tag:blogger.com,1999:blog-9113726419970930271.post8650129583509980176..comments2023-05-27T02:33:34.320-07:00Comments on Nikon CLS Practical Guide: 2. Nikon TTL Flash Metering SystemRuss MacDonaldhttp://www.blogger.com/profile/15288785902650834143noreply@blogger.comBlogger177125tag:blogger.com,1999:blog-9113726419970930271.post-65696476784779759922016-10-11T22:06:37.592-07:002016-10-11T22:06:37.592-07:00Great post. Thank you. I've been digging throu...Great post. Thank you. I've been digging through the user manuals of SB910 and SB700 and no luck until a google search took me here. Problem: I was trying to do high speed sync with the camera in full manual mode. Although in manual mode I had chosen spot metering so it can give the right info to the flash (in TTL). Results were severely overexposed. Nikon doesnt allow TTL_BL when the camera is on spot metering. I eventually gave up and chose matrix + TTL BL to avoid overexposure. Anonymoushttps://www.blogger.com/profile/04751368628580322748noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-7714879792442315442013-12-10T09:04:20.227-08:002013-12-10T09:04:20.227-08:00Russ,
There is some misinformation on this page.
...Russ,<br /><br />There is some misinformation on this page.<br /><br />You say that the Camera metering sensor and the TTL flash metering sensor are the same, but they are not the same! They are located far apart.<br /><br />Look at the diagrams below. Self-explanatory<br /><br />http://www.mir.com.my/rb/photography/hardwares/classics/NikonF5/metering/<br />http://nikonasia-en.custhelp.com/app/answers/detail/a_id/4492<br /><br />Their capabilities are also different. The camera (ambient) metering sensor can detect color (RGB). The flash metering sensor is color-blind - only shades of gray.<br /><br /><br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-64814169195316666182013-01-16T12:22:43.751-08:002013-01-16T12:22:43.751-08:00I can´t stop reading this, these expanations are s...I can´t stop reading this, these expanations are so great !Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-33981713836472928442012-07-13T09:56:20.025-07:002012-07-13T09:56:20.025-07:00Russ,
Thank you so much for the great advice and ...Russ,<br /><br />Thank you so much for the great advice and explanations! I have been using your techniques with great success except for one problem. I consistently get underexposed (about 1 to 2 stops) pictures when using my SB-700 off camera in remote mode. It doesn't matter what the subject is or what color.<br /><br />Here is a typical shooting situation: Nikon D7000 and SB-700. Indoor with typical light, Manual F/4 and 1/80th to 1/125th, ISO 400, iTTL, AF-S, Spot Meter and Focus. I use the SB-700 on camera and the picture looks great. I take it off and use the D7000 flash as commander and SB-700 as remote. I hold the 700 right above the camera so the distance to subject stays the same. I focus on the same subject and the exact same spot and I get an underexposed image, every time. It doesn't matter what the subject is. If I use + 1.0 ev it looks about right.<br /><br />I would greatly appreciate any advice to correct this. Thank you, JamesAnonymoushttps://www.blogger.com/profile/08048810400750388488noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-42676559174271710222012-02-02T01:35:15.191-08:002012-02-02T01:35:15.191-08:00Hi Russ, everything clear now. Thank you.
