Portable Auxiliary Flash Battery Pack?

I'm starting to use more and more flash in my adventure photography. However, I'm finding that for much of it I need the flash to fire repetitively as I'm usually shooting at 4 FPS. The flash needs to fire for each frame.

Two questions:

Is this possible with a separate battery pack for the flash?

If so, are there any lightweight, portable battery packs that would work for such an application? I'll have to tote the sucker with me while hiking/backpacking, so it can't be big or heavy.

I'm using a 5D2 with Speedlite 550EX flash, if that matters.

Thanks in advance for any thoughts and suggestions!

You're asking the right guy. I am mostly a night photographer now, and use an extensive flash system. I have ten Nikon SB flash and four high powered monolights + battery packs. I only photo outdoors. While I mostly do large scale photos (think canyons and railroad trains,) I have also done some small scale nature photos (think giant sequoia trees.) I have some thoughts.

First, you if try firing a little 4AA flash at 4 shots per second, you will likely fry the thing pretty fast. They aren't designed for that. Yes, you can hook up a big o' external battery pack to your flash, but it's only going to work a couple of times. You'll know when the end comes when you see the smoke rising. I'm thinking forget the battery pack idea, unless you are photo'ing in below 0F temps.

Here's what might work, at least in theory based on my knowledge of how 4AA flash works. The batteries load up the capacitators, and then let out just enough power for each flash. (This is the opposite of how monolights work, BTW.) The flash duration of a 4AA flash can be incredibly short, such as 1/4,000 sec. or even faster. That would allow for some very fast recycle rates. Here's the problem though. With one flash, it will likely have to dump all its power or at least half since outdoor shots eat up a lot of light. As you've probably found out, recycle time on most 4AA flash is something like 6 seconds. There is a way around all the problems I"ve brought up.

Here's whay I've done myself. I carry one Nikon SB-800, which is a fancy flash with iTTL and all that jazz. I use it for portraits and other "standard" uses. I also take four to ten Nikon SB-28 flash. (Don't waste money on expensive iTTL flash.) Lots of power, and relatively cheap. I set them on manual, obviously use them off camera. They are triggered by CSRBs and can be set up to 800 ft. away. For what you want, set out about four SB-28 flash with CSRB attached. Set the power level on each flash to one quarter power. That will give you incredibly fast flash duration, will give you instantaneous recycle up to maybe four shots, and won't fry the flash. I haven't tried getting 4 fps bursts with my flash, but I think in theory it would work. I could try it if you want. How much light are you needing here, anyway? Are you lighting up a crab on the beach, a freight train, or what?


Kent in SD

Thanks for the detailed response, Kent. I need enough light to fill shadows on a single hiker/canyoneer/mountain biker/trail runner as they move through the frame. My subject is usually no more than 10' away. More often, they're right in front of the camera. I typically shoot from very low or higher than my subject.

I started thinking about this because of a very difficult shot from a recent hike in a slot canyon. The subject was descending through a "hole" of sorts into a very dark chamber, with the bright mid-day sky visible behind him. The chamber was filled with reflected light. The sky completely blew out, which is okay, but I couldn't get enough light on the subject to make the image a keeper. A flash was definitely required. He was moving though, and the flash would only fire on the first exposure, which usually is not the keeper of the series. I've attached the photo for reference.

I sure appreciate any thoughts or suggestions!

For those uses there may be a workaround for you Bret. I'm betting you were shooting around 100 ISO. Hike the ISO up to 400 or even 800, depending on what you're happy with. You're flash synch speed is going to hold shutter speeds down, and especially at -1 fill or so, you won't be putting out a heck of a lot of flash power. Even at 0, you still won't be putting out a heck of a lot. That is, until you try to bring detail back to that white sky. That's when all heck breaks out on your power needs, and I bet you can't do it for one shot with a single strobe. But you said you didn't need to go there, so not a prob.

In the setting above, I'd meter ambient at several locations around the interior and let that help you decide what ISO you need. If you can expose for the ambient levels while getting the shutter speeds you need for moving subjects, then all that strobe has to do is fill at ambient or some % below.

