Yeah, I was going to query that ... I thought Pentax cameras were only rated down to 4000m below

That is a very distinctive and powerful blue there, and its very illustrative the way you've got two of them from different angles.

No 1 is great! Good pose and branch detail, nice exposure. Perhaps you could have selectively sharpened to avoid the background fine texture?

Second & third have too much contrast I feel.

Its a challenging one there Ralph, exposure wise. Unfortunately you've lost the battle I think, the strong backlighting has washed out the sky and background (did you de-saturate there?) - the sky's gone really. It could only be done with ND grads or multiple exposures I feel.

webba, what camera do you have? If you have the facility then taliz above is right - an external stereo mic makes a big difference. On the DSLRs (certainly the K7 / K5 models) the 'on-board' mic is mono only. For me the biggest drawback with this is wind noise- it is sited on top of the camera and so the airflow across the top exaggerates the sound of wind. A hotshoe fitted mic can eliminate this problem if it has a dampening 'sock' over it. I use a Polaroid model, about £40, and it has a function to control whether you hear sound from 180deg radius or 90%deg in front of the camera. The quality of recorded sound is amazing I find. I believe the K3 has improved the siting of its on-board mic which should reduce wind noise.

The disadvantage of the hotshoe fitted mic is it stops you using the flash, a pain if you're mixing shooting video with flash stills, so in those situations I have to limit myself to the camera mic.

Yes, you've worked well with the kids there to get them engaged, thats a big plus. I find the very bright backgrounds too bright in relation to the subjects, very glaring. Also, I think you've blown out some of the skin tones too much in some - look at the difference in colour of the hands (& foot) in No6 (quite natural) & Nos 3 & 5 - some detail is lost on faces due to this also.

And finally, I'd give a little 'Pop' to the eyes - they are all a little dark and sunken looking. A bit of selective brightening, sharpening and saturation on the eyes should do the trick.

In terms of exposure for the subject I think No2 has it spot on - it also seems to have a softer and more even spread of lighting across the face.

The LV histogram is a guide to the ambient lighting dynamic range spread around the meters measurement of a grey midtone. This is not the same thing as a photos exposure value (EV), which is controlled by the user. By assessing the dynamic range in a scene you come to decide where to pitch the actual photos midtone - either by exposure compensation or manual mode ... In making such a judgement you also re-pitch the whole spread of brightness values, so the judgment is also about what to prioritise (eg shadows, highlights).

So the LV histogram is the guide to the Dr spread in a scene to help make our own exposure value judgement. After taking a shot we can reassess the result based on the graph of our actual photo, which may not be the same as the ambient light levels.

'...and I've had great results (see shots earlier in the thread)...'!
Doh! Sorry, the shots are in Alastair's earlier thread about the 28mm

The small LV histogram does not update to reflect exposure control adjustments. It responds to actual changes in lighting levels, not your exposure settings on the camera (not ISO either). These exposure adjustments are only effective when the shot is taken - then your histogram will show the readings for the actual shot ... bear in mind this is for the Camera JPEG (as processed), not the RAW.

It can be a PITA in RAW as well sometimes

Mines excellent (the A), and I've had great results (see shots earlier in the thread). Amazing lens for the £40 paid for it, looks like it was never taken out of the box, and it operates very tight & smoothly.

IQ-wise, I'm delighted - I don't use f2.8 much, mostly f4.0 - f11. In backlighting I find contrast is reduced, you can get a slight magenta tone on some areas, and there's a bit of PF - nothing that can't be dealt with fairly easily.