Will a Yongnuo 622 work as slave for a.Canon Speedlite 600ex-rt.

[Loelke]

Canon 450D

[Skirball]

The YN-622 is a trigger, not a flash.  You probably know that, but the term "slave" refers to a flash being controlled by another flash.

If you're asking 'can the 622 trigger my 600ex-rt remotely using eTTL', then the answer is yes.  But you won't be able to use the on-camera menu that the 600ex-rt has.

Do you already own the 600ex, or are you looking at buying one?

[Loelke]

A Canon Speedlite 600ex-rt was delivered today,

My question is can the RT mounted on the camera trigger each section of the Nongnuo 622 which would cause the flash mounted on each section to flash. That way I could fire three flashes, the 600ex and maybe two Canon 270's,

[Skirball]

No, it can't do that.

[Skirball]

Not to rain on your parade, but if you just got the 600ex today, then perhaps you're still in a return period?

The only reason to get the 600ex, is if you plan on getting several more (read: investing a couple thousand in flashes).  The radio triggers only work with each other, or the ST-E3.  I'm not going to discuss forward compatibility, that's a weak argument.

Since you mention combining them with 270s it makes me think it's way overkill for your use.  With the cost of a 600ex you could get a whole off-camera setup.  I would recommend one Canon 430exII, and either some Yongnuo 565 if you need a full eTTL setup, or the 560 III with the built in radio triggers if you are ok using manual flash (you would still have the 430exII for on-camera eTTL when needed).  Then depending on your entended use just get an RD-602 trigger ($25) for manual triggers, or you'll need a 622 for each flash.

[Loelke]

Well I also purchased a Canon 270ex-ii. I showed my wife the 2 units (600ex-rt and the 270ex-ii. I want the 600, but my wife said it was too big and heavy
She also said she would never learn (or want to learn how to use a 600ex-rt.). Since we've been married 44 years I know when to surrender. My white flag is up.I want the power of the 600, but I have to wait. I'll return the 600 to Amazon unless I can convince her otherwise. Thanks for all your help. I want to get into multiple flashes with diffusion covers.

[Skirball]

Again, I question why you want the 600.  Unless you have multiple 600s the advantage over other flashes is minimal.  The 580ex, for example, is almost as strong, shoots almost as far.  The Yongnuo generics like the 568 and 560 are as strong as the Canon 580ex, and a fraction of the cost.  As far as "power", two cheapos through a diffuser will provide more power than a 600 can.

Don't get me wrong, the 600ex is a great flash, and as a “strobist” I welcome radio technology being incorporated directly into flash (ahem, and camera).  But right now it’s fledgling technology (the incorporation, not the technology) so you pay a premium for it.  You can do the same for less using third party options.  But I wouldn’t recommend getting the 600 unless you know what it does that the other cannot.  Otherwise there’s a good chance you’re paying for technology you’re not going to use.

[TCampbell]

I would generally disagree with this... and I've owned a lot of flashes -- manual and automatic alike.

Do Yongnuo flashes work?  Yes they work.

Are they as good as the Canon flashes you might compare them to?  No... not even close. 

It's sort of like asking if a Yugo is as good as a Cadillac.  Well... they both have 4 wheels and an engine and "usually" the Yugo will get you from point a to point b without breaking down and leaving you stranded, but let's face it... these cars are not even remotely in the same class.  And if it's actually important that your transportation be reliable... well you might want to make sure you have a back-up plan.

When Canon introduced the 600EX-RT, they discontinued the 580EX II.  It may be difficult to find a new 580EX II.

A "new" 600EX-RT is currently going for about $500.  I shopped around for a "new" 580EX II.  The major sellers (B&H and Adorama) don't have them anymore.  I was able to find a couple of Amazon.com (really a marketplace seller -- not sold by Amazon directly) and the Amazon seller wanted $699 (wow!)

The 600EX-RT has come down in price to where the official list price is $550, but the street price is currently about $50 better than that and that's on-part with what you used to have to pay for a 580EX II (maybe fractionally higher).  But considering how much a decent radio trigger costs (especially a radio trigger that can do E-TTL), that's actually a good price.  

