First play off camera flashguns - what am I doing wrong?

Hi All,

I splashed out a whole $45 on some optical triggers to use with my K200D some of my old flashs that I got for use my ME super. They arrived yesterday and I was eager to have a play.

So Last night I was using the following flash's with the optical triggers
Vivitar 550FD
Cobra D400

I had both flash units set to manual and the pop up flash set to -2 and I was playing with the aperture and the shutter speed to see what would happen.

Two things I thought were wierd, the first was that I couldn't get much more than 1/45 or 1/60 even when going down to f4.xx the other was that some times I got an under exposed image.

So I guess my questions are how come I got an under exposed image with three flash unit when what I expected was over exposed and why can I get a quicker shutter time?

Or is all of that normal ?

Regards
PaulM

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All cameras are equal but.....
Some are more equal than others

A couple of guesses (I am not a flash expert).

Firstly, the shutter speed makes no difference to the exposure with flash (unless you are using "fill in flash" or balancing the ambient lighting) provided the speed is not greater than the synch speed (1/180th on the K10 so I guess the same on the K200). I personally use manual mode on the camera when using flash and set the speed to what I require. I don't know why in Av mode the camera doesn't just set itself to the synch speed but it doesn't.

Secondly, the under-exposed shots might be because you didn't let the flashes recharge fully before taking the second shot. Also, are the off-camera flashes set to manual?

The best way of getting the exposure right is with a handheld flash meter. Failing that, checking the histogram for your shots and adjusting as appropriate works as well.

No doubt Matt will be along eventually to give you the correct answers rather than my guesses.

HTH, K.

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Kris Lockyear
Ask a question and be a fool for five minutes. Keep quiet, and be a fool forever. Chinese proverb.
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.

Thanks Chris,

Yes both flashes were set to manual and they have no power control so they were firing at full power from about 300mm-400mm away from the subject (a bowl fo fruit). I had the camera set to manual and I am pretty certain that both flashes where fully charged before each shot.

I was just expecting very over exposed images with three flashes and was surprised to see some under exposed ones especially as I was down at f4.xx with quite a low shutter speed.

In fact the results seemed to be quite random some times ok and some times under exposed, no I think about it I dont think I got any that where over exposed.

Regards
PaulM

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All cameras are equal but.....
Some are more equal than others

Hi Paul

You can't fire external flash guns in sync with the pop up flash, the external flash guns will discharge on the popup's pre flash. a set CPR-301 radio triggers would be a better bet than optical triggers.

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Regards Brian
www.brianlawson.co.uk www.ephotozine.com/u26064

The pop-up flash will probably fire your slaves too soon. If you have an old flashgun that has a tilt head, put that on the camera and tilt the head towards the ceiling.

Your $45 would have been better used to buy a radio TX/RX triggering system.

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Peter Smith

Body: K10D + BG, K20D(2) + BG's
Prime: FA31/43/77 Ltd, FA50 Macro, DA*55, D-FA100mm Macro, Sigma EX180 Macro, DA*300.
Zoom: DA12-24, DA*16-50, DA*50-135, DA*60-250.
Flash: AF240FT(2), AF500FTZ, AF360FGZ(2), AF540FGZ(2), AF160FC Ringflash (deceased )
Software: Adobe Lightroom 3, Photoshop CS5, Photomatix Pro, Noise Ninja, iWatermark, Picasa 3.
Backpack Bag: Tamrac Expedition 7x, Lowepro Fastpack 350, Lowepro Vertex 100AW, Lowepro Slingshot 200AW
Shoulder Bag: Tamrac 613 Super Pro 13, Lowepro Stealth Reporter 500AW, Lowepro S&F Reporter 300AW

McBrian,

Pretty certain that there is no pre flash, I only see one pulse from the pop up. The only time I seem to get a pre flash is when I use the 2 sec timer. I do get a strobe effect whe it tries to focus in low light but I keep the button half pressed until I can see the charge/ready light on both the flash before I fully press it.

Manesty,
I dont have a flash that I am confident of the trigger voltage so the optical slaves looked like a good compromise.

I am going to have another play tonight to see what I can get. If it still looks rubbish I will get a set of Cactus radio triggers after Christmas I think.

Regards
PaulM

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All cameras are equal but.....
Some are more equal than others

In normal circumstances you can't see the pre-flash simply because it takes place just milliseconds before the main flash and the human eyes/brain just aren't quick enough to take it in. You see it when you have the camera set to the timer because then there's a clear 2 second delay between pre- and main- flashes.

