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Old Dec 10, 2011, 2:53 PM   #1
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Default ISO bracketing on E-pl1 and photoshop

Lately I have been using ISO bracketing and have been shooting RAW. When I view the images in the camera the ISO bracketing shows the appropriately different exposures, but when I upload the images to the computer and view them with Photoshop Elements 9 the images all look identical. The metadata panel shows the different ISO values for each image, but the images appear identical otherwise.

First of all, I have to admit I don't exactly know how the camera handles ISO bracketing. It appears to only take one exposure but somehow produces three images. Does Photoshop just fail to recognize whatever the camera has done to create three different images?

Secondly, it occurs to me that Photoshop might somehow be overriding what the camera has done to give me what it thinks I want. I have been unsuccessful at finding any sort of options dialog that might control this function, or any help dialog that even hints its existence.

I kind of like the ISO bracketing option, in theory at least. It seems to work fine if I shoot in JPEG.

I would like to shoot RAW with the ISO bracketing enabled. I suppose I could try aperture bracketing to see if that works. This would be a second best option, because I often have a good reason for selecting a particular aperture.
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Old Dec 10, 2011, 8:19 PM   #2
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Using ISO bracketing, all the images SHOULD look very close to identical. All the camera is doing is using different ISO settings to produce the same image using different exposure combinations.

If you are using bracketing to try and extend dynamic range by combining the best of multiple files, you need to bracket using exposure compensation so you wind up with files maximizing both shadow and highlight details that you can then combine. ISO bracketing will not do that.
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Old Dec 10, 2011, 8:23 PM   #3
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Lately I have been using ISO bracketing and have been shooting RAW. When I view the images in the camera the ISO bracketing shows the appropriately different exposures, but when I upload the images to the computer and view them with Photoshop Elements 9 the images all look identical. The metadata panel shows the different ISO values for each image, but the images appear identical otherwise.

First of all, I have to admit I don't exactly know how the camera handles ISO bracketing. It appears to only take one exposure but somehow produces three images. Does Photoshop just fail to recognize whatever the camera has done to create three different images?

Secondly, it occurs to me that Photoshop might somehow be overriding what the camera has done to give me what it thinks I want. I have been unsuccessful at finding any sort of options dialog that might control this function, or any help dialog that even hints its existence.



I kind of like the ISO bracketing option, in theory at least. It seems to work fine if I shoot in JPEG.

I would like to shoot RAW with the ISO bracketing enabled. I suppose I could try aperture bracketing to see if that works. This would be a second best option, because I often have a good reason for selecting a particular aperture.
Hi

If your viewing your Raw images in Photoshop, most likely, you're viewing them using Adobe's Camera Raw. The easiest way to confirm that is that you have a set of slider tools on the right hand side of the screen. Up above that set of sliders is the histogram. If that's the case, then above the slider identified as "EXPOSURE" are 2 boxes one is AUTO the next is Default. Press the Default box and the image will appear as it came out of the camera.

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Old Dec 11, 2011, 12:08 AM   #4
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Greg, I use exposure bracketing when I don't trust the camera to get the exposure right. I used it this morning to shoot some eclipse shots. In one set I used a fixed aperture mirror lens with f/8 aperture. When I used the aperture priority mode and spot metering with ISO at 640, the camera selected a shutter speed of 1.3 seconds. The ISO bracketing gave me three exposures at ISO 320, 640, and 1250. Certainly they should be alike, except in exposure. Ideally, I would be able to select the one that started closest to what I wanted for further adjustments in Photoshop. I wasn't planning to stack them, I just wanted to start with an image that was properly exposed.

Zig, I checked the Camera RAW screen and indeed default was checked. I tried auto and it made a complete mess of my eclipse shots. When in the default position all of the exposure, brightness and contrast sliders started in exactly the same positions for the ISO 320, 640, and 1250 shots, and the images all looked identical despite the different ISO ratings. I double checked to see that the shutter speed was the same on all three images. With a full stop difference between the exposures I should be seeing marked differences in exposure, like I did when I used the ISO bracketing function on JPEGs. There is no difference between the shots in either the organizer screen, or in the Camera Raw screen. The camera's playback screen does show the expected exposure differences, it just doesn't work that way in Photoshop. I just checked the images using Picassa and they are appropriately different in exposure, so the problem seems to be in Photoshop.

I just don't understand Photoshop well enough to figure this out.
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Old Dec 11, 2011, 6:28 AM   #5
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I just don't understand Photoshop well enough to figure this out.
Could be that Photoshop does indeed not know what to do with the interpolated data the Pen camera is providing. To my knowledge, Olympus Pen cameras are the only ones that actually provide ISO bracketing.

I personally use Exp bracketing to achieve the desired exposure value while leaving the ISO as low as is possible for the situation so as to minimize noise.

As far as the jpegs vs RAW files are concerned, my belief is that because the RAW data is just that, the actual file as produced, the differences may not be as pronounced as the jpegs which have been compressed.

As for Picasa's ability to show differences- don't have an answer for that as I don't use it.

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Old Dec 11, 2011, 10:29 AM   #6
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Greg, I use exposure bracketing when I don't trust the camera to get the exposure right. I used it this morning to shoot some eclipse shots. In one set I used a fixed aperture mirror lens with f/8 aperture. When I used the aperture priority mode and spot metering with ISO at 640, the camera selected a shutter speed of 1.3 seconds. The ISO bracketing gave me three exposures at ISO 320, 640, and 1250. Certainly they should be alike, except in exposure. Ideally, I would be able to select the one that started closest to what I wanted for further adjustments in Photoshop. I wasn't planning to stack them, I just wanted to start with an image that was properly exposed.
This one's easy. The moon should always be shot using manual exposure because of all that darkness around it. Meters just do not handle it right.

A long, long time ago in, seemingly another life, I learned you should always use manual exposure when shooting the moon and the exposure is based on the sunny 16-rule which, in film days meant f16 at the reciprocal of the film used, so if you were using ISO 100 speed film, the exposure should be 1/125 second at f16. For ISO 200, it was 1/250 second at f16 and so on. I also heard of a later rule called the sunny 16+1, which meant to give an extra stop, making it 1/125 second at f11. The "problem" with this is, of course, you were using film so there was no seeing the result of the picture until you had the film developed.

Enter the digital camera. When you select manual exposure, the cameras' back LCD shows you the image on the screen, exactly how it's going to look BEFORE you shoot it, so there's absolutely no reason to use anything other than manual mode because you can set an exposure and see what it's going to look like before you press the shutter release. If the image looks too dark, open the aperture up or select a lower shutter speed. If it's too light, do the opposite.

You can start with the sunny 16+1 rule and adjust the exposure until you like what you see on the back LCD before you even take a shot. There's no guess work to doing it with a digital camera at all. With your fixed f8 lens, calculating the starting point is easy. Set the ISO to 200. With that setting the typical exposure would be 1/250 second at f11, but with your f8 lens, you have to adjust the shutter speed. 1/500 second at f8 will give you the exact same exposure at ISO 200 as 1/250 second at f11, so that's what you use in manual exposure mode. If the moon looks too dark on the screen, change the shutter speed to 1/250. If it looks too light change it to 1/800 or 1/1000.

The LCD will always show you what you are going to get before you shoot in manual exposure mode. Use it. It will make you life a lot more simple.

Last edited by Greg Chappell; Dec 11, 2011 at 11:19 AM.
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Old Dec 11, 2011, 10:55 PM   #7
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Thanks Zig and Greg. I'll give aperture bracketing a try. Greg, your moon photo was excellent.
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