Newbie - introduction and question about my intention to use raw - RAW Shooting and Processing - CHDK Forum

Newbie - introduction and question about my intention to use raw

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Offline m*sh

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Hi,
my name is m*sh (this is my first post here) and I am a hobby photographer for 35 years. My Dad explained everything to me about photography with his old "Zeiss Icon" back from the fifties. Great cam.

Anyway since switching from analog slides to digital my efforts got even better - at least I think so.
Actually I was waiting for a port of CHDK for my PowerShot SX 110 since I bought the Cam in 2008.

I usually do pictures of landscapes and nature. So I almost always take several shots with the same scenery but different Av/Tv. When omitting this I sometimes feel sad about one shot or other, because it is too dark/light.
[Actually the histo and zebra in preview mode will hep me on this - which is another good reason for using CHDK]
Having an additional RAW/DNG-file seems to be a good idea. Because you are able to adjust the parameters afterwards. I just did some tests for now, but it seems to be a big effort to learn how to handle several pieces of software until you get the desired results.
I am on linux and had some fun with "ufraw" already and some extension for gimp - that is poorly documented.
"ufraw" seems to be the kind of tool that I would choose - but it crashes every now and then when saving )-;
But it has some script abilities that are quite what I need.
On the other hand there are scripts that allow bracketed shots - so there are several shots with de-/increasing Av/Tv
If one is not using a tripod (I rarely do), a series of several shots are harder to handle (alignment) when postprocessing them into hdr-images.

What I am asking is:
1.) Any link to tutorials using ufraw?
2.) What would you prefer? A bracketed series or a raw file where you create the series later?

Thanks in advance

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Offline fudgey

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Re: Newbie - introduction and question about my intention to use raw
« Reply #1 on: 04 / July / 2010, 08:35:22 »
CHDK DNG/RAW isn't very good for the sole purpose of fixing exposure because (unlike RAW from a DSLR) the dynamic range isn't all that much greater than in the JPEG. Also, RAW files may be missing things like lens geometry correction. A burst mode bracketed series of 3-ish photos takes a similar amount of time and card space as a single DNG shot.

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Offline PS

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Re: Newbie - introduction and question about my intention to use raw
« Reply #2 on: 04 / July / 2010, 15:07:49 »
« Last Edit: 04 / July / 2010, 15:10:01 by PS »

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Offline fudgey

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Re: Newbie - introduction and question about my intention to use raw
« Reply #3 on: 04 / July / 2010, 15:26:42 »
Actually I've managed to get pretty good results from sunny holiday photos merging handheld jpeg Tv bracketing sets with just
Code: [Select]
align_image_stack -a tmp *.JPG && enfuse -o out.tif tmp*.tif
But of course there's much more to RAW than just exposure, if you have the time and card space, it's obviously safest to shoot a set of RAW/DNG files.

Oh and for bracketing (especially handheld), CHDK's continuous shooting mode bracketing is usually way more convenient than a script. It can be found in the extra photo operations menu.

Btw, rawtherapee is available for Linux too (for free), sounds like you might enjoy playing around with it as well.


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Offline m*sh

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Re: Newbie - introduction and question about my intention to use raw
« Reply #4 on: 08 / July / 2010, 03:03:50 »
Code: [Select]
align_image_stack -a tmp *.JPG && enfuse -o out.tif tmp*.tif
sorry, I do not get it. What kind of command is align_image_stack?
Where do I enter it and what program do i need for that?

Btw, rawtherapee is available for Linux too (for free), sounds like you might enjoy playing around with it as well.
Thanks I wasn't aware that there is rawtherapee for linux too. I will give it a try.

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Offline fudgey

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Re: Newbie - introduction and question about my intention to use raw
« Reply #5 on: 08 / July / 2010, 15:42:40 »
Code: [Select]
align_image_stack -a tmp *.JPG && enfuse -o out.tif tmp*.tif
sorry, I do not get it. What kind of command is align_image_stack?
Where do I enter it and what program do i need for that?

In the command above, align_image_stack (from the hugin-tools package on my Ubuntu box) takes slightly unaligned JPEG photos (such as an exposure bracketed series, even handheld if your hand is rather steady), attempts to align them (by cropping, shifting and maybe rotating -- I don't really know/remember) and outputs an aligned version of each image as a TIFF file.

In the end of the command, enfuse (from the enfuse package) does an exposure blend of the aligned stack (it makes a single 8-bit image from a stack with greater dynamic range by cunningly selecting which source image(s) to use for each porton of the image -- without using the HDR creation + tone mapping process).

 

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