Raw files

[William Bovington]

Hi hammy,what a great camera the f100 is ,i still use mine,likes batteries though.Anyway regarding the raw file issue,the CCD reads in grey scale and converts into colour by means of a CFA (colour filter array)placed over the sensor which is either RGB or CMGY,now with jpeg ,the cameras intenal image proccesing engine then interpolates colours from value of neibouring pixels to calculate 24 bit colour,now what i have found with some cameras in raw mode is an unatural colour balance which requires more correction later on .Metering is even more critical with digital than with roll film as with high lights especially, you lose all data if overexposed which cannot be recovered.

 

[MarkTheSpark]

I take your point about the highlights, William, but I don't think it helped with slide film to have them burnt out, and they were still unrecoverable.

I'm not sure I share your view of exposure latitude; I'm happy to be within half a stop or even a stop, and in RAW can usually get a pretty good result with some adjustment.

The point, surely, of digital is that you can change film speeds from 100 t0 1600 for a single frame - there's no real reason to get anything too far awry if you use the metering properly.

 

[William Bovington]

Not quite!sensitivity & latitude are different issues as with roll film,sensitivity ie: iso rating,how quickly
film/ sensor reacts to light, and latitude the range of exposure the given film or sensor will except. Some films such as tranparencies wether iso 50 or 400 quite often only have a latitude of 1/3 to 1 stop for satisfactory results, whereas some black and white film can be down rated to 50 or up to 1600 iso, so it has both latitude and sensitivity.Now back to digital, regardless of iso rating i have found that to get optimum results, you need to take a number of meter readings and work out the EV between the highlights and shadows.I currently use an eos 1D mk111 and although it does give excellent results i have reverted back to mamiya Rz,s for the majority of my work.raw files are good if your enlarging beyond A4 if not jpeg, as the on board image processor will fill in the blanks.

 

[Mark Wintle]

A few points to add to the discussion:

If you shoot at a high ISO speed and save in RAW it is possible to push/pull the result through to get rid of most of the noise. I found this when my camera got set to ISO1600 accidently. By resetting in RAW to -1.0 to -2.0 stops, the noise mostly disappears. Then in Photoshop you rebrighten the image. It doesn't always work as the picture may end up much too dark but some pictures can be improved. As you are in RAW you can experiment to your heart's content, and as long as the RAW image is never saved only the TIFF you can try, try again. Knowing this means that you can shoot at a high ISO in poor light or when you want a very high ISO to beat camera shake or freeze action, and still get better results than otherwise.

In digital it is the highlights that burn out worst. Once a bit setting is max it is max = no detail just pure white. There is a case for setting to minus a stop (or similar) in cases where there are bright highlights. You still get some detail in the highlights and can easily rescue the darker areas where there is detail anyway. It's all to do with the sensitivity curve which is different to that of film which tails off less abruptly than digital. As William says slide film is the least tolerant and I would say that digital is well on the way towards B&W, with the caveat of avoiding overexposure.

As I've been converted to RAW/TIFF for the same reason as Graham (it's the same book) I've found after nine months that the disadvantage of extra data space is easily outweighed by the extra flexibility.

 

[Graham Marsden (ACA)]

Latest reply on ThinkCamera:

"Not something that I've ever heard of. Could the default settings of the Raw converter be set wrong?

Would be interesting to know what converter was used."