Can't open up the right dark spots with ISO alone? Head for the hardware store and pick up some of that silver bubblewrap sheeting used for insulation. It weighs nothing (ideal for backpacking and location shoots), it's cheap, and it's eminently reusable. You can unfurl that and use it in pieces as reflectors to help with your trouble spots. Lots of setup time and strategy, but along with the higher ISOs so your flash functions only as fill, I bet you can do it in this setting.

This is a lot simpler than what I was thinking you wanted. (I'm usually dealing with night shots where there is NO ambient light.) The fact that you aren't trying to keep the sky from blowing out is a huge help for you. You really don't need a lot of light here to overcome the shadow on the guy. Here's some basics Hank didn't go in to. You are limited on shutter speed to sync, which is only1/200 sec. on your camera. You might try setting your camera on shutter priority, 1/200.. That will lock in max shutter speed. Find what ISO you need for ambient light in the slot, and I'm betting the camera will figure out how much flash it needs.

Hank's reflector idea is a good one. The rocks in there look like they soak up a lot of light, but putting something more reflective in there can double your flash power. Here's another idea though. You could have a second flash, either a Canon with iTTL, or an older flash (such as SB-28) set to manual. Set it off camera, maybe on a ledge. Mount a simple optical on it. In those tight conditions an optical will probably work. And finally, here's another thought, although I've never tried it. You might get away with high speed sync here. Read your manual. High speed sync allows you to user even faster shutter speeds, but the light output is VERY weak. Might work here though. You can cheat it, too. Put an optical on an SB-28 set to quarter power, on a rock ledge or even just the ground & pointed up. The good news for you is you really aren't talking about very much light here. Practice at home and you'll find something that works. An external battery will give you somewhat faster recycles and since you won't be having full power bursts you can keep from frying your flash if you keep bursts to less than 5 shots and allow complete cooling in-between. I'd try an external as last resort though.


Kent in SD

I have to laugh at myself a little. I looked at your shot, and a very important question popped into mind. Looking at the detail, I'll bet you a six-pack of your favorite brew when we finally cross paths that you were shooting in some kind of program mode. If not, I'll buy the sixpack but I get to split it with you if you had the camera on manual and were using matrix metering. The combo of very bright exterior light and dark interior fooled your meter.

That bright light in the background fooled your camera badly, and the strobe followed right along with it. In the same setting indoors (subject in front of a window), when shooting on any program mode I would dial a +2 or maybe even a +3 into the camera AND NOT the strobe. Pick your degree of fill reduction and leave it at that.

You got me kind of sideways with your original strobe question, but this is a situation I deal with all the time in location and PJ shooting. More strobe power only comes into the picture when you're trying to balance the interior with the exterior. You've aleady said that's not important, so fire away. But don't forget to play with the exposure comp on the camera!

Hank just might be right. I would still try shooting at a fairly high ISO though. You biggest problem is still getting 4+ flashes from your strobe before it runs out of juice and needs to recycle. The less power it has to expend per shot will mean it can do more shots. My original idea of having more than one strobe would give you more shots, as would Hank's idea of boosting the power of your single flash using a good reflector.


Kent in SD

Bret, would the strobe feature of your flash be powerful enough for what you need? Flash power, and therefore range, is greatly reduced but since the subject is quite close to the camera it might be an option. If it works, you still only need to carry the single flash. I don't use Canon flashes so I don't know how to set the strobe feature with them but on flashes I have used that have the feature you can adjust the frequency of the pops to get what you need.

I'm not familiar with Canon strobes and their features any more Robert, but if the strobe is used as fill at some reduction from ambient, that will extend the number of sequential shots it can take too. When using our Nikon SB-800's strictly for fill at around -1, I get many more pops than 4 in a sequence. That's with the 5th AA installed of course, but a single extra AA isn't going to make all that much difference in power. Remember that a 1-stop reduction in strobe output is actually a 50% drop in power output. With no other changes, that should extend a 4-pop strobe to 8-pops for the same power expenditure.

