh way over my head. >> >> On Fri, Mar 27, 2009 at 6:30 PM, Larry Colen <[email protected]> wrote: >>> >>> On Fri, Mar 27, 2009 at 05:58:13PM -0500, Nick Wright wrote: >>>> >>>> Would someone care to explain a little further about the 800 iso thing? >>> >>> If you do some research on the dpreview pentax slr forum, Marc >>> Sabatelle pointed out that someone had written a raw converter (I >>> foreget his name, it's in my archives someplace) and he had discovered >>> that above ISO 800 the circuitry doesn't change, the raw values are >>> just multipled by 2 or 4. >>> >>> >>> ISO real binary hex dec raw file values >>> 200 000000010110 0x016 22 000000010110 0x016 22 >>> 400 000000101100 0x02C 44 000000101100 0x02C 44 >>> 800 000001011001 0x059 89 000001011001 0x059 89 >>> 1600 000010110011 0x0B3 179 000010110010 0x0B2 178 >>> 3200 000101100111 0x167 359 000101100100 0x164 354 >>> >>> You'll see that at ISO 1600 and 3200 that data in the last bit, or two >>> bits is just lost. Mind you, there's a lot of noise in the analog >>> signal anyways, so the actual information you're losing at the bottom >>> end isn't that much. >>> >>> The problem is if you have a pixel that is close to full scale at 800: >>> 800 100000000000 0x800 >>> at 1600 and 3200 it just goes to >>> 111111111111 and clips >>> >>> So when you increase the ISO above 800, not only do you not get any >>> more information from the lowest bits on the darkest pixels, but you >>> clip the information on the brightest pixels. >>> >>> But, don't take my word as gospel, try shooting in some very low light >>> situations, with the camera in manual exposure mode. Assume that at >>> 3200, the correct exposure is 1/10 second f/4.0. Shoot at f/4.0 at >>> ISO 800 1/2.5 1/5 1/10 >>> ISO 1600 1/5 1/10 >>> ISO 3200 1/10 >>> >>> And compare the quality of the shots. I've found that I get as good >>> of a shot at 1/10 f/4 in ISO 800 as I do ISO 1600 and ISO 3200. >>> >>> Given the choice, it's better to expose properly, but if you're >>> shooting dancers or musicians, people who are moving, you may get >>> better results trading noise for shutter speed. >>> >>> -- >>> The fastest way to get your question answered on the net is to post >>> the wrong answer. >>> Larry Colen [email protected] >>> http://www.red4est.com/lrc >>> >>> >>> -- >>> 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. >>> >> >> >> >> -- >> ~Nick David Wright >> http://www.nickdavidwright.com/ >> >> -- >> 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. > > Joseph McAllister > [email protected] > > “If I could tell the story in words, I wouldn’t need to lug a camera.” > –Lewis Hine > > > -- > 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. >
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