Pentax Camera Image Controls vs Computer Editing

Well I did say this sort of thread can go any which way! All interesting stuff chaps ... I did think you were asking for it John, in telling Andrew that HDR was good for churches !

In fairness, I'm hardly the most committed HDR evangelist ... I too have not fired up Photomatix lately, although many of my recent landscapes have involved blending of two exposures (mainly sky / ground). Here I find the transition can be most successfully made natural with minimal effort. My main concern with the church windows was the blend issue, and I still think it has to carried out with some subtlety and much care to create a realistic effect of the light bleeding though and tapering into the interior.


Now, getting back on track ..... ( I have to keep doing that ) ... now you guys are really testing my powers of definition ! Richard, I'll admit to some swaying on the category for in-camera HDR .... you make some persuasive points about the 'baking-in' of the HDR into the JPEG, and of course there's no going back from that, it can't be reverted to a non HDR image on a computer .... so.. OK - HDR becomes an 'Input' camera control ! I think the K3 can in fact offer up the 3 HDR exposures as RAW files, am I right?

Andrew, my original definition of the Input controls does address the ISO setting in the last part ... 'and the way the sensor records that optical image data.". . That was supposed to encompass aspects of sensor performance and its effects depending on changes to ISO. I'm not trying to say the ISO affects the amount of light reaching the sensor, which as you say remains the same regardless (that is only affected by the aperture & time value) .. but rather I am saying that there are inherent IQ matters, or characteristics that change as the ISO changes.

Clearly these differences depend on the camera and the quality of its ISO performance, but in general increases in ISO cause more noise plus a reduction in dynamic range and colour intensity. I'm saying that these aspects are 'baked in' effectively at point of capture ... really, any software manipulation to alter these things later would not likely produce a better result than if the ISO had been set 'correctly' on the camera. So like aperture, time value, AA filter, flash power etc etc, ISO should also ideally be set to the best setting on the camera at capture - that's why I class it as an 'input' control.

I created the church window thread because I genuinely wanted to know whether HDR was the best approach to that subject. The HDR case was certainly not proven - although it was obviously able to produce a result that, when viewed in isolation, looked fine. For me to get hooked on HDR, I would have to see a better result when compared with processing the same image(s) without it. I have seen little or no evidence of that.

Can you please define what you mean by 'later', 'likely', 'better' and 'correctly'? If you are going to have a meaningful discussion in the thread about your original topic, your definitions need to be objective, not subjective. You have four undefined subjective terms in one sentence!!

Andrew

Great fun this thread!

Seems to have more to do with the use of words than taking pictures but then everyone's hobby should be followed by them how they want to do it.

Glad its been fun! That's that idea. I love taking pictures, but that can't always be done any time, so the next best thing is thinking and talking about it I do like to theorise about things, especially where the man/machine interface is involved ... but I do this as I genuinely believe it leads to better practical working.

Andrew, regarding the subjective terms, I guess 'later' is the easy one That just means anytime immediately after pressing the shutter button ... the others are more difficult, I accept, at least where ISO is concerned. I am coming from the standpoint that ISO is the equal (in certain ways) to aperture & time value, and therefore any 'later' adjustments to the effects of ISO should be thought of in a similar way to any later adjustments to the effects of aperture & time value.

So, for example, we generally set a higher ISO in order to allow (given other constraints such as lighting levels and lack of tripod) a higher time value, or smaller aperture (or combination of those) ... thats the most common use of it I think. So, say a shot should ideally have been shot at ISO 1600 (the lowest setting that gave the required other settings), but was not actually shot at ISO 1600, but rather at ISO 200 ... well then, you probably end up with camera shake. Now, this would not be easy to satisfactorily correct 'later', not something we'd be wanting to try and correct in Photoshop. It is unlikely to lead to as good a result than if we had actually shot at ISO 1600 on the camera, and therefore did not have camera shake.

That is how I'm coming at it .. that is why I'm classing it as an 'input' control, because just like aperture and time value and any flash lighting, it is most likely to produce better results if done correctly on the camera in the first place ... later image manipulation is not likely to be ideal.

Similarly, if we did have a tripod, but decided to shoot at ISO6400, when we could have used ISO 100 successfully ... well, then as well, correcting the effects of using ISO 6400 on the computer later is unlikely to produce as good results than if we'd actually used ISO 100 on the camera.

There may be some exceptions, although rare .. eg, say with aperture, a very cheap lens versus a very skilled Photoshopper ... but in general, the optical and sensor 'input' at camera source is most likely to produce the better results. The same does not apply, necessarily, to 'output' settings, such as saturation, sharpness, HDR etc ... here there's good reason to believe that the skilled image processor could improve on the results of the camera controls.

Remember, the point of all this is to give us common grounds for taking attitudes towards specific types of image manipulations and adjustments. But it also can help to clarify the relative importance of specific camera controls and settings depending on our intended onward workflow.