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01-28-2014, 07:59 AM   #1
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digital filters on K5

In Exif data accompanying raw files some information appears for example on contrast, saturation and sharpness. Where does this actually come from? Is it the digital filters? For example, I get information on sharpness = hard, although on the digital filter options (like landscape, portrait etc) I have set the sharpness on the middle line "neutral". The photos actually do turn out hard in sharpness. I would love to hear anyone's experience on this. I'm not quite sure if the digital filters work on raw anyway, but if not, what does the information on sharpness refer to?
Thanks in advance

01-28-2014, 10:56 AM - 1 Like   #2
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Nope! A couple things to begin with.
a DNG and Pef files are merely containers. They contain all sorts of information. The contain the raw data (compressed), preview thumbnails (jpegs, affected by camera settings like jpeg mode, lens correction, and digital filters) and information (exif, aperture, date, and a lot of other info)

b Raw editors might not read all of that data. There might be more info in there that a specific software simply doesn't know about.

c The raw editor will interpret the raw data in its own way. Each software does this in it own way, that is why there can be differences between different software, even in the same photo. There is no "correct" way, but there are different ways, and some might be more visually pleasing than others. This is why some people prefer to use only the official software, but meh

d Raw editors can add data to the file container (dng, pef). This means that another raw editor can see read instructions on how you want this data to be interpreted. So you can open it in Photoshop, change some sliders, and later Lightroom will notice that you did that. Most raw editors only append data, they do not affect the raw data (they work non-destructively, you can always "reset"). These instructions might not be compatible between all software, though.

e Raw editors have non-zero default settings. For example, if you open a photograph and it says "Contrast: 50" that doesn't meant that "50" units were added. And if you turn it to "0" - that doesn't mean "nothing was changed." Its a problem with raw editors, because the user is not perfectly clear on what is being done and in what amount. Its best not to stress over this and simply learn how to use the software to get what you want. The raw editor interprets the data (not merely "shows" - it creates the picture). Then it allows post processing (developing)

f Its not impossible for the camera to specify instructions on how to interpret (develop, post process) the data, but I don't think cameras do that. Usually they only record the raw data, compress it, add metadata, and preview thumbnails. Keep in mind that some "raw codecs" do not actually show the raw data - they only show the preview thumbnails

Last edited by Na Horuk; 01-28-2014 at 11:05 AM.
01-29-2014, 01:00 PM   #3
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Thanks a lot for your informative reply! I usually open the raw files with photoshop adobe raw converter. In my post I made a mistake when refering to digital filters. I actually meant the "custom image" on K5 (portrait, monochrome, landscape etc) with the various options for saturation, sharpness etc. Now, if I have understood the user's manual which I studied again, these options are only for use on pre existing jpeg images. But relative infos appear also on the exif data of raw files on the side ( not in the raw converter window with the sliders ) without - as I now realize - really meaning anything. Strangely enough, I was previously under the impression that the custom image options were working directly on the raw captures. Anyway, thank you for puttting me on the right track.

Still, I have the unresolved question, why some images turn out really hard in sharpness (I mean visibly and not only according to the above mentioned exif data) - mostly when using the kit lens in broad daylight.
01-31-2014, 09:24 AM   #4
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When you press info you can select the jpeg mode (bright, vibrant, landscape, muted, etc.) - these are merely slight twists to colour and sharpness. This is basically developing film for a specific purpose, and the camera's algorithms try to make the photo look a certain way, that should fit the chosen situation. Keep in mind that selecting a different mode on the mode dial (the dial on top of the camera), it will be more than just jpeg mode - this also affects how the camera decides the aperture, shutter speed, etc.
Digital filters are merely addons and are characterized by looking more unnatural.

Jpeg mode and digital filters do not change the raw data. But! They do affect jpeg photos, as well as the jpeg previews embedded with the raw data. The other thing is, the post processing software that comes with Pentax cameras allows you to choose those same settings on your raw files (so you can get the same as in-camera choices would give you).

Sharpness is a whole other can of worms. Something will be sharp if the focus is right, the ISO is low enough, and the shutter speed is fast enough.
Each lens has its sweet spot, the 18-55mm is sharpest at around 35mm and f8-f12. Photos at that zoom and aperture will be sharper than wide open at 18mm.
Sharpness is also affected by the added sharpening (either in-camera or as you post-process). SR can also affect the sharpness. If you are photographing in good light, if you shutter speed is fast enough, you probably want to turn SR off. Unless you have very shaky hands, of course.

I hope this helps, not sure what exactly you meant. If you have specific questions, you might need to post sample photos

02-02-2014, 03:30 AM   #5
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focus points

Thanks again. The relationship between SR and sharpness is something I hadn't thought about up to now. I'm going to do some homework on that. My hands are pretty stable.
Another factor troubling me is about spot metering and multiple focus points. It's difficult to get proper spot readings when the focus points spread out to a range which is wider than the desired specific spot.. So the camera is getting conflicting information when for example dark and light areas are very close to each other and the multi focus points pick up both light sources. Single focus point is on the other hand not good enough for focused images on the K5 with kit lens ( or maybe also with other lenses).
02-02-2014, 04:04 PM   #6
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Metering only affects how the camera chooses the shutter speed, aperture, and ISO (as in, brightness of the exposure). So the metering happens before the photo is taken. Spot metering can be linked to "selected AF point" - just keep in mind that the AF point are much bigger than the little overlays in the viewfinder (little red squares that light up). Spot metering has pretty limited use. Its used when you have big contrasts but you need a specific subject to be well-exposed, at the expense of surroundings. I usually use center-weighted.
But metering is "detecting the brightness of the scene and suggesting settings". AF is different, it doesn't actually meter anything, it only compares wavelengths and moves the focus until it determines a match. AF is not aware of distances.
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