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This seems to be new and is turned on by default. Those of you, who have a 1D4, what is your thought on it? I will check out the differences. I read that it can increase noise in higher ISO but don't know yet if this is true. I will turn it off for now.
Thanks Axel Will check and let you know !!
Auto Light Optimizer Disabled (3)
I did a quick test. These are the same settings and the image is RAW to TIFF without processing, resized and jpg. I focused on the snow with EC +1.66 First image with autolight optimizer turned off, the second one with standard (0) which results in completely blown highlights since the shutter speed dropped to 1/1250s from 1/2000 in the first one. Both are in AV, I left the EXIF intact. I have to test more but for now I guess this might be a reason why I had so much trouble exposing images correctly at Barnegat Light yesterday.
Auto Light Optimizer On - Standard (0)
uhhh that looks bad. I also had some slight trouble metering certain Objects, but didn't think that this might be the reason why.
I am wondering what this function is supposed to do...
Maybe some in-camera shadow/highlight function? I forgot to say that I used evaluative metering in both.Quote:
Originally Posted by Jan Wegener
Yep, I had the same thought. Looks like a poor approach to bring more details in the shadows by sacrifying the lights...Quote:
Originally Posted by Axel Hildebrandt
I cannot test it myself for the next couple of days, but hope you keep us posted on this issue. It looks like something you certainly wanna have turned off
Compared to my 1Ds III metering an object correctly with the mark IV seemed trickier to me....With the Ds III I almost never blew out anything, whereas with the Mark IV I had to be more cautious.
I never had trouble in this kind of light with the Mark III, either. I'm surprised this feature changes the histogram of RAW files, too. In the manual it is stated that the information is appended to the RAW file and can be changed in DPP. I use ACR, though, and will turn it off for now it see how that works.Quote:
Originally Posted by Jan Wegener
Did you try what happens to the blown out file when you turn it off in DPP?
Looking forward to your further testing results.
I don't use DPP but will install it soon to see if that makes a difference.Quote:
Originally Posted by Jan Wegener
I played more with this feature turned on and off and didn't have such a big difference again but it does change the histogram a bit, at least when opened in ACR.
this is on the 7D as well but i have not played around with it so I am curious what you come up with as well
It certainly changes jpgs but is only appended to RAW files. I don't know for sure what or if ACR does with it. In DPP you can supposedly apply it or not but I haven't tried this since I don't have DPP installed.Quote:
Originally Posted by Jamie Strickland
This is from the Canon 1Dmk IV White Paper
The Auto Lighting Optimizer function (ALO) automatically adjusts the picture during image processing to obtain optimal brightness and contrast. It corrects AE underexposure, flash underexposure, low contrast, or backlit underexposure (face detection). The algorithm works by optimally adjusting brightness and tone based on scene information, including the image histogram. This is the first time that the feature has appeared in an EOS-1 series camera. The EOS-1D Mark IV’s ALO algorithm is one generation newer than that of the EOS 50D. It is improved in its handling of scenes without faces. For scenes with faces, the previous algorithm is employed. The default setting is Standard, but optional settings include Low, Strong and Disable.
ALO works with both JPEG and RAW images. With RAW images, photographers can choose the same settings that the camera offers when processing the images in the supplied DPP software. You can select from Standard, Low, Strong or Disable. With previous EOS DIGITAL cameras having ALO, the function worked only in the P, Tv, Av and CA modes. However, with the EOS-1D Mark IV, ALO now also works in the Manual mode and bulb as well, in keeping with the idea of enhanced JPEG workflow.
In the case of manual exposures, noise in the areas brightened by the Auto Lighting Optimizer may increase. The exposure must be set accordingly to prevent excessive correction. For incident-light scenes where the subject’s background is dark over a large area, the correction by the Auto Lighting Optimizer might turn out to be excessive in rare cases. Therefore, if you expose the subject correctly (exposed according to the set shutter speed and aperture), setting the Auto Lighting Optimizer to [1: Low] or [3: Disable] is recommended.