As long as we're disecting a hypothetical situation, I have another concern that would lead me to carefully meter the scene, then shoot manually at higher ISO rather than in any program mode: Will the framing follow a moving subject? If the camera is used in a program mode, automatic metering and exposure setting is going to change dramatically over the course taken by the subject, depending upon how much of that bright exteriror light is in the frame. Set the camera manually, and it will be consistent throughout the pan.

My first step in solving the riddle would be to try the shot once again with no extra battery power, no extra strobes and no reflectors, but with higher ISO, metering for an interior ambient, manual camera settings, and the strobe set TTL for fill at around -1 or so. If that pulls it off, great. You've solved the problem with a highly mobile setup and no extra gear to backpack. If it has problems, fine. Solve them one at a time specific to the scene using additional gear only as you need it.

That's because I still think the root of the problems here is what's probably at least a 5-stop difference between ambient and exterior light, which is compounding the metering problems and exposure on the interior subjects. That's a simple problem to solve via higher ISO and careful metering for the interior exposure- strictly a camera problem and not a strobe problem. Seqential shots and recharge rates are strobe problems, and should be kept really separate from camera problems in both our thinking and our solutions. Take it from a guy with enough strobes to light up a large church or auditorium, you don't want to start chasing your tail and adding light to solve camera and exposure problems if you don't have too.

Canon makes an 8-AA battery pack called a CP-E3 which powers an EOS flash system. This allows quick recycling use with a motor drive. The 5DII shoots at a max of 3 or 4 fps I think. Keep the continuous flash burst to a max of 3 frames per burst, wait about 15 seconds then another 3 frame burst and you won't fry your flash. Also give it a rest of 5-10 minutes depending on how many flashes you use, once you hit about 15 flashes using this 3 frames per burst with a 30-60sec interval. I've been using this with a 550EX on 1DMkII, a 5D, and a 1DsMkIII, for about 3 years now, shooting kayakers playboating, with no problem. I use rechargeable NiMH AA batteries, and they last a long time, even if the subject is more than 20 feet away in which case I use a Better Beamer to conserve battery power. I also use Hi-speed sync (a Better Beamer helps with this as well) whenever I'm close enough.

This is all great info! Thanks to all for taking the time to post such detailed responses.

Don: I'll pick up that battery pack. I appreciate your advice!

Robert: I'll read the manual to see if the 550 EX has a strobe feature. If so, I think it would work perfectly for what I'm doing in many situations. If not, guess I'll have to buy a new flash!

Kent & Hank: I really appreciate your detailed answers. Gives me much to chew on. I'll try some of these techniques this year, for sure. I like the idea of using reflectors which is something I hadn't considered. Might work well in a lot of situations.

A compact reflector would be one of those shiney "space" blankets. Bring some fishing line or string with it to make a sail-like frame. I'm lucky where I am--the snow is the perfect reflector.


Kent in SD

Page 46, Bret.

Brett, check out a Sunpak battery pack for the flash unit. It's not that large or heavy, uses a proprietary lithium ion battery (I think), and is rechargeable. It easy clips to your belt or slings over your shoulder. It has several output levels. I use it when I'm shooting weddings and need a quick succession of flash bursts. The key to the flash firing for all your exposures is aiding the recycling time. The AAs in the flash don't cut it, you need more juice. The battery on the Sunpak definitely provides me plenty of juice for an 8-10 shoot (however this varies based on output, I'm usually using the flash as fill -1 or -1.5). Hope this helps.

I do believe I found a solution: Lite Panels. They are a continuous output LED light panel available in various sizes. Battery life of around 2 hours. They aren't cheap, but they are very portable and the continuous light output will make it easy to see the results before clicking the shutter.

Anyone use them before? I'd be curious to hear opinions from someone who has experience with them.

Bret, Litepanels are something I hope to look at next week at the NANPA Summit. I'm very curious about the myself.

