Calibration lightmeter

[Wilfred]

Last night I've used the simple description you mentioned for calibrating youre lightmeter...

It works perfect!

When I metered the light an than took the picture I saw the hystogram realy close to the center, it is not 100% the centre, but when I change the ISO with 1/3 of a stop the deviation starts to grow to one side or the other. So the lightmeter is close to perfect and the deviation is less than 1/3 of a stop.

I never had the stress to calibrate the device because the results were always good. Before a shoot begins I measure the light with a static object, when the model(s) are coming (in my case often people who never have been in a studio) I position the people and take the first shot which is most of the time a winner. When people see this they come faster in the flow of spontaneous pictures.

Beside this -> It's important to regular maintenance youre equipment. It's the aspect of photography you whant to be sure about (wise lesson from a guy named Francis Doorhove  ).

Tnx Frank

The only extra advise I can give is: won't sit in front of your lightbox after you metered! You will dimm the light... Sounds normal, but for me it was a discovery

Here is the articel I used:

Hi,
The procedure is really simple.

Get an 18% graycard and measure like you would normally measure your model.
Take a shot of the graycard and look in your raw convertor (in the colorspace you normally use).
The spike in the histogram of the 18% gray card should be in the center (arround 128.128.128)

When it's not the case (as it is in most cases) you can do a few things:

For Sekonic : press the two ISO buttons and set the offset.
Now remeasure and adjust the strobes and do the same thing, untill the spike is in the center.

When using the Sekonic target and software (758) set an offset of 1/3 fstop in the software when it asks what you measured.
Now run the procedure as normal and it should render 18% gray as 18% gray.

[Eliot Baker]

Sorry Frank,
     Im pretty new to photography but I just dont fully understand.   Are you saying I can calibrate my light meter in camera?  or is your procedure require the use of a computer?  Can you explain it in more detail, step by step?  I have a Sekonic 758 and a Canon 1D Mark3.  I have PS CS4 and Lightroom2.  Do I meter with a grey card to fill the whole frame?  Do I shoot with strobes to calibrate?  Do I use the histogram on the back of the camera or in lightroom or photoshop?

[frank]

Hi,
It's really simple.

Take an 18% graycard.
Measure that card as you normally measure.
Shoot the card.
Check the histogram in your RAW convertor fitting YOUR workflow.
The numbers should be around 128.128.128 or in other words in the middle of the histogram.

IF NOT (and it's often not).
press the two ISO buttons on the Sekonic and adjust the offset.

Now start from square one.

It's really deadsimple, nothing special.
Total time it should take, not more than 1-2 minutes.

Remember to set your lightmeter to measure on 1/10th stops.

[Eliot Baker]

just to make sure:  set up the shot as usual, set up the grey card on the set, meter it with the sekonic and lets say it says 5.6 at 1/125 (i know when using a stopbe  in studio shutter speed doesnt matter much for exposure unless you want more abient light and cant go over about 1/200th on dslr cameras due to the type of sutter).  then upload the image in, lets say lightroom, and crop the image to the grey card and look at the histogram?  or when i shoot the image fill the frame of the camera with the grey card?  (not sure bout that one) then go to the histrogram in Lightroom.  whichever one you say is correct..then adjust so the histrogram reads as close to 128,128,128 as possible?  is what im saying correct?    so i just need to know how to shoot the grey card.  By the way you really do live by what you say and answer very quickly!  thanks for all your help and love your work!!

[frank]

Hi,
It's easier just hover over the graypart and your program should tell you the RGB values.
If they are for example 110,110,110 adjust your meter for -1-2/10th and see what happens after that.
Shutterspeed should indeed be 1/125 for the studio.

[Eliot Baker]

ok thanks a lot!!  I'll try that and let you know.  Thanks again.  Hey do you ever come to the San Francisco Bay Area?  If so look me up.  I'd love to meet you, in person or if you teach any classes out here.  I was lucky to find a pretty big studio on Treasure Island (an old Naval Base) and your more than welcome to use it.  (As long as you teach me some tricks...lol)  thanks again.  i made a video of my studio if you wanna check it out:


http://www.youtube.com/watch?v=rUGDs3jpoU8

[frank]

Hi,
Amazing space.
For the workshops on site it's very simple.
If you can help organize it and get the crowd I'm there, that's also how we did LA and NY and of course the European workshops.
You can always mail me for more information.

I do have some people in LA that want me to come back so maybe we can make you all connect, would love to visit SF.

[Eliot Baker]

OK Frank!!  OMFG!!   The calibration worked perfect exactly how you explained!!  I just had a hard time understanding but you were exactly right, took like 2 min. flat!  i shot and exposed as I'd regulary do and shot tethered to a laptop to Lightroom2 on a grey card with the black grey and white.  Then, what I did, was crop out the other parts so just the grey was shown and just like you explained, the spike in the middle, well it was off my about 4/10ths so I adjusted and then about exactly in the middle it spiked!!  Then I shot my friend, a really beautiful woman, and it was exposed perfect!  Thanks Frank!  I'll put you on the list of my heros,  your up there with Joe McNally, Scott Kelby and some others...lol. 

     I'd love to organize having you come out here and come do a workshop in my studio!  I've never organized something like this before so not sure where to start, besides talking with you now.  If your people in LA are willing to come up here I'm more than willing to  lend my studio for the cause!  Actually, my studio has a little more "flavor" than my video shows.  It was the old Navy Brig and down stairs there is a cell block and control room and all.   Also in the main building there is a air traffic control tower that I can get access too also. 
     If you can give me a lil direction as to what would be needed to organize this.  You say a class of 12?  how mayny days do your classes go for?  what equipment would you need?  I have 2 Elinchrom ranger packs with S heads and 1 BXRI 500.  but i have a friend who has 3 ranger packs with A heads.   i have 2 53in mini octas, 1 6 foot octa bank, a small beauty dish, 2 sets of gids.  and my friend has numberous soft boxes and light modifiers. 

[frank]

Hi,
Please mail me at info@frankdoorhof.com and we'll work something out.