I'm certainly no expert on the subject, but it seems to me that putting filters in front of the lens of a camera with a digital sensor in it is a bit silly especially for B&W purposes. Your sensor is already filtering the light through three filters to achieve a "red" channel, a "blue" channel, and a "green" channel. I put those colors in quotes, because the raw file reads each channel as a digital "grayscale". ALL of that information is simply digital bits that can then be manipulated in preset ways by your cameras processor (to render the LCD and JPEG images) or in post-processing (myriads of ways). Correct me if I"m wrong, but when you change the white balance on your camera you are changing what you see on the LCD or JPEGs produced, but you aren't changing a THING to the RAW file. All that original scene info is still there in the RAW file.
You can (in post-processing) then make any sort of correction you want to whatever channel you want. But if you put a filter in front of the lens, you are now SUBTRACTING photons from getting to the sensor. The sensor is still doing it's filter and three channel thing, but with less information about the true scene - thus limiting what information you have in the RAW file to play with. I can see wanting to do this to change the dynamic range of a scene, such as a polarizer to affect the sky. And I can understand it with ND filters (good ones would filter all channel's light equally and then simply allow you to achieve longer shutter speeds for motion blur or whatever). In that case you are still getting all of the channel information to the sensor, but it is just taking longer. But I personally can't see much of a justification for limiting one channel's light, particularly when the same effect could be achieved in post. YMMV. Darren Addy Kearney, Nebraska On Fri, Nov 19, 2010 at 1:16 AM, Larry Colen <l...@red4est.com> wrote: > > On Nov 18, 2010, at 6:49 PM, Miserere wrote: > >> On 18 November 2010 20:56, Larry Colen <l...@red4est.com> wrote: >>> Last night I tried a more rigorous test of photographing with and without a >>> cokin blue filter on my camera. I also tried with and without using custom >>> white balance in the camera. The following collection are the best few >>> shots of each of the permutations I tried: >>> http://www.flickr.com/photos/ellarsee/collections/72157625421911182/ >>> >>> My gut feeling is that the biggest difference is due to using in camera >>> white balance. That it allows me to shoot with the colors more balanced >>> without blowing out the red channel. I'm not sure how this works unless it >>> tweaks the gain that goes into the raw file. Shooting with a blue filter, >>> allowed me to set the custom white balance when I otherwise couldn't. It >>> also meant using much slower shutter speeds, so there's a tradeoff there. >>> >>> However the final product is a result of skill level throughout the whole >>> process, and my lightroom skills are fairly rudimentary, a more accurate >>> test would be to have someone that knows post processing clean up the >>> files. A more practical (except for the cost) solution would probably be >>> to get a K-5 with its greater dynamic range, which would allow a lot more >>> room for color correction without blowing out highlights. >> >> OK Larry, I took a look, but they all look pretty good at those sizes. >> What's your take on the experiment? > > I recognize that this is a somewhat unusual situation (though I run into > similar lighting at Don Quixote's in Felton), and until/unless I'm getting > paid to photograph in this lighting, it's only worth so much of my time and > effort to polish all of the details. That being said, I think that there are > indeed things I can learn from it that I'll be able to generalize to other > lighting situations. > > 1) I wish that I knew exactly what changing the white balance did to the > hardware and the raw file. I hate that Pentax (and I assume all other > manufacturers) figure that people are too stupid to understand and just say > what effect the controls are supposed to have, rather than telling us what > they actually do. Digital cameras are made for people who want their hands > held, not for people that like to get their hands dirty. > > 2) To really understand the results, I'd need to go beyond pixel peeping into > raw data peeping and see what happens with the raw data. If you look at the > exif info, there's a couple of stops difference in exposure between > unfiltered and filtered. I don't remember what the difference is between > unfiltered corrected WB and unfiltered tungsten WB. However, if shutter > speed is critical, then I'd say expose for the brightest channel, and take > your lumps in the other channels. If there's lots and lots of light, then my > gut feeling is that the filters will help. > > 3) I'm really looking forward to getting a K-5, which seems to have good > enough performance in every category, that I'll be happy with it for several > years. I'll plan on having it long enough to make it worth while *really* > learning how to suck every drop of performance out of it. I absolutely love > my K-x, and it'll do almost everything I need, but with the dumbed down > controls, it's not a camera that disappears, like the K20 does when I'm using > it within its performance envelope. > > >> >> Is that lady as intense as she seems in the photos? > > Only on stage. Sitting around a table having a drink, she's about as mellow > as they come, but she does seem to come alive on stage. Her name is Aeriol > Ascher, if you google her you'll mostly find links to her Reiki massage > business. I also find her extremely photogenic. A lot of singers just look > like they're making silly faces when you photograph them, Aeriol looks like > she is creating music and energy out of thin air. > >> > > -- > Larry Colen l...@red4est.com sent from i4est > > > > > > -- > 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. > -- Nothing is sure, except Death and Pentaxes. -- 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.
