HDRI Blog » Basics and Terminology

Nikon D7000 HDR

admin — Sun, 02 Jan 2011 19:51:21 +0000

The Nikon D7000 HDR inquiry comes to me weekly so I’m going to address it right here and a work around to get past its limitations.

The D7000 only does 3aeb in camera with a max jump of 2EV between each frame. For creating commercial quality work, that is insufficient for many scenes. Many landscapes benefit greatly by capturing from -4 thru +4, preferably with only 1 EV jumps. The D200/D300/D300s/D2x/D3/D3s/D3x all bracket this much in camera using the 9aeb and maxing out the EV jumps to 1EV per step. The options are 1/3rd, 2/3rds or 1 full EV jump between each of those frames. Also, you don’t have to do a 9aeb, the cameras (which vary slightly) can do 2, 3, 5, 7 or 9 AEB (aeb= Automatic Exposure Bracketing).

A 9aeb using those cameras and using the full 1EV jumps between each frame will result in (-4, -3, -2, -1, 0, +1, +2, +3, +4). When toning your HDR which was captured with that many shots, you’ll get less noise, less banding, reduced color saturation issues, and fewer hue shifts.

3aeb is only useful in about 20-30% of scenes I’ve encountered when shooting non-cloudy day landscapes. For shooting real estate and architectural interiors, 3aeb is completely insufficient… maybe 10% of interior scenes can be captured properly (hi quality toning) using 3aeb.

About 5-10% of landscapes need even more range captured such as a bracket covering -5 to +5 and for real estate interiors shot on sunny days, about 5-10% of scenes need even more than that range bracketed to fully capture all the highlights and some decent shadow data. These scenes are the ones where the sun is either in frame partially/fully in frame or reflections off of water/glass/metal in important parts of the frame with deep shadows in frame as well.

There has been some confusion about the Nikon D7000 -5 to +5 exposure compensation. That feature has nothing to do with automatic bracketing (directly), but it can be used in conjunction with AEB. For example… you can set exposure compensation to -1 and then when you setup AEB using Aperture Priority, then a 3aeb sequence with +/-2EV will shift by -1 (negative 1EV) for each shot taken. So instead of taking lets say a 3aeb at -2, 0, +2…. the AEB will be shifted by -1 EV per shot (off the base of how the camera metered the scene) and the resulting 3aeb would be taken at -3, -1, +1 (again, those numbers revolve around the way the camera metered THAT scene).

Exposure compensation is ignored in Manual mode. That should tell you everything about how it has nothing to do with AEB. AEB works in manual mode because instead of the camera’s metering system deciding the starting point, you determine it in manual mode. You are the metering system in M mode.

Now all that said, you can use exposure compensation in aperture priority mode to work your way through capturing more frames for a wide bracket. But it requires you to touch the camera a few times and it means you might risk moving the camera slightly and won’t be able to align the frames in post. Also, if lighting changes in the time it takes you to change exposure compensation then your frames in post might not all be exactly 1EV step apart. So this works best for sunny days where the sun is not shifting behind clouds.

This is what you could do to get a 9 frame bracket…

Set up the AEB for 3aeb with 1EV steps.
Set the shooting mode to continuous (use a wired/wireless shutter release if possible)
Then start out by setting the exposure compensation to -3
Fire off a bracket (the AEB will give you -4, -3, -2)
Move exposure compensation to 0 (zero)
Fire off a bracket (the AEB will give you -1, 0, +1)
Move exposure compensation to +3
Fire off a bracket (the AEB will give you +2, +3, +4)

Its a hack. Some cameras like Canon have C1, C2, C3 dial settings that allow you to do this with one little turn of the dial, I’ve not looked at the D7000 custom functions so there may be an easier way to program it.

In the end Nikon decided NOT to give the D7000 the 9aeb its more expensive cameras enjoy. Canon does the same thing. 3aeb is better than no-AEB, but 3aeb just …. well…. sucks.

White Balance for Digital

admin — Fri, 19 Feb 2010 15:57:40 +0000

White balance for digital capture is actually similar to days of film in some regards. Especially relevant when dealing with tungsten lighting when shooting stills or video. Why?

Because tungsten lighting is a dynamic-range killer due to it being deficient in the blue channel. Using custom white balance in-camera doesn’t solve the lack of blue light. The amplification in the blue channel raises the noise floor. Its bad enough that the blue channel is the weakest on many sensors, but ramping up that channel often worsens the noise even at relatively low ISO levels and goes downhill quickly as you raise ISO (which amplifies all channels). Solution? 80 series filters.

The 80 series filters were of course for color conversion when shooting daylight color films in tungsten lighting. The 80 series vary, but I”ve found the three most relevant to be the 80-A, 80-B and 80-C, each varying slightly (chart provided later in the post). The result of using an 80A for example is that you suppress everything but blue light. This is what you get when you use a digital camera set to daylight white balance with an 80-A filter in front of it ==>

The following is happening:

— Red, green and blue levels in the light source are approximately equal, and tungsten light looks white. Subjects in that light look normal.

— Blue channel noise is reduced even at high ISO settings because the blue channel is being “fed” per se. Dark shadow noise is reduced tremendously.

— Red-channel overexposure halos (also known as “blooming”) that occurs around edges of light sources, is reduced.

— (THE DOWNSIDE) Exposure time is increased by 2 stops for an 80-A (so 1/250 sec ends up being 1/60 sec, or 400 ISO becomes 100 ISO). It is best to use color-blind centerweighted metering.

