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Old Oct 22, 2007, 1:01 AM   #11
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Raw does not apply any processing whatsoever - no sharpness, saturation, contrast. Also no white balance - it records one, but you gain the ability of changing the white balance when you convert the RAW file in post processing. The two biggest benefits RAW provides is the ability to adjust white balance and the ability to adjust exposure (about 3 stops in either direction). You should note the exposure adjustment isn't magical. If you've blown highlights they're likely gone. Also you will incur noise if you have an underexposed image and you adjust the exposure by a couple stops. But the exposure adjustments are better than what you can usually achieve with JPEG files.

Beyond that it allows people that want very fine control to NOT go through any jpeg compressions and do some other tweaks in the RAW conversion.

If you're not shooting a lot of images, a popular strategy now is to shoot RAW plus JPEG since memory has gotten so cheap. This allows you to use the jpeg files for most uses but have RAW for those instances where exposure or white-balance need tweaking.

That exposure adjustment is particularly useful for a technique called blending exposures. In a high dynamic range scene you can take two exposures and blend them (you don't need raw at this point) - BUT if there is movement, say leaves moving in the breeze you can't rely on two different photos because they wont match up. But if you take a shot in RAW, you can do multiple conversions of the same raw file. You won't get as much of a dynamic range as you would if you took several different photos but it gets you better results than a single jpeg shot.


By the way - some people will try and tell you real photographers only shoot in RAW. That's utter nonsense. Real photographers use the best tool for the job. While memory is cheap, using raw does take up more space, slow your buffer handlingand does add to your workflow. And in most instances - if you know how to get a proper in-camera exposure and white balance RAW doesn't offer you much benefit for that added cost. So, like any other tool if you understand it and when it's beneficial to your process then you can use it effectively. If not, then a fool with a tool is still a fool.

In the end it's simply another tool to use. It's worth exploring at some point in time. If you like to process images then you might like doingRAW conversions on all your files. Again it can save you from some mistakes you made in-camera, but IMO it's more important to learn how to get WB and exposure right in-camera than to work on mastering how to save images you botched. In the end you'll always get better results if you get it right in the camera - whether you shoot raw or jpeg. I think too many people rely on it as a fix for their mistakes in taking the photo and dont spend enough time learning how to get the photo right in the first place.
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Old Oct 22, 2007, 10:46 AM   #12
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thanks man, so if i know i have a good shot and like it as is, i can just save jpeg...and if i feel like combining or changing stuff after i can save raw...ill probably only do a couple in raw lol
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Old Oct 22, 2007, 10:50 AM   #13
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Warning -- long winded post. :-)

Here is an article that explains some of the advantages of shooting in raw. It's not as technical as some (for example, going into the differences between demosaic algorithms used by different converters and more).

But, it explains some of the basics:

http://www.ronbigelow.com/articles/raw/raw.htm

The type of subjects you shoot will also impact how much benefit you get from using raw, and the raw converter you use will have a big impact on the results. Some are much better than others (demosaic algorithms, highlight recovery, and more). Adobe Camera Raw is actually a pretty good converter as those things go. So, your could use the latest Camera Raw plugin with Photoshop CS3 if desired with most popular dSLR models.

The way your specific camera model processes the images can also have a big impact on any benefits you get from raw. Some cameras use a relatively "contrasty" tone curve so that images have more "punch", especially in the entry level category. Each manufacturer tends to take a slightly different approach to image processing.

I tend to shoot a lot of high dynamic range scenes (for example, on the river banks in the morning) where despite my best efforts at proper exposure, I may clip both the highlights and shadow areas in the same image. IOW, I've got both underexposed and overexposed areas in the image that are unrecoverable shooting jpeg, even if I reduce my contrast settings in camera (which does help to some extent).

Are these areas important? It depends on the subject. ;-) You may not care if the shadow areas are too dark to retain any detail, and you may not care if some of the brighter areas in the image are too bright to retain any detail. But, then again, you may want to have some of this detail retained.

That's where a good raw converter can come in (and not all raw converters are created equal).

With a converter like Adobe Camera Raw, you may be able to get dramatically more dynamic range in the same shot, without resorting to techniques like using exposure blending to get it. This will vary by camera model (because of tone curve differences between manufacturers) and will vary by the camera settings used.

With some of the KM and Sony dSLR models, the difference in dynamic range can be rather significant, depending on the image and the raw converter being used.

Take a look at some of Dave Etchell's Imatest results for an example of that. See the Dynamic Range section in his Sony DSLR-A100 review and note his comments on how exposure impacted the image (try to get more of the midtones properly exposed, lose the highlights, try to keep the highlights, lose the shadows).

http://www.imaging-resource.com/PROD...100IMATEST.HTM

This is because of the type of curve the camera is applying to the data from the sensor. Shooting raw allows you to bypass the way the camera processes the images to increase dynamic range. Dave noted that using Adobe Camera Raw provided a "dramatic increase in dynamic range".

Interestingly, this camera model even outperforms the full frame (35mm size sensor) Canon EOS-1Ds Mark II for dynamic range when shooting in raw and converting with Adobe Camera Raw, even though the camera's jpeg processing results in far lower dynamic range.

The same thing applies to my Konica Minolta Maxxum 5D (very good dynamic range with some raw converters, compared to the camera produced jpeg images). But, you may see very little benefit with other raw converters. They are not all created equal.

On the other hand, if you compare the dynamic range from both camera produced jpeg images and raw images converted by Adobe Camera Raw from the Canon EOS-1Ds Mark II, there is very little benefit to shooting raw from a dynamic range perspecitive.

The camera's processing for that particular model is designed to give better dynamic range, straight from the camera (the tone curve applied is not as contrasty as the curve used to process jpeg images from many other models).

Now, some camera models (for example, Nikon dSLR models) even allow you to load a custom tone curve in camera, versus being limited to the standard contrast settings available. There are companies that even specialize in custom curves for Nikon models and some even provide tools so that you can create your own curves. That way, you can use a tone curve that better matches the conditions you're shooting in up front for the way a camera processes the jpeg images.

If you scroll down to the bride in the wedding dress on this page, you'll see an example of a "White Wedding Curve" developed for Nikon dSLR models (use your mouse to see the difference in highlight detail retained by using it). Shooting raw, you could apply a similar curve to your images if shooting that type of subject, or choose a more or less contrasty curve as desired:

http://ufraw.sourceforge.net/Guide.html

Once you have a curve you like with most raw converters, it's easy to "batch process" your raw files with most. That way, you're not really taking any time to "tweak" images on a case by case basis, while improving the results compared to the camera produced jpeg images. Again, the type of subjects you're shooting, the camera model, and raw converter used can have a big impact on the final images. IOW, it all depends. ;-)

Another area that you can see a big benefit by shooting raw (again, depending on camera model) is detail retained as ISO speeds are increased, as well as less artifacting from in camera noise reduction. Some cameras tend to leave "blotchy" watercolor type artifccts in images from smoothing of noise. This is particularly true of some of the non-DSLR models now, where manufacturers tend to smooth away much of the detail as ISO speeds are increased by using noise reduction in the image processing pipeline. Some camera models have more sophisticated noise reduction algorithms compared to others.

Shooting raw allows you to bypass that processing and use more sophisticated tools to get a better balance between retained detail and noise levels later (and the decisions you make on that can depend on the purpose of the images and the print/viewing sizes needed).

Now, since in camera processors are becoming faster and more sophisticated, we're starting to see models that allow even more control of how noise reduction is handled.

Not long ago, the only noise reduction options available in most cameras had to do with long exposure (dark frame subtraction) type noise reduction. IOW, the user couldn't disable the smoothing of detail that many cameras implement in the processing at higher ISO speeds without shooting raw. Hopefully, we'll continue to see more models that give more noise reduction options to users as time passes.

The sophisitication of the demosiaic algorithms being used (by both the camera manufacturers' image processing in camera and in raw conversion software) can also impact the results you get and these algorithms are continuing to improve. I've been particularly impressed with the new AHD based algorithms for a while now, depending on subject type.

