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Author Topic: Sekonic Lightmeter reading problem with Profoto B1  (Read 11447 times)

orc73

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Sekonic Lightmeter reading problem with Profoto B1
« on: October 14, 2014, 11:44:27 am »

Hello

I do have a 2 sekonic light meters they work fine with the Elinchrom.
If I turn on the profoto b1, they will go to E.u. or a very low F-Stop, Before I even fire. When I fire there is usualy no reading, meaning it would stay at the E.v.

The Light meters are set to flash.
If they would only go down to E.u after I fire them, then I would think it has to do with TTL stuff in the B1.
I do trigger the b1 with the profoto remote. No TTL remote.

But as it's jumping to E.u with only the modeling lights, there problem must be somewhere else.
I can switch off the modeling lights, but I want to use them.
If I mount an umbrella deep (indirect), it's fine and the modeling light does not disturb.
If I don't have a modifier mounted or the magnum dish, it reads from the modeling light.


How can I solve the problem?

best regards
« Last Edit: October 14, 2014, 03:06:00 pm by orc73 »
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Some Guy

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Re: Sekonic Lightmeter reading problem with Profot B1
« Reply #1 on: October 14, 2014, 01:23:25 pm »

Just a thought, if the modeling lights are LED they may be flickering at a high rate of speed (to save power and keep from overheating) and then fooling the meter as though they were a weak flash, hence a low underexposure reading.

I have a Sekonic color temp meter and I have to use a sync cord with flash at times with else I see the "Under Exp." warning from room lights that might be flickering (flourescents) and it thinking they are the flash.  It was mentioned somewhere in their manual in some "Exclamation point" in very small print.  I thought the meter was at fault and about ready to send it in for repair too, but seems it doesn't like the flickering lights along with a flash coming along later.  Said to use corded for flash and it fixed that matter.

I got around it by shutting off all the room and modeling lights to get the color temp off the flash.

Added:

When I did get around to using a cable, I found some flash units will not fire with the push-button on the C-500 meter using a cord.  Some external radio units will not trip either.  Turns out the flash firing switch inside the meter is electronic (Not a regular mechanical contact-type switch.).  As such, it needs some minimal current and voltage to operate the flash (Where it gets the power from.).  Maybe some sort of opto-isolator circuit in the meter.  Drove me mad with an ohmmeter trying to figure out if the switch was working, but it always showed an open even when pressed as the ohmmeter didn't have enough voltage to trip the electronic switch  in the meter.  Almost sent it in for that too.

SG
« Last Edit: October 14, 2014, 10:25:40 pm by Some Guy »
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orc73

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #2 on: October 14, 2014, 03:04:50 pm »

yes this is what I did when it happened the first time, I just grabbed a cable and it was working.
I did not have time to find out what is faulty.

However it is 2014. The b1 is promoted as a cable less head. now got to stick in a cable and hope the subject is not to far from the flash head so I could measure it :)

Really it would be very poor from profoto, if they produce a unit, that does not allow flash metering.

Profoto anybody in this forum?
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Conner999

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #3 on: October 14, 2014, 04:25:27 pm »

Interesting.

Could also pick up a used (non-TTL) simple AiR trigger or full (again, non-TTL) Air Remote and plug into sync port on the Sekonic to trigger the lights (full disclosure: I have one of the former for sale here). Stick a self-adhesive cold shoe on back of the meter, mount the AiR unit, a short cable and trigger away.  A fill AiR remote would also give you a backup remote to control power (manually) and trigger lights if your TTL unit went down.
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synn

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #4 on: October 14, 2014, 07:03:11 pm »

Another reason why I stick to pocketwizards is because the Sekonic meters have PW transmitters in them. It has never failed to give me proper readings scross various brands of flashes, but I must admit that I have not tried this system on the Profoto B1.
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orc73

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #5 on: October 18, 2014, 01:09:44 pm »

Synn,the Lightmeter is getting readings before triggering.
If the pocketwizard trigger in the sekonic does block readings between triggerin (just like the cable mode does) it could be a solution.
Adding a PW receiver to every flash unit(that has AIR build in), can not be a solution. not in setting up and not terms of cost.

Attaching the Air remote to a cable does work. Are you trying to sell me one Conner? :)
I don't have TTL anyway, I don't work with canikon.
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Conner999

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #6 on: October 18, 2014, 04:55:14 pm »

If you set the Sekonic to trigger just via a radio insert vs. "standby, wait to see flash", it would solve the issue (same as if plugging a PW or AiR unit via the sync port).

The only issue of course is that you'd need a PW receiver for the strobe(s).  