When using the continuous shooting mode, AE is enabled and ALO locks. Therefore, when using continuous shooting mode in environments where brightness is rapidly changing, set ALO to “1: Low” or “3: Disable.” The reason for this is that the camera adjusts ALO when the first frame is taken, then employs the same setting for subsequent frames in the sequence. This is especially important if the first frame happens to be shot when lighting is relatively dark. Subsequent frames taken in brighter conditions will be overexposed since the camera “locked” the ALO setting based on the darker lighting conditions of the first frame. (Setting ALO as described above assures more evenly exposed images whether or not faces are recognized in the composition.)
When using Manual or Bulb modes, ALO compensation is based on the exposure set by the photographer. Backlit subjects have a tendency to be underexposed. If the photographer tries to compensate for this by exposing for the subject, the background becomes overexposed. However, by enabling ALO and exposing for the background, the main subject will be brightened for a more balanced image with regard to brightness and contrast between background and main subject. Adjusting exposure can be tricky when photographing a brightly lit subject set against a large dark background, such as a shaded forest or crowded stadium; ALO may be affected by the background and overcompensate. In situations such as these, expose for the main subject and set ALO to “1: Low” or “3: Disable.”
Here is the link to the entire White Paper:
http://www.usa.canon.com/uploadedima...20IV%20WP1.pdf
I hope this helps.
Thanks, Jeff! Do I understand correctly, that this feature changes the RAW file, no matter what converter is used or is the ALO something only DPP can read?
The exposure data is written to the Raw file, but not applied. If the Raw image is developed in Canon's DPP the ALO settings can be applied or adjusted by the software. If you process the Raw file with any other software the ALO settings are meaningless.
The reason you see the histogram moving is because the on camera histogram is based on a jpeg and the ALO data is directly applied to any jpeg files.
This feature is on the Canon T1i, 50D, 7D and 1DMkIV only, to the best of my knowledge.
so when i do not use DPP I should turn it off. When I do not intend to use it it shows me a wrong histogram while shooting, right!?
In any case this feature sounds pretty useless. It greatly increases the risk of badly exposed images without doing much good...
The key phrase in the material I quoted from the white paper is . . . in keeping with the idea of enhanced JPEG workflow. I think Canon is trying to offer many different features to many different shooters. Not everyone uses Raw and ALO is an attempt to help jpeg shooters get it right in the camera.
Thanks again, Jeff. Since I use RAW exclusively, I will just turn it off in camera.
Thanks Jeff :)
This just brings up the question why Axel's snow file looks different. He shot RAW, but obviously something was change and he didn't use DPP.
One thing to note is that if you do use ALO and evaluate your exposures based on the histogram and highlight alert, this may cause you to make exposure adjustments which WILL affect the raw file.
Good point, I had EC at -1 and still some seriously overexposed whites while the BG looked too dark.Quote:
Originally Posted by Jim Neiger
The reason ALO produced the light file is that Exposure Compensation was used with ALO. ALO is meant to work with no EC. In Axel's example it saw the corrected file and applied further compensation, sort of a double correction.
This means you have to turn it off, when you want to have correct exposed files and a histogram shwoing the truth.....
I start to wonder why the default setting is "on"
Interesting, next time I'm in the field I will experiment more. I hope the metering/exposure problems are only due to this setting.Quote:
Originally Posted by Jeff Donald
On a related note, what contrast setting do you use in 'picture styles', 0 or a minus value?
Are you referring to the Picture Style applied to jpegs and jpegs files affect the histograms? I use Faithful and set the Contrast to -4, and saturation to -1. All the other settings are 0. I've found this to produce the most reliable histogram under various lighting situations, when compared to Photoshop.
Thanks, I have contrast at -4 and saturation at 0, I will try -1. I increase the sharpness to be able to see in the field if an image is actually in focus.Quote:
Originally Posted by Jeff Donald
Sharpness seems to have no effect on the histogram, many photographers do as you and pump up the sharpness to aid in determining critical sharpness.
If you are shooting in RAW, then ideally you are supposed to set the default contrast and sharpness to zero. Else, the jpeg will get impacted and the histogram you see in the lcd and the histogram of the raw file will be different.
