[Mmzmptvk]

Well, I've been reading up on HDR the last few days, and I am trying to get the most info about it...

Basically I've seen people saying one should take a 3, 5, 7 or more shots using different aperture sizes. My concern is though, doesn't this affect the focal length, i.e. won't I end up getting different pictures because the bigger the aperture also the smaller the focused area? Shouldn't the exposure of the shots be done all with the same aperture but different exposition time?

[sniskelsowwef]

Well, I've been reading up on HDR the last few days, and I am trying to get the most info about it...

Basically I've seen people saying one should take a 3, 5, 7 or more shots using different aperture sizes. My concern is though, doesn't this affect the focal length, i.e. won't I end up getting different pictures because the bigger the aperture also the smaller the focused area? Shouldn't the exposure of the shots be done all with the same aperture but different exposition time?

It wouldn't change the focal length; it would change the depth of field. But yes, HDR shots absolutely require a tripod. Change the shutter speed, NOT the aperture.

[ballingham]

You need to change the exposure (shutter speed) - not aperture, as SC has said.

Most modern DSLRs also have an exposure bracketing option, which basically works as follows:

If you set exposure bracketing to "1", then when you take one shot, your camera will actually take 3, one after the other. The first shot will be exposed at the settings you specified on your camera. The second shot will be exposure one stop UNDER, and the third shot one stop OVER. if you set the exposure bracketing to "2", then you will get three shots again, but with one TWO stops over, and the other TWO stops under, for a more visible exposure shift.

You can then take these 3 files, and combine them in Photoshop (or other programs on your PC), to make an HDR image.

A tripod is really required, however if you are shooting in good daylight (so high shutter speeds) and your camera has a fast multiple shoot option, then at a "pinch" you could get away with a 3-frame exposure bracket shot whilst handholding - especially if you are using an image stabilised lens. I would still recommend a tripod though.

[Poreponko]

You need to change the exposure (shutter speed) - not aperture, as SC has said.

Most modern DSLRs also have an exposure bracketing option, which basically works as follows:

If you set exposure bracketing to "1", then when you take one shot, your camera will actually take 3, one after the other. The first shot will be exposed at the settings you specified on your camera. The second shot will be exposure one stop UNDER, and the third shot one stop OVER. if you set the exposure bracketing to "2", then you will get three shots again, but with one TWO stops over, and the other TWO stops under, for a more visible exposure shift.

You can then take these 3 files, and combine them in Photoshop (or other programs on your PC), to make an HDR image.

A tripod is really required, however if you are shooting in good daylight (so high shutter speeds) and your camera has a fast multiple shoot option, then at a "pinch" you could get away with a 3-frame exposure bracket shot whilst handholding - especially if you are using an image stabilised lens. I would still recommend a tripod though.

Yep, that's the AED function on my 40D, I've been fiddling with it already. Thing is, to make sure it changes shutter speed and not aperture, I'd have to use the Tv-mode, right?

[Niobaralegra]

Yep, that's the AED function on my 40D, I've been fiddling with it already. Thing is, to make sure it changes shutter speed and not aperture, I'd have to use the Tv-mode, right?

Not necessarily. I shoot in AV mode all the time - and just adjust the ISO and/or aperture setting in order to get the resulting shutter speed that I want for whatever I am photographing.

You can't get a different combination of aperture/ISO/shutter speed in Tv mode as opposed to Av mode. The only difference between the modes is which setting your are adjusting in order to arrive at any given point.

A good example of controlling shutter speed when in Av mode would be this shot of mine:

http://www.picturepunk.com/costa2.html

Situation: I knew I wanted a fairly slow shutter speed in order to make the water look smooth. What I did with my camera in Av mode was to:

1) Select ISO 100 (the lowest ISO setting, which gives the longest shutter speed, relative to say ISO 400 or ISO 800.

2) Select a larger aperture number (in the case of this shot F10), as it gives a slower shutter speed, and also ensures the whole scene is in focus, which is what I wanted.

Having selected these two options my resulting shutter speed was about half a second - which was still not slow enough for me. Then I had basically two options left:

1) I could have used an even higher aperture number (e.g F18) to slow the shutter speed down even more. The reason I did not do this is that at that F-stop, any dust on your sensor will show up on your images a lot a blobs. Also, you start to suffer from lens diffration and loss sharpeness at those kinds of aperture values.

2) What I did was to attach a circular polarizing filter to my lens (which is basically sunglasses for your camera). What this does is to cut down the amount of light reaching the sensor, which slows the shutter down even more for your given settings. It also has the added benefit of cutting down the water reflections on the wet leaves as well as the splash-pool, resulting in less harsh highlights.

The end result after all that was a shutter speed of 1 second, which gave just the right amount of blur to the falling water. I used a tripod for the shot obviously. I was able to control the shutter speed without needing to put the camera in Tv mode, as I wanted to be able to also control the aperture, which you cannot do directly in Tv mode.

[xkQCaS4w]

Having selected these two options my resulting shutter speed was about half a second - which was still not slow enough for me. Then I had basically two options left:


2) What I did was to attach a circular polarizing filter to my lens (which is basically sunglasses for your camera). What this does is to cut down the amount of light reaching the sensor, which slows the shutter down even more for your given settings. It also has the added benefit of cutting down the water reflections on the wet leaves as well as the splash-pool, resulting in less harsh highlights.

The end result after all that was a shutter speed of 1 second, which gave just the right amount of blur to the falling water. I used a tripod for the shot obviously. I was able to control the shutter speed without needing to put the camera in Tv mode, as I wanted to be able to also control the aperture, which you cannot do directly in Tv mode.

Or, option 3: Use a neutral density filter. Or stack a neutral density filter with a polarizer for maximum ultra-smooth waterfall goodness.[thumbup]

[sposteTipsKage]

i remember when i was getting some HDR shots for some 3d stuff, and my friend had a setup to get it which just involved taken a photo of a reflective garden orb on a tripod and different settings of some sort and with his magical wizardy he given me some good HDR shots to use, ill have to ask him the process =o

[Sniliabiz]

i remember when i was getting some HDR shots for some 3d stuff, and my friend had a setup to get it which just involved taken a photo of a reflective garden orb on a tripod and different settings of some sort and with his magical wizardy he given me some good HDR shots to use, ill have to ask him the process =o

That method (shooting a spherical lightprobe) is only used for 3D rendering to create accurate HDR light maps and such. It's not the same thing that we're discussing here, and it's pretty useless for general photography.

[Immarsecice]

That method (shooting a spherical lightprobe) is only used for 3D rendering to create accurate HDR light maps and such. It's not the same thing that we're discussing here, and it's pretty useless for general photography.

e.g:


light probe:




Resultant lighting on scene: