Less lens contrast to cope with narrow DR of camera?
So since less contrast "sometimes" means less sharpness, you end up
putting up with softer images? http://forums.dpreview.com/forums/re...hread=24340033 |
Less lens contrast to cope with narrow DR of camera?
RichA wrote in news:1190291390.186946.120710@
22g2000hsm.googlegroups.com: http://forums.dpreview.com/forums/re...hread=24340033 Reducing contrast in the optics is like under-exposing, only with more noise in the shadows, once you have re-normalized the tones. Basically, what is happening is that some of the light is not forming a sharp image on the focal plane, but is scattering randomly. This means that black becomes brighter, and even colored. That means more shot noise for the lower tonal ranges than if you had used a high-contrast lens, even if you under-exposed a bit. The apparent increase in exposure latitude is an illusion. Under-exposing with a high-contrast lens in such a way as to give the same exposure as the low-contrast image minus the false "black" leaves less noise in the shadows, and leaves more room for highlights. -- John P Sheehy |
Less lens contrast to cope with narrow DR of camera?
John Sheehy wrote:
RichA wrote in news:1190291390.186946.120710@ 22g2000hsm.googlegroups.com: http://forums.dpreview.com/forums/re...hread=24340033 Reducing contrast in the optics is like under-exposing, only with more noise in the shadows, once you have re-normalized the tones. You might not want to re-normalize the tones though. And supposedly there are some lenses which aren't as contrasty but are still sharp. Flare reduces contrast in the way you describe and is rarely desirable but if this was desirable for high contrast scenes, it probably would be easy to make a flare filter or contrast reducing filter like how a polarizer increases contrast. Otherwise you'd want whole other set of lenses for high contrast shooting. Basically, what is happening is that some of the light is not forming a sharp image on the focal plane, but is scattering randomly. This means that black becomes brighter, and even colored. That means more shot noise for the lower tonal ranges I'm not sure why there would be more noise... because the flare *is* noise? If the shadows are brighter, there should be less noise. If you try to increase contrast in the mid-highlights, that does increase noise and looks awful trying to re-contrast a flared out shot but if you leave the contrast alone, it might look just fine. Noise comes from recording the signal too dark and trying to lighten it in post processing but if you don't raise anything, just darken the shadows, it should be OK, right? than if you had used a high-contrast lens, even if you under-exposed a bit. The apparent increase in exposure latitude is an illusion. Under-exposing with a high-contrast lens in such a way as to give the same exposure as the low-contrast image minus the false "black" leaves less noise in the shadows, and leaves more room for highlights. -- Paul Furman Photography http://edgehill.net Bay Natives Nursery http://www.baynatives.com |
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