What on earth is going on here?

Well it definitely is there in the original.

It's a lot more obvious on my monitor (calibrated with a Huey today, as it happens) from some viewing angles than others. At its worst, it looks like raw flesh.

It's basically in the underexposed shadows.

I've changed the white balance to daylight (higher colour temp, so less red), whacked it up by two stops and added a little fill light in ACR, and then fiddled about a bit with shadows/highlights.

Desaturating the red a little might it less unpleasant in the shadows, as might a 10-15% opacity lightening clone from some of the nicer skin.

Apols, I've only just moved over to a new computer, and I'd forgotten to set 'save for web and devices' to include the Exif.

This is what PhotoMe exports:

Camera: PENTAX K-5
Lens: Tamron SP AF 17-50mm F2.8 XR Di-II LD (A16)
Software: K-5 Ver 1.03
Focal length: 36.25 mm (equiv. 54 mm)
Aperture: F11
Exposure time: 1/100"
ISO speed rating: 160/23°
Program: Manual
Metering Mode: Pattern
White Balance: Daylight Fluorescent
Focus Mode: AF-S
Image Stabilizer: stabilized
Noise Reduction: Off
Flash: Flash did not fire, compulsory flash mode

I've also had this effect when I've overdone the 'Shadows/Highlights' in Photoshop CS.....but as you have this on a batch of 'raw' photos I'm also baffled:

Well I have just tried a different laptop and firstly I have to say that on the jpg images I have posted on here the effect is not as noticeable as on my other laptop (calibrated screen apparently.)

However when I load the RAW into Lightroom the effect is still there but bizzarely disappears when fill light is added. The shadows aren't clipped in the areas I am talking about and I can presume that a RAW file will not run out of colours even in shadow areas so I can only come to the conclusion that it's a problem that monitors have in that colour range. I just have never seen it before.

By the way, these were outtakes before I had the flash and ambient light balanced in correctly but I liked a couple of the poses so was seeing if I could salvage them.

Here's another go:

[IMG]http://i162.photobucket.com/albums/t244/chris5gd/Other%20Peoples%20Pics/_IGP9356-1.jpg[/IMG]

I think it would print fine. If you wanted to be kind to gran, I'd be inclined to soften her skin a bit.

Quite an appealing shot, really, with the right hand space cropped away.

thanks Chris, could I trouble you for the high res copy?

Nice processing Chris.
It is a nice image. Closer crop for sure but I quite like the red fingernails, adds something to the story.

Sure. I'll PM you a download link. It possibly won't be this evening though.

Actually, I had a few minutes while I was waiting for something to run - PM sent.

Reds don't photograph too good and different lenses produce
different results.

The Pentax-A 35-105mm is supposed to be one of the best
for reds.

I haven't taken a look at the RAW yet... but there are two or three things to watch out for (ok, maybe 4 in the style of Monty Python ):

1) Down in the shadows, even in RAW, the chance of posterisation increases. The sensors are linear, but photography is logarithmic - consequently the first 1-stop of data takes up the full top half of the available numbers (so, 14-bit RAW with 16384 values will have 8192 for the first one stop). The second stop will take half of the remaining = 4096. Third stop = 2048, Forth = 1024, Fifth = 512 and so on. The K5 is excellent in this regard - but you can see that you can quickly lose colour detail in shadows.

2) Limits of JPG. When outputting to JPG, the colour information is restricted. You only have 8 bits, but the colours are 'mixed', and you will lose of lot of blue detail. You can test for this by exporting from RAW to TIFF instead and comparing.

3) Colour Gamut. You may find that you have an exposure that is correct, but that produces an output colour that cannot be represented within sRGB (and even not in AdobeRGB). Under these circumstances, depending on the colour mapping used, you can experience posterisation. For example, an area that has fine colour gradations but which are all out of gamut will be output as a colour-clipped area and will appear as a block of colour. You can test by exporting to (a) 8-bit sRGB TIFF, and (b) 16-bit ProPhoto TIFF - the ProPhoto colour space is massive and should have no issues with colour clipping.

4) Gamut of the display. Like colour-clipping on output to sRGB/JPG, the display may well be clipping when trying to display rich colours. (Even a Huey calibrated display will have a restricted gamut and will be unable to render all colours accurately.) Some displays are better than others

...much of the above reasons are why the full version of Photoshop has "Soft Proofing" and colour gamut warning ability

Hope that helps!!
Matt

Top info as usual Matt.
.
Some stuff on colour gamuts
.

Nothing evident on my monitor either certainly no blocks of red
Hope this helps you isolate the issue