Odd black line at bottom on photos?

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Captain_Kangaroo

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Hi,

Can anyone help with a problem i have with taking flash photos:

Not always, but from time to time when i take a shot i get this black line at the bottom of my shot and i cant figure out why. I'm using a Nikon D3100 with a flashgun on top. Do i need a particular setting or something?

Example image below:

6178653810_3dc8cef20b_b_d.jpg
 
Your shutter speed is too high. It needs to be 1/250 or slower. That black band is the shutter curtain.
 
Looks like that's it then. Shutter was 320.

Thanks for the quick response.

Is there a way to get round this with fast shutter speeds?
 
I think it could be your sink speed im not 100% on this as i am new to flash photography myself and i had the same issue i just changed the shutter speed and it stoped the issue. From what i read the camera speed must match the speed of your flash think mine was 1/250th of a second or something like that i presume it will also depend on the power your flash is set to aswell.
If im wrong im sure somone will point you in the right direction
 
Some flashguns have higher sync speeds that 1/250th must most budget models are stuck at that.
 
TCR4x4 said:
Some flashguns have higher sync speeds that 1/250th must most budget models are stuck at that.
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The sync speed of the flash has nothing to do with it, its the sync speed of the camera that matters and is usually from 1/125th to 1/250th on most digitals (with the exceptions of several cameras from a few years ago that went up to 1/500th like the Nikon D40 (Not the D40X though) and the Nikon D1 as well as the Minolta Dynax 9 which went up to 1/300th, all recent cameras have retreated back to to a max of 1/250th).

It is possible to go beyond the max sync speed by using high speed sync mode on the flash where several extremely quick pulses of light from the flash during the shutter opening/closing allow you to take it up to incredible shutter speeds like 1/12000th of a sec on a Minolta Dynax 9 or 1/16000th of a sec on a Nikon D1. There is however also a slight loss of power over normal flash mode when using HSS.
 
s162216 said:
The sync speed of the flash has nothing to do with it, its the sync speed of the camera that matters and is usually from 1/125th to 1/250th on most digitals (with the exceptions of several cameras from a few years ago that went up to 1/500th like the Nikon D40 (Not the D40X though) and the Nikon D1 as well as the Minolta Dynax 9 which went up to 1/300th, all recent cameras have retreated back to to a max of 1/250th).

It is possible to go beyond the max sync speed by using high speed sync mode on the flash where several extremely quick pulses of light from the flash during the shutter opening/closing allow you to take it up to incredible shutter speeds like 1/12000th of a sec on a Minolta Dynax 9 or 1/16000th of a sec on a Nikon D1. There is however also a slight loss of power over normal flash mode when using HSS.
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If you use a non-dedicated flash with the D40, or tape over the relevant contacts on a dedicated flash, you can synch at the maximum camera shutter speed of 1/4000th sec. :)
 
s162216 said:
The sync speed of the flash has nothing to do with it
Click to expand...

You were saying?


High speed flash sync

Some camera/flash combinations (typically high end ones) support high speed flash sync. Different manufacturers have different names for it: focal plane flash, FP flash, FP mode, high speed sync, etc. The basic working principle is the same. Instead of using single flash pulse, the flash unit sends out very fast repeated pulses as the shutter curtain slit travels across the sensor. On average, different sensor areas will receive the same amount of flash exposure. In theory, this can be done with a constant flash light source during the whole exposure time. This is however not practical because the flash units do not emit constant light intensity during a single discharge cycle, causing uneven exposure across the frame.

High speed flash sync is not available on all cameras/flash combinations. You cannot get this capability if any of your flash or camera does not support it. Another issue with that is the greatly reduced effective flash power (guide number, or GN) because of the pulsing outputs of the light and blocking by the shutter curtains.
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The max sync speed is set by the camera. Nikon D3100 has a nominal x-sync speed of 1/200sec, though there is sometimes a little leeway and if that shot was at 1/320sec you will probably find that you can get away with 1/250sec. Auto guns will usually lock you out of going above 1/200sec though.

If you use a radio trigger they usually introduce a slight delay and you might have to drop down to 1/160sec. Whatever, if there's a dark band at the bottom the x-sync is too fast.

The high speeds quoted with different cameras above are because they have a CCD sensor that uses sensor switching instead of a mechanical shutter. But there's a big loss of power and no current DSLRs have a CCD.

High Speed Sync (HSS or FP Sync) is a feature only found on some high end guns, which changes the way they fire from one big flash to hundreds of smaller ones spread over a longer preiod - long enough for the focal plane type shutter to complete a full cycle. That also wastes a lot of power, and the higher the shutter speed, the greater the loss.
 
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i think some people have their terminology a bit skewed on this subject but in all effect, they're talking about the same thing. Yes, being correct from the start with how you describe something is a better working practise, but providing the message gets across then thats really all that matters. We're all human after all.... :)

Captain Kangaroo - you'll notice this black line when you've maxxed your camera sync speed (without resorting to high-speed sync) but as ambient comes into play more (i.e with lower flash power and/or brighter ambeint), you'll see this effect diminish as the flash plays a lesser part in being the main light source. That's when you can cheat your sync speed (when using triggers that send a 'fire' signal and not TTL info) by using higher shutter speed, although if the flash contributes enough light to the exposure, you will still see a darker band. How noticeable that band is depends on the ratio between ambient and flash..... :)
 
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Thanks for all the info on this. Makes sense now and at least I know it's not an issue with my camera which was my first thought. I lowered to 200 and it was fine.

I'm using a cheap Speedlite YN460 II (eBay purchase)
 
s162216 said:
The Pentax 645D has a CCD sensor and thats still a DSLR technically, it just has a bit of a bigger sensor.
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That's true enough. I think most medium format cameras also use CCD (Kodak sensor?) but they don't use sensor switching for x-sync. Hasselblad's leaf shuttered lenses sync up to 1/500sec though.
 
HoppyUK said:
That's true enough. I think most medium format cameras also use CCD (Kodak sensor?) but they don't use sensor switching for x-sync. Hasselblad's leaf shuttered lenses sync up to 1/500sec though.
Click to expand...

Yes it is a Kodak sensor, Pentax (in the past, not sure if their production has been restarted like some 645 lenses) did do leaf shutter lenses for their 645 and 67 medium format cameras and on a Pentax 67 are really necessary for fill in flash as the sync speed is only 1/30th!
 
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