580 exII flash is weak at 1/1 compared to yongnuo 560 IV

[Nates96]

Hello,

I recently decided to pick up a used canon 580 EX II, and I am having trouble with the power output of the flash. I got the unit from Adorama and I am kind of assuming they have some sort of quality control testing on their units. However, when firing the flash on full power I have noticed that it is MUCH weaker than my $70 yongnuo 560 IV. I have checked that I am using fully charged eneloop batteries on both units, each on the same manual settings (no high speed sync), and each being triggered by yongnuo triggers, and am getting drastically different results.

At powers below 1/8, the two flash's match power quite accurately, but anything above that and the canon just doesnt seem to be able to output anything more. I have attached a picture of both flashes firing at full power with a zoom of 105mm, and at the same distance and height from the wall. The yongnuo 560 IV is on the left of the frame and the canon 580 ex ii is on the right. The exposure is F22 at a shutter speed of 1/200 with an ISO of 100. 

If anyone has any ideas as to how I can resolve this, I would greatly appreciate it! I have done some research and suspect it could be an old tube light, but I am unsure.

Thanks!!

[ScottyP]

I'm not sure if this is nonsense or what, but I have read that if you don't use a flash regularly, "changes" occur in the flash tube. They suggest you not let them sit more than a few months without popping a few flashes. Maybe at some point in its life this used unit was not fired in a long time. 

[Nates96]

Thanks for the relpy, ScottyP!

It could be possible! If so, do you recommend I try to do the replacement on my own or send it to Canon to do it? I don't believe there is a warranty on it because I bought it used.

Thanks again!

[ScottyP]

F

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@Nates96 wrote:

Thanks for the relpy, ScottyP!

It could be possible! If so, do you recommend I try to do the replacement on my own or send it to Canon to do it? I don't believe there is a warranty on it because I bought it used.

Thanks again!

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I personally have never done it but I might if I had an older flash that I didn't pay a lot for that wasn't working.  In case I screwed it up. 

I watched a YouTube video and a guy did it in 12 minutes. It did involve cutting tiny wires and soldering the new tube in. Not a screw in or clip in kind of deal. 

In ETTL I suppose the flash will just power up to compensate for the dimmer output, at least as best as it can?  Is it usable?  

Is it still returnable?

[diverhank]

Look like we're making the assumption that's there's something wrong with the 580.  Too bad there's no way to tell if the 580EXII is putting out the light output per spec and the Yongnuo just put out more beyond spec...

I once tested the flash output between the Canon 600EX-RT I and the Yongnuo YN600EX-RT using a flash meter and found that the Yongnuo consistently outperforms the Canon by almost one stop in any manual setting.  

[RobertTheFat]

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@ScottyP wrote:

I'm not sure if this is nonsense or what, but I have read that if you don't use a flash regularly, "changes" occur in the flash tube. They suggest you not let them sit more than a few months without popping a few flashes. Maybe at some point in its life this used unit was not fired in a long time. 

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"Changes in the flash tube" is an explanation I've never heard. But it is plausible that if the unit hasn't been used in a few years, it may be necessary to re-form the capacitors. To do that, they tell you to turn the unit on and keep firing it every time the ready light comes on. After a while, the capacitors will start to recover their ability to gain and hold a charge. Whether that fix will affect the flash power or just the recycle time, I don't know. But if all else has failed (and it seems it has), then it should be worth a try.

[RobertTheFat]

Is it possible that the Canon is set to produce only the AF-assist pre-flash? The latter would be much weaker than a "real" flash and would probably be insensitive to the power level setting. If you can't find documentation of the settings that would cause that, try resetting the flash to factory settings and try again.

[Nates96]

Thanks for the thought, RobTheFat!

After looking into it and clearing my custom functions and resetting my external flash settings in my camera, I am still not getting any more power from the flash. From 1/8 power all the way to 1/1 power are the exact same flash output on the histogram, and toggling between the various settings doesn't seem to aid much.

Thanks though!

[RobertTheFat]

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@Nates96 wrote:

Thanks for the thought, RobTheFat!

After looking into it and clearing my custom functions and resetting my external flash settings in my camera, I am still not getting any more power from the flash. From 1/8 power all the way to 1/1 power are the exact same flash output on the histogram, and toggling between the various settings doesn't seem to aid much.

Thanks though!

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And the flash is set to manual mode (not TTL or ETTL), right?

[Nates96]

This is correct. Full manual, not in master mode.