Continuous Burst Mode Only Utilizes Flash On First Shot

My 430EXII on lower power can keep up fairly well with my 1DII on burst. Never really tried it much, but it's not too bad.

MT Stringer wrote in post #13510932
I guess I am just a dummy because I find that hard to believe. Note: I am not a flash newbie.

Believe it - the internal resistance of the batteries limits the current that they can supply to the boost converter that charges the caps - I=V/R, the higher the R (even in the form of source resistance), the lower the I.

Quality NiMH cells have a much lower internal resistance than alkaline cells, my personal opinion is that Sanyo Eneloops are about the best currently offered.

siginu wrote in post #13511203
Believe it - the internal resistance of the batteries limits the current that they can supply to the boost converter that charges the caps - I=V/R, the higher the R (even in the form of source resistance), the lower the I.

Quality NiMH cells have a much lower internal resistance than alkaline cells, my personal opinion is that Sanyo Eneloops are about the best currently offered.

Are you using high speed sync? Even though I have the 2700 Powerex, I can't get more than two or three in succession even with a battery pack. That is shooting ETTL at night (flash football). I don't know anything about shooting at low power. And, I am not about to test the overlaod on the 580EX II. That is a costly repair if it burns up.

MT Stringer wrote in post #13511391
Are you using high speed sync? Even though I have the 2700 Powerex, I can't get more than two or three in succession even with a battery pack. That is shooting ETTL at night (flash football). I don't know anything about shooting at low power. And, I am not about to test the overlaod on the 580EX II. That is a costly repair if it burns up.

One can get a lot more bursts in a fixed time frame from a Speedlite at low power than at high power. There are two very simple parts to the explanation. The higher power takes longer to make the flash burst as output from a Speedlite is controlled by how long the burst is allowed to be. In addition, the more power one pulls from the capacitors in the flash unit, the longer it takes to recharge them. The two time delays add up.

Take a peek here

http://www.photomalays​ia.com …ormance-is-the-difference

I find this hard to believe. You got some dead cells or they were not charged up or the plug is bad. I consistently got 7 full power shots before dropping one, then 6 more, and that's at 8fps.

jwcdds wrote in post #13509570
Well, $500 might mean a lot to you. But in the world of R&D, $500 is like 1, maybe 2 hours of pay for the engineer to come up with something.

I'm pretty sure the technology is out there, except you'll have to carry a giant battery pack. Don't blame the flash, blame Duracell.

Off subject: What is pixel-peeping? I see it in your signature.

jwp721 wrote in post #13509591
Besides if you get your flash to fire as fast as you want you are going to risk causing damage to it due to overheating......

Definitely don't want that to happen!!!!

muusers wrote in post #13510496
Me neither... At first i put some normal batteries in.. And ran into the exact same problem.

Posted a thread similar like yours, and got the answer i gave you. Went out and bought some 2700 mAh batteries, and that did the job. recharge time reduced. My 430 keeps up with my 6 fps. Except when you demand a high ouput from your speedlight like full power. But for the most indoor shots, that isnt neccesary.

I'll be looking for these batteries this weekend!

You know what...............aft​er reading the damage I may cause I don't know how interested I am in getting continuous burst with a flash each time anymore. I'm scarred! Lol!!!! I'm shaking in my Clark's....

I can't afford to burn up my 580.

LOL, it takes a lot to get them hot. A few bursts won't hurt it.

People are forgetting a critical factor in the equation; subject distance.

MT Stringer said "That is shooting ETTL at night (flash football)." and canonloader said "I consistently got 7 full power shots before dropping one, then 6 more, and that's at 8fps."

It is likely that these two individuals are not making a valid comparison. Flash football is likely to be at a relatively long subject distance with minimal light being reflected back to the camera. We don't know the subject distance for canonloader. The amount of energy dumped by that capacitor is very closely related to the subject distance. A shot at 5 feet subject distance will take a certain amount of energy, lets say 10% of the full capacitor charge. That means one shot is taken and 90% remains in the capacitor. Lets expand the scenario and say minimal charging occurs and you take another picture at the same subject distance while on continuous. At 90% the capacitor dumps another 10%, yields a properly exposed picture and is now at 80% of full charge. Hopefully you can readily see that you might be able to get as many as 8 more shots properly exposed. Somewhat simplified but try to understand the concept.

Now lets go to the scenario of the "flash football" at night and say the subject distance is at 15 feet (and it likely is more). The amount of light needed varies as the square of the distance so this means we need 8 times the energy for the 15 foot shot. Again, lets start with a 100% charged capacitor and fire the first shot. 80% of the capacitor charge is dumped for shot #1 and 20% remains for shot #2. At this time a second shot would be at best significantly underexposed, or if the camera/flash combination controls things, the 2nd flash doesn't occur. To get a minimum of 80% charge for that 2nd shot, the flash must recharge. This recharging of course is much slower than the shutter on continuous; depending on the flash/battery combination the recharge time will be several seconds.

On another matter, that of bursts damaging the flash due to build up of heat. Yes, in theory it can happen but the camera/flash is somewhat self protecting. Back again to the picture needing 10% of the capacitor charge. At 10% the energy to the actual flash tube is small and thus it doesn't heat up much as compared to the shot that would require 80% of the charge. This is a simplification but hopefully the concept comes across.

Distance has no meaning when shooting with the flash on Manual and full power, which was how I was using it.

cannonloader, for the average user, that (full manual @ 100%) is an unusual way to shoot and likely not what the OP was doing. What are you using for a flash and what is the power source?

uneek78 wrote in post #13512661
Off subject: What is pixel-peeping? I see it in your signature.

"Pixel-peeping" is the act of zooming in your photos down to the pixels. So while you, as the photographer, frame/compose your photo by looking through the viewfinder... yet instead of evaluating the photo as you composed/framed as a whole, you come home and obsess over how the images look fully zoomed in to look for flaws in your equipment.

That's my definition of pixel-peeping.