 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
| PhotoKB HomeDiscussion Groups Digital Photography Digital PhotoDSLR CamerasZLR CamerasPoint & Shoot CamerasFilm Photography 35 mmLarge FormatMedium formatDarkroomFilm and LabsOther EquipmentPhoto Technique Nature PhotographyPeople PhotographyTechnique GeneralGeneral Photo Topics General TopicsAustralian PhotographyUK PhotographyDirectoryPhoto Clubs |
Photo Forum / General Photo Topics / General Topics / August 2008Blown highlights @ 50 ISO
I am using a Canon 1ds and noticed that in some pictures that were taken yesterday in overcast conditions that the highlights were blown even though the histogram was fine, this only occurred at 50 ISO (L), when set to 100 it was fine. Strange and unsettling, maybe a software glitch because I very rarely use 50 ISO so I haven't noticed it before. >I am using a Canon 1ds and noticed that in some pictures that were taken > yesterday in overcast conditions that the highlights were blown even > though > the histogram was fine, If the histogram is fine then they are not blown. I suspect its not "fine" though. Overcast is difficult because the sky is massively brighter than the thing you arte trying to photograph. So the camera has a bit of programming that says "ignore the bright sky" so that you get a better exposed image of your true subject. Otherwise it would (in a pro camera) not overexpose the sky at all, but the subject would be very dark. Point and shoots and entry level DSLSs do this. this only occurred at 50 ISO (L), when set to 100 it > was fine. Almost impossible for that to be the case. Strange and unsettling, maybe a software glitch because I very > rarely use 50 ISO so I haven't noticed it before. It could be. >> I am using a Canon 1ds and noticed that in some pictures that were taken >> yesterday in overcast conditions that the highlights were blown even [quoted text clipped - 18 lines] > > It could be. The camera was in manual mode and there was no sky in the picture, but there was a white dress (which was blown), the other tones appear to be slightly harsh. Interestingly I used the camera today (ISO 100) and it was perfect. Maybe that 'L' mode is some kind of a trick by Canon, I know I had to enable it because it is not in the normal operating mode. : >> I am using a Canon 1ds and noticed that in some pictures that were taken : >> yesterday in overcast conditions that the highlights were blown even [quoted text clipped - 24 lines] : Maybe that 'L' mode is some kind of a trick by Canon, I know I had to enable : it because it is not in the normal operating mode. Is the histogram computed before or after the shutter is fired? A Canon DSLR with flash turned on will not allow you to use a shutter speed too slow for the flash, i.e. one that requires the second curtain to start closing before the first curtain has finished opening. In such a case the shutter speed is automatically reduced, and overexposure can occur. If the histogram is computed before the shutter is fired, it might not take account of that phenomenon (which would, I guess, be a software glitch). Note that if this is what happened to you, the issue is the shutter speed, not the ISO setting. Did you actually run tests using the two ISO settings with a constant shutter speed, or did you merely observe that your ISO 100 pictures were OK while the ISO 50 pictures weren't? Bob <snip> > : The camera was in manual mode and there was no sky in the picture, but there > : was a white dress (which was blown), the other tones appear to be slightly [quoted text clipped - 9 lines] > computed before the shutter is fired, it might not take account of that > phenomenon (which would, I guess, be a software glitch). I don't follow the whole thread closely, but I can tell you that the flashing above saying "flash turned on will not allow you to use a shutter speed too slow for the flash" may not be true. Cuz - I am not an experted on using flash with slow shutter speed to have much experience to share. I tried on very fast moving subject, and only testing - But if you want to learn about Slow Shutter Speed with Flash On style then you may be able to find on Google. Cuz I have seen several times in the past some people using the slow shutter speed with flash on technique in night club and they turn out pretty unique. About 2nd curtain, unless it's part of the auto-process requires no extra setting then you may be right because my DSLRs have option to set the 2nd curtain (which I never tried myself), but if you mean the 2nd curtain option has to be setup manually then I guess it may not be true. I know I didn't set the 2nd curtian, and the ones who use slow shutter speed (you are looking at 2-3s or even slower not just slower than 60's standard for flash) with flash didn't mention anything about 2nd curtain, but flash on with shutter speed set VERY VERY SLOW. And I didn't see the original but whatever they posted on their webs and no overexposured but very sharp, well balance, and unique. > Note that if this is