Scroll down on this page and you can see links to some comparisions between different raw converters and how they handle different types of detail:

http://www.rawtherapee.com/?page=compare

The raw file produced by a given camera model is somewhat unique, and a complicated process is needed to convert the image into a viewable format (and diffferent raw converters will have different approaches to giving you the best image possible, with some of them using better algorithms compared to others for this conversion).

A camera's image processing when shooting jpeg is making decisions that may not always be what you want.

Manufacturers have to decide on what kind of tone/contrast curves to use to make an image that looks good to most viewers, and sometimes they use processing that can be a bit too contrasty (causing loss of detail in shadows and highlights), in order to give cameras owners a more "punchy" image straight from the camera.

Ditto for things like sharpening, which is mostly increasing the contrast at color/brightness transitions in an image using edge detection techniques (which can destroy detail if overdone). The same thing is true for how the camera compensates for the temperature of the lighting you're shooting in (your White Balance settings handle that). You can easily modify things like White Balance later if you shoot in raw.

The camera's jpeg processing is also limited by the speed of the cpu/hardware for image processing built into the camera, as to the sophistication of the algorithms used, since they are trying to process images in a split second between shots. I am seeing a trend now towards more sophisiticated image processing in camera though.

Keep in mind that the individual photosites in a sensor are only sensitive to one color each, and with most Bayer Pattern CCD designs, you have twice as many sensitive to green.

The raw conversion algorithms take the values from the red, green, and blue photosites and combine them via sophisticated interpolation techniques so that all 3 colors are stored at each pixel in order to give you a usable/viewable image.

The raw file has not combined the photosites in any way.

That's what the raw conversion process does (or in camera processing if you shoot in jpeg). There are a number of different algorithms used, and some are better than others. You can see some of the common ones discussed here (requires Adobe Acrobat Reader):

http://www.ece.gatech.edu/research/labs/MCCL/pubs/dwnlds/bahadir05.pdf

Here is another document discussing raw conversion techniques:

http://www.dalibor.cz/files/Ting%20C...erpolation.pdf

When you convert the data from the sensor using a raw converter, you've gone through this demosaic process of combining the values from the red, green and blue sensitive photosites so that red, green and blue are stored at each pixel location. Ditto for shooting in jpeg (the camera is performing the raw conversion if you shoot jpeg) and you can also convert a raw image to jpeg using most raw converters.

Most raw converters are doing some additional processing, too (sharpening, contrast curves, etc.). Ditto for in camera processing (which is doing the raw conversion for you).

Shooting raw allows you to bypass the in camera processing, using more sophisticated techniques later if desired. If you shoot jpeg, you can't "undo" the demosaic process.

Personally, I shoot raw + jpeg almost all the time.

Most of the time, I'm just fine with the jpeg images for the print/viewing sizes I need. But, for some shots (especially high dynamic range scenes), it's not uncommon for me to run the same image through several diffrerent raw converters if it's an image I may want to print at a larger size, to try and pull the most dynamic range and detail possible from the image before deciding which conversion algorithm works best for the image as a starting point.

RAW also allows you to more easily correct mistakes. You may not always have the luxury of taking test shots and tweaking in camera settings for best results, especially in rapidly changing lighting.

On the downside, I'm going to need larger hard drives and memory cards soon. My latest "playtoy" (a Sony DSLR-A700) produces some pretty large files. lol

To be frank, I'm not as impressed with the in camera processing of jpeg files from this camera as I was with my KM 5D, even though the Dynamic Range seems to have improved a little bit. I'm really not that thrilled with the way it's handling noise suppression at it's highest ISO speeds, either.

From what I've seen, I can do far better shooting raw, with *this* particular camera model. So, I will probably start using the raw files far more often with it compared to previous cameras I've owned, despite the storage requirements.

Right now, the jury is still out (I haven't used the camera that much yet, and I haven't had a chance to try a wider variety of camera settings). But, first impressions tell me that I'll probably be using the raw files a lot more from this model. On the other hand, at typical viewing/print sizes for many shots, I may not care that I can get better results by shooting raw (because the differences would be too hard to notice at smaller viewing/print sizes).

