Poor Dynamic Range from My 50D...

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04-24-2009, 11:11 AM
Benjamin

Poor Dynamic Range from My 50D...

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<p class="MsoNormal"]<span style="font-size: medium;"]<span lang="EN-US"]If there is
one thing that I cannot be impressed by my 50D, it’s got to be the poor dynamic
range. Here are two pictures from the 50D along with a film shot for
comparison.
<p class="MsoNormal"]<span style="font-size: medium;"]

<p class="MsoNormal"]<span style="font-size: medium;"][img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.24.70.Sample+Pictures/LS-2009.jpg[/img]
<p class="MsoNormal"]<span style="font-size: medium;"](A Sweet Smile from Lina, 50D + 24-70/2.8L @ 32mm, F2.8, 1/60, ISO1600)
<p class="MsoNormal"]<span style="font-size: medium;"]<span lang="EN-US"]The
portrait was taken yesterday at dinner with dim indoor light available, ISO1600
was used on my 50D along with my 24-70/2.8L wide open. The early evening light
came from the window (indirect and not strong at all) to light the right side
of her face, and the highlight blows out almost immediately…<o:p></o:p>
<p class="MsoNormal"]<span style="font-size: medium;"]

<p class="MsoNormal"]<span style="font-size: medium;"][img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.24.70/Steinway1.JPG[/img]
<p class="MsoNormal"]<span style="font-size: medium;"](Steinway @ Hart House, 50D + 24-70/2.8L @ 27mm, F2.8, 1/50, ISO640)
<p class="MsoNormal"]<span style="font-size: medium;"]<span lang="EN-US"]The second
shot was taken with the same setup in a similar situation; I can see how fast
the highlight part of the image loses detail due to the early afternoon sunlight
direct from the window on the left. There barely is any transition between the
properly exposed part of the image and the completely blow-out highlight.
<p class="MsoNormal"]<span style="font-size: medium;"]<span lang="EN-US"]For comparison,
there is a picture of the Guelph church I took in a winter morning not too long
after sunrise. The difference in brightness between the ground and the sky is huge, and
my Fuji Pro 400H (print film) holds every detail from bright clouds and snow to
midrange church and statue to dark trees and ground perfectly.
<p class="MsoNormal"]<span style="font-size: medium;"][img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.24.70.Sample+Pictures/Guelph-Church.jpg[/img]
<p class="MsoNormal"]<span style="font-size: medium;"](Guelph Church of Our Lady Immaculate, Canon 1V-HS + 16-35/2.8L II @ 16mm, F11, ISO 400, Fuji Pro 400H)
<p class="MsoNormal"]<span style="font-size: medium;"]<span lang="EN-US"]I think I’m
in a dilemma now. Digital gives me lots of convenience and the ultimate ISO I need
to shoot in dark environment (I simply cannot find an ISO3200 color film, even
if so it’s not going to be usable…). However, film’s dynamic range and the
unique color rendition still hold me tight as a film shooter. <o:p></o:p>
<p class="MsoNormal"]<span style="font-size: medium;"]<span lang="EN-US"]I don’t
know when it’s really time to surrender to digital; but as far as I can see not
any time soon, just for the sake of getting a picture which in no way look like
digital and for the sake of holding every detail I need on my pictures.<o:p></o:p>
<p class="MsoNormal"]<span style="font-size: medium;"]<span lang="EN-US"]Open for opinions.[:)]<o:p></o:p>
<p class="MsoNormal"]<span style="font-size: medium;"]<span lang="EN-US"]Ben<o:p></o:p>
04-24-2009, 11:45 AM
Mark Elberson

Re: Poor Dynamic Range from My 50D...

Quote:

Originally Posted by Benjamin

<p class="MsoNormal"]<span>If there is one thing that I cannot be impressed by my 50D, it’s got to be the poor dynamic range.
<p class="MsoNormal"]

<p class="MsoNormal"]Have you tried "C.Fn II -3 Highlight tone priority". I haven't played with it myself but per the 50D instruction manual, "The dynamic range is expanded from the standard 18% gray to bright highlights. The gradation between the grays and highlights becomes smoother."
<p class="MsoNormal"]If anyone has experimented with this setting I would love to hear about it. Does it work well? When do you use it?When won't you use it? Is increased noise in the shadows a problem?
04-24-2009, 12:42 PM
Daniel Browning

Re: Poor Dynamic Range from My 50D...

