Shooting in black & white?

hi everyone,

I've completely new to DSLRs. I've just bought myself a Pentax K20D and am very happy with it. Still learning how to use it, though...

Hope this hasn't already been addressed (if it has, please re-direct me to the right place): in the K20D I've just found out that it's possible to "take black & white photos" (FN > OK (custom image) > BW monochrome). The images appear in b & w on the display.

I'm wondering if there's any difference in terms of quality between RAW files produced in monochrome and RAW files produced in colour? I seem to recall reading somewhere that it'd be advisable with DSLRs to shoot in colour and then convert to b & w...any idea?

Thanks!

Your desktop computer has much more power than your camera, and much more sophisticated software at its disposal to make any adjustment to a picture.

So, do it on the computer.

And hello!

G

Hi George,

are you saying that the camera is anyway set to take photos in colour, and that - if I shoot in the monochrome mode - the camera actually converts the photo from colour into monochrome the moment after I took it?

In other words: I noticed that

a) with the K20D it's possible to convert/modify/edit any RAW colour photo in-camera (something I wouldn't do, I'd agree with you, better do it on a computer). To do the conversion, I think (not sure) you need to first convert the file into a JPEG anyway;
b) it's alo possible to (but this is exactly what I'm not sure of) to choose between creating a RAW colour file and a RAW monochrome. I'd assume that the difference is that you can take colours away from a RAW colour but you can't add colours to a RAW monochrome, but other than that...I hoped that either way I'm producing RAW-level quality...

Did I get it completely wrong?

Any monochrome picture you take, whether produced in camera or on your computer, has been created from a colour original.

The sensor on a digital camera always records in red, green and blue because that's how it's set up (Google Bayer Pattern for more information). Any monochrome end product is a processed picture so yes you'd generally expect to get a better result using your PC.

Having said that, any improvements are likely to be marginal at best and so if you value convenience then there's nothing wrong with letting the camera take the strain - especially if you like the results it gives.

To be honest, I don't know exactly how the camera produces the B&W image. I recommend doing on computer because most computer software offers a choice of ways to do the conversion, and each way will give different results. And you might find that one of those ways does a nicer job, in your view, than the way the camera does it.

But Matt will no doubt be along shortly to explain the technicalities.

G

Is it possible that the K20D never actually converts colour RAW into b&W RAW but simply shows a b&W JPEG version of the pic on the display if you have selected FN > OK (custom image) > BW monochrome (to make people like me happy)?

I've just took a colour RAW and a b&w RAW of the same subject + saved them both as JPEG. Opened the b&w RAW, clicked on Tool>Image Tone>Natural (on Pentax Photo lab), saved it...and this JPEG looks identical to the colour JPEG (converted from a colour RAW). Pixels are the same, only the size slightly differs.

I checked on the camera, and the option for shooting in colour (factory settings) is incidentally called "Natural".

This is not very scientific, I know...if it's not the case I'll stick to your advice and think b&w in front of my pc only!

Been on Nikon manual SLRs for a couple of decades but never got a feeling for their DSLRs. Somehow with the K20D I feel at home but it feels a bit weird to think colour. It took ages to be able to think b&w...the arteries of change has begun to harden

I'm looking for that shot at Dagenham. Can see anyway that it's better to work on a colour image in photoshop, in spite of my limited experience with this technology. What might save my need for visualising in b&w is a post I've just come across (http://www.pentaxforums.com/forums/pentax-dslr-discussion/56909-black-white-shoo...):

"That said, on the Pentax K20D, it is possible to ask the camera to show you a black and white conversion in the preview screen.(...) NOTE that, if you use this option and you shoot raw, you don't lose the color info. You just get a black and white preview and a black and white embedded jpeg."

This would confirm my little test. On the K20D, you can choose to either look at your RAW files on display as colour or b&w JPEG. For some reason, if you choose the b&w, you may conclude that a conversion has taken place when you export the RAW to your PC, as you still see it in b&w. The thing is that colour info gathered by the sensor is there, it's just been temporarily put aside.

If this was really the case, my move to digital is going to be less traumatic than I thought

It really is the case

The RAW file has three chunks of data:
1) The original pixel data. This is in the Bayer matrix form (2xG, 1xR, 1xB per 2x2 square). Effectively colour.

2) The preview JPG. This JPG is generated from (1) by the camera.

3) The EXIF information. This contains piles of information - not just aperture, shutter speed etc, but also loads of "Pentax only" info about metering, the chosen picture style, etc, etc (PhotoME will show you pretty well all of the EXIF data)

So, using the Pentax supplied software, it will pull out the EXIF data (3) and show you what you expect to see

Other RAW software will mostly ignore the EXIF data and just work with the Bayer matrix data - showing you colour. (EDIT: Which is one reason that RAW converters differ so much. The way they decode the Bayer matrix data varies; the way they represent colour can be wildly different - you have to try 'em all and find one that works for you!)


As George says, there are LOADS of ways to do colour to B&W on the PC. However, sometimes it's helpful for visualisation to see the B&W in-camera... but when shooting RAW you always have everything possible to work from

Matt

Matt you made my day I knew I should get a Pentax

It is probably easier to think of it this way.

When you were shooting BW film, you would think "this photo needs a red filter" or whichever colour filter you wanted to use to bring out the contrasts etc. that you wanted from the shot.

With digital, you do not need those filters anymore. Think BW, but shoot in colour (preferably RAW). Then 'add' the filter at the conversion stage in your software package. In Adobe CS3 I add a BW conversion layer which gives me the choice of 'adding' a red/yellow/green etc. filter and/or adjusting the darkness of specific colours on screen by dragging the mouse across the image. You want to darken the sky? Then drag the mouse on a patch of blue sky. Lighten skin tones? Then drag the mouse in the other direction on a patch of skin.

I hope this helps.

Kris.