I'd really check on the intensity of their light output before spending a cent, Bret. I do a whole bunch of light balancing using everything from reflectors to incandescent light to spots and very large studio strobes, and you'll be shocked just how much light it takes to balance even a little sunlight if you're covering a large area. That's the foundation for my happiness with reflectors of all sorts, including commercial versions along with the bubble wrap version I recommended. Compare cost, weight and bulk with the various Photoflex LiteDic products and recognize that you are likely to need a light source (or reflector) nearly as large as the area you need to fill, in order to achieve any kind of controllable and uniform fill. We use the translucent versions because they can function both as reflectors and as diffusers to soften harsh light. The 52" circular version gives a fair bit of coverage, but the 41x72" oval is more versatile while not folding quite as small and weighing a little more.

In truth though, neither is large enough for many applications, and you have to become fairly strategic in their placement. And NO light panel is going to put out equivalent levels of light and still be portable enough for your needs, much less as affordable. You could be looking to generate 5-7 stops of fill in the circumstance you illustrated, and I'm guessing I'd need somewhere between 2400 and 3200 w/s of fill with studio strobes to bring that large an area to within a stop or two of the exterior sunlight. Less may be acceptable, as you state, but it's really nice to have the option of balancing interior and exterior light if you need it. That's possible with enough reflectors, but I bet not with your light panels. I'd sure meter the light panels for output, but I'm betting that they can't manage more than a stop or so of fill, and that only when they're very close to the area being filled (and potentially within view of the camera). Subject distance is a KILLER when it comes to lighting.

Hank: I spoke to a sales rep at Lite Panel and she claims the Micro throws light about 8' while the Mini throws a beam close to 20'. Not sure if either will work but the concept certainly sounds enticing. Thanks for the warning!

Ask her how many of stops (at what distance) or watt/seconds of light they put out. It's easy enough to stand 8' or 20' away from the panel with an incident meter and measure directly, but hard to do without the product in hand. Unless there's some new law of physics at work with their LEDs and reflectors, I can't imagine that they will add more than a single stop of light at those distances. Sorry if I sound skeptical, but experience is a tough taskmaster.

Come to think of it a GN for those panels would provide the info you need. But for the ultimate control in setting up the shot, I'd sure add an incident light meter to your equipment list. My wife and I are blind without ours when it's time to blend and balance multiple light sources.

Warning : This may all be completely wrong In fact, it likely is.

Just out of curiosty, I took a look...the 1x1 ft panel gives an equivalent light of 500 watts according to the webpage. A watt's a joule per second, so 500 joules per second. According to a photo.net forum page, a Canon 580 outputs about 100 watt-seconds (or joule-seconds per second, which is just joules) of power; And that's high compared to other sites. So the 1 ft x 1 ft panel, in an exposure of 1/5 second, would equal the max output of the 580. Now this is a long duration and a large area, with no real reflector, so distance from the panel the light is effective is probably pretty short. And of course, faster exposures will cut the amount of light down a lot.

Now the SLR litepanel is 3.3" x 3.3". Assuming that it's just a shrunken version of the larger panel, it will have about 8% the power of the large panel.

Maybe the website has a clue, when on the smaller panels page, it says "great for close-ups".

You're thinking along the right lines David, and you're correct that huge limiting factors will be the shutter speeds required for a moving subject along with apertures required for suitable DOF. That could easily spell 1/125 or even 1/250 at f/11 or f/16. I doubt that the panels' specs are for even f/11, much less f/16, but even if they were, chopping the shutter speed from 1/5 second to f/125 would require a 4-stop increase in light intensity. If the 1/5 second is required for f/4 or f/5.6 on the other hand, you can count the f-stops increase in light that would entail to achieve f/11 or f/16 on top of the requirements for faster shutter speeds.

And if you really want to complicate things, consider changes in distance between the panels and the subjects. They still have to be far back and out of view. And don't forget the squaring rule when you start changing subject distance. Back to the KILLER of subject distance.