Yeah, film is hard to beat for dynamic range. One of the advantages of digital, though, is that dynamic range scales with print size. If you shoot for large prints (30x20), you have to get clean shadows, so you let highlights blow out. But if you shoot for wallet-size or web images, you can let the shadows get very noisy, because the noise will not be visibile in the final output image. Film, on the other hand, does not have linear response, so it's not possible to use this little trick.
04-24-2009, 05:29 PM
Benjamin

Re: Poor Dynamic Range from My 50D...

Quote:

Originally Posted by Mark Elberson

<p class="MsoNormal"]Have you tried "C.Fn II -3 Highlight tone priority". I haven't played with it myself but per the 50D instruction manual, "The dynamic range is expanded from the standard 18% gray to bright highlights. The gradation between the grays and highlights becomes smoother."
<div style="clear: both;"]</div>

I haven't had time to evaluate the Highlight tone priority yet. I don't know how much better it can hold highlights and hence to provide better dynamic range. I guess the highlight tone priority is a software thing just like the in-camera noise reduction, while getting "better" highlight detail one must trade off some other aspects, that's also why I have left this feature disabled all time...

Maybe Daniel knows more about such a feature and how it works?

Thanks in advance!
04-24-2009, 05:40 PM
Daniel Browning

Re: Poor Dynamic Range from My 50D...

Quote:

Originally Posted by Benjamin

while getting "better" highlight detail one must trade off some other aspects, that's also why I have left this feature disabled all time...

Correct. That's why Canon includes "priority" in the name, because the features just prioritizes one thing (highlight headroom) over another (shadow noise). It doesn't actually increase dynamic range, it robs Peter (shadows) to pay Paul (highlights).

The way it works is by setting the ISO one setting lower than what's indicated (e.g. 200 -> 100) and increasing brightness with a curve (in-camera JPEG engine or DPP) to preserve highlights. You can do the same thing by using EC or changing the ISO yourself.

I only use HTP at ISO 3200 and above.
04-24-2009, 05:42 PM
Jon Ruyle

Re: Poor Dynamic Range from My 50D...

Were you shooting jpeg or raw? Don't jpeg converters tend to blow highlight detail that might be preserved in the raw?
04-24-2009, 06:32 PM
George Slusher

Re: Poor Dynamic Range from My 50D...

Some film, especially B&W, has better dynamic range than most digital sensors, except in a few cases. One example is low light. Film has problems with reciprocity failure that doesn't really affect digital sensors. The photo below was shot at about 12:39 AM with a 30-second exposure. (Note the odd shadows cast by streetlights. That should tell you that it wasn't in daylight.

[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.23.54/IMG_5F00_3066_5F00_600.jpg[/img]

To make matters "worse," your computer's display has even less dynamic range than the digital sensor does. One way to get around that is to use "high dynamic range" (HDR) techniques. Some HDR-processed images look a bit fake, especially if one is used to seeing "normal" photos on a display. The idea is to take several photos (usually at least 3) over a range of exposures. The "best" way is to meter the brightest highlights and deepest shadows you want to show, then take a photo at each of those exposures and several in between. A simpler way is to use the camera's exposure bracketing function to take photos at 0, +2, and -2 stops. That will increase the dynamic range, though not as much as the first method. It's a lot easier to do, though.

Once you have the shots, you can combine them in a number of ways. Photoshop will let you do it, though in a sort of "brute force" method. There are other applications that add in sophisticated "filters" that, for example, look at "micro-contrast" (pixel-by-pixel) and enhance it locally. Thus, the program will weight the +2 exposure where the shadows are and the -2 where the highlights are, but at a micro level. The software I use is Photomatix. It has several modes of operation and more controls than I can figure out. You can download the software and play around with it.

Of course, this only works with "static" images, though Photomatix can try to reduce ghosting for SMALL movements. See the examples on their site.