what happened to you, the issue is the shutter speed, not > the ISO setting. Did you actually run tests using the two ISO settings with a > constant shutter speed, or did you merely observe that your ISO 100 pictures > were OK while the ISO 50 pictures weren't? > > Bob And in the general, I agree with you that the ISO may not have much or anything to do with the overexposured the OP has. > <snip> >> : The camera was in manual mode and there was no sky in the picture, but [quoted text clipped - 47 lines] > And in the general, I agree with you that the ISO may not have much or > anything to do with the overexposured the OP has. Flash was off > > <snip> > >> : The camera was in manual mode and there was no sky in the picture, but [quoted text clipped - 49 lines] > > Flash was off OK, *if* the flash was off, then there could be many different things as well as the behavior of the camera. - A wrong combination of ISO + Shutter Spped + Aperature + Mode's + Flash Off. IOW, just a single wrong combination would cause the problem - In same case(s) (and some difference between DSLR vs P&S vs Film) flash on doesn't always mean brighter image (sharper yes *but* not always brighter) IOW, if you want to go for more detail then the FLASH is a little more complicate than just ON or OFF, but also indoor/outdoor, internal/external/strobe, and the combination of which mode's used. As well as I have mentioned the flash also work differently between P&S and DSLR > OK, *if* the flash was off, then there could be many different things as > well as the behavior of the camera. [quoted text clipped - 9 lines] > internal/external/strobe, and the combination of which mode's used. As well > as I have mentioned the flash also work differently between P&S and DSLR Just to clarify, I am a professional photographer and have been for many years. The reason I brought it up is because it was unusual and unexpected and, inexplicably, has not recurred under the same circumstances the very next day. I have posted the EXIF data and the flash *was* off. > > OK, *if* the flash was off, then there could be many different things as > > well as the behavior of the camera. [quoted text clipped - 14 lines] > and, inexplicably, has not recurred under the same circumstances the very > next day. I have posted the EXIF data and the flash *was* off. Besides those I mentioned above, with digital cemera sometime pressing the shutter button 1/2 down (for auto-focus and adjustment) at one spot, then move to different spot which is either brighter or lighter than where you 1/2 pressed can give a different result. Some people use this type of trick to shoot the bright sunny sky. And that's some of the thing we may need to pay closer attention to gain some personal experience, and this is one of the reasons why I don't quote from any book for any one_person's opinion which could be right in general or at some point but wrong at other situation. : <snip> : > : The camera was in manual mode and there was no sky in the picture, but there [quoted text clipped - 44 lines] : And in the general, I agree with you that the ISO may not have much or : anything to do with the overexposured the OP has. Sorry, it's been a busy week with several late nights. I meant, of course, too *fast* for the flash. Bob > : <snip> > : > : The camera was in manual mode and there was no sky in the picture, but there [quoted text clipped - 49 lines] > > Bob For built-in flash and regular flash connects to camera 1/250's is the fastest for the camera can go, and some may require a special setting for the 1/250's. And in order to overcome the 1/250's difficulty then strobe may be needed because flash can only fore once when strobe can deliver the continuously flashes (how many time I never care to know, but I know more than once). And usually 1/100's to 1/125's should be plenty fast for nite shot, or 1/60's is pretty good for normal movement, and 1/125's should be fast enough for faster movement. Of cource I am talking about walking speed *not* sport, and it isn't that the flash isn't fast enough (it's hard to beat the speed of light) but the fast movement may cause some blurry (out of focus). > Is the histogram computed before or after the shutter is fired? A Canon DSLR Histograms are generated from the image, not the exposure system. > with flash turned on will not allow you to use a shutter speed too slow for too fast, you mean. Unrelated/Pedantic note: In so-called "HighSpeed" flash, the flash will start strobing just *before* even the first curtain has begun opening and stop strobing just after the rear curtain has closed and the shutter speed may be the fastest available on the camera (eg: I can shoot 1/12,000 flash on my Maxxum 9 ... though the effective GN goes from 56 meters to 3) > the flash, i.e. one that requires the second curtain to start closing before > the first curtain has finished opening. In such a case the shutter speed is > automatically reduced, and overexposure can occur. If the histogram is Ambient overexposure may occur, but flash overexposure would be due to a scene that is darker that 12% grey in turn driving the flash exposure over. That's what the flash EXP comp is for...  Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. -- usenet posts from gmail.com and googlemail.com are filtered out. I agree overexposure due to flash throttling down the shutter speed sounds like the most likely explanation. >> Is the histogram computed before or after the shutter is fired? A >> Canon DSLR [quoted text clipped - 23 lines] > > That's what the flash EXP comp is for... SignaturePaul Furman www.edgehill.net www.baynatives.com all google groups messages filtered due to spam > I agree overexposure due to flash throttling down the shutter speed > sounds like the most likely explanation Flash was off. >> I agree overexposure due to flash throttling down the shutter speed >> sounds like the most likely explanation > > Flash was off. Who says it WAS over exposed??? If the histogram says not then its really not. Because the histogram is taken from the file saved. For the histogram to say it is (a line up the right side on any of the three colour channels) there has to be max saturation in one chanel or another. Where is this photo? If you are deciding its over exposed just because theres no detail then maybe there really was no detail. Or maybe there is but your monitor isnt good enough to display it. >>> I agree overexposure due to flash throttling down the shutter speed >>> sounds like the most likely explanation [quoted text clipped - 9 lines] > maybe there really was no detail. Or maybe there is but your monitor isnt > good enough to display it. See previous posts for explanation (DP Review) > I am using a Canon 1ds and noticed that in some pictures that were taken > yesterday in overcast conditions that the highlights were blown even though > the histogram was fine, this only occurred at 50 ISO (L), when set to 100 it > was fine. Strange and unsettling, maybe a software glitch because I very > rarely use 50 ISO so I haven't noticed it before. ISO 100 is base ISO, that's a pushed setting. SignaturePaul Furman www.edgehill.net www.baynatives.com all google groups messages filtered due to spam >> I am using a Canon 1ds and noticed that in some pictures that were taken >> yesterday in overcast conditions that the highlights were blown even [quoted text clipped - 5 lines] > > ISO 100 is base ISO, that's a pushed setting. Seriously, I'm pretty sure this is the cause. http://www.google.com/search?hl=en&q=canon+1ds+iso+50&btnG=Google+Search www.dpreview.com/reviews/canoneos1ds/ "ISO 100 - 1250 in 1/3 stop steps, ISO 50 available from a custom function" ISO 50 is pushed from the true ISO 100 and that has to be paid for somehow. I'm surprised the histogram isn't based on the final jpeg. The solution is simple: if you need ISO 50, crank down exposure compensation a bit or check the histogram & make sure it's not too close to the right edge. >>> I am using a Canon 1ds and noticed that in some pictures that were taken >>> yesterday in overcast conditions that the highlights were blown even [quoted text clipped - 17 lines] > a bit or check the histogram & make sure it's not too close to the right > edge. Thank you for that, that is the answer I was looking for. I was not aware the there is almost a stop difference between equivalent exposures (ISO 50 and 100), I didn't read that in the manual, bad dog. Now I have been furnished with this info I will take this phenomenon into account, funny that the histogram doesn't indicate anything amiss though. Cheers. >>>> I am using a Canon 1ds and noticed that in some pictures that were taken >>>> yesterday in overcast conditions that the highlights were blown even [quoted text clipped - 13 lines] > Thank you ...I will take this phenomenon into account, funny > that the histogram doesn't indicate anything amiss though. Cheers. That is odd. Are you shooting raw format? Still I wouldn't expect that. SignaturePaul Furman www.edgehill.net www.baynatives.com all google groups messages filtered due to spam > >>>> I am using a Canon 1ds and noticed that in some pictures that were taken > >>>> yesterday in overcast conditions that the highlights were blown even [quoted text clipped - 22 lines] > > - Show quoted text - >>>>> I am using a Canon 1ds and noticed that in some pictures that were taken >>>>> yesterday in overcast conditions that the highlights were blown even [quoted text clipped - 15 lines] > > That is odd. Are you shooting raw format? Still I wouldn't expect that. Yes, RAW and jpeg. > >>>>> I am using a Canon 1ds and noticed that in some pictures that were taken > >>>>> yesterday in overcast conditions that the highlights were blown even [quoted text clipped - 17 lines] > > Yes, RAW and jpeg. In general RAW or JPEG won't give much or any difference except that RAW gives more option for recovery. >>>>>> I am using a Canon 1ds and noticed that in some pictures that were taken >>>>>> yesterday in overcast conditions that the highlights were blown even [quoted