Introduction to HDR Thank you Debbie and Sarah.

Some of us look at a HDR photo, say "wow, wish we knew how to do that" and move on. So we decided to ask the practitioners of this art form in the group to help us out.

blueeyeddebby Debbie and sarah22333 Sarah volunteered and we are extremely grateful to both of them. Both have stressed that for them photography is a hobby and they do not hold formal degrees in it. What they are happy to do is share their learnings, tips and tweaks.

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The definition in category 10 - HDR, IR & Orton says:

- HDR, High Dynamic Range, a technique in which by combining multiple exposures with different exposure values you get an image that has a larger dynamic range. Something closer to what the human eye can see.

So what is Dynamic Range?
For our purposes in photography, Dynamic range (DR) is the range of luminance values from the darkest to the brightest. The DR of the real-world scene in front of you is the range of darkest to brightest portions available to your eye, film or imaging sensor. The DR of a camera is the subset of the scene’s DR that can be captured without being clipped on the highlight end, or reduced to noise or outright blocked up on the shadow end. [Source credit: naturescapes]

This brings us to why HDR?
In some situations the contrast of a scene is higher than your camera can capture in a single exposure... this is why you need to take multiple exposures with varying exposure time.

We will now have Debbie and Sarah take over. Over to you ladies:

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If you're out shooting and you come across the dilemma of correctly exposing for the highlights or the shadows...simply think HDR and do both!

HDR Simplified
*** Take a picture. Then take another that's exposed for the highlights. Then take another that's exposed for the shadows. Process and tonemap them in the software of your choice. ***

The first question to answer is always - does the shot NEED to be HDR? When you first start its really easy to use it unnecessarily. Sunsets are the most obvious choice - with the bright sky and dark foreground. But start seeing things in the shadows. If your shot doesn't have wide swings in the light and the dark then does it really need to be tonemapped?

How to shoot for HDR
To get all the exposures correct in a scene try this....also if your camera doesn't support auto bracketing this method will work:

a) Pick your camera settings

a1) Exposure mode to AV (Aperture Priority)....this will be changed to manual mode but not just yet

a2) Metering mode to spot or centre weighted

a3) Select an aperture setting, in this example I’ve used f/22

a4) Select your white balance setting, not the automatic setting

a5) Image quality RAW (although you can still do HDR in jpeg format...but some information is lost)

a6) Set the ISO to the lowest setting

a7) Focusing ....turn this to manual

B) Evaluate the range

b1) Squint at the scene you have chosen and identify the darkest and brightest areas

b2) Now point your camera at the darkest area and make a mental note of the shutter speed

b3) Now point your camera at the brightest area, the aperture will remain constant as you are in AV mode but the shutter speed will change, so make a mental note of the new shutter speed

C) Compose your shot

c1) Put your camera on a tripod

c2) Focus the lens manually (this will stop it drifting between exposures)

c3) Now switch the exposure mode to manual (M) making sure you set the same aperture you used for the initial readings

c4) Change your shutter speed to the lower of your two shutter speed readings

c5) Turn your drive mode to self timer or use a remote release/ cable release (this will prevent camera shake)

c6) Take your first shot

c7) Increase your shutter speed by 2 stops and take your second shot (trying not to move camera or Tripod)

c8) Continue in this manner, increasing by your shutter speed by 2 stops until you reach the faster (the higher of the 2 you made a mental note of earlier) of your shutter speeds

c9) That's it....done...you have all the shots you require for HDR

NOW TO UNDERSTAND EXPOSURE STOPS

In photography the use of stops helps us think of light in a series of units and that makes working out exposure values much easier.

The amount of light that reaches your camera sensor is controlled by your aperture value and shutter values and each time your shutter speed is halved, (from 1/125sec to 1/250 sec for example), or the aperture is made smaller (say from F8-F11) the amount of light that hits the sensor is halved. This halving means we're reducing the exposure by a stop.

For HDR, if the shadows of a scene meter at 1/2sec at F22 and the highlights meter at 1/30sec at F22, then the time the shutter needs to remain open has to be halved 4 times between correctly exposing the two areas, covering 5 stops in all.

