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Precision of Flash

rem

New member
How exact did you photographers find the output from your flash (mono and generator)? Normally you can make 1/10f steps. But already when you test it from one full stop to the other, what is your experience? Anyone made a test?
When I go from 4 to 5 (one fill stop) and I measure it with a Sekonic 558, then its only 1/2 stop. Sometimes at higher level its much more precise. Also, the 7stops fits exactly, but with finer steps and lower levels...
Or see I something wrong?
Thanks, rem






(I tested it with the new Hensel Porty 1200L and the new Hensel Expert D"
 

Godfrey

Well-known member
How exact did you photographers find the output from your flash (mono and generator)? Normally you can make 1/10f steps. But already when you test it from one full stop to the other, what is your experience? Anyone made a test?
When I go from 4 to 5 (one fill stop) and I measure it with a Sekonic 558, then its only 1/2 stop. Sometimes at higher level its much more precise. Also, the 7stops fits exactly, but with finer steps and lower levels...
Or see I something wrong?
Through testing with a flash meter and experience. I ignore what the manufacturers' output ratings are.
 

rem

New member
Yes Godfrey. But on the other side it would be practical if you now that when you reduce one Stop on the flash it is also one stop in the light and not only 1/2 f stop...
Anybody measured with his flashes? Thanks!
 

Godfrey

Well-known member
Yes Godfrey. But on the other side it would be practical if you now that when you reduce one Stop on the flash it is also one stop in the light and not only 1/2 f stop...
That's the point of making my own measurements. Once I've measured the response curve of the flash unit, I know what the settings will produce.
 
L

langone_peter

Guest
I found this flash disappointing. I am not a professional photographer but I am experienced and have owned Cannon SLR's and done some medium format photography. To the positive it does tilt, swivel and the flash head does have a 4 position zoom shroud. It has an auto sensor that is designed to adjust the power of the flash. It comes with a PC cord which the instructions indicate, "is NOT required for normal use,"

Regards,
Peter Langone
 

fotografz

Well-known member
How exact did you photographers find the output from your flash (mono and generator)? Normally you can make 1/10f steps. But already when you test it from one full stop to the other, what is your experience? Anyone made a test?
When I go from 4 to 5 (one fill stop) and I measure it with a Sekonic 558, then its only 1/2 stop. Sometimes at higher level its much more precise. Also, the 7stops fits exactly, but with finer steps and lower levels...
Or see I something wrong?
Thanks, rem

(I tested it with the new Hensel Porty 1200L and the new Hensel Expert D"
How are you performing this test?

Distance from strobe head to subject will affect meter readings ... pretty drastically actually.

Did you test everything as a constant (same modifiers, same distance to subject, and same position/direction of the meter)?

Just for kicks, I just ran a test like this using my Profoto D2400 generator and one head with a beauty dish modifier. Constant placement/direction of the Sekonic Flash Master L-358 light meter with built-in Pocket Wizard trigger, and I did multiple separate pops to be sure at each setting.

The meter was set 27 inches away from the front of the beauty dish, and was directly facing it.

Lowest setting is 19w/s @ f/9 every time ... 38w/s @ f/11 ... 75w/s @ f/16 ... 150w/s @ f/22 ... 300 w/s @ f/32 ... as so on. These are full click steps on the D2400 digital control dial.

At 19 w/s, when I moved the meter 6 inches further away ... 6 inches! ... the f stop dropped from f/9 to f/8, and at a 9 inches away it dropped to f/7.1 and 2' more inches away it dropped to f/6.3 ... I was able to repeat this multiple times.

Moral of the story is that tests must be extremely consistent in distance to meter ... especially when the inverse-square law is applied as the distance from the light grows further (where a subject at twice the distance receives only 1/4 the energy).

-Marc
 

johnnygoesdigital

New member
+1 for the inverse square law. Also, when measuring a multiple light set-up, make sure the white diffuser is pointing directly at the light to be measured, recessed into the meter itself, so as to NOT be influenced by the others. As Godfrey mentioned, knowing the response curve regardless of what the manual says, usually produce good consistent results.
 

fotografz

Well-known member
+1 for the inverse square law. Also, when measuring a multiple light set-up, make sure the white diffuser is pointing directly at the light to be measured, recessed into the meter itself, so as to NOT be influenced by the others. As Godfrey mentioned, knowing the response curve regardless of what the manual says, usually produce good consistent results.
Or turn off the other flashes and measure each one separately.

-Marc
 

rem

New member
Marc, shure, I fixed everything, so the Distance, the Sekonic, the Reflector etc. I made also everything in the atelier with black and grey walls, to avoid any uncontrolled lights. From minimum to maximum is perfect 7 stops, but not so between. Will see, how the new one is working....
 

rem

New member
To update, yesterday I received the new Porty 1200L. No bigger difference then 2/10 stops and very linear. ;-)
rem
 
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