tag:blogger.com,1999:blog-9113726419970930271.post8083261074525745735..comments2023-05-27T02:33:34.320-07:00Comments on Nikon CLS Practical Guide: 10. Auto FP High Speed Sync ExplainedRuss MacDonaldhttp://www.blogger.com/profile/15288785902650834143noreply@blogger.comBlogger117125tag:blogger.com,1999:blog-9113726419970930271.post-7130211197004451242013-11-30T07:31:23.309-08:002013-11-30T07:31:23.309-08:00congratulations for the wonderful articles. One qu...congratulations for the wonderful articles. One question that lo flash when the high-speed operation, working as a strobe light. Thanks in advanceAnonymoushttps://www.blogger.com/profile/00884836027197627701noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-16292036163859810032013-03-07T09:56:29.952-08:002013-03-07T09:56:29.952-08:00Lissa,
Also, it is not correct that the FP Sync m...Lissa,<br /><br />Also, it is not correct that the FP Sync makes a series of pulses. That is something that was published years ago and continues to be misunderstood.<br /><br />The FP flash pulse is a continuous pulse - not broken.<br /><br />It is created by pulsing the circuitry internally, but the output waveshape is continuous.<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-79125955998677995292013-03-07T09:54:07.775-08:002013-03-07T09:54:07.775-08:00Lissa,
I worked in a camera design group for many...Lissa,<br /><br />I worked in a camera design group for many years, and we always called it FP Sync.<br /><br />You see, for the old leaf shutters, we didn't need to stretch the flash pulse, because the leaf shutter could work up to 1/500 sec and it sync'd perfectly with the normal 1/1000 flash pulse.<br /><br />In fact, I never heard of stretching the flash pulse with any type of shutter except the FP shutter.<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-89428019726467375892013-03-02T20:51:49.848-08:002013-03-02T20:51:49.848-08:00Hi Russ,
Just a bit of history I found helpful. I...Hi Russ,<br /><br />Just a bit of history I found helpful. I hunted high and low for a definition of what the FP stands for in FP sync. Your statement that "FP stands for Focal Plane" sounds authorative but makes no sense to me. Then I found the Wikipedia article at en.wikipedia.org/wiki/Flash_synchronization which ties the term back to the old pre-electronic era where some flash devices were designed to produce uniform light output throughout their flash. They were described as "Flat Peak" and allowed photographers to push beyond the camera shutter's X-sync speed limit. The electronic flashes now emulate this behaviour with a burst of rapid pulses and commonly retain the FP moniker. To me, understanding the history helps me make better sense of the FP abbreviation. Also, using such a flash is not limited to Focal Plane shutters alone although the letters still fit.<br /><br />LissajousAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-82067509376613651742012-05-22T09:19:46.953-07:002012-05-22T09:19:46.953-07:00Russ:
Outstanding blog! You have the gift of taki...Russ:<br /><br />Outstanding blog! You have the gift of taking complex concepts and expressing them into easy-to-understand language. Well done!<br /><br />I am an avid amateur and a team photographer for my daughter's high school drill/dance team. I had a question about use of Auto FP. I have a D700 and the SB-900 using the 24-70 2.8. As you suggest, the standard starting point for normal sync (250 or below for the D700) is to stop down the flash by -1.3 to -1.7. At those times I need to exceed the shutter speed of 250, which then invokes the Auto FP, should I not stop down the flash conmensation while in Auto FP mode? Should my starting point be 0.0 compensation value due to weaker flash output?<br /><br />SteveStevenoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-5091936684478339712012-04-08T08:50:37.618-07:002012-04-08T08:50:37.618-07:00Many thanks for your valuable reply Russ.Many thanks for your valuable reply Russ.Frank C.noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-12503145847503341432012-04-05T12:39:23.226-07:002012-04-05T12:39:23.226-07:00Hi Anonymous (wish you would sign your name),
Tha...Hi Anonymous (wish you would sign your name),<br /><br />Thanks for the kind feedback on my blog articles.<br /><br />In general, you should not use flash when shooting a subject that is in direct sunlight. Anywhere the sunlight hits the subject at the same place as the flash, it will overexpose and often 'blow out'.<br /><br />If your flashes are close enough to the birds, you should use Auto FP High Speed Sync, so you could select a higher shutter speed. However, be aware that in FP Sync mode it is the shutter that stops the action and not the flash. The flash stays on for the full shutter cycle, about 1/250th of a second, when in FP Sync mode.<br /><br />Also, in general, you should use TTL-BL instead of regular TTL when shooting in bright ambient conditions. TTL-BL tries to balance the power of the flash to make the subject brightness equal the ambient brightness. This means the flash will fire at a much lower level and possibly avoid some of the overexposure.<br /><br />If you could get shade the birds with a scrim, and then use TTL-BL, you would have much better results.Russ MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-67392158837443387422012-04-05T11:54:05.045-07:002012-04-05T11:54:05.045-07:00Have just found this info.
