What do expensive external flashes have the cheap ones lack?

anubis404 · Oct 12, 2008

Overread said:
Yep = the flash unit will attempt to pick the best powersetting for itself.

As for the flash you link at $8 - that is £4 to me I would not touch it. Its cheap, and it looks plasticy. So chances are first off that its build will be weaker; next the controls on the back hint at an auto mode, but chances are that its a weak auto mode (ie not very good) following on from there you would probably have to use it in full manual and that would mean knowing how to use it well.
After that its flash power will be weaker, and its recycle time (time it takes for it to recharge after flashing) will probably be long - so no quick firing shots.

Its dirt cheap so expect dirt cheap results -

Ah, ok. So no improvement from the built in?

frXnz kafka · Oct 12, 2008

RyanLilly said:
Some flashes do offer "high speed sync" but usually they eat up a lot of power reduce their usable distance from flash to subject. There are some other triggers such as the radio poppers that allow faster sync speeds, but that is a whole other subject.

This isn't exactly right. High speed sync typically requires that your flash be on the hot-shoe, or in the line of sight of an infrared or preflash signal of a transmitter like the ST-E2 or from an on-camera flash. What the Radio Poppers do is detect the electromagnetic pulse this signal gives of, transmit it wireless from your camera to your flash via a radio signal, and then a fiber optic cable sends the signal to your flashes IR receiver. Basically, no matter how you do it, HSS requires a camera and flash capable of HSS. This means a more expensive flash. The Radio Poppers can't do HSS with any old flash.

TBAM said:
This may be a "duh" moment. But, the reason why you can't sync over 1/180 on most flashes, is because hypothetically, if you were using faster shutter speeds than that, the shutter would be closing faster than the flash was firing. So you would get a much lesser effect of the flash.

A flash that would fire with the same intensity of light, but fast enough to keep up with faster shutter speeds, would be quite difficult to obtain without spending a good deal of money.

Actually sync speed has to do with the shutter of the camera. Your shutter has a front curtain and a rear curtain, and your flash needs to fire when neither of those is in the way. When you shoot above your sync speed, you get a black bar at the bottom of the image. This is shutter getting in the way.

Some cameras (older Nikon DXX models, most famously the D70 and D70s) have an electronic shutter, which is wide open for a longer period of time, and the sensor is turned on and off electronically to make the exposure. This allows sync speeds as high as the shutter speed will go (1/8000).

Mitch1640 · Oct 12, 2008

how much better would the sb600 be then this?

http://www.bhphotovideo.com/c/product/515451-REG/Bower_SFD728N_SFD728N_TTL_Flash_for.html

frXnz kafka · Oct 12, 2008

Mitch1640 said:
how much better would the sb600 be then this?

http://www.bhphotovideo.com/c/product/515451-REG/Bower_SFD728N_SFD728N_TTL_Flash_for.html

If you actually plan on using the functions of the SB-600, it is MUCH better.

If you don't plan on using the functions of the SB-600 (TTL, high speed sync, etc) and you just want to save some cash, there are much better options than the Bower. Old Nikon SB-2Xs (24, 25, 26, and 28) for example.

Mitch1640 · Oct 12, 2008

the sb600 has a repeat or strobe function right?

DeadEye · Oct 12, 2008

tenlientl said:
If I wanna shoot at like 1/400, is there a way to use my built in(sync speed of 1/200) WITH an external? So built in flash goes first, the second flash will be from the external?

I'd like to know this before I decide to get a flash. Which is not soon, but I would like to know what I'm dealing with.

Nope it wont work that way. But with most modern camera bodys you can put the flash in Focal Plane FP mode or High Speed mode and use any shutter speed you want. Basically the flash stays lit during the entire shutter event simulating continuous light by rapid pulsing the flash.

Look up how focal plane shutters work. Faster than 1/200 they are a traveling slit were by only a fraction of the film plane will expose with the very short duration of a flash.

A way to cheat this (not often used as its somewhat impractical) is to use a very long duration flash. This needs lots of power as it is very inefficient

Bifurcator · Oct 13, 2008

TBAM said:
This may be a "duh" moment. But, the reason why you can't sync over 1/180 on most flashes, is because hypothetically, if you were using faster shutter speeds than that, the shutter would be closing faster than the flash was firing. So you would get a much lesser effect of the flash.

