help with my flashgun please

D

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Dwayne Mathers
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hi all,

i got a very cheap flashgun from a hung kong seller and it works a treat. the problem is there are no settings on it and some pictures are coming out to bright.

im having to rely on camera settings to resolve this but what is best to vary, the shutter speed or the aperature.
 
Perhaps you could tell us the model and what camera you are using it with?
 
yep quite right i completely forgot.

im using a nikon D40 (love it) and the flash gun is a Yinyan BY-24ZP
 
thanks fabs i'll try varying the shutter speed then, so the higher the number the less brightness, im sounding so amateurish lol i swear i take alright pics
 
I did see an online video tutorial on here a few days ago, but can't remember where. It explained it a lot better that me. But yes, the slower the shutter speed, the more ambient light gets to the sensor. It's the ambient light that is causing the extra brightness. At the camera's sync speed (Usually 1/200th sec) only light from the flash will reach the sensor. I suspect you may be looking for something in between.
 
Having looked it up, it was designed for older 35mm slr cameras with mechanical shutters.
Thats why you have to adjust it manually on your D40 and it will probably work best at a 1-60th second flash sync which is where most older slrs would have synced.
 
If the flash is the sole light source changing the shutter speed will have little if no effect on the brightness of the image. The flash duration will be in excess of the fastest shutter speed you can use , so it's the aperture that controls the exposure. By all means use a slower shutter speed if you want some ambient light on the subject, to give it some "character."

On the back of the flash gun or somewhere in the instructions it should give you some "Guide Numbers" for different ISO settings. Yo simply divide this by the distance from the flash to the subject to give you the aperture to set. For example If at ISO 100 yo have a guide no of 56, and the distance to the subject is 10 ft then the aperture to be set is f5.6. You should also find guide no's in metric as well. As you are probably using the flash on the camera you can use the cameras focus scale to give you this information.

If you use the flash in a big room or outdoors then you may (will) find these guide nos are inaccurate, as they rely on reflective surfaces to throw some light back. However a test shot will give you some indication what adjustments need to be made to compensate for this.

Hope this helps
 
Chappers said:
If the flash is the sole light source changing the shutter speed will have little if no effect on the brightness of the image. The flash duration will be in excess of the fastest shutter speed you can use , so it's the aperture that controls the exposure. By all means use a slower shutter speed if you want some ambient light on the subject, to give it some "character."

On the back of the flash gun or somewhere in the instructions it should give you some "Guide Numbers" for different ISO settings. Yo simply divide this by the distance from the flash to the subject to give you the aperture to set. For example If at ISO 100 yo have a guide no of 56, and the distance to the subject is 10 ft then the aperture to be set is f5.6. You should also find guide no's in metric as well. As you are probably using the flash on the camera you can use the cameras focus scale to give you this information.

If you use the flash in a big room or outdoors then you may (will) find these guide nos are inaccurate, as they rely on reflective surfaces to throw some light back. However a test shot will give you some indication what adjustments need to be made to compensate for this.

Hope this helps
Click to expand...

I am sure you are right and that you have much more experience with me, but when would a flash be the only source of light? Surely there will always be ambient light, which is what my original advice to the OP was based on.
 
fabs said:
I am sure you are right and that you have much more experience with me, but when would a flash be the only source of light? Surely there will always be ambient light, which is what my original advice to the OP was based on.
Click to expand...

Even with a lot of ambient light - even daylight - you can make it disappear quite easily and make flash pretty much your only illumination. Here is an example of a shot of a robin during the day. The first picture shows the setup, and the general ambient light available. You will note the home made flash diffuser on my off camera 580EX, close to the feeding table. By setting the camera to kill the ambient I was able to make the background pretty much vanish, while my subject was lit almost exclusively by the flash.

EXIF for the robin shot was 100 ISO, 1/250, f/11, thus killing the daylight and making the flash work harder to achieve good subject illumination. EXIF for the room shot was 100 ISO, 1/50, f/5.6 and flash to balance the room with the daylight.

20080514_160338_02899_LR.jpg
20080514_151205_4196_LR.jpg
 
Fabs

My assumption was that the ambient light was to low so Flash was required. With a reasonable amount of ambient then adjusting the shutter speed to balance the illumination works as you suggest. However if the flash output is to high and blasting the subject it won't completely cure the problem.

dmp

I've Googled the Flash gun and having got a past the original site in Chinese I've found the following information

Flash Duration 1/1000 sec
Guide No ( I assume metric as there is no indication) 24 @ ISO 100: so at 3 Meter's (10 feet) the aperture will be F8; at 6 Meter's (20 feet) the aperture is F4

Hope this helps
 
Chappers said:
Fabs

My assumption was that the ambient light was to low so Flash was required. With a reasonable amount of ambient then adjusting the shutter speed to balance the illumination works as you suggest. However if the flash output is to high and blasting the subject it won't completely cure the problem.

dmp

I've Googled the Flash gun and having got a past the original site in Chinese I've found the following information

Flash Duration 1/1000 sec
Guide No ( I assume metric as there is no indication) 24 @ ISO 100: so at 3 Meter's (10 feet) the aperture will be F8; at 6 Meter's (20 feet) the aperture is F4

Hope this helps
Click to expand...

Thanks for the clarification. I'm only just getting into this part of photography myself and it's like starting all over again in many ways. Just as you think you've cracked it something else comes along. :D
 
yeah thanks for all this advise guys.

so mental note to myself is, on bright days dont use flash and use faster shutter speed to have less ambient light getting through.

when flash required in dull areas use aperature to adjust and trial and error is best option.

if im wrong shout me lol
 
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