Below are two examples I did from the same 3-shot sequence by varying the white balance (shade vs daylight) and the parameters in Photomatix. Following them is the original "0" shot.

[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.23.54/IMG_5F00_1149_5F00_50_5F00_48_5F00_shade_5F00_comp 1_5F00_2_5F00_800.jpg[/img]

[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.23.54/IMG_5F00_1149_5F00_50_5F00_48_5F00_auto_5F00_comp1 _5F00_2_5F00_800.jpg[/img]

[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.23.54/IMG_5F00_1148_5F00_800.jpg[/img]

Finally, two more done with Photomatix. The first was done when I was trying it out, thus the watermarks. It's fairly typical of HDR shots, enhancing contrast and detail in the clouds (bright) and in the trees (shadows). The second is, well, different. I wonder if anyone can figure out how it was done (other than using HDR)--and, no, it was NOT processed in Photoshop, at all, and the same color effect could have been done without Photomatix.

[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.23.54/IMG_5F00_0957_5F00_5_5F00_6_5F00_details_5F00_800. jpg[/img]

[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.23.54/IMG_5F00_1195_5F00_4_5F00_3_5F00_tungstn_5F00_tm1_ 5F00_2_5F00_800.jpg[/img]
04-25-2009, 12:27 AM
peety3

Re: Poor Dynamic Range from My 50D...

Quote:

Originally Posted by Benjamin

<p class="MsoNormal"]<span style="font-size: medium;"]<span>If there is
one thing that I cannot be impressed by my 50D, it’s got to be the poor dynamic
range.
<p class="MsoNormal"]<span style="font-size: medium;"](A Sweet Smile from Lina, 50D + 24-70/2.8L @ 32mm, F2.8, 1/60, ISO1600)
<p class="MsoNormal"]<span style="font-size: medium;"]<span>The
portrait was taken yesterday at dinner with dim indoor light available, ISO1600
was used on my 50D along with my 24-70/2.8L wide open. The early evening light
came from the window (indirect and not strong at all) to light the right side
of her face, and the highlight blows out almost immediately…
<p class="MsoNormal"]<span style="font-size: medium;"](Steinway @ Hart House, 50D + 24-70/2.8L @ 27mm, F2.8, 1/50, ISO640)
<p class="MsoNormal"]<span style="font-size: medium;"]<span>The second
shot was taken with the same setup in a similar situation; I can see how fast
the highlight part of the image loses detail due to the early afternoon sunlight
direct from the window on the left. There barely is any transition between the
properly exposed part of the image and the completely blow-out highlight.
<p class="MsoNormal"]<span style="font-size: medium;"](Guelph Church of Our Lady Immaculate, Canon 1V-HS + 16-35/2.8L II @ 16mm, F11, ISO 400, Fuji Pro 400H)
<p class="MsoNormal"]<span style="font-size: medium;"]<span>I think I’m
in a dilemma now. Digital gives me lots of convenience and the ultimate ISO I need
to shoot in dark environment (I simply cannot find an ISO3200 color film, even
if so it’s not going to be usable…). However, film’s dynamic range and the
unique color rendition still hold me tight as a film shooter.

What an unfair comparison. Shoot a few shots on your 50D at ISO 400 and compare the dynamic range there. If you find a loss of detail at one end or the other, dial in some exposure compensation to suit.

It's like choosing your film because of its strengths and weaknesses: digital can't handle extreme brightness with detail, and the meter isn't perfect, so you may just have to learn how to help the meter. Look at Arthur Morris' bulletins and books, showing all sorts of guidelines, such as metering the sky then shooting the bird, or dialing in a certain amount of EC before even trying a shot based on the conditions.

Do realize that digital has limits. At the bright end of the spectrum, red/green/blue brightnesses get captured as values, and when they get to "100%", there's no more room for detail. None, nada, zip, zilch. It's similar to what audio people suffered through when digital recording came out - audio clipping would always sound absolutely horrible, so when converting analog to digital they had to scan the entire album to find the one loudest moment, make sure they had the "volume" low enough to not clip that moment, and then transfer the entire album without ever touching that knob. At the dark end of the spectrum, there aren't a lot of bit combinations left for much detail, but you'll probably find a fair amount of detail in the shadows if you try.
04-26-2009, 01:46 AM
Benjamin

Re: Poor Dynamic Range from My 50D...

