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Photo Forum / General Photo Topics / General Topics / November 2006What is RAW?
Please give me the short explanation of RAW. And why I should use it rather than other ways. Just want to learn. Steve > Please give me the short explanation of RAW. And why I should use it rather > than other ways. > > Just want to learn. > > Steve The most generic answer would be that RAW is the sensor data saved into a file straight after it has gone through A/D conversion, without conversion to a compressed bitmap file type (as in jpeg). Generaly the RAW files from a camera have a greater bit-depth than a jpeg file, so can store greater dynamic (dark to light) range than a compressed bitmap. A RAW file is like a film negative, not directly usable in most applications and must be converted to a bitmap file type of some sort (such as tiff or jpeg) before they can be edited or printed. >> Please give me the short explanation of RAW. And why I should use it >> rather than other ways. [quoted text clipped - 12 lines] > applications and must be converted to a bitmap file type of some sort > (such as tiff or jpeg) before they can be edited or printed. Thank you. I am wanting to buy a larger camera than my 5.1 mp Sony. I keep hearing about RAW, and how much better it is. Is it that much better? I also learned that the file sizes are 2 to 6 times larger, which is no problem because I anticipate getting a much larger computer to just do photos on anyway. With the investment in a larger camera and computer, I just want to make educated choices. Thanks Steve >>> Please give me the short explanation of RAW. And why I should use it >>> rather than other ways. [quoted text clipped - 25 lines] > > Steve Depends on your particular needs as well, if you only ever print at 6x4 size then you may not need the extra step in your workflow, if you want to print posters then it most certainly will be a good idea to use RAW. >Thank you. I am wanting to buy a larger camera than my 5.1 mp Sony. I keep >hearing about RAW, and how much better it is. Is it that much better? I [quoted text clipped - 8 lines] > >Steve Steve, Good answers - all. However, "larger" computer does not get it. Make sure you get a "faster" computer with as much memory as you can afford. At least 1gb, but go for 2 if you can. My Nikon D200 produces a 15mb RAW image. My old/slower computer takes up to one minute 30 seconds to open a RAW shot in Photoshop. I long for a faster computer - some day. Brian  Signature---------------------------------------------------------------- Brian J. Rueger "Who dares wins" Capt.(Ret)/Paramedic Hampton, VA. B.S.Comm/I/Pilot MSgt, USAF (Ret.) 49199 Check out my personal home page: http://members.cox.net/brueger Check out my photography: http://www.usefilm.com/member/skypilot "Life's too short to drink LITE beer!" ---------------------------------------------------------------- > Good answers - all. However, "larger" computer does not get it. Make > sure you get a "faster" computer with as much memory as you can > afford. At least 1gb, but go for 2 if you can. My Nikon D200 > produces a 15mb RAW image. Two comments: 1) Then, you meant also "a computer with lots of hard disk space"... (of course, with today standards for new PCs, almost the lowest- capacity hard disk is plenty to store 10 years worht of RAW images). 2) Have you upgraded the Firmware?? RAW images *do have* some form of compression (*lossless* compression, unlike e.g. JPEG), and newer versions of the firmware do a better job at compressing RAWs (at least it did for my D70 when I upgraded teh firmware to 2.0 --- it almost *doubled* the capacity of my flash card, when measured in number of pictures you can store in RAW mode). 15MB sounds excessive (is the D200 10MP? 8MP?), unless we're talking about a photograph with an extremely high amount of details and very very sharp lines. I don't recall ever seeing a RAW image of more than 5MB taken with my D70 --- and that is *before* I upgraded the firmware. Carlos -- > 15MB sounds excessive (is the D200 10MP? 8MP?), unless we're talking > about a photograph with an extremely high amount of details and very > very sharp lines. I shoot jpeg fine plus RAW on a 10MP D200, from almost 200 shots yesterday the jpegs are 1.8 - 4.8 MB and RAW are 7 - 12.3 MB and that is compressed RAW, I'm not sure how much bigger the uncompressed RAW is. SignaturePaul Furman http://www.edgehill.net/1 Bay Natives http://www.baynatives.com I would say only use RAW mode if you have a difficult shot to take (tricky exposure etc). Or if its a once in a lifetime shot that you may want to print out very large. Personally I can't justify using RAW mode as standard as I take a lot of photos (55,432 photos since 2001) so if was using raw all the time then I would be having problems storing them on hard disk. Another thing to remember is it takes longer to store a raw photo onto the cameras card. So make sure you buy a good fast card and that your camera supports it. If you are doing lots of photos quickly then you don't want to have to keep waiting ages between shots while our camera is writing to the card. And shop