Nikon's TTL BL (balanced lighting) flash option details.
Posted: Mon Nov 13, 2017 2:15 pm
Hi Everyone,
I was after some information on this flash option available on Nikon flashguns. (and also probably Canon systems?)
Nikon seems to be a bit vague about it in their descriptions and I wondered if anyone out there was an expert in these things.
I use it a lot in forest bird photography as it pleasantly blends natural with flash light and does not result in a "midnight effect" - black backgrounds.
I am mostly operating at distances of 3-8 metres from the birds.
Shooting in RAW, I also underexpose by 2-3 stops in-camera and turn the flash system itself down by a further stop.
As you can imagine this results in some pretty dark images, but Nikon NEF's are amazingly tolerant and shadow areas don't seem to suffer greatly when I adjust the exposure back up to where it should be in ACR later.
With careful adjustment I can produce a really subtle effect where it is not obvious that flash has been used at all unless you really know what to look for, like catchlights in eyes and slight leg shadows. Feather details really "pop" with tiniest barb details clearly visible.
Importantly, using 1/8 or 1/16 of the "normal" TTL BL light intensity does not seem to bother the birds, and even shy species will remain doing whatever they were originally doing even after a series of perhaps 8+ shots of them in this flash mode.
I use a Better Beamer to limit the spread of the flash beam so that the entire forest is not illuminated with a wide angle beam. Batteries last forever with this useful gadget.
So my questions are:
1. Does the BL mode of TTL flash involve a certain "% reduction" in flash output compared to the "normal" TTL option? (presumably it does, in order to let the natural background illumination "show through")?
2. What would this % reduction of flash output normally be? (probably varies with conditions - so what would the approx range of variation be?)
3. Does the flash sync speed vary to achieve this balance - (a slower sync speed would allow more background light to dominate in a picture) I will sometimes get a "post flash trail" when a bird is moving as it feeds/courts etc. because of the slow flash sync speed.
4. Do both TTL and TTL BL use "monitor pre-flashes" to calculate the final flash output? I know TTL BL does.
Thanks!
John Sibley
I was after some information on this flash option available on Nikon flashguns. (and also probably Canon systems?)
Nikon seems to be a bit vague about it in their descriptions and I wondered if anyone out there was an expert in these things.
I use it a lot in forest bird photography as it pleasantly blends natural with flash light and does not result in a "midnight effect" - black backgrounds.
I am mostly operating at distances of 3-8 metres from the birds.
Shooting in RAW, I also underexpose by 2-3 stops in-camera and turn the flash system itself down by a further stop.
As you can imagine this results in some pretty dark images, but Nikon NEF's are amazingly tolerant and shadow areas don't seem to suffer greatly when I adjust the exposure back up to where it should be in ACR later.
With careful adjustment I can produce a really subtle effect where it is not obvious that flash has been used at all unless you really know what to look for, like catchlights in eyes and slight leg shadows. Feather details really "pop" with tiniest barb details clearly visible.
Importantly, using 1/8 or 1/16 of the "normal" TTL BL light intensity does not seem to bother the birds, and even shy species will remain doing whatever they were originally doing even after a series of perhaps 8+ shots of them in this flash mode.
I use a Better Beamer to limit the spread of the flash beam so that the entire forest is not illuminated with a wide angle beam. Batteries last forever with this useful gadget.
So my questions are:
1. Does the BL mode of TTL flash involve a certain "% reduction" in flash output compared to the "normal" TTL option? (presumably it does, in order to let the natural background illumination "show through")?
2. What would this % reduction of flash output normally be? (probably varies with conditions - so what would the approx range of variation be?)
3. Does the flash sync speed vary to achieve this balance - (a slower sync speed would allow more background light to dominate in a picture) I will sometimes get a "post flash trail" when a bird is moving as it feeds/courts etc. because of the slow flash sync speed.
4. Do both TTL and TTL BL use "monitor pre-flashes" to calculate the final flash output? I know TTL BL does.
Thanks!
John Sibley