Unfortunately your slave devices *can* tell the difference and they'll be triggered by the pre-flash, as their duration is only measured in thousandths of a second they'll have already done their bit before the main flash fires and the shutter opens. This is why you need a "dumb" flash on the camera that doesn't have a pre-flash for triggering a set up like yours.

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Bodies: K10D | Spotmatic SP K Lenses: DA12-24 | DA35 Macro Limited | FA43 Limited | FA77 Limited | D-FA100 Macro M42 Lenses: Takumar 58/2 | Super-Takumar 50/1.4 (early)

If you have an A series lens or earlier, set the 'Allow use of aperture ring' option to allow, set the lens aperture manually (not to the A setting) and try your setup again. I think in this situation the pre-flash will not occur, but the popup flash will fully discharge and will therefore contribute light to your scene.

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Peter Smith

Body: K10D + BG, K20D(2) + BG's
Prime: FA31/43/77 Ltd, FA50 Macro, DA*55, D-FA100mm Macro, Sigma EX180 Macro, DA*300.
Zoom: DA12-24, DA*16-50, DA*50-135, DA*60-250.
Flash: AF240FT(2), AF500FTZ, AF360FGZ(2), AF540FGZ(2), AF160FC Ringflash (deceased )
Software: Adobe Lightroom 3, Photoshop CS5, Photomatix Pro, Noise Ninja, iWatermark, Picasa 3.
Backpack Bag: Tamrac Expedition 7x, Lowepro Fastpack 350, Lowepro Vertex 100AW, Lowepro Slingshot 200AW
Shoulder Bag: Tamrac 613 Super Pro 13, Lowepro Stealth Reporter 500AW, Lowepro S&F Reporter 300AW

Thanks Hefty,

I do want to get an AF-360 but I just cant quite justify a new one to the wife yet, would that emit a pre-flash?

Interestingly though I have just been having another play and after changing the lens I started to get what I was expecting

I was initially using my sigma 55-200 1:4-5.6DC lens (with no f ring) which was producuing the random results.

So I tried switching to an old Tokina 28-70 1:3.5-4.5 SD KA mount as it was to hand. I had the lens set to f22 and the shutter at 1/180 and it was way over exposed. So after moving the flashes further away and using a bodged up diffuser made from a plastic milk container I started to get consistant well lit results.

I need to try some other lenses (the 18-55 kit lens because its my only other lens ith no aperture ring, some of my other K and KA mounts and the Tammy 70-300 because its the most modern lens I have with an aperture ring) but it seems like with the sigma on, the K200D was still trying to compensate for the for the amount of light and hence the inconsistant resuts, even when I had it set to M mode and set the f stop and shutter myself.

I will have a try with some more lenses this weekend and see what I get

Regards
PaulM

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All cameras are equal but.....
Some are more equal than others

Mannesty our posts crossed, but thats what I have just discovered.

So its more likely to be a pre flash than the camera taking control and trying to balance the scene?

Regards
PaulM

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All cameras are equal but.....
Some are more equal than others

I bought an AF160 from ebay for a fiver and use that to trigger my AF360FGZ remotely. The radio triggers would be the way to go, obviously, but the little old flash is quite a handy bodge.

Wouldn't it be useful to be able to turn off the pre-flash?

K.

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Kris Lockyear
Ask a question and be a fool for five minutes. Keep quiet, and be a fool forever. Chinese proverb.
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.

Well I took the plunge and treated myself to the following




A cactus v4 single transmitter / reciever unit and with a the small amount of testing (ie playing) I have done so far its very good escpecially for the price. I am using the radio trigger to fire one flash and the optical triggers to fire the others.

Now I really need to play around with diffusers and distances etc.

So thanks for all of your input guys.

Regards
PaulM

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All cameras are equal but.....
Some are more equal than others

I missed your previous question for some reason but the answer is yes and no. In P-TTL mode the AF360 will emit a pre-flash but if you set it to Manual mode then you just get a main flash. It's quite a flexible little gun

Better late than never...

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Bodies: K10D | Spotmatic SP K Lenses: DA12-24 | DA35 Macro Limited | FA43 Limited | FA77 Limited | D-FA100 Macro M42 Lenses: Takumar 58/2 | Super-Takumar 50/1.4 (early)

Thanks Hefty



Regards
PaulM

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All cameras are equal but.....
Some are more equal than others

Just bought cactus as well with a stand and umbrella.
Fist the cactus didn't sync good for the first 100 shots for some mysterious reason, flash fired of the photo or if I had shutterspeed longer then 1/10 no all is fine and can get 1/180.

Only the shop has giving me the wrong stand and swivel-head for the flash mount.

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Stefan

K10D
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