Greeting...Hi Russ, everything clear now. Thank you.<br />Greetings, WolfgangAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-44995407804047773252012-02-01T13:17:16.563-08:002012-02-01T13:17:16.563-08:00Hi Wolfgang,
The ISO value is sent to the flash c...Hi Wolfgang,<br /><br />The ISO value is sent to the flash computer.<br /><br />Of course, the flash computer is located in the camera. You do realize that, right?<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-54841201896056808902012-02-01T13:04:25.190-08:002012-02-01T13:04:25.190-08:00Hi Russ, thanks for the speedy reply. I understand...Hi Russ, thanks for the speedy reply. I understand, but i am after some more technical explanation (hope it is not too detailed): When the aperture changes, the lense widens or closes, more or less light comes in and the metering sensor detects it and informs the flash computer. Same when amount of light changes due to bouncing on the ceiling or so. But when ISO changes what happens in the camera that makes the flash computer aware that he has to adjust? Amount of light that comes in and is measured is not influenced by ISO change or am i wrong? Regards, WolfgangAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-63407710994049321892012-02-01T08:36:21.611-08:002012-02-01T08:36:21.611-08:00Hi Wolfgang,
The flash computer adjusts for chang...Hi Wolfgang,<br /><br />The flash computer adjusts for changes in ISO just exactly like changes in aperture. If the ISO is increased, the flash power decreases and vice versa. The flash computer will always keep the brightness of the subject the same with changes in ISO.<br /><br />Also, you can change the maximum range of the flash by changing ISO. If you increase ISO you increase maximum flash range and vice versa.<br /><br />Also, you can change the number of flashes per charge. If you increase ISO, the flash will fire at a lower power, and you will increase the number of flashes per charge and vice versa.<br /><br />However, when you change ISO, you also change the ambient contribution to the image, just like with the aperture, so you have to adjust the shutter an equal amount in the opposite direction to keep the ambient the same when changing ISO. The shutter does not affect the flash [power, since the entire flash occurs within the shutter 'open' period of time. For instance, if you are using 1/80th shutter and ISO 400, and you increase ISO to one stop to 800, you have to also increase the shutter by one stop to 1/160th to maintain the same ambient contribution.<br /><br />Hope that answers your question.<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-44495015181389514452012-02-01T07:40:52.697-08:002012-02-01T07:40:52.697-08:00Hi Russ, after a while i was studying your blogs a...Hi Russ, after a while i was studying your blogs again, i must say everytime i find new information. A very helpful summary. <br />What puzzles me is the influence of ISO: The flash computer adjusts the flash power according to the reflected light. So, if you modify the aperture, it adjusts automatically and the subject remains at the same brightness. The same correction occurs when bouncing the flash. What about ISO change, how detects the computer that he has to reduce/increase power? I thought the ISO values lead to higher/lower amplification of the pixel values on the sensor which is way after the brightness measurement takes place in the camera.<br />Regards, WolfgangAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-11166716531157292782012-01-25T06:49:58.585-08:002012-01-25T06:49:58.585-08:00Hi KVS Setty,
I read the article you referenced, ...Hi KVS Setty,<br /><br />I read the article you referenced, and all I can say is that it is not correct. When a flash is in Remote mode it cannot work in TTL-BL mode.<br /><br />It's easy to understand why TTL-BL cannot occur when the flash is set to Remote. For TTL-BL to operate, the flash must be located at the same location as the camera (or close). This is so the ambient measurement that the camera makes will send the correct value of flash power to the speedlight. If the speedlight is positioned off to one side, the power sent to it will not be right.<br /><br />So, when the flash is in Remote mode, the only mode it can function in is regular TTL.<br /><br />This same issue comes up when using an SC-28 or SC-29 flash cable to attach the flash to a bracket or even hand-hold it. This cable will allow the flash to be put in TTL-BL mode, but you have to be very careful to keep the flash close to the camera or the power it fires at will not be right.<br /><br />The TTL-BL system depends on the flash being at or near the location of the camera.<br /><br />Once you understand this, you can see that there it impossible for the system to fucntion in TTL-BL mode when the flash is in Remote mode.<br /><br />The rest of the article appears correct, but I did not study it too closely for all the details.<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-86669309175866154912012-01-25T04:34:44.505-08:002012-01-25T04:34:44.505-08:00Very very informative content,