THIS BLOG IS BRILLIANT...Have just found this info. <br />THIS BLOG IS BRILLIANT.<br />Have now found out why I couldn't get a shutter speed above 1/320th.<br />I'm trying to photograph some Blue Tit birds nesting in a garden nest. I'm taking the images in the sunshine and keep getting highlights on the birds inner wings which I'm told is not the best for a good photograph. Once again many thanks for this info.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-56356347729154419762011-12-21T21:14:43.052-08:002011-12-21T21:14:43.052-08:00Two other considerations. If you use an ND filter ...Two other considerations. If you use an ND filter outdoors you can get wide aperture and moderate shutter speed. Of course the flash is attenuated by the filter, however if you get to below FP speeds the DOF control for portraiture becomes available.<br /><br />Of course one could always find some old FP foil filled flashbulbs. Those were fun!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-73462344563713626942011-09-23T19:01:26.249-07:002011-09-23T19:01:26.249-07:00Hi Alan,
I'm glad you found my blog useful!
...Hi Alan,<br /><br />I'm glad you found my blog useful!<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-16838909570411279822011-09-23T18:01:13.355-07:002011-09-23T18:01:13.355-07:00Excellent explanation. My lack of understanding o...Excellent explanation. My lack of understanding of auto FP on my D7000 was really bugging me.Alan Cliffordhttps://www.blogger.com/profile/07203284236816302240noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-33327783801757677822011-07-26T13:57:33.263-07:002011-07-26T13:57:33.263-07:00BTW, I have a D700 and SB-900BTW, I have a D700 and SB-900Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-68620546622971186582011-07-26T13:51:43.620-07:002011-07-26T13:51:43.620-07:00Hello again Russ!
I know it's rude to pop in o...Hello again Russ!<br />I know it's rude to pop in only when you need something but if you ever need to brush up on your swimming skills let me know ;)<br /><br />My question concerns the loss of power in HSS vs having an ND filter on. I know you previously said "The problem is that the ND filter will also attenuate the light from the flash by the same amount." <br />However, some claim that you will still get more light from strobe working @ 1/250 @ full power with ND x8, than 1/2000 at HSS. I guess the question is: is the light attenuation of a 3 full stops ND filter really equal to the loss of light without ND but @ 1/2000 HSS?<br /><br />David.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-26793678736849681942011-05-17T01:24:09.167-07:002011-05-17T01:24:09.167-07:00Very good articleVery good articleArt Zaratsyánhttp://www.artzaratsyan.comnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-34198859385318442112010-12-09T16:28:06.631-08:002010-12-09T16:28:06.631-08:00Hi Phil,
Thanks for the nice feedback!
