Sekonic 758 calibration procedure

[frank]

I've always done my calibration of the lightmeter by hand.
Just shoot an 18% graycard, check if the spike is dead center and if not adjust the lightmeter untill the meter reads what is needed.

With the upgrade to the new Sekonic software this option is done with.
I still don't have a clue about what Sekonic was thinking by making this route impossible, well I do think I know......
For the calibration of your meter you now need a target from Sekonic, and the lovely thing retails for app 160.00 euro.........
Add this to the not so low price of the 758 and you can imagine why I'm not happy that the option to manually calibrate your meter is gone from the software.
Sekonic is now FORCING people to buy their target or otherwise you can't calibrate the meter anymore.

After I got over my anger (and I really can get angry about this) I ordered the target and decided it was time to calibrate my meter according to the target.

Setting up the lights is of course the same as with the manual procedure, make sure the whole target is illuminated evenly.
Now take a measurement and adjust the lights to f11....
Why f11 you might ask.
Well Sekonic wants three pictures, one 0 EV and one -3EV and one +3EV.
For me that meant switching lenses on the Mamiya 645AFD/III simply because my 105-210 did not have the reach needed, it starts at f4.5 and ends at f32, and we need f4 to f32.
Luckely the 120mm Macro I use a lot for my work does have this range.

After taking the shots and running the automatic calibration procedure the results were dissapointing.
My meter out of the box underexposes 1/3rd of a stop, after calibration it underexposed 1/10th more.
What was going wrong ??
To be honest I still don't know.
Whatever I tried the unit underexposed by 4/10th after calibration.

Finally I decided to fool the software and added +3/10th in the first setup, this works perfectly and my meter is after the procedure 100% accurate on both reflective and incident for ambiant and flash.
It took me (after I figured out the offset problem) app 30 minutes to do the whole setup of the leaf Aptus on 25/50/100/200/400 ISO.
So that's fairly quick.

The procedure itself is rather painless.
You make the shots and in the software you edit the profile of  the camera you want to change.
Let's say camera 1 Leaf Aptus on 645AFD/III
You will now be promted for the ISO and the measurement your meter gave you while you shot the target for incident and reflective.
Now it will import the files.
When the files are loaded and there is no exif you can set it manually (as I had to do for the Leaf).
After that you have to set 4 crosshairs on the corners (very easy) and you can start calculating, well the computer does the work.
A nice diagram is shown with the clipping points and the middlegray part and that's it.
Safe and upload.

And repeat for all ISOs.
Glad my camera has only 5

It all is a good procedure and what I can see the results are constant, I did it several times and for ALL ISOs the results were constant.
The only problem I experienced as mentioned before was the offset of 4/10th.

The first you think about is human failure however that is not possible in this case.
You shoot the target with the 18% gray patch, the graypatch is selected and the picker shows 3/10th underexposure.
Now everything is run through the procedure and voila we now have a 4/10th underexposure.
Remember this is by shooting the SAME target with the SAME lightsetup.

The only thing that I can imagine is that because I have to convert to JPEG from the Leaf software there is a problem there, but I did not have the time to check this (it's rather late now) I will however check this tomorrow.
To be honest that is also a problem I have with the procedure as it is now.
In the old situation you could work straight from the RAW convertor, look at the problem, adjust in the software manually and upload and shoot again.
Now because everything is in a wizard form you have to convert to jpeg/tiff and use that as a source.
That means you are taking into account the conversion and the problems that can happen with the conversion into your calibration.

In the end you can fool the software like I did with an offset but I think most consumers don't double check their calibration and will end up with underexposed or maybe overexposed pictures.
So a good tip (and you should actually always do this) :

AFTER CALIBRATION CHECK WITH A 18% GRAYCARD IF THE SPIKE IS IN THE CENTER IN YOUR RAW CONVERTOR....

(sorry for shouting).

Overall I like the way Sekonic is doing the calibration, however I think the pricing of the target should be lower or free with the meter, because let's be realistic when you buy a meter that retails for app 700.00 euros 160.00 for a target to use the meter is a bit...... well overkill ?


Order your Sekonic 758 from BH on http://www.bhphotovideo.com/c/product/460371-REG/Sekonic_401_758.html/BI/6344/KBID/7055

[Kim Bentsen]

It would be nice if the radio unit in the 758 could be swithed with an elinchrom skyport compatible unit, so you could trigger without pocket wizards. I realise you could add a pocketwizard for triggering purposes but that is crazy when you already have skyport units.

It would be even nicer if Sekonic would add the "+" and "-" button to the meter so you don't need the skyport transmitter in one hand.

Hey, they could do a radio unit for each flash manufacturer, or allow the flash manufacturer to supply such a unit as an add-on. When Quantum can reverse-engineer Canon and Nikon ETTL-II, Sekonic could do the same for Elinchrom and others.

[frank]

It would be nice but I think money is a big issue.
The skyports are gaining much popularity so who knows.
At the moment I just have two triggers one for on the camera and one to trigger the strobes when measuring.

[raffi]

Hi Frank

can you tell if ther is differences with th 538 so why did you choses this one since 358 look about the samefor studio use ?

[Steveathome]

It can still be done manually Frank, but takes a little time.

The problem is getting your head around inserting the values to upload the data to the meter - again this can be done manually, but what a bind.

The target is expensive, but personally I do find mine accurate when matching the values to 118 118 118. I did use Photoshop, but nulled all settings first in the hope for a flat response histogram. It seems to work very well, as now I open all my raw files with settings nulled (it seems to make sense as thats how the meter was calibrated).

