Not directly Photoshop related I am afraid, but I don'r subscribe to any photography forums, and there are going to be a few photographers on this forum.
I have a pair of Bowens Gemeni 500 which I rarely use nowadays, but I blew the dust off to take some realestate pictures today. I was expecting to achieve total white-out with 1/4 power, but they were dramatically under performing. I was using a Canon 5DS at ISO400 F5.6 and 1/125th and slower, and with both strobes on full power. That should have melted the ceiling! I was trigering the strobes via a speedlite.
I later tried them again when I got home, and also with a Canon 1DC using identical settings. While the 1DC initially gave the same poor results, after a dozen shots or so I suddenly got the expected white-out, and the 5DS was doing the same.
So it had to be the strobes, but they were making the usualy POP when firing, and looked bright enough (I had spots before my eyes after testing them). Has anyone heard of strobes needing to cycle a few times to regain full power after a few years of disuse? I tried to Google an answer but found nothing.
Thankfully there's no panic now and I can get my pictures done, but I'm interested to know what was going on with the lights. Also, any thoughts on what shutter speed I can get away with? I doubt they will sync properly at the 1/250th that speedlites are OK at.
It does actually sound quite plausible. Not the tubes, but the capacitor that stores all that juice. It may need to be exercised from time to time...?
I have two 500W sets and both are used fairly regularly, so this hasn't happened to me. The longest unused period for either is probably two or three months.
1/4 power at ISO400 and f/5.6 sounds just about right for bouncing off a white ceiling or wall. That should give good exposure right off. All my Sonys and Nikons supposedly synchronize at 1/250, but when I try it I always get a slight shutter curtain shadow. It can be corrected in an emergency, but I usually stick to 1/125.
The studio units seem quite a bit slower than an on-camera unit, with a much longer burst duration. I have actually seen a hint of motion blur using these units. So maybe that's why.
Thanks Dag. Capacitors losing their efficiency does sound more plausible than the tubes.
ISTR reading that speedlites have about 1/1000th flash duration at full power, so I can easily believe a studio strobe taking twice that or more. I heard Graeme Guy talk about his hummingbird paragraphs a few years ago. He freezes motion using seven small strobes set at 128th power which he esitmated gave 1/30,000th second flash duration.
Yes, I think that's right, I read something similar. Less power is achieved by shorter bursts, not by reducing the actual output.
I did get this one with the integrated flash on a Nikon D800. Why this shot was important is a different and long story, but this was at midnight out in a forest here in Norway, not under controlled conditions at all. It was dark, so I didn't want to fudge it by fiddling with flash controls. I waited two hours for this, camera on tripod.
But the interesting thing is that even here there is motion blur, seen clearly on the left. So yes, Graeme Guy clearly has a point.
i would assume power to be the real issue
Grahame, studio strobes are hugely more powerful than something like the Canon 580EX and 600EX speedlites. Google tells me they have up to 100W/S (watt seconds). My Bowens 500 lights are rated at 250W/S each, and IME, using them without a modifier requires me to turn the power way down to balance an interior with outside light. So I was wondering what the heck was going on when using both lights flat out in a smallish room with freshly painted white walls and ceiling was barely making a difference. I should seen massive overexposure with the settings I was using.
I think they are working OK now, and I'll be going back today so will let you know. I'd never heard of this sort of problem before, and I was anxious to hear other opinions, and I was, frankly, a wee bit stressed that I couldn't get my pictures with a very tight deadline.
I found an interesting troubleshooting and repair guide here:
"Cycling the unit at full power several times should reform a capacitor that has deteriorated due to lack of use. If the flash intensity and cycle time do not return to normal after a dozen or so full intensity flashes, the capacitor may need to be replaced or there may be some other problem with the power supply. "
This is strictly for people who know their way around high voltage electronic equipment. Don't be tempted to open it up and poke your fingers in it:
"the amount of charge contained in the energy storage capacitor may be enough to kill - especially with larger AC line powered flash units and high power studio equipment"