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05-15-2013, 07:33 PM   #1
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Some questions about metering and greyscale

I posted this over in the K-o1 forum and it was suggested that perhaps I post in a more general forum...so here goes:





Some questions about metering and greyscale
Hello all,

I had some questions regarding the K-o1 and, maybe this is more a general question about technique, but I am using only the K-o1 and so it makes sense to me to frame in that way. Also, I should mention that I am using FW v.1.03 and Picasa for post. Part of this inquiry is for me to try and understand how much mitigation of "issues" I can expect to resolve in post, and how much should I customize the capture settings in-camera in order to compensate for my (unfortunate) choice of post-production tools, which is the only thing I can run reasonably on my current computer (a netbook)... Okay...here goes:

--Spot Metering: I am finding that I can get a much better exposure if I spot meter the brightest area in the frame and then use the resultant shutter speed in Av mode (or sometimes a stop or two one way or the other), usually I will meter, recompose, then set exp. manually. Sometimes, if I am shooting street scenes, I try to determine on the fly what the brightest thing in frame is and center it (which has consequences compositionally), get reading, snap photo, crop composition in post. Sometimes this works, other times it leads to way underexposed areas that clip to black very quickly especially if converting to B&W in post. I am wondering if it is Picasa (I have been able to bring out midtones that looked completely clipped in the trial version of DxO O.P. 8, so I am thinking that there is something about Picasa that has a more limited range than what was actually captured?). I could use some pointers in regard to the (two available for manual lenses) metering modes on the K-o1 -- spot and center weighted. Matrix (full scene) metering with the 40 XS, I am not really very well versed in, but seems like it would exhibit more of the 'drawbacks' of center weighted metering (lower shutter speed requiring higher ISO or use of stabilization device) and a tendency toward blown highlights.

--B&W conversion: If Leica's press-kit for the monochrom M is to be believed, you lose a third of your resolution if you convert to B&W. Anybody know exactly the number of steps between black and white (I think of things in terms of oil painting..so I am thinking about chroma and its relative value on the musell greyscale. For instance violet is nearly black on the munsell grey scale when it is at full chroma/saturation. I may be wrong, but this would seem to make sense as to why you can get those really contrasty, almost black skies with a red filter (blue +red = violet)) that the K-o1 is capable of? I saw in another recent post that it comes out to at least 11 or 12 EV steps (please clarify this...what exactly is an EV step?). My suspicion is that I am loosing resolution by converting and loosing my range of values by using Picasa's rather hamfisted approach to contrast adjustment.

--Use of 'Contrasty' v. "Neutral" lenses and in-body compensation/custom settings: I have a theory, and I wonder if I am thinking about it correctly, that if you try to minimize overall contrast in-body, you will have more lateral headroom in post production in terms of range of values, provided you are within the middle of the range and not too far to one side or another of the histogram. I have been using as my primary lenses the 50 f/1.7 "M" and very recently the 30mm f/2.8 "K" which I have found to be contrasty and neutral-ish respectively. Which is kind of strange, because I seem to be getting the opposite result of my theory. I seem to get more lateral freedom with the 50mm than the 30mm. Particularly, darks seem to clip and 'grow' into mush a lot more quickly than with the 30mm (this was corrected to say 30, originally it said 50 which was a typo). Now, it did occur to me that contrasty could mean not just high-key, but wider range of values. In any case, is there anything that can be done to affect the DNG in order to open up a full range of black and white values in-camera? I have almost given up on the idea that Picasa will ever be very good at anything other than very large adjustments of black and white. Also, it seems that Picasa tends towards a rather 'soft glow' in the highlights, which I find somewhat annoying. Maybe its my negative, maybe its picasa's algorithm for looking at DNG files....I am not sure. Anyone?

In any case, I appreciate any feedback on these issues and value the input.

Thanks!

Greg



Last edited by cristigj; 05-15-2013 at 07:38 PM.
05-15-2013, 07:44 PM   #2
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also, I want to point out that I am not using any filters, digital or otherwise. Finally, one question regarding B&W conversion in post, vs shooting and editing JPEG in camera as B&W. I am wondering if shooting as B&W Jpeg may not result in higher pixel-per-pixel fidelity? It sounds counter intuitive, and maybe I am thinking about it too much, but I was just curious if anyone has tested this?
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