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Power Comparison of Yongnuo YN-565EX, Neewer VK750 II, and Nikon SB-800 Flashes

Three flashes are metered, Yongnuo YN-565EX, Neewer VK750 II, and also the Nikon SB-800 for reference. The idea is about comparing their actual power, and to show what their expected aperture results might be, in an umbrella and also direct flash. Each flash is metered with a hand-held incident meter, and this value is used for an actual picture to be able to judge and verify it.

All of the pictures should be equally exposed, because all were metered individually to make that be true. The actual camera f/stop metered and used for each is shown for comparison.

All pictures below are ISO 100, with D800, 1/125 second shutter. Flashes are always 1/1 Full manual power level, and zoomed to 24mm. Each flash is placed on the same light stand.
Each flash is metered from above the brown bear's ear, to ensure from exactly the same location (incident reading with Sekonic L-308S meter).
White Balance is individually corrected on the Porta Brace White Balance card in Photoshop CS6 Adobe Camera Raw. Correction leaves the card being a neutral color with equal RGB components (no color cast).

Metered in tenth stops, which are just that... A third stop is + 0.33 stop, and 2/3 stop is + 0.67 stop.
f/5.6 + 0.9 stop is almost f/8.   f/5.6 + 0.6 stop is f/7.1 (2/3 stop past f/5.6), etc.
The necessary nearest third stop camera aperture setting might be up to 0.17 stops different than the true metered value.
FWIW, the purpose of tenth stops is for adjusting multiple lights. If we want fill ratio to be 1.2 stops less than main, we immediately know in our head that 1.2 stops less than f/5.6 + 0.9 stops is f/4 + 0.7 stops. Try that with f/7.1. :)

45" white reflected umbrella close, at five feet to fabric


Yongnuo YN-565EX
Metered f/5.6 + 0.9 stop
Camera is at f/8 (0.1 EV less than meter)
White Balance 6400K -4 tint
Power difference: 0 EV base

Neewer VK750 II
Metered f/5.6 + 0.1 stop
Camera is at f/5.6 (0.1 EV more than meter)
White Balance 6600K -12 tint
-0.8 EV

Nikon SB-800
Metered f/5.6 + 0.6 stop
Camera is at f/7.1 (0.07 EV more than meter)
White Balance 5950K +2 tint
-0.3 EV

45" white reflected umbrella at ten feet to fabric


Yongnuo YN-565EX
Metered f/4 + 0.2 stop
Camera is at f/4.5 (0.13 EV less than meter)
White Balance 6300K, 0 tint
Power difference: 0 EV base

Neewer VK750 II
Metered f/2.8 + 0.5 stop
Camera is at f/3.5 (0.17 EV more than meter)
White Balance 6400K -12 tint
-0.7 EV

Nikon SB-800
Metered f/4 + 0 stop
Camera is at f/4 (same as meter)
White Balance 5800K +2 tint
-0.2 EV

Bare direct flash at ten feet (flash moved to be where fabric used to be)


Yongnuo YN-565EX
Metered f/5.6 + 0.8 stop
Camera is at f/7.1 (0.13 EV less than meter)
White Balance 6450K -8 tint
f/7.1 x 10 ft computes GN 71 at 24mm
GN chart in manual says GN 91.9 (feet)
Power difference: 0 EV base

Neewer VK750 II
Metered f/5.6 + 0 stop
Camera is at f/5.6 (same as meter)
White Balance 6400K -18 tint
f/5.6 x 10 ft computes GN 56 at 24mm
GN chart in manual says GN 91.9 (feet)
-0.8 EV

Nikon SB-800
Metered f/5.6 + 0.6 stop
Camera is at f/7.1 (0.07 EV more than meter)
White Balance 5850K, 0 tint
f/7.1 x 10 ft computes GN 71 at 24mm
GN chart in manual says GN 98 (feet)
-0.2 EV
FWIW, another test with another meter in another situation verified these (24mm zoom, direct bare flash at ten feet) as:

Yongnuo YN565EX f/8 + 0,   VK750 f5.6 + 0.2,   Nikon SB-800 f/8 + 0

Bare flash at ten feet. It is the same images as above, but now shown with standard 5500K Flash White Balance


Yongnuo YN-565EX
White Card is RGB(243,245,248) 5 diff.

Neewer VK750 II
White Card is RGB(239,242,247) 8 diff.

Nikon SB-800
White Card is RGB(239,241,242) 3 diff.

The Yongnuo and Neewer may have a slight blue or green tint, and it can be worse at low flash power, but you can see that it's a rather minor effect in this try. Still, it's always satisfying to know we made it perfect.

Re Exposure: Here the red in the flowers is very bright, and the red clipping needs -2/3 EV compensation to fall to 255 (the white card is well less than that level). The 18% gray card is just above midpoint, and it should be a little below. Not saying the light meter is wrong (it's much more complicated than that), but red really gets boosted in Flash or Daylight white balance (even more in Cloudy or Shade WB).


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