Cheers,
Sabyasachi
My experience is that by lowering the contrast 'blinkies' only happen if it really is overexposed in RAW, at neutral it gives you blinkies even if the histogram looks perfectly fine in the RAW converter and hence decreasing the dynamic range of the image.Quote:
Originally Posted by Sabyasachi Patra
In my experience, I would have to disagree. Many people think that setting the Picture Style settings to zero is an "off" setting and it is not. Chuck Westfall (Technical Advisor for Canon's Consumer Imaging Group), has commented on this on many occasions, the zero setting is applying Canon default settings for that Picture Style. Moving the sliders towards the minus decreases the affect and towards plus increases the affect. But there is no off setting. I think Canon recommends using either the Faithful or Neutral Picture Style for people who shoot in Raw.Quote:
Originally Posted by Sabyasachi Patra
If you read the description of the Standard Picture Style, can uses such terms as Vivid, Sharp and Crisp to describe the look. This produces a jpeg that Canon feels most of their consumers will like. However, this tends to produce a histogram that is not accurately displaying the scene as it really exists. Based on the histogram from the "vivid" jpeg the photographer adjusts the exposure and perhaps under exposes. The exposure/histogram error will vary with the Picture Style used and the scene being photographed.
I use a Picture Style that produces a histogram that closely resembles the histogram that my default Adobe Camera Raw settings produce. What I'm aiming for is a WYSIWYG managed workflow.
If you want the in camera jpeg to match what is in the raw data file, check out universal white balance. There is a way using a custom WB that you can match the raw file data. It produces a very strange looking jpeg that must be altered during raw conversion, but it does allow you to really fine tune exposures to the extreme. I played with it for a while, but decided it wasn't worth the effort. UNIWB just wasn't practical IMO.Quote:
Originally Posted by Jeff Donald
I get very close to matching histograms by selecting Faithful Picture Style and altering the Contrast and Saturation as outlined above. I'll look into UNIWB. I also use custom camera profiles as well. I wouldn't normally go through all this hassle, but I have students that do copying of art work and are after the highest degree of accuracy. If I can do it, then I can teach it to my students.Quote:
Originally Posted by Jim Neiger
Turning off ALO made all the difference. I went back to Barnegat Light and had no problems with metering and exposure whatsoever. Thanks for all the help and suggestions!
I just posted an image that I made in soft afternoon light if you are interested: http://www.birdphotographers.net/for...ad.php?t=54400
Interesting in 7D, 50D and 5DMKII cameras ALO has no effect on RAW files, you can choose to enable or disable it later in DPP, has this changed in MKIV?
So what is your impression of 1DMKIV so far? Is the AF any better?
I don't think ALO has a direct effect on the RAW file but adjusting EC made the images look less than great since the histogram is misleading in this case. With this problem gone, the Mark IV is great. The AF performs well with birds in flight, focuses quickly and even with moving water in the BG doesn't lose the subject easily. Noise is at least as good as the Mark III, maybe even better, but I have to test more. It drains the battery faster than the Mark III and fast UDMA 6 cards make a big difference in burst mode.Quote:
Originally Posted by arash_hazeghi
Thanks Axel, that makes more sense, so it is the same as before I figured Canon knows corrupting RAW data is not a good idea at all :) One more new feature that you need to check for is the ambient light sensor that the new LCDs have (MKII and 7D have this) it sometimes brightens or darkens the LCD too much and it can be very misleading so you always need to check histogram.Quote:
Originally Posted by Axel Hildebrandt
Have you tried the expansion AF mode or single point only? What lenses did you try?
Thanks
Thanks, good to know about the light sensor. I have only tried single point so far, it was only my second day out with the camera. I will check if the expansion points cause trouble with varying BGs. I tried the 300f/4 to photograph some paintings in one shot and the 500f/4+TC combination for birds. Interestingly, with the Mark III I had to microadjust the 500/TC combination but not with the Mark IV.Quote:
Originally Posted by arash_hazeghi
The LCD image on the back of the screen always lies. The 7D has about 18MP and the screen display about 900,000 pixels. Just doing the math in my head, that at about a 20:1 interpolation. Meaning for every 20 pixels in the image, 1 pixel is displaying the color, detail etc. of 20 pixels in the digital file. The image displayed in the back of the screen is almost useless, only the histogram gives you clue as to what is really going on.