A Diagram to demonstrate this



Using auto-bracketing
Unless you're luckier than me and have one of those 17 FPS cameras, use a tripod. AND use a remote for the shutter. It really sucks to miss a great opportunity because you moved the camera when you pressed the shutter. Hopefully your camera can bracket at least 3 shots. In order to get 5 exposures, I set for 3 bracketed shots at +2 0 -2. Take those 3 shots then change the bracket settings to +1 0 -1. You'll end up with two 0 exposures shots one stop apart. This is an arguable point, but I really truly believe that no HDR needs to be more than 5 shots. If you get your kicks taking 9 exposure brackets then you need more hobbies......

_____________ -2 exposure ________________________  +2 exposure ___________
 

0 exposure


_____________ -1 exposure ________________________  +1 exposure ___________
 


And this is what the final result will look like after tone-mapping and final processing [explained later]




Tips and Tweaks
This is one of my personal favourite HDR images



The shot is bracketed at -2, 0 and +2 exposure at f11. I did try it with an f22 but was way over exposed and blown highlights. To auto bracket, go to your camera menu - look for AEB, hit set (least it is on a Canon) and move the sliders to -2, 0 and +2 and hit set again.

Each of the 3 shots was loaded into photomatix pro [Tutorial here] and then tone mapped. With details enhancer selected I have my settings at :-

Strength 70

Colour saturation I play with but usually between 50-70

Luminosity 0 or plus 1 but will play to see what effect I get

Light smoothing I normally stick to the centre circle

White point 2.5-3.5

Black point quite close to the left hand marker....may move it just slightly

Colour settings to my liking

Highlight smoothing reduced to get rid of highlight artifacts

Shadow smoothing, to my liking

Once I have the image to my liking I save it and ALWAYS finish it off in photoshop...trying to get it looking either realistic or as way out as my mood takes me at the time

For sharpening which is always my final step I tend to go to filters-other- high pass and set it between 2 and 5. The picture looks greyed out but don't panic. In the layers palette change your blending mode to overlay and voila job done.


Tips and Tweaks
Tonemapping
I use Photomatix 3.0 Beta. I'm going to post my starting settings with a few cautions. But keep in mind that you should never be afraid to move that slider all the way left or crank up a setting and check out your options. But if you like the look of my shots, here's how I do it:

Strength 70-85 *usually 80

Color Saturation 50-55 max

Luminosity 1 or 2 - I don't use this setting to lighten the midtones. That's what Gamma is for....

Light Smoothing high or very high - medium will look 3d and fake. If that is your thing then so be it.

Microcontrast 6 or 7

**** Tone Settings ****

White .4 to .9 - but really play with this one depending on the shot

Black .2 to .4

Gamma 1.0 to 1.4 - this is what I used to lighten midtones

Temp whatever you need - but get this in camera if you can

Saturation Highlights - this can help if the sun area is blown out

Saturation Shadows 0 - I don't mess with these much

Microsmoothing 0 to 10 use this if you have fences or bridges that have halos on the lines... dont overdo it - it will also lighten midtones

Highlight, shadow smoothing - don't use these much either



Look at this one large on black . You can see the perfect detail in the back of the flower, but the sky is well exposed.

Final processing If you want a natural look (that's what I call mine) then it's important to open it up in PS or whatever you use and layer the 0 exposure back over the top. In extreme lighting situations I will blend 2 different exposures back over the top - one for light and one for dark. I change the type of layer to overlay or soft light and reduce the opacity to anywhere between 10 and 30%. That will give you a more saturation and contrast while keeping detail. Get as dramatic as you want. My final adjustments are usually curves, contrast and sharpening. Then you have a beautiful magical mystical HDR that is guaranteed to get you into explore. As long as you've remembered to include a kitten posing for a emo self portrait at sunset.




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Here are a few links that may be helpfull:
Photomatix software
If you wish to buy it, the good soul stuckincustoms is offering a Photomatix Coupon Code with 15% discount at his blog which also has a HDR tutorial

en.wikipedia.org/wiki/High_dynamic_range_imaging
www.cambridgeincolour.com/tutorials/high-dynamic-range.htm
www.vanilladays.com/hdr-guide/

Another good fellow adamfj is offering zipped HDR raw files - 3 bracketed exposures - Canon CR2 files at his site for you to use and abuse.

A flickr group dedicated to HDR which can provide advanced level information and support.

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Thank you Debbie and Sarah.