Fill Flash with a 70-200 question/tips please

Pegasus_Thrust

Pegasus_Thrust

Messages
510
Edit My Images
No
Running the risk of being hailed a fool and but if you don't ask......

On a few recent shoots I've tinkered with shooting the subject (couples/families) from range with a 70-200 and have had mixed results- mixed from a sometimes the flash barely makes a difference and sometimes its a little too much.

Can anyone recommend some settings to get a better more constant result?.... I appreciated lighting is different but I am more on about whether to plug for manual everything, or to let the ISO run on auto and the flash should I put that in full manual also?

Camera is either a nikon d3 or d800e and the flash is the sb910.

Any pointers to help me emulate some of the crackers I've got when I got it right would be great- thanks
 
Fill flash is balancing ambient and flash. As ISO effects both exposures I would personally set the ISO to something fixed, rather than ISO. But I am only an amateur, and there are definitely more people on here with much more experience and knowledge of the Nikon systems too.

Out of interest are these indoor shots, or outside? Can you post an example?
 
You have 2 light sources to consider, both of which behave in different ways, and both need controlling separately. I am assuming that there is no wireless TTL system, so it is therefore important not to 'auto' anything, but purposely control each through manual settings.

Flash should be controlled through a combination of gun output and aperture. The gun will have a guide number, and you can calculate the aperture required using (GN/feet distance)/aperture @ 100ISO. So if you plan to use the gun at full power and it has a GN of 60 placed 10 feet away from the subject, if it is to provide all the light for the exposure then you'll want to shoot at f6 approximately. If just using it for fill then decrease the aperture accordingly, so that it's providing half (f8) or one quarter (f11) etc. or decrease the gun output using controls on the gun itself.

Since your aperture is fixed by the output of the gun, you then need to control ambient light with shutter speed, keeping at or below the shutter speed required for using a flash, unless your gun has high-speed sync. You may want to slightly underexpose to allow for the extra fill light coming from the gun.

Just to say that I'm far from an expert at fill flash, but this is a fairly straightforward system to operate.
 
Last edited:
Thank you for your input both, much appreciated. The GN number is 34/48 (just googled it)- based on that then basing it on 48 at 1/1 power at 10ft I'd stick it at f4.5 or thereabouts?..... and shutter speed doesnt matter?
 
if the flash is barely making a diffrence and you are shooting with a 200m the chances are that you are too far away from your subject for the flash to carry
 
I had considered that. I am rarely beyond 100mm to be honest- what sort of range is possible?..... would 10 metres be workable, I can't say that I'm ever really any further back.
 
Hi there sorry if I am being dumb but are we assuming the flash is on top of the camera ?
If on camera I would say you will get more consistant results if you use manual settings for the camera and use the flash in ttl mode and adjust it's power +/- compensation as needed.

Gaz
 
Last edited:
Hi Gaz, yes its on camera and I do very often use the flash compensation button in other scenarios its just that more often than not I am using the D3 with the 70-200 and unless its my turn to be dumb the D3 doesnt have that feature.
 
Pegasus_Thrust said:
I had considered that. I am rarely beyond 100mm to be honest-.
Click to expand...

10cm distant ? no wonder your shots are overexposed :LOL:

If you are rarely beyond 100mm focal length, why are you using a 70-200 ?
 
Last edited:
Ha, yes that would be why. I meant to sort of say I rarely have my subject that far away from me in order for it to require me going beyond 100mm focal length but it came out wrong. Re the choice of lens its just my second body set-up primarily where time is of the essence and the oppportunity to swap lenses is minimal- I also love the results the 70-200 along with the D3 produces.
 
Inverse square law vs a comfortable shooting distance with a telephoto lens would put an on camera flash into the mix as a variable.

If the ambient isn't too great and you're shooting H&S you stand a chance, but if you're trying fill flash for groups in bright sun, you've no chance.

The 100mm focal length tells us nothing, you could be talking headshots or groups and the flash distance would need about 8x the power from one to the other (double the distance = quadruple the power required, 3x the distance and 6x the power.
 