No, I don...Hi Phil,<br /><br />Thanks for the nice feedback!<br /><br />No, I don't think what you describe will work. Both CLS Remotes must have direct line of sight to the Commander.<br /><br />How about staggering them on the bracket?<br /><br />Maybe you can rotate them say 45 degrees and then turn the bracket 45 degrees. That might open up the back one to communication with the Commander.<br /><br />SU-4 on the blind one wouldn't work at all, because it will fire when the other Remote fires its monitor preflash, which occurs before the shutter opens.<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-17125434416845682112010-12-09T15:46:46.439-08:002010-12-09T15:46:46.439-08:00Hi Russ,
Great series of posts here! I'm ver...Hi Russ, <br /><br />Great series of posts here! I'm very grateful for your help to fellow Nikon CLS users. I've recently discovered how useful and fun Auto FP HSS can be in the right situations. <br /><br />I have a few questions that I hope you might be able to help me with. If I pick up another SB-800 and mount both of them off camera in a dual bracket setup, (both set to Remote and controlled from a D300) and only one IR sensor can see the beam (from built in pop-up or SU-800) could I wire the sync port out of the "seeing" SB-800 into the other "blind" SB-800 and get both to function in HSS correctly? I know SU-4 mode on the blind one would only give me a full pop. Could I daisy-chain more together or use inexpensive wired splitters?<br /><br />Would all this be too taxing on the whole system or should I look for a different bracket so both IR sensors can see the IR beam? I'd like to make an inexpensive "light stick" for an assistant to move quickly with doing outdoor wedding/portrait work. <br /><br />Thanks again Russ for your insights and sharing your knowledge. <br /><br />PhilUnknownhttps://www.blogger.com/profile/05257712323843721505noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-11762258374659734202010-12-07T09:59:30.083-08:002010-12-07T09:59:30.083-08:00Hi Cho,
I'm glad you find my articles useful....Hi Cho,<br /><br />I'm glad you find my articles useful.<br /><br />Thanks,<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-35208002130712499662010-12-07T02:50:35.919-08:002010-12-07T02:50:35.919-08:00I just found your blog through a search and found ...I just found your blog through a search and found your tips very usefull.<br />Thank you.<br />KhunchoUnknownhttps://www.blogger.com/profile/08676985044630383786noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-62792283961327795762010-12-03T15:19:14.292-08:002010-12-03T15:19:14.292-08:00Hi Don,
Glad you found me. I seem to remember you...Hi Don,<br /><br />Glad you found me. I seem to remember you on Nikonians. You should come back. There are lots of really great discussions there. No flaming allowed and always constructive, or they're taken down. It's a great site for Nikon owners.<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-11132157447245802562010-12-03T10:41:30.094-08:002010-12-03T10:41:30.094-08:00Russ,
Hadn't looked at your writings since in...Russ,<br /><br />Hadn't looked at your writings since in Nikonians and glad I found you again. Trying to get more comfortable with flash.<br /><br />Got you bookmarked now. Good explanations, I'll check back here a lot.<br /><br />DonDon Wesselhttps://www.blogger.com/profile/04390183602170777411noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-85729756247113112282010-11-26T19:50:31.972-08:002010-11-26T19:50:31.972-08:00Hi Richard,
I'm glad you find my posts useful...Hi Richard,<br /><br />I'm glad you find my posts useful.<br /><br />This post is really not old at all. I only post a couple each year, and people ask questions all the time.<br /><br />About Auto FP: It is perfectly OK to leave the Auto FP turned on. It will only switch to FP mode if you set a shutter speed above flash sync speed.<br /><br />I don't know why you were seeing any difference at all between FP on and FP off with the shutter below flash sync speed. It's supposed to be identical.<br /><br />The reason FP isn't on by default is that if you don't fully understand FP mode, it will bite you. Any time your shutter goes above flash sync speed, the flash begins to act like a continuous light source that is ON only when the shutter is open. That means that the flash will no longer will stop action (action must be stopped by the shutter), and its intensity is directly affected by the shutter (the higher the shutter speed, the less maximum flash you have available).<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-18595016366614026442010-11-26T06:51:27.149-08:002010-11-26T06:51:27.149-08:00Russ,