I agree with one exception, with the new VGA LCDs you can zoom up to 1:1 ratio so you can check the critical sharpness, before I could never judge sharpness on the camera LCD now I can tell if a photo is pin sharp or not and immediately delete the soft photos in the field :DQuote:
Originally Posted by Jeff Donald
Not meaning to be argumentative, but how many pushes of the magnify button achieves 1:1? I can't find this in any Canon literature.
Take a look at this http://www.dpreview.com/reviews/canoneos7d/page7.aspQuote:
Originally Posted by Jeff Donald
max magnification is 10X since the LCD is 640X480 pixel at 10X you are looking at 6400 pixel wide image so it is even more magnified than 1:1
Jeff, and gang this is a very good discussion. Jeff, are you saying that you chose a picture style of old faithful, and you shoot your raw in this style, with the above mentioned adjustments, in photoshop when you process, or in the camera.
Thks for your clarification.
Don
The histogram that is displayed on the back of the camera is produced from a jpeg file the camera creates, even if you have your camera set to shoot only Raw files. The camera uses the jpeg because it would take too much processing power and too much time to demosaic the Raw file and use it for the histogram. The jpeg the camera produces is processed in the camera using Picture Style settings that are set in the camera. The Picture Style settings are meant to aid the in-camera jpeg workflow for some photographers. The settings adjust Contrast, Sharpness, Color Saturation and Color Tone (Red/Yellow axis).
Contrast, Color Saturation and Color Tone all affect the histogram. If the photographer is using the histogram to aid in determining exposure, the Picture Style settings in the camera could adversely affect the jpeg and thereby cause exposures of Raw files that are either under or over exposed. Many photographers that use the "Expose to the Right" technique rely heavily on the histogram to produce files that have the most detail and least noise. If the histogram is displaying incorrect data due to the Picture Styles, again the Raw files may be under or overexposed.
I edit the Faithful Picture Style to reduce the errors in the histogram by adjusting Contrast to -4 (lowest setting) and Saturation to -1. I leave Color Tone alone because of the unpredictable nature of color in the field. However, I know studio photographers that will change Saturation and Color Tone when photographing scenes with a predominant color, such as red or yellow. I feel this is overkill, specially if you shoot tethered in the studio. Many photographers set the Sharpness control to the highest setting to aid in determining critical focus using the cameras rear display. Adjusting the sharpness setting does not have a major affect on the histogram.
The Picture Style settings do not affect the actual Raw file (except indirectly as noted above) created by the camera. However, if you use the Canon software DPP, the Picture Style settings will be applied to the Raw file when it is processed. The settings can be further adjusted in DPP to suit the photographers style and taste. Adobe software does not use the Picture Style settings for Raw processing.
As I understand it. The feature was added to help those of us who tend to blow white bridal gowns. (that really ticks off the bride) I have the same problem with seagulls. As soon as we see the sun again here in Vancouver I'll give it a try. On gulls that is...
The Histogram on the camera will also change depending which color space the camera is set to, aRGB or sRGB.
Bill
Many items are affected by a change in color space, including ISO which affects exposure and will change the Histogram.Quote:
Originally Posted by William Malacarne
I looked into UNIWB and the procedure is greatly simplified and takes maybe 3 minutes to complete. It is stored in the camera as a custom manual WB. It does however produce at jpeg file that is useless (very heavy green cast). The Histogram is almost dead on to the Raw files histogram. The UNIWB can be easily switched to any other WB, including Auto and switched back to check the histogram. It could also be set with other Custom User settings and switched to when needed. UNIWB may prove very useful in tricky lighting conditions to keep from blowing out certain color channels when photographing saturated colors.Quote:
Originally Posted by Jim Neiger