explaining a very c...Very very informative content,<br />explaining a very complex subject in very simple and precise form. thanks a lot for the great job.<br /><br />I have a question, if we move the flash off the camera, you said we loose TTL- BL metering , that means the off camera metering is standard TTL right? but in DPanswers.com in an article they say quite a opposite way.<br />see this link:<br /> http://dpanswers.com/content/nikon_flash_use02.php<br /><br />Under the heading:<b> 3. Speedlight Flash Modes </b><br /><br />Please help me to know the correct metering method in off camera flash methodKVS Settyhttps://www.blogger.com/profile/03067702038580418304noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-55358103807300970582011-11-26T13:41:02.836-08:002011-11-26T13:41:02.836-08:00Hi Anonymous (wish you would sign your name when y...Hi Anonymous (wish you would sign your name when you post):<br /><br />No, this invention is not one of the CLS patents. The CLS patents were all filed in the 1990's. This one was filed in 2008.<br /><br />This patent filing is for a new invention that is not in production yet.<br /><br />It involves adjusting the temperature of the light in both the monitor preflash and the main flash, to get more accurate flash power settings. Currently, the flash power is set by a monitor flash pulse and main flash pulse that are both 5500K. This causes problems. A single temperature light will reflect different amounts from different color surfaces leading to flash power deviations. You would like your flash to reflect the same amount from whatever color surface it hits, so the power will always be set the same. This invention will theoretically correct this problem.Russ MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-38334950877601265322011-11-26T12:32:54.158-08:002011-11-26T12:32:54.158-08:00Russ,
Thanks for your very informative web site. ...Russ,<br /><br />Thanks for your very informative web site. I thought you might be interested in this link which I believe is one of the major patents for the CLS:<br /><br />http://www.google.com/patents?id=1bBQAQAAEBAJ&zoom=4&dq=nikon%20creative%20lighting%20system&pg=PA1#v=onepage&q&f=false<br /><br />Apparently Hidehiko Aoyagi was its inventor.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-73641601509337783502011-09-05T19:55:37.705-07:002011-09-05T19:55:37.705-07:00Hi Russel,
Quote: I don't know if this is t...Hi Russel,<br />Quote: I don't know if this is the appropriate forum but i really need your help.<br /><br /> I take pictures of dance recitals (street and cheer dance)and i almost always end up with either dark, under and overexposed, blurry pictures.<br /><br /> If the use of flash is allowed, could you please recommend appropriate camera settings which i can adopt so my pictures wouldn't end up bad.<br /><br /> I'm using a nikon d50 and a nikon sb800. The lighting at the venue is always changing. I would be about 15-20ft from the stage and i use a tamron 28-75mm f/2.8 lens.<br /><br /> Should i go manual or program mode? TTL or manual in the flash? Use a stofen or not? Auto ISO or not?<br /><br /> I know i'm asking a lot but i've been taking pics of events (dances and concerts) for so long that i feel i haven't been learning from previous shoots though i've been applying what i read from your articles and others. Help please.<br /> September 22, 2008 5:11 PM <br /><br />Can you share the solution or advice of this problem please as I am new to photography and CLS.<br />This blog is the best one I read. Thanks for your good work.<br />Regards Whanauli.<br />My email: whanauli@gmail.comwhanaulihttps://www.blogger.com/profile/04262873061868230149noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-31719737448658061762011-05-23T05:24:28.089-07:002011-05-23T05:24:28.089-07:00snaps are reality..and wedding photographers done ...snaps are reality..and <a href="http://www.iwedplanner.com/User/wedding-photographers.aspx" rel="nofollow">wedding photographers</a> done a great job to have this.Anonymoushttps://www.blogger.com/profile/02919206318532083476noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-54220796132922283542011-02-01T13:55:52.217-08:002011-02-01T13:55:52.217-08:00To D:
I was looking back through the questions an...To D:<br /><br />I was looking back through the questions and noticed that I neglected to respond to you.<br /><br />You asked what I mean by the terms 'on-camera' and 'off-camera'.<br /><br />I haven't gone back and checked every entry in my blog, but in general, when I say 'on-camera', I mean that the flash is mounted in the hot shoe.<br /><br />When I say 'off-camera' I mean the flash is NOT mounted in the hot shoe.<br /><br />Now, if the flash is 'off-camera' but it is connected to the camera by one of the flash cables (like the SC-29), the camera will 'think' the flash is still mounted in the hot shoe, so it will performs all the same computer algorythms. This works correctly in regular TTL mode, but in TTL-BL mode it can cause it set the flash power incorrectly. This is because the distance that the lens reports is often the main input to the flash power calculation. So, if the flash is positioned at a different distance to the subject than the camera, the flash computer will set an incorrect flash power.<br /><br />Hope this answers your question.<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-25191671561767518822011-02-01T13:34:17.130-08:002011-02-01T13:34:17.130-08:00Hi Michael,
I'm glad you found my article use...Hi Michael,<br /><br />I'm glad you found my article useful. Let me know if you have questions.<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-57765801663647746242011-02-01T13:04:29.030-08:002011-02-01T13:04:29.030-08:00Russ,