around, ebay is a good place, I got a new SANDISK 2G ULTRA II COMPACT FLASH MEMORY CARD for £30. Another thing is browsing the photos on your computer. jpgs can be browsed as thumbnails is just about any package but raw files need to be viewed in a pakage that supports that cameras raw format such as Photoshop CS2. So don't expect to be able to look at your raw thumbnails using Paint Shop Pro 7. Another thing is backing the photos up. My camera creates 19Mb raw files these would soon eat up DVD-R discs if I were backing them up all the time. There is a detailed description on wiki... http://en.wikipedia.org/wiki/RAW_image_format Andy > Thank you. I am wanting to buy a larger camera than my 5.1 mp Sony. I > keep hearing about RAW, and how much better it is. Is it that much [quoted text clipped - 8 lines] > > Steve Save speed depends upon the camera. What you day is true, but with my D200, when I trip the shutter, the RAW image is saved before I can pull the camera from my eyes. (Then, again, I may be just too relaxed and slow.) SignatureYou can take good photos with a bad camera, and horrible photos with a good camera. Stan Beck > From New Orleans to Brandon MS To reply, remove 101 from address. *** >I would say only use RAW mode if you have a difficult shot to take (tricky >exposure etc). Or if its a once in a lifetime shot that you may want to [quoted text clipped - 37 lines] >> >> Steve Digital cameras have a more limited dynamic range, and unless you shot a lot of slides, you might have trouble getting the optimal exposure, and may result with a lot of clipped highlights. RAW can give you a second chance at exposure, if you didn't get it right. Also, I made a mistake a couple of times by shooting a batch of photos outside, with my white balance set for incandescent. With RAW, I was able to change the white balance after, and saved the shots. If you are doing great with these things, shooting JPEG is just fine - faster and more images on your card. SignatureYou can take good photos with a bad camera, and horrible photos with a good camera. Stan Beck > From New Orleans to Brandon MS To reply, remove 101 from address. *** >>> Please give me the short explanation of RAW. And why I should use it >>> rather than other ways. [quoted text clipped - 25 lines] > > Steve >Digital cameras have a more limited dynamic range, and unless you shot a lot >of slides, you might have trouble getting the optimal exposure, and may >result with a lot of clipped highlights. Digital cameras have more dynamic range, not less. >RAW can give you a second chance at exposure, if you didn't get it right. >Also, I made a mistake a couple of times by shooting a batch of photos >outside, with my white balance set for incandescent. With RAW, I was able >to change the white balance after, and saved the shots. All of which is possible *because* of that extra dynamic range. >If you are doing great with these things, shooting JPEG is just fine - >faster and more images on your card. There are advantages each way. Which you should choose depends on the situation. SignatureFloyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska) floyd@apaflo.com >>Digital cameras have a more limited dynamic range, and unless you shot a >>lot [quoted text clipped - 9 lines] > > All of which is possible *because* of that extra dynamic range. No, it is because no adjustment is made to a RAW file until post processing, the white balance setting will only be made during conversion to jpeg. >>If you are doing great with these things, shooting JPEG is just fine - >>faster and more images on your card. With the newer D-SLRs shooting RAW will allow you to get plenty of shot, rarely limiting. > There are advantages each way. Which you should choose depends on > the situation. >>>Digital cameras have a more limited dynamic range, and unless you shot a >>>lot [quoted text clipped - 9 lines] >> >> All of which is possible *because* of that extra dynamic range. It is specifically because of the dynamic range available. That is true for any post processing that changes gamma or the relationship between different colors. >No, it is because no adjustment is made to a RAW file until post processing, >the white balance setting will only be made during conversion to jpeg. I use a Nikon D2x which has a sensor with a 4 channel analog output. White balance is done *before* the signal is even digitized, much less post processed or converted to JPEG! YMMV, depending of course on the camera you use. >>>If you are doing great with these things, shooting JPEG is just fine - >>>faster and more images on your card. > >With the newer D-SLRs shooting RAW will allow you to get plenty of shot, >rarely limiting. That seems to be a matter of opinion, and everyone has a different view of it. >> There are advantages each way. Which you should choose depends on >> the situation. I'll stick with that statement! SignatureFloyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska) floyd@apaflo.com "Digital cameras have more dynamic range, not less." Nope. SignatureYou can take good photos with a bad camera, and horrible photos with a good camera. Stan Beck > From New Orleans to Brandon MS To