HDR: why 3 images?

[OogyWaWa]

I'm a total newb just learning some stuff about photography. I understand why you need at least 3 images, but would you get a higher range if you had say, 5 images (super dark, dark, normal, light, super light) ? How about 20 images (lol) ? Or does 3 just work better for most pics?

 

[vshah]

3 is sufficient for most pics. you may get better results with more than 3 in certain situations with extreme dynamic range. but i've never done more than 3

 

[OogyWaWa]

3 is sufficient for most pics. you may get better results with more than 3 in certain situations with extreme dynamic range. but i've never done more than 3

well, wouldn't a big landscape pic (of mountains or whatever) have pretty high range?

on the side: can you stitch together some panorama pics and HDR these as well, or does it get too difficult having to stitch the panorama and match up the 3 images for hdr?

 

[996GT2]

well, wouldn't a big landscape pic (of mountains or whatever) have pretty high range?

on the side: can you stitch together some panorama pics and HDR these as well, or does it get too difficult having to stitch the panorama and match up the 3 images for hdr?

For a panorama of a landscape, it is usually better to use a graduated ND filter instead of trying to do HDR. A GND filter gives you a more realistic look and also makes it easier to stitch, since you don't need to stitch 3 separate panoramas and then try to HDR them. Also, unless you're quite good at doing HDRs, you will end up getting post-apocalyptic looking images that just plain suck.

For example, I shot this using a 2-stop GND to bring out more of the sky during sunset:

http://www.flickr.com/photos/morganyang/4452720903/

You CAN do an HDR panorama, though. I've done it on several occassions and it works out quite well. But even then, I only do it when I am going for the "HDR look" instead of the more realistic look that you would get by using a GND or even using gradients in Photoshop.

 

[Gooberlx2]

well, wouldn't a big landscape pic (of mountains or whatever) have pretty high range?

on the side: can you stitch together some panorama pics and HDR these as well, or does it get too difficult having to stitch the panorama and match up the 3 images for hdr?

Yeah, a panoramic landscape would have a good chance of having high dynamic range (especially if snow and/or bright skies are involved ). Again, it all depends on how much range you desire in your picture, how much actually exists in the scene, sensor capabilities, etc... Taking all the range and pushing it towards neutral gray won't look natural either.

I think you'd want to stitch together the +/- groups first, then make your HDR from the 3 (or more) resulting panoramas. Just auto-bracket and exposure-lock for each shot of the panorama.

 

[Dubb]

I often find that three images is actually excessive. Most scenes don't have range beyond what you can capture with one slightly under exposed and one slightly over exposed image.

You can also double process a single raw file in a pinch, though two exposures work better.

I also usually take the final HDR and layer mask in the source files to replace darks and lights where I want them.

 

[fuzzybabybunny]

Depends a lot on the scene. 3 images is just your standard bracket that's easy to use as an example in tutorials. You can use 5, 2, 4, 9, whatever. It really depends more on the exposure spread than the number of images you use. For outdoors, 3 images at +/- 1 or 2EV is often sufficient. For interiors with windows showing the outside, more brackets are often needed along with a larger exposure spread. I shoot from -4 to +4 for my interiors, and there are small cases where that's not even enough. Also note that the file type plays a factor - since you can get back more detail from over or underexposed shots in RAW than you can from a JPEG, a +/- 2EV spread shot in RAW will have a greater dynamic range than a +/- 2EV spread in JPEG.

 

[klocwerk]

I can easily set my camera to do a 3 shot bracket, not so much a 5 shot bracket, so for me it's a practicality issue.

+/- 2 stops is plenty for anything I've played with in HDR so far, and definitely do it in RAW, not in-camera jpg.