Quote:

Originally Posted by peety3

What an unfair comparison. Shoot a few shots on your 50D at ISO 400 and compare the dynamic range there. If you find a loss of detail at one end or the other, dial in some exposure compensation to suit.
<div style="clear: both;"]</div>

I do have shots from ISO 100 or 200 and they blow out highlight in a sudden too, not noticeably better than the shots done at ISO 400 or higher. All I have found is that film will provide more dynamic range than digital in some harsh situations. EC is something that I use frequently too, but I found that it most of the time will just give me underexposed pictures rather than providing me with valuable highlight detail. I also use ABE when I'm serious about getting a good shot, but in the end I will still have to choose to lose either the shadow or the highlight. Maybe there's something wrong with my way of doing it, I'll keep learning...[:)]

On the other hand, the Photomatix is certainly something to try out. But... So far I found some of the processed pictures look "fake" in the way that the white balance does not quite match. For example the Eiffel Tower on the mainpage of Photomatix, the tower and sky seem to be just right but the ground with flowers appears to be yellowish. Do I have to maintain a constant WB or do I need to adjust the WB in some way when trying to take multiple shots for HDR purposes?

I made my assumption without any theoretical support, hopefully someone will stand out and correct me...

Ben
04-26-2009, 03:41 AM
George Slusher

Re: Poor Dynamic Range from My 50D...

Re: Photomatix and white balance

If you work from RAW images, you can choose a white balance to apply to all of the shots in a series. If you want to tweak the WB for each shot, do it in Digital Photo Professional, Lightbridge, etc., and convert to some format that Photomatix can accept.

Of course, it's very possible that the original photo of the Eiffel Tower showed just what you see--the light may have been different in different parts of the scene. See my images of the barn as an example. Those both came from the SAME series of three shots. The difference was in the WB I chose. Part of the scene (the barn) is in shade and part (the background and foreground) is in daylight. Which is better? Using "Shade" makes the barn grey but turns the background and foreground yellowish, as one would expect--"Shade" has an overall "warming" effect. Using "Daylight" does the opposite: the barn becomes bluish, while the background and foreground are more realistic. (It was nearing sunset--note the long shadows--so the "daylight" portions of the foreground and background will look yellowish even with "Daylight" white balance.) See my shot of the island in daylight for an example where the white balance is pretty uniform across the image. (That was done from JPEGs, I think.)

Here are some examples where the scene has huge dynamic range. The sequence was taken just before 9 AM PST on Dec 19, nearly the shortest day of the year, in Eugene, OR, at latitude 44 deg, more or less, so the light is slanting. Plus, some of the image is in shade, while other parts have bright very early morning light. (I took these because this much snow is very unusual here, despite the latitude.) I didn't take the shots to be "pretty" or even particularly "good," just to get a series that I could experiment with of a scene with an inherently wide dynamic range. (I took several series with different exposures, as well.) They were taken from my front porch, which was convenient, as I could set up the tripod under cover on a hard surface and not have to trek through the snow. I could also retreat into my house to keep my hands warm. There's only so much I'll sacrifice for "art's sake."

This shot is the original, using auto white balance.

[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.23.54/IMG_5F00_6038.jpg[/img]

Now, here are several HDR renditions, using different modes in Photomatix, using the "as shot" white balance. There's no real need to go into details about the settings, in part because I don't have them, other than the broad description. The first uses Photomatix's "tone compression" mode, which is supposed to give more "film-like" or "photo-like" images. (Photomatix also has an "exposure blending" mode, which is much the way that Photoshop does it. That does not generate an HDR image...see below.)

[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.23.54/IMG_5F00_6038_5F00_39_5F00_40_5F00_tonecompressed. jpg[/img]

The next uses Photomatix's "details enhancer," which uses microcontrast to, you guessed it, "enhance details" in both shadow and highlight areas. This is obviously more dramatic.