reply, remove 101 from address. *** >>Digital cameras have a more limited dynamic range, and unless you shot a >>lot [quoted text clipped - 15 lines] > There are advantages each way. Which you should choose depends on > the situation. From a practical point of view, the only dynamic range you have is what you can use. Today's digitals have a usable dynamic range similar to slides (less than that of negative film). It is a range of about maybe 4 stops, at best. There are lots of articles on this - here is one: http://www.pcphotomag.com/content/2006/may/double_process_raw.shtml Actually, I'm not in a mood to debate this. It is sufficient to say that exposure is critical. Cheers. SignatureYou can take good photos with a bad camera, and horrible photos with a good camera. Stan Beck > From New Orleans to Brandon MS To reply, remove 101 from address. *** > "Digital cameras have more dynamic range, not less." > [quoted text clipped - 20 lines] >> There are advantages each way. Which you should choose depends on >> the situation. >From a practical point of view, the only dynamic range you have is what you >can use. Today's digitals have a usable dynamic range similar to slides >(less than that of negative film). It is a range of about maybe 4 stops, at >best. Most top of the line DSLR's are pushing the envelope on 12 bit linear RAW files when it comes to dynamic range. Simply put, even if we only talk about something like "useful dynamic range" (which is entirely reasonable), it is fairly common to define the lower end of the digital range as a full fstop level that has at least 8 values. For cameras that use 12 bit linear RAW files, that is *9* fstops (maximum due to use of a 12 bit encoding). For JPEG files that is 8 fstops. Fstop | 12 bit | Levels 8 bit 8 Bit JPEG Range | Linear | Linear Gam.Cor. Gam.Cor. Gamma Corr | ------|--------|-----------------------+---------------------+ 1 | 2048 | 1.0 1.0 255 69 | 2 | 1024 | 0.5 0.72974 186 50 | 3 | 512 | 0.25 0.53252 136 37 | 4 | 256 | 0.125 0.38860 99 27 | 5 | 128 | 0.0625 0.28358 72 20 | 6 | 64 | 0.03125 0.20694 53 14 | 7 | 32 | 0.015625 0.15101 38 10 | 8 | 16 | 0.007812 0.11020 28 8 | 9 | 8 | 0.003906 0.08042 21 6 | 10 | 4 | 0.001953 0.05868 15 4 | 11 | 2 | 0.0009765 0.04282 11 3 | 12 | 1 | 0.0004883 0.03125 8 2 | >There are lots of articles on this - here is one: Yes, and they all agree that digital sensors have more dynamic range than film. >http://www.pcphotomag.com/content/2006/may/double_process_raw.shtml Your cited article says you are wrong. Did you read it? "The human eye can perceive a contrast ratio of 800:1; the best slide films, 30:1; and the best digital sensors, 40:1." That is the one and the only statement in the article relating to dynamic range, so I don't see how you missed it. >Actually, I'm not in a mood to debate this. It is sufficient to say that >exposure is critical. So is understanding what you are looking at... SignatureFloyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska) floyd@apaflo.com >>Digital cameras have a more limited dynamic range, and unless you shot a lot >>of slides, you might have trouble getting the optimal exposure, and may >>result with a lot of clipped highlights. > > Digital cameras have more dynamic range, not less. I'm no expert on the subject, but from what I've read in here, the absolute consensus seems to point in the opposite direction (i.e., you are mistaken on this one). The RAW format gets *the full* dynamic range from the sensor (which JPEG doesn't, for instance) --- but that full dynamic range is still below the dynamic range of film (not sure if all types of film or all qualities, or if it's just the super-pro-grade film the ones that do have higher D.R.) >>RAW can give you a second chance at exposure, if you didn't get it right. >>Also, I made a mistake a couple of times by shooting a batch of photos >>outside, with my white balance set for incandescent. With RAW, I was able >>to change the white balance after, and saved the shots. > > All of which is possible *because* of that extra dynamic range. Extra dynamic range of the RAW with respect to the JPEG --- not extra dynamic range with respect to film. >>If you are doing great with these things, shooting JPEG is just fine - >>faster and more images on your card. > > There are advantages each way. Which you should choose depends on > the situation. That, you got absolutely right! Carlos -- >>>Digital cameras have a more limited dynamic range, and unless you shot a lot >>>of slides, you might have trouble getting the optimal exposure, and may [quoted text clipped - 4 lines] >absolute consensus seems to point in the opposite direction (i.e., >you are mistaken on this one). It is not a matter of consensus or opinion. It is a measureable matter of *fact*. (I would disagree with you on what the consensus is anyway...) Roger N. Clark, who post here frequently, has a fantastic website filled with data about photography, you'll find this page most interesting. http://www.clarkvision.com/imagedetail/film.vs.digital.summary1.html Scroll down to the section titled "Dynamic Range and Signal-to-Noise" and look at Figure 2. The text says it all, "There seems