Godox K-150A - weaker than an SB800.


Godox have been producing some good value products lately, flashes, studio strobes, fittings etc. I bought an E300 studio strobe for around $75 a year ago and it has worked well in my ‘garage-studio’.

I recently purchased a Godox K150A on Aliexpress for around $40 which included shipping which is a VERY good price for a 150Ws flash/strobe IF it actually is that power. When it arrived it felt very light which isn’t always a bad thing with these days, things are getting lighter, smaller and more powerful with advancing technology. I fired it a few times and wondered if I was judging correctly because it didn’t quite look all that powerful at full power, so the only way to be sure would be to test it against my trusty Nikon SB800. I looked up the Ws rating of the SB800 and found this discussion and this one suggesting that it is about 75 Ws - meaning that the Godox K-150A should be twice as powerful.

One thing you need to remember with the K-150A is that is has a remote sensor that is ALWAYS on which can be quite annoying. If you compare its power with another flash you have to keep turning it off at its main switch so it doesn’t also fire when you fire the other flash. I imagine this would be a major nuisance to some users, maybe not a big deal for those on a budget.


The strobe tube itself looks like it means business as well and I imagine it could take a fair bit more energy than the smaller Nikon SB800 flash tube could. I decide to place them side by side in my garage and do a few tests to be sure it was a fair comparison - after all, the SB800 can zoom while the K-150A is a bare bulb flash.


Please excuse the scene, the 'dark circle on the garage door is due to a potassium nitrate and wax smoke bomb explosion - it made quite a mess but I leave it there as a reminder to use an insect smoker rather. Here is the plain bounce flash test, both the same distance from the ceiling, camera settings D7200 iso100 1/100th f11 to give me an idea of the power it would have in daylight. [I know the sunny 16 rule but most days have enough haze to only require an aperture of f11]. Notice the power difference? The 75Ws SB800 seems to be more powerful than the “150Ws” K-150A! I used the Sigma 8-16mm lens at its widest setting on my D7200 to show all the light in the scene.

Bounce flash.jpg

Now for the direct flash test. The SB800 was at its widest setting and of course the K-150A only has one setting and fires at a much wider pattern. Here they look quite similar when you look at the ceiling, but when you look at the centre the SB800 is brighter - the K-150A is throwing most of its light outwards and upwards towards the left - the floor is darker as well.

direct flash.jpg

Now we try to even things out a bit - I set the SB800 at full zoom and put a standard reflector on the K-150A. The K-150A still seems to fire upwards and to the left a bit more than expected.


Then of course the way most people would use it, with a softbox.


The strobe head was battling to stay up with the relatively light weight on it - perhaps it’s best to use this strobe with a shoot through umbrella rather. It has a fitting that doesn’t have any means to tighten it - just a spring loaded clip that holds the shaft in place - for now, if it lasts. With the SB800 I used a hand-held S-mount adapter which holds the flash nice and central, and I had the flash at its widest zoom setting. Both lights are feeling the strain of trying to light a subject through double diffusion - but the SB800 still looks twice as powerful as the “150Ws” Godox K-150A.


Conclusion: The Godox K-150A is NOT a 150Ws flash, unless of course I got a dud. We’ll see what the supplier says when I contact them. On a few discussions it was suggested that because the K-150A spreads its light over a much wider area it would be superior in a softbox and not create hotspots as the SB800 would. So of course I had to try that, both at full power and minimum aperture to see how the softbox looked from the front. I’m afraid the SB800 wins again. After that I put it up against the Godox E300 and gave the E300 a 1 stop disadvantage to even things out a bit - the results weren’t substantially different but the K-150A was still weaker.

softbox hotspots.jpg

While I had things set up I decided to do a few more tests with some fresnel lenses I bought. I’ve been thinking about how to focus the flash for when you are shooting in bright sunlight from a distance and diffusion isn’t practical - you may as well get as much power as possible focussed on the subject. Here are the two fresnel lenses, a rectangular sheet and a nice round lens. They were $3 and $7 respectively.

fresnel sheet.jpg

It’s not so much the shape of the lenses, rather the fact that they were different focal lengths that gives the different patterns. The round one had a 55mm focal length and the rectangular one is only advertised as “3.5X magnification” they don’t mention actual focal length but you can get the same results from either based on how far from the flash you hold them..

round fresnel.jpg

I held this round lens right up against the front of the reflector. I think it has real potential in outdoor shoots.