[Deni]

I have a k100d and use a p-ttl flash from digital concepts.

The problem I have with this flash is that it underexposes by about a stop. easily corrected in raw conversion.

I've been shooting 2 indoor football matches and the lighting sucks. I'm using iso 3200 to get all the light I can, so every correction in exposure while converting raws results in way too much noise.

If I use Av mode and dial the exposure to +1, the exposure is correct, and the flash looks powerful enough to light up the field. The problem with Av is that the camera sets the shutter speed according to the focal length. So when shooting at 30mm it'll shoot at ~1/45s which doesn't work very well in a soccer match.

If I use Tv mode, the camera will choose the widest aperture which amplifies any deficiencies of the auto focus. But again, I have to dial exposure to +1 to have a properly exposed photo.

In these circumstances I use manual mode and I set the shutter speed between 1/90s and 1/180s and the aperture at f/4.0. The problem is that the flash underexposes by a stop. Is there anyway I can correct this?

yesterday, at home I tried the sports mode, but the problem is that it chooses f/5.6 aperture which is a bit low. I'll try that the next match, on friday. But I'd like more to have the flash correctly expose in M mode.

Thanks!

Deni

[roscot]

What is the Guide number of this unit? You could try putting the camera in manual, leave the flash in P-TTL mode. Select an f stop somewhere in the middle of the distance range you are shooting. Set an appropriate shutter speed high enough to prevent shake, low enough to light the background. You will probably need to experiment a bit to get it right. What you are doing is forcing the flash to adjust it's output rather than adjust aperture/shutter speed, or use you thyristor units.

[Deni]

What you are doing is forcing the flash to adjust it's output rather than adjust aperture/shutter speed

Well, that's the idea. I need fast shutter speeds to stop the action and need some dof to work around the slow af.

I tried the thyristor flash but it's difficult to use it when the action can be 3 meters away from you or 15m.

[Deni]

The flash's guide number is:

Guide Number ( ISO 100 ) 42 (m) / 138 (ft) At 85mm Position

The flash is powerful enough because if I dial +1ev it exposes correctly.

[reknelb]

Use your flash in manual mode if possible. This will give you max flash power. Set your camera to manual. The flash will freeze action, the shutter speed and apperture controls ambient exposure (existing light in the arena). If your trying to freeze action you'll have to shoot at 1/120 -1/180. Any slower and you'll start exposing the ambient light too much and your subject will have motion blur just like a non flash picture.

[Deni]

Use your flash in manual mode if possible.

Things happen too fast to mess up with various flash powers. If I set it to max power, I may get correct exposure for distance action, but up close everything will be overexposed.

[Deni]

Just to give you an idea of the indoor field, this was taken at:

28mm

1/125s

f/4.0

iso 3200

[reknelb]

Things happen too fast to mess up with various flash powers. If I set it to max power, I may get correct exposure for distance action, but up close everything will be overexposed.

pttl is under exposing your shots, you can dial in the +1 and hope for the best? The only other option would be to set up multiple flashes wirelessly, or expensive strobes, and expose an area of the field/arena and shoot the action when its in that spot. Thats why indoor sports shooting is the most difficult to get acceptable shots on a regular basis. Most pro sports shooters use fast glass and high iso without a flash, or they rent the strobes from the arena where the event is being played. Obviously Im talking about the big arenas here in the US.

[Deni]

pttl is under exposing your shots, you can dial in the +1 and hope for the best?

That's my question. How can I dial +1 in M mode?

The only other option would be to set up multiple flashes wirelessly, or expensive strobes, and expose an area of the field/arena and shoot the action when its in that spot.

I'm just doing this for fun, so that's out of the question .

I think I can get acceptable shots if I overcome this problem, not that I'm not happy with my improvement considering it's only the second match i tried.

[reknelb]

Wow, not much light in there. You may have to expose for one small area and shoot the action as it's in that spot.

[Deni]

Yes, not much light at all. Without a flash, it'd be around 1/30s, f/2.8 and iso 3200.

[reknelb]

Yes, not much light at all. Without a flash, it'd be around 1/30s, f/2.8 and iso 3200.

Unfortunately, i dont think your flash is going to reach out that far. Light falls off quicly past 20 feet in my experience. I bought a pair of vivitar 383 flashes with cheap ebay remotes to go with my af540 on camera for situations like this. (and wedding receptions)

[Deni]

Unfortunately, i dont think your flash is going to reach out that far. Light falls off quicly past 20 feet in my experience. I bought a pair of vivitar 383 flashes with cheap ebay remotes to go with my af540 on camera for situations like this. (and wedding receptions)

Actually it does. As I said I'd get correct exposure if I dial ev compensation to +1ev and the flash gives a more powerful light, but don't know how to reproduce the same thing in full manual.

[Peter Zack]

You can't "dial in" Ev comp in manual mode so what you need to do (maybe before the game starts) Is take a couple of test shots and let's say you're seeing 1/125th f4 @ISO300 as the reading but that is 1 stop under. Then you're only option is to shoot at f2.8 or 1/60th (a one stop difference either way).

Now there might be a better solution to help. Get a Better Beamer type of hood for your flash or make one. These hoods focus the light from the flash to shoot it in a more concentrated beam toward the subject. It helps to keep the light from dispersing as much and allowing more flexiblity in shooting settings.

Many wildlife shooters use these to freeze a moving bird or other things when using a moderately long lens.

You could also benifit from a longer lens that is fast. The shot above is too wide. there's a ton of wasted space on the right and bottom of that sample shot. I'd use the Sigma 28-70 f2.8 you have.

[Entropy]

That's my question. How can I dial +1 in M mode?



I'm just doing this for fun, so that's out of the question .

I think I can get acceptable shots if I overcome this problem, not that I'm not happy with my improvement considering it's only the second match i tried.

I don't know about the K100D, but on the K10D:
Function menu
Choose the Flash Mode menu from the Function menu
In addition to choosing the Flash Mode you should have the ability to dial in flash exposure compensation. My K10D is permanently set to +1 - P-TTL is notorious for underexposing. Auto-thyristor usually works much better.