Auto flash question

[John]

Hello, can you help? The G2 manual recommends I take flash pictures in auto mode with the TLA 200 set to ttl. This results in a variable shutter speed, (at least I think it does). I did not remember this and thought I knew what I was doing. I set the camera to X. My flash sync was 200 - constant. The flash was set ttl - because I wanted auto flash.
Please explain what I did wrong and what I should be doing. In X mode should the flash be set to manual? If so - why can't I get a constant flash speed sync and ttl? I would like to learn one way that I can use for most snapshots where flash can help. I am hoping this new technology can get me away from syncing at 1/30 and 1/60. Sorry if I sound confused but I like to know in my mind what is going on and then try to choose the best answer based on the situation. Thanks

 

[Marc Jutras]

I don't know the G2 and the TLA 200 but cameras and flashes are usually based on the same ideas.

A TTL flash will use the info it gets from the camera (through the lens) to determine the amount of light it has to produce. Flashes using a Thyristor corcuit (like Vivitar's 283 or 285 for example) don't communicate with the camera.

Your camera synch speed should not be affected by the type of flash you use. I don't see why your camera should switch to variable speed because a flash is atached to it. You still have your max synch speed (in your case: X or 1/200). You should still be able to set it to any speed from 1/200 and slower. That's if the camera is manual which I believe the G2 is.

By the way, why do you want to synch at higher speeds than 1/30? Unless you have to freeze movement or have fill flash in daylight, synching at lower speeds will let more ambient light in, resulting in a much better shot. Synching at high speeds yields a deer-in-the-headlights look with a pitch black background.

My 0.02$

 

[John]

Thanks Marc. I have been getting some dark backgrounds and washed out faces. The auto mode would allow me to shoot slower than 1/200. The exact speed shows in the viewfinder as you pan around from light to dark. The G2 in auto mode allows the slower speeds, (which you say are good and now makes sense to me). My mistake has been thinking I needed 1/200 all the time. I can only get that if I set to X sync.

By default I try for higher shutter speeds with or without flash. This may be paranoia about shakiness, ultimate sharpness, etc. It could also be brainwashing because most of the "ultimate" gear has astronomical shutter speed specs compared to what I was used to with older equipment. (1/500 top, 1/60 flash)

 

[Marc Jutras]

Even at work, using DSLRs, I always use the manual mode for flash photography. I set the speed to 1/30 or !/60 (max) and the aperture I want and let the flash do its job. Since the flash is the main source, I don't care what the meter says (and it's probably wrong anyway in such situations). My subject will be properly exposed and I'll have some ambient light to get the effect I want.

Using high speeds all the time is, I guess, a natural reflex which we have to get rid of. Since I've switched from SLR to RF, I feel very confident shooting at 1/15 and even down to 1/8 or 1/4 if I can get good support. It makes a huge difference in the type of situations I shoot in.

Higher sync speeds on modern gear is usefull when you want to freeze very fast movement or use fill flash in daylight without having to stop down to f/22. Depending on what you shoot, it can be a true blessing.

 

[Socke]

Hm, with the flash TLSA00 on TTL and the camera on auto it switches to 1/60th, on X it switches to 1/200th.

I usualy use the flash in TTL and the camera in manual below 1/200th for fillflash.

 

[jlw]

There's nothing wrong with using the G2's auto flash system with the camera shutter speed manually set to X. As you noted, this keeps the sync speed at 1/200, which reduces the influence of ambient light.

It's been a while since I brushed up on this, but I believe that when you leave the shutter speed on 'Auto' and use a dedicated flash, the camera chooses a shutter speed in the range of 1/60 - 1/200 to try to maintain a balance between ambient and flash light. If you hold down the AEL button, it will use shutter speeds even slower than 1/60 -- whatever it takes to get a realistic-looking balance. In really dimly-lit places, this can cause ghost images because the ambient-light exposure is long enough to allow moving subjects to blur. Sometimes it's a cool-looking effect, sometimes not.

If you're getting unexpectedly dark backgrounds in your flash photos, setting the shutter speed manually to X is probably the reason -- the background is exposed mostly by ambient light, not by the flash, so if there isn't enough light to expose it well at 1/200 and whatever f/stop you've chosen, it will look too dark. This is why the manual recommends leaving the shutter speed at A.

The washed-out faces are a different problem; having the shutter speed on X wouldn't cause this, as subjects close to the camera are exposed mostly by flash rather than by ambient light. More likely, what's happening is that your subjects are off-center and don't occupy much of the frame. Remember, the TTL flash metering system is basically a full-area-averaging pattern: If someone's face fills up only a small portion of the frame and most is filled by a large expanse of dark background, the TTL system will try to put out enough light to expose the background correctly (since that's mostly what it "sees.") The flash won't be powerful enough to do this, but it will be powerful enough to drastically overexpose the foreground subject.

The remedy is to use flash exposure compensation; I forget the exact procedure, but it's explained in your manual (and on the Contax website, if you can find the listing.) It involves locking the exposure with the flash switched off, then turning the flash on and dialing in exposure compensation. You'd want to go in the minus direction, to reduce the output of the flash relative to the total exposure.

 

[John]

I will try what you gentlemen have suggested. It makes much more sense than what I have been doing. I will try some manual flash at 1/15, 1/30, 1/60. I will not concern myself if I am using auto and the shutter indicates speeds under 1/200. I will stay with X or manual at 1/200 for daylight outdoor fill. I will exposure lock in auto or manual and dial down exposure compensation 1 or 2 stops for tougher situations, where I believe the center weighted meter could be fooled.

 

[NoTx]

Also, remember, the TLA-200 is a zooming flash. Make sure the flash zoom is set to the length of the lens. Or weird things may or may not happen.