Beginner Extending flash life/ recycle time vs ISO

[cmcm789]

I have 2 flashes to use at an event tomorrow evening (pitch black shooting runners). I have already done a trial set up and found that camera at f5.6, ISO 1600 with flashes set manually at 1/32 and 1/64 exposes the scene as i want. I will have spare batteries but was hoping to have a set up which would recycle quickly as the runners will be every second or two (on a single track forest path) and i may have to fire of 400+ shots.

My question is, could i increase the flash power on both to 1/16 and 1/32 and still get good recycle times and battery life while reducing the ISO to 800. At ISO 1600 on my crop sensor i can see noise, although it's not terrible and will clean up, i would rather not have it but don't want to compromise on getting the images in the first place.

Flashes are Godox TT600 rated at GN 60 and 250 flashes per charge and TT350 rated at GN 36 and 210 flashes per charge.

Thanks

 

[swanseamale47]

You used to be able to get a plug-in big battery pack for the old flashes, certainly I had them with the metz 45, (the 60 came with it's own) if If I remember rightly they were made by quantum, but it was a long time ago. If your handy with a soldering iron and willing to risk a flash it should be easy enough to make your own.
Edit a quick google brought up this battry pack for the godox (amazon link)
link

 

[cmcm789]

You used to be able to get a plug-in big battery pack for the old flashes, certainly I had them with the metz 45, (the 60 came with it's own) if If I remember rightly they were made by quantum, but it was a long time ago. If your handy with a soldering iron and willing to risk a flash it should be easy enough to make your own.
Edit a quick google brought up this battry pack for the godox (amazon link)
link

Wayne, thanks for the suggestion. I hadn't thought about battery packs, will have a look and see if my flashes can take them. I have decent batteries and a full spare set in case i run out. Don't think i'll try the DIY route just yet. this is a first attempt at this sort of photography so i want to make sure i have what i need this time round.

I was looking at my test image and i think i need an additional fill light to the front. I have a small camping LED lantern at home which i think i could tape to the tripod just to give a little fill. But the lantern is fixed power so this may impact on the flash set up. I.e. if the lantern is too much as a fill i will have to lower the ISO and increase the flash outputs or visa versa if it's too dark.

There are other things i want to change (such as tighten flash zoom (it was 24mm there) so not so much of the forest is illuminated in front) but this is what i'm trying to achieve but as you can see the shadows on the face are too dark. All i want is a little detail in that area.

 

[sirch]

My question is, could i increase the flash power on both to 1/16 and 1/32 and still get good recycle times and battery life while reducing the ISO to 800.

Dropping the ISO one stop and increasing the flash power one stop as you suggest should give you the same exposure, I guess it's easy enough for you to test the recycle time at those flash settings. The recycle time is affected by the amount of charge in the batteries so it will get longer as the batteries run out, so maybe you could start at ISO800 and bump it up and drop the flash power if it starts to get too long.

 

[mike weeks]

there is a Godox rechargeable pack that you can get leads for called the PB960 that can power up the flashes https://shop.photomart.co.uk/flash-power-pack-960-dual-output-lithium-battery-pack-black.html
Mike

 

[cmcm789]

Dropping the ISO one stop and increasing the flash power one stop as you suggest should give you the same exposure, I guess it's easy enough for you to test the recycle time at those flash settings. The recycle time is affected by the amount of charge in the batteries so it will get longer as the batteries run out, so maybe you could start at ISO800 and bump it up and drop the flash power if it starts to get too long.

Chris, thanks i didn't realise the recycle time increases as the batteries discharge. i'll look out for it.

 

[Scooter]

As your speed-lights are IGBT, at 1/16th power, there is effectively no recycle time unless you fire off ~16 shots continuously. The capacitors are always charging up unless they are full (unlike traditional voltage regulated flash where it pre-loads the required amount of charge for the amount of light you need, dumps this into the flash tube and then recharges again). The flash duration will be longer at 1/16 vs 1/32 and so overall, each flash event will take longer, but this is still a much shorter time than your camera's shutter operation takes.

So you shouldn't notice it slowing down unless you take a lot of shots at once. Of course you could take more shots in a row at 1/32 before it will begin to slow down. And as Chris said, as the battery voltage drops, it will be charging slower and so you'll be able to take less shots before you exhaust the capacitor and you start to notice a recycle time. Think of the capacitor like your camera's image buffer - the speed of the card makes no difference until the buffer is full. Same with the battery in an IGBT regulated flash - it'll go at full speed until the capacitor is empty and then you're waiting on it to achieve some nominal charge to squeeze another flash out.

You will be pushing more energy into the tube over the same period, so heat will build up more, and pulling more from the battery so those will heat up more too. At night, in January though, it will also lose this heat pretty rapidly. I've shot my SB900's at full power in bursts of 4 or 5 shots every 10 seconds or so, and it'll do this on a warm afternoon for about 30 minutes before the heat protection kicks in, so 1/16th every few seconds should be no problem.

The battery will of course last about half as long. At 250 shots at full power though, 1/16th power is going to give you 4000 shots in theory. The electronics and radio take a bit of energy too though, and it may not be as efficient for lots of little flashes, however I reckon you'll get 2000 pops at 1/16th from the TT600. You can control the lantern with the shutter speed and if it's still too bright at max sync speed for your flash setup, stick some tape over some of it

 

[HoppyUK]

I believe Godox don't use a temperature sensor to operate the over-heat protection, but instead count the number/power/interval of flashes discharged. In other words, it'll shut down at just the same time in summer of winter. Details in the handbook.

Take plenty of spare batteries and keep them in a warm pocket.

 

[cmcm789]

Thanks for all the advice, i just thought i would post back with the outcome from the event.

Took all the equipment i spoke about along with a number of sandwich bags as it was forecast for heavy showers. Arrived at my location in the middle of the forest, pitch black as expected with strong winds (not ideal in a forest!!). I was on a single width winding track. I found the flattest place i could with space at either side for my flashes. I also picked a spot where i was not immediately before a sharp bend, rocks or a steep drop. This limited me really to one location.

I set up the flashes as i had planned. Took a couple of test shots with timer and adjusted settings a bit.

Generally i was very happy with the outcome. Shots were taken at ISO 1000, any higher and i was worried i would blow highlights on reflective clothing. Was able to increase the exposure by 2/3 stop in PP.

Downside was my Mirrorless Canon. Some oddity (which upon googling is common for the model) meant that there was a delay between me pressing the shutter and the shot being taken of 2-3 seconds and unfortunately this was not always the same delay. I had to anticipate runners pace and keep my fingers crossed. The area that was properly illuminated and sharp was maybe 2-3m so this was my target.

Here is one of the shots. I was restricted by the location of trees and branches, and probably would have preferred the light to the right to be further back and created less fill and more edge/ring light. Any comments welcome for future set up.

 

[cmcm789]

Should have added, at 1/32 power, over the 200+ images there was no issue with recycling times. Twice my trigger locked and i was on continuous shooting and fired off a series of 6/7 shots at i guess 3/4 fps and the flashes had no problems illuminating all images.

All in all happy with the event as a good test of my technique/ equipment.