Why use Camera Manual with Flash Indoors?
Keywords: nikon, speedlights, lighting, flash, cls
I am often asked why you should use your camera in Manual Mode when shooting flash in low ambient conditions, and why is that better than shooting in Aperture priority. This study will explain the reasons, plus I will show the effects of Rear Sync versus Front Sync when there is any subject motion involved in flash pictures.
But first it is important to fully understand that when you use your camera in Manual mode and your flash in i-TTL, the flash handles the exposure of the subject, as long as the ambient is dim, and the subject is in the center of the frame. So the image is still exposed automatically even though the camera is in Manual mode.
Here are my conditions that do not change during this study:
- Dim ambient light
- ISO 400
Image 1 below: Test Image, Flash off, 1/60th, Manual Mode.
The purpose of this image is to indicate how much ambient light there is. You can see that at 1/60th, it is about two stops underexposed. When using the camera in Manual mode and the flash in i-TTL mode, you want the camera controls to always underexpose the ambient by about two to three stops. Also, I moved my hand, so you can see what motion blur looks like without the flash.
Image 2: Flash ON, Aperture Priority.
I was moving my hand toward my face. Look closely at my fingertips. That orange blur on each finger is called ghosting or ghosting trails. The flash froze my moving hand and then the ambient caused the ghosting. Also, noticed the direction of the ghosting trails. The ghosting trails appear to preced the motion of my hand. This is what we call ghosting trails on the 'wrong' side of the motion. The position of the ghosting trails was caused by using Front sync.
Image 3: Flash ON, Camera Manual Mode, 1/120th shutter.
I was moving my hand toward my face. Notice that there are no ghost trails. This is because the shutter speed was increased high enough to eliminate the ambient from the image.
Image 4: Flash ON, Camera Manual mode, Rear Sync, 1/60th shutter.
Again, I moved my hand toward my face. Look closely at my fingertips. Now, you can see ghost trails going in the opposite direction. This is because Rear Sync was used, which caused the flash to fire at the end of the shutter cycle rather than the beginning of the shutter cycle as in the previous images. Now, the ghost trails are on the 'correct' side of the motion.
Image 5: Flash ON, Aperture Priority mode, Rear Sync, 1/15th.
Again, I moved my hand towards my face. Notice the much greater amount of ghosting. This is because when you select Rear Sync in Aperture Priority, you also get Slow Sync, and Slow Sync, causes the shutter speed to reduce to fully expose the ambient. This also caused overexposure.
Image 6: This has all the same settings as Image 5.
I just wanted to show the great sensitivity to movement. All I did was move my head.
1) When shooting flash in low ambient conditions, like normal indoor artificial lighting, it is best to use Camera Manual mode with Rear Sync to control ghosting.
2) Using Aperture priority with Rear Sync is not a good choice for dim ambient conditions. It will lead to overexposure and way too much ghosting and general motion blur.
3) Using Aperture Priority is also not a good choice when using Front Sync when shooting in dim ambient conditions, because the camera will always select 1/60th sec shutter (Flash Shutter Speed). This is too slow to stop ghosting during motion like a speaker waving his arms or a couple dancing.
Always use Camera Manual Mode with Rear Sync when shooting flash in dim ambient conditions so you can control the ghosting.
Never use Aperture Priority when shooting flash in dim ambient conditions, because you cannot control the ghosting.
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Originally written on September 23, 2013
Last updated on January 24, 2021
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Geoff Byrns (Jeffersonb) on August 28, 2021
Well written explanation of some of the basic terms I come across when reading about flash. Finally, I’m beginning to understand these terms. Thank you.
Robin Hancock (robBiker54) on May 19, 2020
Brilliant and clearly written explanation of the use of flash in TTL mode and manual mode on the camera. I have several books on flash photography and none of them explain how to use and set up flash in the way this article does in so few words! I think I should consign the books to the bonfire?!
JOSE SILVA (Jcasilva) on August 2, 2018
Very good tip; I wonder about rear sync even in manual mode in ambient dim light if is it necessary to avoid ghosts?
Steve White (boogie34950) on January 1, 2017
Bob Arkow (Bob Arkow) on January 16, 2016
Interesting article, Thanks. Bob
Preston Moochnek RPh. (massulo) on June 12, 2015
Henry M. Ford (Team) on January 20, 2015
I'm really enjoying my membership.Big Thanks
Mark Cremona (MarkCremona) on November 7, 2014
great little refresher for us Pro's too. Thank you.
Doug Murphy (Douglas1) on October 2, 2013
Thank you , thank you. No more Aperature priority and 1/60 sec speeds
Robert de Jonge (RobertS46) on September 30, 2013
At last someone who can it explain in simple term and very clear.Tonight I will do some experiments. Thanks !!!!
Tim Marchant (timpsm) on September 28, 2013
Yow, look at that . . . when I select rear sync and release the button the display shows slow sync also selected . . . I never noticed that and I never knew what slow sync was used for . . . okay, back to the manual for another read . . . thank you Russ
James Dane (FFN) on September 26, 2013
This kind of article is why I subscribe to Nikonians. Thank you.
User on September 26, 2013
The pictures make this clear. The bit about slow sync in aperture priority might explain some missed shots. Thanks once again, Russ!
George McLelland (georgemc) on September 25, 2013
Thank you very much. I have had trouble with this. Now I know (I hope). I'll experiment.
DONALD J MCKAY (djmckaytx) on September 25, 2013
Thanks for this...
David Ziff (davidziff2) on September 25, 2013
I'm a professional photo-journalist shooting events and I always shoot auto flash with manual settings. Not sure why you're discussing rear or front sync at all. The usual mode is manual flash with auto flash. I'm not challenging your position here. I just don't understand it
Verne Wonderlich (Cowboy Charley) on September 25, 2013
Excellent, very informative giving and showing the why and why not theory .
Conny Eriksson (Mindmeld) on September 25, 2013
Nice info, thank you :)
Richard Luse (DaddySS) on September 24, 2013
Thanks Russ, well done and informative.....again!
Y V Tyagi (yvtyagi) on September 23, 2013
Some camera models offer an option of choosing slowest shutter speed when using TTL flash (like D800E). Would there still be any difference if A or P mode is used in flash photography in low ambient light?