Advice on flash photography for motorsport

yiannich

yiannich

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Yiannis
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Hello everyone, this is my first post asking for some advice. I have already posted some of my photos from Plains Rally in the C&C section. As I am new to this I would really like to hear your advice on this.

I am planning to attend a rally event in next month and then later on the Wales Rally. Both event will have late night stages in the dark and forest, where the only way to go is use a flash. Since there are limited opportunities for me to play with my setup, I would love to hear your advice on technique to get a head-start and then refine my technique.

What are you people using? On-camera TTL, or completely manual (both camera and flash I mean)? Some pros use off-camera flashes as well lately, but this will complicate things a lot I think.

I am a user of a Nikon D5100, if you have a particular suggestion of a flashgun, please let me know (I am on a budget, approx. 100-130GBP). What approx. GN should I go for? I am thinking for the Yongnuo YN-468 II due to its low price.

Looking forward for your suggestions!! Many thanks
 
I'd probably wait for a rally specialist to give you a definitive answer, however, my personal opinion is that using a flash as a primary illumination (ie not just fill which is what its normally used as but instead as the only source of light) in motorsport gives you some pretty gash results.

The problem is that you get a very harsh light and the flash duration is so small - this is the shutter speed that when used as the only light source it will produce.

A Nikon SB900 produces these numbers:

1/880 sec. at M1/1 (full) output
1/1100 sec. at M1/2 output
1/2550 sec. at M1/4 output
1/5000 sec. at M1/8 output
1/10,000 sec. at M1/16 output
1/20,000 sec. at M1/32 output
1/35,700 sec. at M1/64 output
1/38,500 sec. at M1/128 output

Even at the slowest duration, these are very high shutter speeds in motorsport terms, meaning all you get is a static car, harshly lit with startled occupants.

Its not a great shot.... I can say this because I've taken them just like that and they were pants.

Getting the flash off camera and getting creative with backlit cars is interesting, but complex to set up and not something you'll be able to do probably - it requires a lot of access and forward planning
 
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I think you're going to have to find out what works for you by trying it yourself but here's some stuff to bear in mind:

-The flash needs to be close enough to the car to illuminate it in whatever way you're aiming for or you're just going to be wasting batteries. That might seem daft to point out but you may forget it if you usually only shoot with ambient light - which works the same at any distance.

-As desantnik has pointed out a flash gives the same effect as using a very, very high shutter speed, which usually isn't very desirable as it makes the car look static. You can sometimes hide the frozen wheels depending on the angle the car is at but you're not going to be able to see a great deal through the viewfinder to judge the angle and rally cars are usually fairly high off the ground which makes the wheels and tyres more visible. Rally cars do have an advantage over circuit racers in this situation because they tend to kick up bits of the road surface which helps to show the car is moving.

-On camera flash also looks pretty terrible in and of itself.

-Any automated exposure is going to be confused by the headlights moving across the frame. You're either going to have to compensate for that or go manual. The headlights will influence exposure more as the car points towards you and less as it turns away so if you're taking shots at a few different angles they might need different levels of compensation. How much headlight-lit ground is in the frame will also affect the metering.

-Manual exposure on the camera is particularly easy with so little ambient light around, you don't have to worry about the sun going in and out of clouds for example. You can use the safety/zero cars to dial it in so the area where the headlights light the ground looks how you want it to look (slightly blown highlights, not blown at all, etc) and that should be it for camera settings. If the safety/zero cars don't have extra lighting on them (i.e. just standard headlights) you'll have to compensate for that as the competition cars will have either spotlights or lamp pods (which will be brighter).

-Manual flash exposure is a little harder as it is dependant on how far away the subject is and rally cars move around. If you double the distance between the flash and the subject you have to quadruple the power of the flash (this is called inverse square law), so if you take multiple shots as the car moves towards/past you you would need multiple different flash power settings to get the same exposure. In practice the exposure will probably be "close enough" at a decent range of distances and you can always tweak it on a PC later to get it bang on.

-You don't have to use your own flash. If other people are around there'll almost certainly be someone with a camera and they'll almost certainly be using their flash. If you use a longer shutter speed you'll have a good chance of their flash going off during your exposure, effectively giving you off camera flash. Obviously you won't have any control over the power of their flash, where it is positioned or whether it goes off at all so it will be very hit and miss.

-If the headlights are pointing at you you'll get a big flare effect on your image. If they're almost straight at you it might cover the whole frame with lens flare or glare from the lights and ruin the shot. It'll also confuse your autofocus system as it can't see anything other than a bright light over the whole frame.

-There'll probably be people around wearing high visibility clothing and if they get in the background of a flash-lit shot the reflective strips will be very distracting.

-I've read mixed reports of whether drivers are affected by the flash going off. I always try and use the camera settings to minimise the flash power needed and try to avoid triggering a flash if the driver is likely to be looking at the flash's position (e.g if they're entering the corner they're probably looking at the apex, but if they're exiting a corner they're probably looking up the road ahead). Flash in the corner of your vision isn't too bad but straight in the eyes isn't nice.
 
Thanks both for your long and insightful posts!

@desantnik I am aware that the short duration of a flash will freeze the motion completely, but especially for the WRC rally where I will be just a spectator in a spectator zone it will be almost impossible to try and use off-camera flash, although I will love to try in the future when I am more comfortable working with flashes.

@Darren, many thanks for the long post! this includes a lot of tricks and things that I have not considered yet. I hoped that it could be a bit more straight forward. Although it seems that there a huge lot of parameters going on.

It seems that a lot of practice will be needed to get me some decent shots!
 