Yet, I've got a smaller Konica KD-510z that seems to have super in camera processing. I've spent *days* working with it's raw images, trying to improve on the camera produced jpeg shots, and it's tough to improve on this camera's jpeg images, even with very high dyanamic range scenes. It's going to vary by camera model, settings, conditions and subject type how much (if any) benefit you get from shooting raw.

Whether you shoot raw or jpeg is not a "black and white" issue. There are many variables involved, including the camera model, subject type/conditions you're shooting in, raw converter used, purpose for the images and more.

Whatever camera you choose, I'd suggest trying it both ways, using more than one raw converter with different types of subjects.

That way, that you can get a feel for any benefits that you may find in the conditions you plan on using a camera in, and decide if the additional processing time and storage requirements are worth it or not (to you, as each shooter may look at it differently and have different requirements for the images).

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Old Oct 22, 2007, 12:09 PM   #14
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(jaw falls off) wow!...i read a lot from the top article...and it says that the camera sharpens the image..so if i shoot in raw...there should but no sharpening..so i could def. do that in photoshop!

also i like how little details end up slightly better, but for normal shots of landscape views and etc. i will probably shoot jpeg, especially with extended shutter times since the camera has a noise filter that will reduce the overall noise which would be there in a raw file
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Old Oct 22, 2007, 12:18 PM   #15
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Keep in mind that you can reduce setttings for things like contrast, sharpening and more in camera with most models to give you more latitude for processing later, too.

But, the amount of flexibility you have in changing how the final image looks will vary by camera model (for example, one model may significantly change contrast with each step in one direction or the other, and another model may make more subtle changes to the final image).

So, you really have to take any benefits of doing it one way or another on a case by case basis. All cameras are not the same.

Also, from some shooter's perspective, it can be just as hard or harder from a workflow perspective to process the jpeg images using that kind of technique, versus just shooting raw to begin with and batch processing the images using custom settings. ;-)

It's not a black and white issue.


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Old Oct 22, 2007, 12:35 PM   #16
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very true..so i guess ill just have to wait until i have it, then experiment for about a month and see what i like, which i am guessing i will use a little bit of both worlds (jpeg and raw) just for the heck of it

thank you for answering all of my questions!
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Old Oct 22, 2007, 2:42 PM   #17
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Correction. This was wrong:

Quote:
On the other hand, if you compare the dynamic range from both camera produced jpeg images and raw images converted by Adobe Camera Raw from the Canon EOS-1Ds Mark II, there is very little benefit to shooting raw from a dynamic range perspecitive.
I was looking at the the EOS-5D in the table of dynamic range tests. The newer EOS-5D doesn't have much difference in dynamic range between jpeg and raw (at least with Adobe Camera Raw).

You'd still get a big improvement in dynamic range shooting raw with the EOS-1Ds Mark II according to Dave Etchells' tests. That kind of thing is going to vary a lot between cameras, settings and and more though. See the Dynamic Range test table in this Sony DSLR-A100 review:

http://www.imaging-resource.com/PROD...100IMATEST.HTM

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Old Oct 22, 2007, 7:53 PM   #18
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i seem to have another question lol

when buying a lens by say canon or anyone else (most likely canon)...do i always have to multiply by 1.6x on the focal length?

like a 50mm 1:1.8 canon lens would be 80mm on the xt?
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Old Oct 22, 2007, 8:15 PM   #19
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Yes, if you want to determine what focal length lens you'd need to use on a 35mm camera to get the same angle of view you'd have with a Canon entry level dSLR model, use 1.6x.

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Old Oct 22, 2007, 8:24 PM   #20
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thanks

but one question...say i buy the rebel xt...and the kit lens is a 28-90mm

and right now i have the 35mm film camera rebel t2 with the 28-90mm lens...shouldnt they both be 44.8-144 on the dslr...or is the one with the kit made for the smaller sensor?
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