Thanks for a very clear and useful article....Russ,<br /><br />Thanks for a very clear and useful article. I just had a real "Eureka" moment!<br /><br />Regards,<br /><br />MichaelAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-38633244161667966582011-01-22T18:02:52.531-08:002011-01-22T18:02:52.531-08:00Dear Russ,
I am dumbfounded by the kindness and g...Dear Russ,<br /><br />I am dumbfounded by the kindness and generosity demonstrated by your patient replies to the many questions posted to your site. And this on top of your excellent posts.<br /><br />Please forgive the stupidity of this question. You have mentioned frequently the difference between on-camera and off-camera use of speedlights. I suddenly realised that I'm confused by what "on-camera" and "off-camera" actually means. I'm assuming that a speedlight mounted in the camera's accessory shoe is "on-camera". What if the speedlight is mounted on a bracket attached to the camera and connected to the accessory shoe with an SC-17, SC-28 or SC29 cable? Is it "on-camera" or "off-camera"? What if the speedlight is clamped to a nearby pole but connected to the accessory shoe with a cable? Physically it's "off-camera", but...<br /><br />Does "on-camera" and "off-camera" refer to the physical location of the speedlight, or the nature of its connection - wired or wireless - to the camera?<br /><br />Again, please excuse the stupidity of this question. And thanks again for sharing your knowledge so lucidly.<br /><br />D.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-21578836340895965692010-08-12T04:35:17.502-07:002010-08-12T04:35:17.502-07:00Hi again David,
That's a great idea about tap...Hi again David,<br /><br />That's a great idea about taping the diffuser dome to the SU-800. I don't own an SB-900, so I will have to figure out a way to try that with the dome from my SB-800.<br /><br />Thanks!<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-37290701188379549172010-08-12T04:08:28.236-07:002010-08-12T04:08:28.236-07:00BTW, I've read somewhere that if you put a dif...BTW, I've read somewhere that if you put a diffusion dome onto su-800 commander you'll increase the angle range for communication with remote units. I put this claim to the test and it proved to be a GREAT improvement! By simply attaching the plastic diffusion dome(the one that comes with sb900) with a rubber band onto the su-800 I was able to place the remote unit about 30 degrees behind me (12' away 6' high) and trigger the flash. Normally, you can't even do 90 degrees when out in the open. Sorry for this off-topic post but maybe it'll help somebody. David.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-91205712121357920042010-08-12T03:55:37.454-07:002010-08-12T03:55:37.454-07:00I understand now-many thanks! My mistake was to as...I understand now-many thanks! My mistake was to assume that the flash computer/software is located inside the sb 900. <br />David.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-71804980684260221482010-08-09T13:15:35.803-07:002010-08-09T13:15:35.803-07:00Hi David,
Yes, the SB-800 and SB-900 function ide...Hi David,<br /><br />Yes, the SB-800 and SB-900 function identically (except for the more extensive zooming capability of the SB-900).<br /><br />The reason that the flash body doesn't have to be aimed at the subject is because it is a TTL (Through The Lens) system.<br /><br />The measurement of the monitor preflash is actually done in the camera by the flash computer software.<br /><br />Then the camera calculates the correct power for the flash and sends it to the flash, either through the hot shoe or via the IR pulses sent to the Remote flashes.<br /><br />So, for the Remote flash, all the Commands and Power Data pass through its IR window.<br /><br />Hope that helps,<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-48861480552849466252010-08-09T11:21:28.846-07:002010-08-09T11:21:28.846-07:00Hello. I am using D700 coupled with SU-800 command...Hello. I am using D700 coupled with SU-800 commander and a SB-900 in remote mode. I mostly shoot in M(camera) in this setup. You've written before, in regards to SB-800(but I hope it's also valid for SB-900), that when in TTL, the front of the flash(red window) does not have to be aimed at the subject. This is good news to me because I often have to rotate the whole unit to get that IR sensor(which unfortunately is only on one side of the flash) point my way, which often results the front pointing away from the subject. My question is, in that case, how(by what) is the pre-flash measured to calculate the proper power?<br />Thank you,<br />DavidAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-8819528167003105092010-08-06T16:02:18.219-07:002010-08-06T16:02:18.219-07:00Hi again jshelbourn,
Thanks for the feedback.
I ...Hi again jshelbourn,<br /><br />Thanks for the feedback.<br /><br />I do this for a hobby and to try my best to help others. What I write about, and how often I publish, depends on how much time I have.<br /><br />Also, I try to keep my comments generic so they apply to all Nikon cameras and speedlights. I don't think I would ever be interested in something as specific as how to set up a D200 to use with a remote SB600, for instance.<br /><br />However, I would be glad to help you by email if you will send your questions to me. Just get my email off my profile or website.<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.com