Making the flash head bigger with a cheapo soft box or defuser will reduce flash look, but robs u of power, a rogue flash bender could be useful, to extend range, or a clone of it for cheap
I'd recommend a 568 or whatever the ttl on is
 
desantnik said:
The problem is that you get a very harsh light and the flash duration is so small - this is the shutter speed that when used as the only light source it will produce.

A Nikon SB900 produces these numbers:

1/880 sec. at M1/1 (full) output
1/1100 sec. at M1/2 output
1/2550 sec. at M1/4 output
1/5000 sec. at M1/8 output
1/10,000 sec. at M1/16 output
1/20,000 sec. at M1/32 output
1/35,700 sec. at M1/64 output
1/38,500 sec. at M1/128 output

Even at the slowest duration, these are very high shutter speeds in motorsport terms, meaning all you get is a static car, harshly lit with startled occupants.
Click to expand...

Just a technical note...these are the T5 times as published. The T1 time is the "effective SS" of a flash and it will be ~ 1/3 of T5. So ~ 1/300 at full power.
 
pingu666 said:
Making the flash head bigger with a cheapo soft box or defuser will reduce flash look, but robs u of power, a rogue flash bender could be useful, to extend range, or a clone of it for cheap
I'd recommend a 568 or whatever the ttl on is
Click to expand...

Modifiers of any type use flash power (requires more). I don't think you could do much of anything with a flash to make it significantly "larger/softer" in relation to a rally car track. It will just eat batteries and increase T1 times.
A flash bender doesn't extend the range, a beamer does...but they both cost you power/batteries.

Your best bet, is to use it bare, zoomed out appropriately, set a bit under (-FEC). IMO, the results will be "mixed" but mostly on the bad side.

I might be inclined to set the aperture as wide as possible, set the desired SS, set the ISO to the noise limit (800 on the 5100) and let the images be underexposed... shoot raw and recover in post.
 
There are lots of things you can do with a flash as fill, you can turn the power down, you can difuse and everything.... but that's when you have ambient light.

This will be the darkest forest you've ever seen.... the only light will be the headlights and the flash.

Our OP has also said, he's a paying spectator in a spectator pen.... really, I'd just enjoy it and leave the camera and the photography for an event where you can get to play properly. Maybe shoot some video on your phone or something instead?
 
think you can use a flashbender to make a tube/snoot to narrow the spread of light, i think it gains you a little bit, shouldnt cost you any light if you only need a narrow beam of light
 
pingu666 said:
think you can use a flashbender to make a tube/snoot to narrow the spread of light, i think it gains you a little bit, shouldnt cost you any light if you only need a narrow beam of light
Click to expand...

Using a snoot just makes it smaller. It doesn't "refocus" the light into the center, it just restricts the spread. "Smaller" would be problematic in this situation. (if there is any gain it is very minimal. i.e. Fong's "power snoot")

A snoot is different than the zoom function of the flash head which does focus the light and results in an increase in power/GN.

And since we're on the topic. A "beamer" does refocus the light and increase the distance, it's essentially an external "zoom" function. The problem is it doesn't catch all of the light emitted by the flash. It is recommended to use one with the flash head zoomed out (~50mm I think) so that the "hotter center" fills the fresnel lens. This results in quite a bit of "spill" and light loss; and so the resultant "gain" is not much compared to a flash head that can be zoomed to 200mm (SB900/600EX). For a flash with no/limited zoom it is more "useful."

There are a couple other "beamers" out there that are completely enclosed, but they are not designed so as to refocus the light prior to the lens. They might be a little better but I wouldn't expect it to be significant.

"Zoomed" is also "smaller."
 
Oh and I forgot to add... the cars will be covered in stickers that are light reflective too... that thing with the people with hi-vis in your shots? That will be the car as well...
 
I tried a rogue flashbender clone as a snoot, kept same size as the flashhead, and it did seem to help, with a flash with less or no zoom, it'll bounce that wide light down the tube, and should make a brighter, but smaller area.
maybe my camera metered differently, but it did seem to help, was birding in dull overcast weather.
 
desantnik said:
Oh and I forgot to add... the cars will be covered in stickers that are light reflective too... that thing with the people with hi-vis in your shots? That will be the car as well...
Click to expand...

I don't think many have reflective stickers on (I've only seen one and it was the driver's name on the rear window) but they do have numberplates with reflective backing - which ranges from ugly to absolutely horrid looking depending on the angle the flash hits it at.
There are some exceptions like the cars with the old black and silver plates or some that have non-reflective stick on numberplates (Perez's Stratos for example) but most have the modern ones.
 
pingu666 said:
I tried a rogue flashbender clone as a snoot, kept same size as the flashhead, and it did seem to help, with a flash with less or no zoom, it'll bounce that wide light down the tube, and should make a brighter, but smaller area.
maybe my camera metered differently, but it did seem to help, was birding in dull overcast weather.
Click to expand...

Almost certainly metered differently...

Light bouncing around doesn't "align" and end up at the subject. It "dies out" in essence. The light energy is lost thru absorption into the reflecting surface (converts into heat), diffraction/interference with other photons, and simply passing thru matter (air/moisture). The ones that do leave the end of the snoot will leave at an angle and have less energy; they don't make it to the subject. If they did make it to the subject, it wouldn't be a very good snoot. (it will have a gradual light falloff at the edges)

Even optically "clear" glass and metals absorb some light.

These reasons are why you can't put a light source between two mirrors, turn it off, and still have the light bounce back and forth between them indefinitely (or even perceivably).
 
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