I've no doubt it's me trying to do something and get it a*se about t*t. I'm just primarily probably getting a mixture of H&S and full length shots and just wanting the subjects to pop a little more against the surrounds. I'm quite confident now thinking about it that the distance is playing a part, I had possibly incorrectly presumed the SB910 would have enough poke with the flash head adjusted to the relative focal distance at about 200mm for it to cover the distance with a standing couple centre of the composure..... so anything less would also work.
 
Pegasus_Thrust said:
I've no doubt it's me trying to do something and get it a*se about t*t. I'm just primarily probably getting a mixture of H&S and full length shots and just wanting the subjects to pop a little more against the surrounds. I'm quite confident now thinking about it that the distance is playing a part, I had possibly incorrectly presumed the SB910 would have enough poke with the flash head adjusted to the relative focal distance at about 200mm for it to cover the distance with a standing couple centre of the composure..... so anything less would also work.
Click to expand...
Physics.

The 2 important considerations (and you seem to be ignoring them) the intensity of the light you're trying to match, and the flash to subject distance.

The rest is incidental, and your getting caught up in details that aren't making a difference.
 
I don't quite get the 'physics' element though Phil- surely despite light coming at the lens it shouldn't directly affect light falling on the subject the other way?
 
I'm not arguing the toss physics wise by the way, is it simply a case of what the sensor can see/expose?
 
Pegasus_Thrust said:
I don't quite get the 'physics' element though Phil- surely despite light coming at the lens it shouldn't directly affect light falling on the subject the other way?
Click to expand...
No. It's all about the amount of light illuminating the subject.

Like when you photograph the moon, you use sunny 16, because what you're photographing isn't the night time on earth, it's the 'daylight' falling on the moon.

The only 2 considerations to make are flash to subject distance and the ambient you're trying to balance.

I alluded in my first post, have a read up on the inverse square law. I haven't time to do the calculations for the lens and distance, but let's say for a head and shoulders you're at 3metres and for the wider shot you'd be at 9 metres.

Let's say a typical English summer day we're 1 stop down from sunny 16. So f11 at ISO 100 1/100.

Your flashgun will just manage that as it'll go to 3.62 metres with a full power pop (we're lucky because we have the flash zoomed to max)

But at 9 metres your flash at full power will only give enough light for f5, so it's several stops underpowered.

If you really want fill flash and to shoot from that distance, you have to get the flash off camera and back closer to your subject, the bad news is now you'll need it even closer because you're zooming it out.

Guide numbers explained.

The other consideration you have is that iTTL whilst great isn't perfect, if your subject is in partial shade but there's a bright subject in the background, you might get underexposure. That's where you probably need FEC, I'm not an expert on Nikon, but either the camera or the flashgun can usually be used to set exposure compensation for just the flash.
 
Last edited:
I almost exclusively use my 70-200 but always with off camera flash.


Builders bum by metroman on Talk Photography

Some "good friend" of mine captured me at work photographing Anna recently and this is the result.


Anna
by
Brian Lewicki,
on Flickr

I used a Nikon SB800 mounted in the stand and softbox with a YongNuo YN-622N Wireless trigger on the flash and a YONGNUO YN-622N-TX i-TTL Wireless Flash Controller on my Nikon D700.
For some reason I used f13 on the lens and can't think why??? I can't tell you what the power output of the flash was but quarter power is quite normal and I might move the flash nearer or further from the subject as required. Looking at the finished image it clearly shows I used flash which is not always desirable but I like the image non the less.​
 
Phil V said:
The other consideration you have is that iTTL whilst great isn't perfect, if your subject is in partial shade but there's a bright subject in the background, you might get underexposure. That's where you probably need FEC, I'm not an expert on Nikon, but either the camera or the flashgun can usually be used to set exposure compensation for just the flash.
Click to expand...
I was thinking it was probably just erratic/different metering. The metering for the TTL flash exposure and for the normal camera exposure are not the same and will not always give consistent results. I feel I have the best results when the camera is in CW metering, others feel they get more consistent results with matrix metering.

IMO, it is best just to apply FEC on the flash body (I normally start at -.7). Once it's set you can then push both exposures around together with CEC, maintaining the ratio (default Nikon behavior/setup).
 
You must log in or register to reply here.
Back
Top