Black and white and dynamic range?

[masp]

Does taking pictures in a black and white mode on any DSLRs increase your dynamic range like it would with black and white film? I'm guessing that it would not, except for possibly giving you more latitude to tweak the white balance to prevent clipping of any one channel. Any ideas on this subject?

[Richard]

I've not tried this but, apparently if you shoot in RAW, and the camera is set to BW, all the colour information is still retained in the RAW file.

If this is correct then it would suggest shooting B&W doesn't have any advantages over shooting colour, apart from having a B&W preview on the LCD.

Maybe someone with more experience can shed some light on this?

[JAS_Photo]

It is my understanding that taking photos in B&W with digital would not change your dynamic range. I believe that your camera just does an in camera conversion on what would otherwise be a color photo. I think your best bet is to use your camera's RAW function and convert it to B&W in post. You have more control over the contrast and tonality that way as well.

Old Tri-X has about 9 stops, but your digital camera has about five. Here is a good explanation of dynamic range:

Expose Right (http://www.luminous-landscape.com/tutorials/expose-right.shtml)

[masp]

This realization carries with it a number of important lessons, the most important of them being that if you do not use the right-hand fifth of the histogram for recording some of your image you are in fact wasting fully half of the available encoding levels of your camera.

Oh, this is very interesting. Thanks for that link JAS. Marko mentioned that you should use the right hand side of the histogram on the podcast too, but I don't remember the exact details. Also, do black and white histograms let you know if you're clipping one particular RGB channel? I'm wondering how many DSLRs have tri color histograms available. It seems like a pro-ish option. This is something from CHDK that I might miss. :D

[Marko]

AFAIK.....
- Yup get the histogram to the right border without actually touching it.
- Shooting in B/W mode will not increase the dynamic range.
- Shooting in RAW in B/W is identical to shooting in colour. The only difference is the image you see in preview in camera, is B/W. When you open it up in Bridge and lightroom (I believe) it will be in colour. THUS, the image is really a colour image. THUS, the histogram will show colour information.

Hope that helps - Makro

[masp]

Hmm, does Tri-X have the best dynamic range for film at 9 stops or is there anything with more than 9 stops? I'm thinking I might want to occasionally old film camera for when I'm shooting outdoors on sunny days and can't take multiple exposures (like with street photography).

[Marko]

It's been a while...but 9 stops sounds about right to me, and I think that's the standard for negative films in general.

[ericmark]

Very interesting report the comment
This means that it's possible to blow out one of the R G or B channels without realizing it. I have noticed with HDR and Photoshop tends to give purple edges to clouds as a result but Picturenaut seems to have a better control over colour. Turn the image into Black and White and you can still see the line. Careful adjustment of Cyans, Blues and Magentas can remove this in Black and White but very touchy on the controls would be interesting to turn to Black and White first before using HDR but I found with Panorama, HDR had to be done first so I will not hold my breath.
However with the idea of doing HDR I have been taking 3 bracketed images on regular basis. I have been surprised at the different results when the same image has been taken with three different exposures two normally being within the range where they can easy be used.
Although as already said the same RAW image is used for Black and White and colour where the result would have been grey then one would expect there to be three times the information as to if whole was in red for example. So I would think the result would depend on original colours to start with.
Having taken so many to use with HDR I have been surprised to see at bottom of the Convert histogram 8 or less EV steps recorded as having data although the odd one has full 12 where taken in buildings with views of outside through windows. Bit this is rare and most really did not need HDR.
However they often did need bracketed exposure as the centre point was not at true centre. Although one could take very careful exposure readings and adjust to lightest as described in article in real life one does not say to people "can you just stand there while I set camera for best light" so in real terms bracket and select is only practical method.
Two things I have noted. People do not move that fast and as long as auto bracketing is used one can often get away with odd person standing around when you take photo. And often where 2 EV stops are used you can deselect centre image and this removes the ghost and people can still be in picture without being able to see ghost as only one of the pair has the people within exposure range.
However it is this uncertainty as to how the images will combine which causes the problem. Take 36 pictures and that's 108 exposures and on my PC about 3 days work to convert them all to HDR before you know which work and which do not. Even on the college MAC where I wanted to both use HDR and Panorama it took near 2 hours to produce one picture. It became 2.61GB so not surprising and had 15 RAW images combined to make one. OK it was for an exam and I needed to show I knew how to do it. But in real life who can afford that time to make one picture?
According to articles I have read not all camera have the same range on the CCD and some large format camera can take in one picture what on my cheap single lens model needs three pictures. So if the dynamic range is all important then maybe one needs to pay out for a twin lens camera? But sorry they are well beyond my pocket. See http://www.dpreview.com/reviews/fujifilms3pro/page18.asp

[ericmark]

Message was posted here in error it was to answer a completely different post and I could not find how to delete. My camera takes picture then you change to monochrome and only in Jpeg no option in RAW.
In fact it has been a cause of debate as for my exam unaltered images had to be used and my camera does not report in meta data when the cameras filters have been used so only way to be sure unaltered is to use RAW files.
However not all cameras will produce RAW files and so how can one require RAW files in exam?
To me whole exercise from exposure to final print needed to be under exam conditions.