[frank]

I choose the 758 for the spotmetering and the option to store 3 cameras per ISO.

I did not know it was still possible to manually add the settings.
I asked a tech on Photokina and he confirmed that it was only possible with the old software.
Maybe if you can edit the profiles and store them.

I try to balance on 127,127,127 because that should be the center of the histogram.
It does indeed balance on 118,118,118 but with the offset it works fine for me at the moment.

[Eero Makela]

I am now glad my 358 does not have a computer interface no need to deal with a 160.00 target.

Frank is it possible that the reason you are off by about 1/3 is the difference between 18% and 12% , that ANSI standard that may be what Sekonic calibrates to?

I have a 30+ year old Kodak Gray Card that I have only recently started using.

Is it possible that the gray has changed over the years?

I recently got a 3 shade smaller card (White, Gray, Black) target, as the Nikon NX program has
a option to pick these 3 color points for setting the balance.

I may some day get a SPOT scope for my 358. We did a test with my Ambient head and another Sekonic that has spot scope. Dave the instructor took my meter and walked right up to the backdrop and measured the reflected light up close pointing toward the backdrop and it measure close to what his spot scoped did from the camera position. So it looks to be possible to do spot reading this way as well. Not as easy but cheaper.

[frank]

The simple thing is that 18% gray should register as a spike in the dead center in the histogram.
So when I shoot the graycard it should be a spike in the dead center.
When I calibrate the meter it should also render that spike in the center.
When it calibrates to 12% it's not accurate as it should.

But maybe it's just me

I just want when I shoot something and measure it that it's rendered the way it is in real.
The 18% graycard is a great way to check this.
I don't want my meter to underexpose so I have to correct.

[Eero Makela]

http://www.sekonic.com/images/files/HistogramsLightmetersWorkTogether.pdf

here is a cool PDF file. I know may have seen it but it is still useful information

[inkyneil]

Thanks for sharing the link to the file Eero! I think I should seriously calibrate my lightmeter after reading this post.

[Derk]

It would be nice if the radio unit in the 758 could be swithed with an elinchrom skyport compatible unit, so you could trigger without pocket wizards. I realise you could add a pocketwizard for triggering purposes but that is crazy when you already have skyport units.

I'm afraid, chances of that are not big als Sekonic has not only liaised with Pocket Wizard, but with Profoto as well. Profoto being probably the closed rival in the market for Elinchrom, I imagine Sekonic/Profoto must have struck some kind of deal about using shared technology which, business wise, would make system integration with Elinchrom not very logical. unfortunatelly 

[frank]

An answer on the subject I posted on OPF.
Maybe good to also bundle that here.

I don't know what the problem is with your meter but I do know what I experienced and it's similair and I have a FEELING I know what's going "wrong".

In photography 18% gray will render a spike in the histogram dead center.
When you calibrate your meter it would best be with photographing a 18% graycard with a very large lightsource so there is even light on the card.

When you look at the histogram in your RAW convertor (with everything flat) the spike of the card should be dead center, if it's underexposing set the meter to the value it's underexposing, measure again, adjust the light, measure again and take the shot, now it should be ok.

With the new 758 software you HAVE to use their card, which is a big FLAW in my opinion, with the last software you did not have to do this and you could manually take the shots and add the offset in software.

The first problem I have with the card is that I can't use all my lenses, it's simply with the MF system not possible to take the whole range of exposures (most lenses have a range of 4.5-32)
But I do have one 2.8-32 so I did it with that lens.

When you do EXACTLY as the manual states my meter underexposed app 1/3 off a stop.
It really puzzled me why this happened and to be honest it drove me nuts.
I tested it with both the Leaf system on the RZ67ProII and the 645AFD/III and finally I did the same with the Canon 5D, all three were CONSISTANT in their underexposure.

What I did was give an offset of -1/3 stop in the first option (what did you measure) and after that the calibration process was flawless and the meter did exactly what it supposed to do.

I know that a lot of camera makers are not working with 18% gray anymore but with 12% gray, this is mostly used as far as I understood to make sure the exposure of the reflective metering IN THE CAMERA is protected against blowing out highlights.
This would explain why the meter is underexposing I guess.

HOWEVER for a METER this is incorrect in my opinion.
A calibrated meter should render the subject you measure ACCURATE.
And the "laws" still say that 18% gray should render a spike in the dead center of the histogram, not 1/3rd stop down.

I have talked about this with Sekonic but got no response, which I think is weird.
The funny thing is that you see alot of people on the net praising the calibration of the 758DR and that's it's the best thing arround while they clearly are using a meter that underexposes........
The problem is that they probarbly trust the calibration process and don't check it, and still use photoshop to change the exposure slider.

I have calibrated the 758 the way I described and I have perfect exposures with the meter (never have to use the exposure slider with the 645AFD/III and 5DMKII) so the meter is VERY RELIABLE and good, but the new software in my opinion is faulty.

But I COULD BE WRONG.

[apneaimages]

I have try to calibrate my Lightmeter, with the exposue Target that i have but the software (data transfer Software 2.0) crashes.
I have try it both in my stationar and laptop and get the same problem. Its crashes after i upload the 9 files and push the button to analyse the data. 

[frank]

do you use a mac or PC ?
It did crash sometimes with me but not straight after booting.

[apneaimages]

Its PC  Frank , Both are Windows XP pro.
I try again to reboot clean and to see what happens.