80 Series Filters Color conversion (blue filters)
3200 K to 5500 K	80A	Loss of stops =	2
3400 K to 5500 K	80B	Loss of stops =	1 2/3
3800 K to 5500 K	80C	Loss of stops =	1

Again, tungsten light is a dynamic-range killer, and using your camera’s custom white balance abilities can’t fight it alone. If you value using every ounce of the dynamic range of your sensor, it is important to make adjustments to light temperatures BEFORE the light hits the sensor. Dynamic range is measured from the noise floor, which is affected by blue-channel noise. Using a blue filter in tungsten lighting will help allow your camera’s sensitivity perform as well as it does in daylight color white balance where channels are more even (RGB).

In real estate photography this becomes extremely common and relevant where the goal is to find ways to INCREASE dynamic range. You certainly don’t want to make your life more difficult by relying solely on a camera’s custom white balance. And if you are bracketing for HDR and you are concerned about noise???… well this is just as relevant. Because most shots are taken from a tri-pod, the loss of stops using an 80-A 80-B or 80-C filter are less dramatic then if you hand hold shots.

72 dpi

admin — Wed, 10 Feb 2010 16:31:51 +0000

The 72 dpi myth was something that had me scratching my head years ago. I was wanting to use some high end compositing packages to edit photos, but I was concerned about the fact that they deal in video “speak” and 72dpi was/is the norm. So I was wondering how I could get an image I was working on in 300 dpi, there and back and not lose resolution. I felt so dumb when I found out about the whole DPI myth and how it was/is tied to legacy printers, etc.

I still get people losing sleep over this stuff so I’m going to link a site with a ton of info on it. There are a TON of other sites online. If you want more opinions, just google:

72 dpi
72 dpi myth
The DPI Myth

…etc.

All About Digital Photos
http://www.rideau-info.com/photos/index.html

The Myth About DPI
http://www.rideau-info.com/photos/mythdpi.html

How to Properly Change DPI
http://www.rideau-info.com/photos/changedpi.html

I hope this helps clarify.

Merge to HDR Tip

admin — Thu, 31 Dec 2009 06:45:58 +0000

I found this little known fact out first hand when I was first experimenting with different tone mapping operators a few years back. I was testing out the various softwares that will take your bracketed shots and “Merge to HDR” to create either a .hdr or .exr. Turns out the act of merging to a High Dynamic Range Image using bracketed images, can be and IS unique amongst the various apps on the market.

The process the application goes through to merge to hdr is not as standardized as I thought it would (or should be) and is slightly differently with various apps (done under the hood with their code). Hence the reason that merging raw files to save in one app and then opening that .hdr or .exr in another app could and can does lead to different results than just using that 2nd app to merge and then tonemap the same files. One would think that it should be a standardized formula that would lead to the same .hdr / .exr. But as it turns out… different chefs make different dishes despite starting out with the same ingredients.

So the next time you are planning to use an application to provide automation (merge to hdr for dozens of folders) using one app, then tonemapping those .hdr / .exr saved files in a totally different app… you should know what the tendency of the original app you are using to merge “tends” to do (create). Color, saturation, etc…

Just a little HDR tip to close out the 2009 year.

Tonemapping is not HDR

admin — Wed, 23 Dec 2009 06:50:50 +0000

I’m not starting a war over this, but I would like to shed some light here. Hell, I think the concept needs to be tonemapped to reveal the details in the shadows (blatant pun intended).

Anyone have any online resources linked they can send me? I’m looking for links online that explain what tonemapping is as well as why tonemapping is necessary for 8bit viewing and printing. [[[ HINT: Anything viewable on the web or in print is NOT hdr. ]]] If you didn’t even know this much then the links I post from users or an example I create myself if necessary will hopefully shed some light on the matter.

I’d rather not recreate the wheel and just link to current resources. If there are none out there that clarify the concept for mere mortals then I’ll have to do so myself (only if necessary). It needs to be simple enough so that my mom can understand. She can barely use a DVR so she is my ultimate technology challenged litmus test. If you have a link that cuts through technical jargon, send it to me and I’ll post it.

No comments on this post. Send the links through my contact page (use navigation above).

If I don’t get responses or if the links provided to me can’t be understood by my mom, then I guess I’ll have to step up to the plate and create an example myself… but I’d love to save the time and just link to current resources.

DSLR Cinematography (and more)

admin — Wed, 26 Aug 2009 07:32:41 +0000

[vimeo]http://www.vimeo.com/5602151[/vimeo]

Learn high end techniques used in Film and Broadcast at FXPHD.com. Best online training experience I’ve had. Period. Extremely experienced instructors who actually work on major Film and Broadcast productions for a living.

If you have plans in the future to shoot video on a DSLR, then you definitely need to look at this terms course on DSLR cinematography taught by Stu Maschwitz, who spent four years at Industrial Light & Magic before co-founding The Orphanage in 1999. And if those company names don’t mean anything to you, let me put in context. Imagine you wanted to be cartoonist, but had never heard of Disney.

I’ve taken courses from them in the past and have never been dissappointed. This term I’m taking:

C4D101 – Introduction to Cinema 4D
CLR202 – Grading with Apple Color II
DOP210 – DSLR Cinematography
FUS202 – Intermediate Fusion 6
MOG201 – Creative Concepts in Graphics Design

If you join, then look for me on the forums. My user name is: Mike James