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PostPosted: Wed Feb 20, 2008 12:21 pm 
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Location: Malmö, Sweden
Well seems as if i gotta get that software if yeat dont have it!

Going to start shooting my "potencial" HDR images in RAW, as most of the time i shoot in jpg, quite the shame when i now think about it cuz i got some great images take i unfortunetly took in jpg

As i have the D40x when i place the cam on "P" i cannot adjust the shutter speed because this is done automaticly, but of course it can be done in "M" but i will have to learn a bit more to knw what the perefect settings are for certain conditions

is there a general rule for the shutter speed for certain occasion that you could give me a tip on.

Thanx Zorro

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PostPosted: Wed Feb 20, 2008 12:35 pm 
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Photography's a balancing act really. There's no optimum shutter speed just as there's no optimum aperture. It all depends on your chosen subject. For HDR you need to decide on the aperture first. i.e. how much, front to back, needs to be focussed? Once you decide that you need to check just how slow that's going to make the longest exposure. This is important as shooting hand-held has obvious limitations due to camera-shake. If you're using a tripod then this doesn't really apply but you will need to take subject motion into account. Clouds can move a surprising distance in the time it takes to get three exposures. If this is an issue then you need to choose a larger aperture. This will reduce the shutter speed times but alas will also reduce the subsequent depth of field in the image. Swings and roundabouts really.

Try your camera in "A" mode and set the aperture to f8 or thereabouts. Switch off AutoISO and choose 100 or 200.

Good luck.

Zorro 8)

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PostPosted: Thu Feb 21, 2008 1:39 pm 
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Thanx zorro,

now i just gotta wait for the sun to come out...its bull quite som dull and depressing weather these pasts days!

Update: i shot some images last night, this was my first shot at HDR really that whent all the way and i can say its the closes thing i have to a real HDR image, but there is quite a lot of noise on the image could be that the conditoins that i shot in wherent really good for HDR. Semms as if i got some "dust/dirt" on my camera but i dont knw where, i have to find it and give at a clean

lets try this linking thing

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PostPosted: Mon Aug 18, 2008 2:40 pm 
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Hi folks,

This thread has been one of the highlights (sic) of our forum but scanning through it I see that a significant number of the images are no longer available.

If any members so affected would like to restore their posts to their former glory then please consider "editing" your posts to update the image links.

Thank you. 8)

Bob.

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PostPosted: Wed Aug 20, 2008 12:04 pm 
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Hi folks,

It maybe be stated before but, as far as I know, a camera sensor covers 4-5 EV while the human eye covers ~9EV. So, setting AEB to +/-2EV will give the ~9EV coverage for tha HDR photo.

Quote:
Information stored in high dynamic range images usually corresponds to the physical values of luminance or radiance that can be observed in the real world. This is different from traditional digital images, which represent colors that should appear on a monitor or a paper print. Therefore, HDR image formats are often called "scene-referred", in contrast to traditional digital images, which are "device-referred" or "output-referred". Furthermore, traditional images are usually encoded for the human visual system (maximizing the visual information stored in the fixed number of bits), which is usually called "gamma encoding" or "gamma correction". The values stored for HDR images are often linear, which means that they represent relative or absolute values of radiance or luminance (gamma 1.0).

HDR images require a higher number of bits per color channel than traditional images, both because of the linear encoding and because they need to represent values from 10^−4 to 10^8 (the range of visible luminance values) or more. 16-bit ("half precision") or 32-bit floating point numbers are often used to represent HDR pixels. However, when the appropriate transfer function is used, HDR pixels for some applications can be represented with as few as 10–12 bits for luminance and 8 bits for chrominance without introducing any visible quantization artifacts.

One problem with HDR has always been in viewing the images. Typical computer monitors (CRTs, LCDs), prints, and other methods of displaying images only have a limited dynamic range. Thus various methods of converting HDR images into a viewable format have been developed, generally called "tone mapping".

Early methods of tone mapping were simple. They simply showed a "window" of the entire dynamic range, clipping to set minimum and maximum values. However, more recent methods have attempted to compress the dynamic range into one reproducible by the intended display device. The more complex methods tap into research on how the human eye and visual cortex perceive a scene, trying to show the whole dynamic range while retaining realistic colour and contrast.

Images with too much "HDR" processing have their range over-compressed, creating a surreal low-dynamic-range rendering of a high-dynamic-range scene.


Hope that helped, at least a bit!
Cheers,
HNV

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