Thank you thank you thank you! I finally u...Russ,<br /><br />Thank you thank you thank you! I finally understand what Auto FP High Speed Sync is. I know this post is old but my quest is new and thankfully Google led me here. I do have a question that I'm not sure of from your base post and responses:<br /><br />If I'm running M or S mode at slower than 1/250 (D300), does it matter whether I select 1/250 or 1/250(FP) in menu item e1? In other words, does it matter if Auto FP HSS is enabled if I'm not pushing the shutter speed into that range? In a completely non-scientific experiment, the histogram seems to shift ever-so-slightly when I flip back and forth between those settings but I'm not convinced that's anything more than my failure to have coffee before trying it.<br /><br />I can hardly wait to dig into the rest of your blog. Thanks again for taking the time to write all of this down.<br /><br />-rRWChttps://www.blogger.com/profile/11872973807868940278noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-57505655229649354972010-11-23T17:52:57.455-08:002010-11-23T17:52:57.455-08:00Hi Tom,
Tell, you what. Email me directly, at rus...Hi Tom,<br /><br />Tell, you what. Email me directly, at russ@russmacdonaldphotos.com, and let me address your questions that way. I am trying to keep this blog focused on Auto FP High Speed Sync.<br /><br />Thanks,<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-70468846687597820182010-11-23T14:39:33.631-08:002010-11-23T14:39:33.631-08:00Russ, after reading my email that I posted so lat...Russ, after reading my email that I posted so late at night (must've been half asleep), I realized that I forgot to tell you that the flash was set on Manual and was not connected to the camera at all. I was using Pocketwizards to fire the flash. It was putting out a steady f/9.5 light (measured by my Sekonic), since it was set to manual at 1/2 power and 12-15 feet away from the subjects. It was due to the 9.5 light from the flash that I set the camera to 9.5, figuring that the 9.5 from the flash was being sent to the faces, just as it was the light meter.<br /><br />With the flash and camera not connected, I am assuming that the FP mode will not work?? Does the FP mode only work when you have the flash physically attached to the hotshoe or via a sync cord?<br /><br />Saturday am, I got my wife in the backyard to duplicate the setup and as you said, only at f/2.8 could I get any light on her face. The flash was set at 1/2 power, 10 ft away, on manual again, with pocketwizard. The flash again read f/9.5 light, at her face, and when the camera was set to 9.5 just would not give proper exposure. In my studio, my main is at 9.5 and I set my camera at f/10 and it gives me a perfect exposure. So why does the 9.5 from the SB-900 won't do the same?tom rainsnoreply@blogger.comtag:blogger.com,1999:blog-9113726419970930271.post-46434130886280446802010-11-20T07:12:47.352-08:002010-11-20T07:12:47.352-08:00Hi Tom,
Your light meter reading on the faces was...Hi Tom,<br /><br />Your light meter reading on the faces was 1/125 @ f/5.6, but you had the camera set to 1/1200 @ f/9.5. Not considering the flash, this means the faces would be almost 4 stops darker than metered. That's a LOT of required fill.<br /><br />Then, with the flash in Auto FP mode, the effective flash power is so low at 1/1200 and f/9.5 that it simply can't add enough light. In fact, the effective power of the FP mode is so low that at 15 feet, at 1/1200 the aperture needs to be about f/2.8 to add acceptable fill.<br /><br />I'm not sure if there is any way to use a meter to measure the flash in FP mode, since the long flash pulse will mess up the meter reading. In FP mode it is ON for about 1/250th sec for all speeds above 1/250th, so you have to treat it like we used to treat fast flash bulbs.<br /><br />In your SB-900 User's Guide, on page F20, is a table of Guide Numbers for FP mode. The table is for 1/500th sec, so the calculated f/ stop will need to be opened up by a little more than a stop for the 1/1200th shutter. I don't know what zoom setting you were on, so I will assume 50mm. The chart shows the guide number for 1/500th at 50mm to be about 60 feet, which indicates f/4 at 15 feet. Then, at 1/1200 shutter, that will be a little wider than f/2.8.<br /><br />So, in your case, you had to open up the aperture to allow the flash to have enough power to fill. Of course that would brighten the sky.<br /><br />Normally, if you want to darken the sky, you have to use the flash in regular sync, so it will have enough power to add the required fill. Of course, this means using a shutter speed of 1/250th and using the aperture to darken the sky. It will often take a really small aperture; maybe f/22 at ISO 100.<br /><br />Hope that helps,<br /><br />RussRuss MacDonaldhttps://www.blogger.com/profile/15288785902650834143noreply@blogger.com