More terrible sky noise with A700

[bakubo]

I have always thought that it was supposed to be best to get the image as close to what you want during raw conversion while working on the raw data rather than do most of it after the raw conversion. I think what I am getting from you though is that it is better to get a very dull, low contrast, far from finished raw conversion and then do most of the work later. Is that right?

That's quite right. If you do most adjustments early, you already cut out all the 'unnecessary' raw levels, and hence risk being left with far too reduced data set for a smooth representation in the final image. Exactly that happened in your original image.

Actually, I used to do raw conversions more like that, but in the last year or two started doing more and more in the raw converter since it became more capable and I had thought that doing it early with the raw data was better. I am a bit befuddled by this though since the trend with LR/ACR, Bibble, etc. is to do more during raw conversion rather than less. It seems you are saying this is actually detrimental and post-raw conversion processing is often better? If I am misunderstanding what you are getting at then forgive me. I would like to understand this enough so that I can avoid getting myself into trouble with some of my photos though.

[agorabasta]

Actually, I used to do raw conversions more like that, but in the last year or two started doing more and more in the raw converter since it became more capable and I had thought that doing it early with the raw data was better.

Henry,

The 'raw converter' has two stages of processing - the operations done before conversion to bitmap and then the operations done after conversion. The latter is the same stuff as graphic editors do; no diff if done inside or outside the raw converter - just do it as you like.
It's the first step that is important, namely the group of controls of exposure/recovery/fill light/ blacks as per ACR/LR convention (I hope that 'camera calibration' is also done at that early stage).
You must ensure that those settings do not lead to destructive results in further bitmap editing. E.g. it's always wise to leave the blacks at zero and compensate for that with shadows/darks in curve adjustments. It's also wise to use recovery and fill light to adequately populate your raw histo; and then use curve adjustments to bring the tone response at desired levels.

Hope I made my point sufficiently clear this time...

[bakubo]

agorabasta, thanks for your help!

[Argonaut]

Agorabasta, I don't understand why doing corrections before getting out of raw and into bitmap is the wrong way to go. Can you give me the theory? I mean, correcting a 12 or 14 bit image and then converting it to a 16 bit tiff would seem to leave all the headroom the original had. Where am I going wrong?

Thanx - Argonaut

[Dusty]

Agorabasta, I don't understand why doing corrections before getting out of raw and into bitmap is the wrong way to go. Can you give me the theory? I mean, correcting a 12 or 14 bit image and then converting it to a 16 bit tiff would seem to leave all the headroom the original had. Where am I going wrong?

Thanx - Argonaut

The problem is that once you go to a lossy format, like a JPEG, you lose something every time yo save it. If you export to a TIFF, then you always have good file to work against. TIFFs don't lose information when saved. There is also the possibility that conversion out of RAW into another format loses something. RAW files are all really just proprietary TIFFS, but converting from one to another may lose some vital information that you want to adjust later.

Hope this helps.

Dusty

[agorabasta]

Agorabasta, I don't understand why doing corrections before getting out of raw and into bitmap is the wrong way to go.

If you pass the info from raw format to a 16bpc bitmap without cutting out blacks and highlights and generally avoiding highly non-linear transforms, then it's as good as can be. My point was that you have to avoid throwing info out at the early stage as that's quite irreversible.

Also, you should keep in mind that 16bpc TIFF still doesn't hold all raw info. Every demosaiced pixel most often holds parts of info from the total of 9 raw sensels data. So, generally speaking, the info at one site is represented in nine 12bit (or 14bit) raw values which amounts to a minimum of 108 bits of data and then something else; and the pixel value in that TIFF is only 48bit. Hence, certain operations on such TIFF may still lead to sub-optimal results if the raw data doesn't get properly normalized at early stage processing.

[douglasf13]

Check this link from Iliah Borg: http://www.libraw.org/articles/raw-module.html

[lepidopteran]

I had a similar problem on my a700 but not with skies. I my case I had horrendous noise on dark out of focus backgrounds even at ISO 200 ! For some reason it only happened with shots taken with flash. At the time I has the creative style zone setting on "+2" to try to maximise highlight and shadow detail, but it seems to have maximised noise as well. Returning to the "0" zone setting seems to have cured the situation, but it could be coincidence. Maybe the camera suffered a major glitch but somehow corrected itself. The attached 200 ISO image is cropped, and there is a full image to show the degree of cropping. I could fix the noise afterwards with Noiseware luckily.

Adrian
http://www.learnaboutbutterflies.com

[01af]

I my case I had horrendous noise on dark out of focus backgrounds even at ISO 200 ! For some reason it only happened with shots taken with flash.

Adrian, are these shots taken as in-camera JPEGs with DRO set to a medium or high level? I guess the background is seriously under-exposed (as it is typical for flash-illuminated close-ups), and DRO then pulled it up by several EV steps.

-- Olaf

[lepidopteran]

Hi Olaf

Yes, DRO was somewhere between "+3" and "+5" for these shots at 200 ISO. I generally try to balance ambient and flash so that the background is about 2 stops underexposed, but in many of these shots the difference was greater because they were taken in the middle of a dark rainforest in Peru with the background at least a couple of feet behind the subject. It was much too dark to shoot by ambient light, even at 800 ISO so I elected to shoot by flash at ISO 200 and got a right old mess.

At the time the camera was fairly new to me, and I didn't realise that using DRO would have such a dramatic effect on noise levels. I now use the camera with DRO off, and have no problems in normal lighting conditions. Maybe a good idea to keep DRO off for rainforest flash shots next time, and rely on twiddling curves or selective lightening when editing ?

Happy Xmas
Adrian
http://www.learnaboutbutterfies.com