[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.23.54/IMG_5F00_6038_5F00_39_5F00_40_5F00_details.jpg[/img]

Now, here's the same methods but setting the white balance to "shade" in Photomatix. First, tone compression:

[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.23.54/IMG_5F00_6038_5F00_39_5F00_40shade_5F00_tonecompre ssed.jpg[/img]

Now, details enhancer:

[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.23.54/IMG_5F00_6038_5F00_39_5F00_40shade_5F00_details.jp g[/img]

Now, here's the original after processing in Digital Photo Professional with "click white balance" plus an exposure adjustment to make the scene look more like snow. I tried clicking the white balance eyedropper on various bits of snow to see what I'd get and chose one that I liked. (FWIW, I like using the WhiBal card, but that would have been no better here because the light varies so much across the image.)

[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.23.54/IMG_5F00_6038_5F00_dpp.jpg[/img]

Now, the Photomatix output with tone compression:

[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.23.54/IMG_5F00_6039_5F00_dpp_5F00_38_5F00_dpp_5F00_40_5F 00_dpp_5F00_compress.jpg[/img]

Finally, with details enhancer. This is, perhaps, the best image, though the other two "details enhancer" images are also interesting. The "tone compression" images do look more like "normal" images.

[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.23.54/IMG_5F00_6039_5F00_dpp_5F00_38_5F00_dpp_5F00_40_5F 00_dpp_5F00_details.jpg[/img]

Note the rather dramatic differences among these images, even though they were ALL done from the SAME sequence of three shots (except for the "original" shot) using auto exposure bracketing at 0, -2 and +2 stops. To make matters worse (or better--depends upon one's POV), Photomatix has lots of adjustments that can make a big difference. I can't describe the differences--you should get the trial copy and experiment with it, yourself. I've used it on landscapes as you've seen here, flowers, garden plots with deep shadows and bright highlights, etc. The two main caveats in taking the photos are 1) to use AV mode to keep the DOF consistent (you may need to choose the ISO in order to get three usable shutter speeds) and 2) that NOTHING should move, if possible. That means locking the camera down tight, using a remote release or the self-timer (it will automatically take the three shots with one shutter release push), and picking subjects where nothing is moving very much. If something moves, it can create ghosts.

Oh, I need to also mention the way that Photomatix works. (Not HOW it works--that's far beyond me.) Once you have your sequence of images, you use Photomatix to generate an HDR "image." You should save that as a file (extension is .hdr), as it can take a while to create, especially from RAW files. Once you have the .hdr file, you can start from there at any time. You CANNOT "display" that image as-is because it more bits per pixel than your display and OS can handle. Then, choose "tone mapping" and Photomatix will create a preview. Choose either "Details" or "Tone Compression" in the tabs and the preview will adjust to that mode. Then, you can use the preview to choose options and adjust the 18,437 parameters (well, not really
that many, but it can seem like it--it's as bad or worse than adjusting curves in Photoshop or Photoshop Elements), etc. (I always start with
"Default" settings, which the folks at Photomatix have set up for
general-purpose uses.) If you're smart (I wasn't), you'll write down the settings you use for each rendition. (A good way to keep these might be in a text file that you keep in the same folder as the images. You could devise a template with a spreadsheet or table to make it easier.)
04-26-2009, 04:16 AM
George Slusher

Re: Poor Dynamic Range from My 50D...

I should also note that it's easy to go overboard with HDR. First, not all scenes/images are amenable to HDR. (Some examples on the Photomatix site are a bit too much for me.) Second, one can play around with the parameters in Photomatix to come up with a really fake-looking image--e.g., lots of detail, but very flat.Third, it takes time--how much will depend, in part, upon your computer's speed. (Try not to run any other applications at the same time.) Fourth, the "improvement" you get (e.g., more detail in highlights and shadows) may not be worth the effort. I've done something like 150 HDR images but only a few are worth showing. (The images of the snowy street were not intended for showing to anyone, just for practice.)
04-29-2009, 12:44 PM
Ragingblues

Re: Poor Dynamic Range from My 50D...

Actually, the sensors are analog not digital. The conversion comes after the image has been captured on an analog sensor.

Of course, you probably knew that, but I wanted to clarify for readers that might not have known. I'll crawl back under my rock now.

Ken