Yongnuo Flash Guide Numbers

The information in this post is outdated, you find more comprehensive information on the Yongnuo flash comparison page.

Yongnuo publishes guide number 33 (meters) in the instruction manuals for the YN-460, YN-462, YN-465, YN-467 and YN-468 models. At the same time, the newer ones have recycle times of only 2 seconds with alkaline AA batteries (these are measured values), and compared to the Canon and Nikon middle class, you wonder how that can be. Here is a table with the numbers:

Model Guide number
(as specified, meters)
Recycle time
(as measured)
YN460 33 5 sec alkaline
YN462 33 / 28? 5 sec alkaline
YN465 33 5 sec alkaline
YN467 33 5 sec alkaline
YN468 33 5 sec alkaline
430EX II 31 3.0 sec alkaline, 2.0 sec NiMH
SB-600 30 3.5 sec alkaline, 2.5 sec NiMH

 

Stronger and Faster than SB-600?

So we have shorter recycle times and at the same time a higher guide number on some of the Yongnuo models!?

Well, this is an example for how manufacturers sometimes post a number that is too optimistic whereas other manufacturers’ numbers are much closer to real life – like Nikon in this case. Canon specifies a guide number of 43 at 105mm (maximum zoom), but this comes down to 31 at 35mm. I use 35mm as the reference focal length on this site as it is both relevant for real life photography as well as the standard focal length for many of the flashguns without a zoom reflector – like the Yongnuo’s without zoom, but also the legendary Metz 45 series for example.

Yongnuo flash: 2 seconds recycle time

On all my Yongnuo’s and also the Nikon SB-600, I did my own recycle time testing already. And here these units do shine, at least the YN-465 and the YN-468 that I own: they need a mere 2 seconds at full power, both with AA alkaline batteries as well as with NiMH rechargeable batteries. My two YN-460 flashes need 9 seconds to be recharged with alkaline batteries, but they meet the 5 seconds specification with NiMH.

Yongnuo YN-460 battery door

Model Specified recycle time Measured recycle time
YN460 w/ alkaline approx 5 seconds 9 seconds
YN460 w/ NiMH not specified 5 seconds
YN465 w/ alkaline approx 5 seconds 2 seconds
YN465 w/ NiMH not specified 2 seconds
YN468 w/ alkaline approx 5 seconds 2 seconds
YN465 w/ NiMH not specified 2 seconds

 

So in that respect, Yongnuo meets or clearly surpasses their own specification. But let’s have a look at the guide number now.

Real Yongnuo Guide Numbers

In my experience, the flashes from Yongnuo are usually strong enough for everyday photography when it comes to their power output. At the same time, they clearly did not seem stronger than my Nikon SB-600, but I rarely have to rely on full power anyways. On the flickr strobist boards, people have speculated about the Yongnuo guide numbers, and on lightingsrumors.com you can find a guide number of 24 for Yongnuo.

Yongnuo Guide Number Test

According to wikipedia, the guide number is a measure of a flashgun’s ability to “correctly illuminate” a subject at a certain focal length and ISO. A guide number of 33 thus means that the flash unit is able to send out enough light to illuminate a subject 33 meters from the flash unit away if f1.0 is used. At f4, the subject can be max 33/4 = 8.25 meters away and at f11 the maximum distance is 3 meters.

The only tough thing here with a quick test is the “correctly illuminate” part, as this is a subjective measure for me outside of a lab situation. But let’s give it a try.

Scene 1: Indoors

For the first test shot, I mounted the strobe on a lightstand and triggered with RF-602′s. The transmitter was mounted on the camera’s hot shoe. As you might see from the pictures the camera was hand held, so some small errors due to slightly differing frames introduced here. But the whole test was not meant to be scientific anyways.

I fired the Yongnuo at full power and adjusted the f stop on the camera (manual mode) to the point where I had an exposure close to the right border of the histogram, but not overexposed yet.

Then I replaced the Yongnuo 465 with a Yongnuo YN-460 and got exactly the same result. And also with YN-468 – these units are identical in guide number. Next model was the Nikon SB-600 – zoom reflector at 35mm, so that is is identical to the Chinese flashguns. At f8, the image was clearly brigther. Next stop downwards is f9 on my camera, and there the result looked quite similar to the Yongnuo outcome, there was a bit more light on the frame actually. But at f10, the Nikon image was darker clearly.

Yongnuo guide number test vs Nikon pt 1

Scene 2: Outdoors, reflective subject

Scene number two was taken outdoors, as I wanted to eliminate any reflection from walls or ceilings in my house. It showed over time that there was another source of reflection in the frame, which is the subject itself. But again, I got a similar result: Yongnuo was a third stop behind the Nikon: f10 versus f11.

Yongnuo guide number test vs Nikon pt 2

Scene 3: Outdoors, wooden fence

To eliminate the reflection, I shot a darker scene in the form of a wooden garden wall. In this case it’s actually not easy to evaluate if you look at the pictures alone, but the histograms tell a story: Nikon SB-600 at f4.5 is pretty much the same histogram as Yongnuo 465 at f4, whereas the histogram shows a clear difference at f5 with the SB-600 at full power. And from f4 to f4.5, we have the 1/3 stop difference again, just like in the 2 previous scenes.

Yongnuo guide number test vs Nikon pt 3

Result: Guide number 26.5 for Yongnuo

Assuming that the Nikon SB-600 guide number is true to the 30 that is published in their handbook, then Yongnuo 460-462-465-467-468 can’t be 33, but must be lower than that. From the f-stop ratio 4 / 4.5, 10 / 11, and 8 / 9 in the 3 test rounds, I come to a 10% to 12.5% difference, and that must also be the difference in guide numbers, as the 3rd variable in the equation (the distance) was kept constant.

GN 30 minus 10% is GN 27, and GN 30 minus 12.5% is GN 26.25. So the guide number of the Yongnuo models 460 (mk1), YN-462, YN-465, YN-467 and YN-468 is around 26.5 roughly, according to my testing. Weaker than the middle class from Canon and Nikon, but stronger than the entry level models SB-400 with its guide number of 21. Canon’s entry level model is the 270EX, and guide number is 22 (or 27 at the 50mm setting, but we’re comparing at 35mm here).

With this guide number, Yongnuo sits between the middle class and the entry level class from Nikon and Canon in terms of power. But not in price: when it comes to value, they offer more bang for the buck.

Where to find Yongnuo flash

Yongnuo speedlights are available from the official Yongnuo store “hkyongnuophotoequipment” or from other sellers on eBay.

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