I used to use Sekonic 358s, but now use a Gossen and just plug an AiR unit into the sync port via a short cord. I also fasten one of these adhesive cold shoes (they're the same ones Profoto sells) on the back of the Gossen. Hell, I have them stuck all over the place.

http://www.bhphotovideo.com/c/product/613979-REG/Impact_9031540_Adhesive_Backed_Accessory_Shoe_2_Pack.html

I just wanted to mention I had a basic Air Transceiver for sale so it wouldn't LOOK like I was trying to sell one ;>  It's CDN$150 shipped in NA via Canada Post. No case, manual, etc. Just the unit and a lanyard. I have too many of them.  

Regardless if/where you buy one, the nice thing about having an AiR unit is that should the TTL version die, you have a spare trigger on hand. B&H also sometimes has them on sale used as well - including the full remote power-control version (which mine is not).

Your issue is an odd one and a PITA, but good to know. Light meters in standby mode picking up LED flickr is something no one thought of.  Many folks apparently see it in LED Xmas lights, etc - the flicker being caused by the AC line cycle and the driver used for the LEDs.

If Profoto made light meters, it might not have happened, but since it's a TTL unit, I think most users won't even notice.
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orc73

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #7 on: October 18, 2014, 05:26:19 pm »

I did not take it in a bad way, if you have something used to sell it might be of advantage for somebody!
It is a good idea and always good to have a spare one anyway.
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synn

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #8 on: October 18, 2014, 11:57:16 pm »

FWIW, my Quadra's photo cell goes off every time a CFL tube is switched on. It's very annoying, especially if the model isn't ready for a burst of strobe. So if I am in a location with CFL tubes, I keep them switched off throughout and/ or not use the photocell.

As for the meter, ever since I moved to the completely PW integrated metering, everything has been rock solid. You could go for the Plus X, which is cheaper and works just as fine. In fact, if I am not grouping, I prefer the X as it is a lot simpler to set up (And is more battery efficient) than my Plus IIIs.
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Conner999

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #9 on: October 19, 2014, 09:47:45 am »

No worries. If decide that's the way you'd like to go and interested, drop me a line - and thanks for the post.

I'll eventually be adding 1-2 B1s to my Profoto gear (currently AcuteBs, 1200s, Compact 600s and D1s) and it's good info re: the LED modelling light flicker.
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orc73

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #10 on: October 19, 2014, 12:29:35 pm »

Anybody else working with Profoto B1 and using a lightmeter?

I did try yesterday after 1 hour shooting, and the reading was fine suddenly. So I thought I might have had some wrong settings on the lightmeter.
Today switched them on, took the lightmeter: bam E.u. reading again. So it seems the problem disappears, when the light is on for a while already, and shows up when they are cold. I do only have 1 unit, bought it to test and decide if I want more of them.

Anybody outthere with a b1 or maybe d1? I wonder if it's only my unit causing problems.
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Conner999

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #11 on: October 20, 2014, 07:33:42 am »

I have D1s, but being line-powered, they have tungsten modelling lights, not LED, so no issues.  I've never heard of your issue, but with the B1s being TTL units I suspect most people wouldn't notice. You might have a bum LED or, it or the electronics driving it could, for some reason, just stabilize (e.g. not flicker) as it warms up.

Please let us know if you ever find an answer.
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Ellis Vener

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #12 on: October 21, 2014, 03:52:06 pm »

When i had a loaner B1 from Profoto, I also tested output with the AirTTL in manual trigger mode and metered the output with a Sekonic L-758dr (also set to cordless but not radio mode) and did not have the issues like you describe.
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orc73

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #13 on: October 27, 2014, 06:32:39 am »

The answer from Profoto support:

"The LED light from the B1 is a modulated square pulls. The LED needs fixed voltage, and there for the variation on modeling light is controlled by a pulls length modulator. The pulses can be measured as a flash pulls from the light meter, so recommendation is to switch of the modelling light when using the flash meter."


The good thing, Air Remote has a button to turn off the modeling lights, which makes it easier then with other brands. So I do that for metering after I found the position.

Maybe softboxes and umbrellas will dim the modeling light in some circumstances, if you are a bit farther away, to be less prone to the problem.
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adi.tanase

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #14 on: November 13, 2015, 01:27:12 pm »

Hi,

I have a B1 getting the same E.u. error on my L-758DR. The way around it was to increase the modelling light to 100%.

Regards,

Adi
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MarkL

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #15 on: November 13, 2015, 03:37:21 pm »

Hi,

I have a B1 getting the same E.u. error on my L-758DR. The way around it was to increase the modelling light to 100%.

Regards,

Adi

Yes, that will be the other option based to the fact the output level on modeling light is controlled PWM; no pulsing = no fooling of the meter.

Modelling lights on battery strobes are so low on power and drink battery so fast I've never used them.
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Neil Williams

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Re: Sekonic Lightmeter reading problem with Profoto B1
« Reply #16 on: April 23, 2016, 02:10:46 pm »

Guys
I have the profoto B1 heads and I am in the market for a new meter, with the Sekonic L-758DR now fire the flash for a test shot??
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