A flash that would fire with the same intensity of light, but fast enough to keep up with faster shutter speeds, would be quite difficult to obtain without spending a good deal of money.

My flash syncs at 1/4,000th sec. and it's on (built-in) a cheaper (now $200) bridge camera.

frXnz kafka · Oct 13, 2008

Bifurcator said:
My flash syncs at 1/4,000th sec. and it's on (built-in) a cheaper (now $200) bridge camera.

This is because you have an electronic shutter, No shutter curtains to worry about.

Village Idiot · Oct 14, 2008

The OP has one too. D40 can sync up to 1/4k iirc.

And just because a flash is going for cheap on E-bay doesn't mean it's crap. I couldn't find specs for the Sunpak 331, but it looks just like a 383, so I'm assuming it's an older version. The 383 is just as powerful as the 580EX 1.

usayit · Oct 14, 2008

IIRC, D40 has a 1/500 max sync. Just like Canon systems, it can achieve sync to a max shutter (1/4000 on the D40). To obtain faster than 1/500 sync, the flash has to go into high sync mode which (as mentioned prior) eats up battery and power.

Older flashes generally that are not 100% compatible with the Ettl/iTTL functions of Canon/Nikon do not have the ability to work at high-sync speeds thus you'll be limited to a max sync speed of 1/500 on the D40. They still work great but you'll have to figure out the metering and stay under max sync speed of your camera (also check trigger voltages).

So in general... expensive flashes

* have E-TTL/iTTL automatic metering modes (exposure and output is automatically adjusted)
* automatic zoom heads (flash adjust as you zoom in and out)
* ability to high speed sync
* more features (strobing, wireless etc...)

From what I've seen, one of the best (expensive) dedicated flashes on the market is Qflashes from Quantum Instruments:
http://www.qtm.com/

frXnz kafka · Oct 15, 2008

usayit said:
IIRC, D40 has a 1/500 max sync. Just like Canon systems, it can achieve sync to a max shutter (1/4000 on the D40). To obtain faster than 1/500 sync, the flash has to go into high sync mode which (as mentioned prior) eats up battery and power.

The D40 actually has an electronic shutter, which means the shutter blades don't get in the way when you go over the sync speed, so you can sync at any speed without going into FP mode. Typically the limiting factor with electronic shutters is if you're using cheap (eBay/Cactus) wireless triggers.

I didn't notice the OP had a D40.

usayit · Oct 15, 2008

frXnz kafka said:
The D40 actually has an electronic shutter, which means the shutter blades don't get in the way when you go over the sync speed, so you can sync at any speed without going into FP mode. Typically the limiting factor with electronic shutters is if you're using cheap (eBay/Cactus) wireless triggers.

I didn't notice the OP had a D40.

Page 101 in the D40 manual:

"The shutter will synchronize with an external flash at speeds of 1/500S or slower."
also in the specs sheet at the end of the manual.

Perhaps the manual is wrong.

frXnz kafka · Oct 15, 2008

usayit said:
Page 101 in the D40 manual:

"The shutter will synchronize with an external flash at speeds of 1/500S or slower."
also in the specs sheet at the end of the manual.

Perhaps the manual is wrong.

http://strobist.blogspot.com/2008/01/control-your-world-with-ultra-high-sync.html

I would guess that below 1/500th on the D40 you run into either loss of flash power (flash duration is about 1/1000th, so anything about that will cut your power) or maybe lower reliability with CLS or AWL. Whatever the issue, I'm sure the 1/500th sync is just Nikon protecting themselves from unhappy customers.

After reading the Strobist post more carefully, it seems if you're using an iTTL flash on the shoe of the camera it will only let you sync up to 1/500th. Any non-TTL sync method (PC cord, radio triggers) will let you sync at any shutter speed. You will experience loss of flash power about a certain shutter speed though.

TamiyaGuy · Oct 16, 2008

I think you can flash sync with higher shutter speeds than 1/500 with TTL metering as well, but that requires some sort of firmware hack. But you are right, Nikon's limit to 1/500 flash sync speed is just them saving themselves from a ton of angry e-mails about how they always sync at 1/4000, then complaining about how their battery life has halved.