text clipped - 10 lines] > > Yes, RAW and jpeg. Well that still doesn't make sense. I'm pretty certain the in-camera histogram is based on the jpeg, even shooting raw-only, the camera makes a jpeg embedded in the raw file for displaying on the LCD. SignaturePaul Furman www.edgehill.net www.baynatives.com all google groups messages filtered due to spam >>>>>>> I am using a Canon 1ds and noticed that in some pictures that were taken >>>>>>> yesterday in overcast conditions that the highlights were blown even [quoted text clipped - 14 lines] > histogram is based on the jpeg, even shooting raw-only, the camera makes > a jpeg embedded in the raw file for displaying on the LCD. Tell me about it. > I am using a Canon 1ds and noticed that in some pictures that were taken > yesterday in overcast conditions that the highlights were blown even though > the histogram was fine, this only occurred at 50 ISO (L), when set to 100 it > was fine. Strange and unsettling, maybe a software glitch because I very > rarely use 50 ISO so I haven't noticed it before. The in-camera histogram is a guide. Most cameras will show "blink over" for areas of the image that are blown out in white in the display (and blink over for areas that are dead black as well). ISO 50 might (depends on the sensor) be desensitized in s/w, not hardware which could contribute to the problem. Many camera sensors seem to have a natural base ISO somewhere in the 100 - 200 range. In appropriate moderation blown highlights are not image killers and can even enhance a photo. Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. -- usenet posts from gmail.com and googlemail.com are filtered out. > The in-camera histogram is a guide. Most cameras will show "blink over" > for areas of the image that are blown out in white in the display (and [quoted text clipped - 6 lines] > In appropriate moderation blown highlights are not image killers and can > even enhance a photo. Yeah I had the overexposure blink on, it wasn't over exposed in the preview and the exposure was normal. I am thinking it is a software fault. The images are still usable but not up to my standards, they look like they were captured on a video camera. >> The in-camera histogram is a guide. Most cameras will show "blink over" >> for areas of the image that are blown out in white in the display (and [quoted text clipped - 11 lines] > images are still usable but not up to my standards, they look like they were > captured on a video camera. Hope to see your shots in the SI ... Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. -- usenet posts from gmail.com and googlemail.com are filtered out. : I am using a Canon 1ds and noticed that in some pictures that were taken : yesterday in overcast conditions that the highlights were blown even though : the histogram was fine, this only occurred at 50 ISO (L), when set to 100 it : was fine. Strange and unsettling, maybe a software glitch because I very : rarely use 50 ISO so I haven't noticed it before. Were you using flash? What kind of metering (evaluative, centerweighted, spot, ...) were you using? Bob > : I am using a Canon 1ds and noticed that in some pictures that were taken > : yesterday in overcast conditions that the highlights were blown even though [quoted text clipped - 7 lines] > > Bob Here are the details; File Name AA3V2068.TIF Camera Model Name Canon EOS-1DS Shooting Date/Time 08/23/08 14:08:05 Shooting Mode Manual Tv(Shutter Speed) 1/160 Av(Aperture Value) 5.0 Metering Mode Evaluative ISO Speed 50 Lens 24.0 - 70.0mm Focal Length 24.0mm Image Size 4064x2704 Image Quality RAW Flash Off White Balance Auto AF Mode One-Shot AF Parameters Tone Curve Standard Sharpness level 5 Pattern sharpness Standard Color Matrix 2 Noise Reduction On File Size 11572KB Custom Function 00:Focusing Screen 1:[L] Ec-A,B,C,CII,CIII,D,H,I,L 01:Finder display during exposure 1:Finder display on 02:Shutter release without CF card 1:Not possible 03:ISO speed expansion 1:Expanded sensitivity 04:Shutter button/AE lock button 0:AF/AE lock 05:Manual Tv/Av set. for M exp. 0:Tv value: Main dial, Av value: Quick Control dial 06:Exposure level increments 0:1/3-stop set, 1/3-stop comp. 07:USM lens electronic MF 1:Turns off after One-Shot AF 08:Top LCD panel/Back LCD panel 0:Remain. shots/File No. 09:Auto bracketing sequence/cancel 1:0,-,+/No cancellation 10:AF point illumination 0:On 11:AF point selection method 0:AF point selection button + Main (horizontal) / Quick Control (vertical) dial operation 12:Mirror lockup 0:Disable 13:Number AF points/Spot metering 0:45/Center AF point 14:Auto reduction of fill flash 1:Disable 15:Shutter curtain synchronization 0:1st-curtain synchronization 16:Safety shift in Av or Tv 1:Enable 17:AF point activation area 1:Expand(TTL. of 7 AF points) 18:Switch to registered AF point 0:Assist button + AF point selection button 19:Lens AF stop button function 0:AF stop 20:AI SERVO tracking sensitivity 0:Standard Drive Mode Single-frame shooting |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.