to be an urban legend that says digital cameras have less dynamic range than film. The legend is wrong" The chart shows that slide film has about a 5 stop range, print film has about a 7 stop range, and the Canon 1D Mark II camera tested is beyond the 10 fstop range of the tests (it has just more than 11 fstops of dynamic range). There is further discussion at this page, http://www.clarkvision.com/imagedetail/dynamicrange2/ Which includes the same chart in Figure 8b except it is labeled directly in fstops, making it perhaps easier to understand. Note that these are repeatable tests that come up with the same results no matter who does them. >The RAW format gets *the full* dynamic range from the sensor (which >JPEG doesn't, for instance) --- but that full dynamic range is still >below the dynamic range of film (not sure if all types of film or >all qualities, or if it's just the super-pro-grade film the ones >that do have higher D.R.) The dynamic range of the Canon 1D Mark II is about 11 fstops. The Fujifilm S3 Pro is 12 fstops. The Pentax *istDs hits 10.1, various Nikon models range from 9.8 to 10.7. http://www.imaging-resource.com/PRODS/D200/D200IMATEST.HTM Can you cite even one film that has the same range? Moreover, even if we looked at dynamic range available for "high quality" images, all of those cameras match the 7 fstop range of film at a minimum there too! >>>RAW can give you a second chance at exposure, if you didn't get it right. >>>Also, I made a mistake a couple of times by shooting a batch of photos [quoted text clipped - 4 lines] >Extra dynamic range of the RAW with respect to the JPEG --- not >extra dynamic range with respect to film. Of course, but JPEG is limited to only 1 fstop more (useful) dynamic range than typical print film (8 fstops vs 7), so RAW necessarily has to have more than film. >>>If you are doing great with these things, shooting JPEG is just fine - >>>faster and more images on your card. [quoted text clipped - 4 lines] > >That, you got absolutely right! Right along with the rest of it too... ;-) SignatureFloyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska) floyd@apaflo.com > Digital cameras have a more limited dynamic range, and unless you shot a lot > of slides, you might have trouble getting the optimal exposure, and may > result with a lot of clipped highlights. If shooting in jpeg this is true. Otherwise, a RAW image has at least as much dynamic range as colour neg film. > RAW can give you a second chance at exposure, if you didn't get it right. > Also, I made a mistake a couple of times by shooting a batch of photos > outside, with my white balance set for incandescent. With RAW, I was able > to change the white balance after, and saved the shots. I shoot mainly in jpeg, and I've never had a problem adjusting the white balance of a photo with Corel Photopaint (assuming that there is something white or grey in the picture, otherwise it is to personal preference for the adjustment). Possibly it is your software which is the limiting factor? > If you are doing great with these things, shooting JPEG is just fine - > faster and more images on your card. Just make sure that you set the image quality to the highest setting and compression to the lowest setting, to maintain the maximum information in the photo. Also it is a good idea to to set contrast to it's lowest setting available on the camera, that way the jpeg conversion engine doesn't push the highlights into clipping as often. Sharpening to it's lowest setting available is also a good idea, to avoid "sharpening halos" around edges in the image. >>> Please give me the short explanation of RAW. And why I should use it >>> rather than other ways. [quoted text clipped - 24 lines] > > Steve Check out the beta version of Adobe's Lightroom. It is a program that is used to process raw images. It also integrates with Adobe Photoshop &/or Elements. http://labs.adobe.com They also have tutorials that will demonstrate how to use the product and what it can do for you. >Check out the beta version of Adobe's Lightroom. It is a program that >is used to process raw images. It also integrates with Adobe Photoshop [quoted text clipped - 4 lines] >They also have tutorials that will demonstrate how to use the product >and what it can do for you. If you end up with a Nikon, I'd highly recommend that you go with their Capture NX software. It is the only one out there that will automatically read the unique settings in their cameras, and it will give you the best possible quality from the Nikon RAW files. It will also do some neat tricks that even Photoshop can't do, like making nondestructive local adjustments to a RAW file without the need to first convert to a bitmap or create separate layers & selections. If you get something other than Nikon, check out CaptureOne LE from Phase One. It is a highly regarded program that many pros use, very nice interface and produces excellent quality output right out of the box that is harder to achieve with some other converters. You can even get that one for free in specially-marked packages of some SanDisk memory cards. Steve |
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