The 600EX-RT is the most versatile flash product I've ever used and, regardless of how complicated it looks, it actually a lot easier to use then one might expect.

There's a button that cycles through it's modes... one button access, no digging through menus or press-and-hold button combinations like the older flashes had.  Each time you poke it, it switches to the next mode.  The modes are standalone flash, radio flash as a master, radio flash as a slave, optical flash as a master, or optical flash as a slave.  The screen changes colors to indicate if the flash is master or slave, and if you're using radio mode then you get a green "Link" light to confirm that master and slaves are all talking.  

The first two digits of Canon's speedlight model number indicate the "guide number" of the flash as measured in meters.  So a 270EX II has a guide number of 27 meters.  A 600EX-RT has a guide number of 60 meters.   The guide number is the distance the flash can provide adequate coverage to take an exposure assuming the ISO is 100 and the f-stop is set to f/1.0. Nobody makes an f/1.0 lens anymore (not that I'm aware) but the number is used because it's a baseline that makes the math easy to get to the ACTUAL distance you can use.  

Just divide the guide number by the f-stop you plan to use when shooting. E.g. shooting f/5.6 then you divide the guide number by 5.6.  So 60 ÷ 5.6 = 10.7 meters (about 35 feet).  

Most diffusers tend to eat about 1 full stop worth of light (but you'd really need to test the diffuser).  1 full stops means you divide by 1.4 (the rounded off value for the square root of 2).  So 35 feet becomes about 25 feet.  

Want to bounce that flash off the ceiling?  That's going to not only increase the distance for the light path, but the reflectivity of the ceiling is going to come into play and that will eat even more light.  

So while that 600 sounds really power, you can quickly see the power getting eaten away by light modifiers, bouncing, etc.

To be fair, you can bump up the ISO (each "full" stop of ISO means you get to multiply the distance by 1.4 rather than dividing by 1.4).  

You can quickly imagine how the 270EX II isn't going to work in many of these situations.  I own a 270 but I use it with my PowerShot G series and I'm very careful to be aware of it's power limits.  I mostly use it as outdoor fill flash (where I want the flash compensation set to -1 stop of power anyway) and/or if I'm indoors I keep the subjects close.  (I also own the 430EX II)

But it's not just the power level difference... the 600EX-RT is _vastly_ more full featured.  It works statalone or as a master or slave.  It works via optical or radio (in addition to wired of course).  I supports mulit-strobic mode, 2nd curtain mode, hi-speed sync mode, it can be clustered with up to 15 flashes.  It's weather sealed.  It can accept external battery power (it can even divide the power so that the internal batteries operate the electronics but the external battery pack fires the light).  It has the focus-assist beam for focusing in the dark.  You can configure it to control remote speedlights without actually flashing itself. You can even use it as a remote firing trigger or to remote fire other cameras (e.g. I can take a photo with my camera and speedlite and configure it so that once it fires, it also fires one of my other cameras and flashes -- btw this is configured to have a very slight firing delay which is deliberate so that the two cameras' lighting don't interfere with each other.)

BTW, real world testing on the Yongnuo YN-560 consistently show it to be weaker than what Yongnuo claims.  It's actually much closer (nearly identical actually) to the Canon 430EX II.

Every time I do a thorough investigation into 3rd party low-cost flashes I find that they lack a lot of the features that the Canon flashes have ... and once I get a 3rd party flash that comes close to matching what Canon offers, the 3rd party flash's price tag _also_ comes close to matching Canon's price tag (you might save $50 -- for me the assured full compatibility and support are worth more than $50.)

The YN-560 doesn't support E-TTL.  The YN565 does support E-TTL but only as a slave and with limited functionality.  It doesn't support high-speed sync (which can be a deal killer.)  This is where I mentioned that once I did thorough enough reviews on a flash I found that they didn't come close to matching the features of the Canon flash that you might think they compete with (they really don't compete at all.)  

The YN-565 is NOT like own a 580EX II... it's not even close.  In terms of power, it's almost identical in power output to the 430EX II... but it's not equivalent in build quality or features (the 430EX II is actually much better.  A 430EX II actually does high-speed sync.)

I learned years ago that it's better to buy the product you're only going to buy ONCE because it's DURABLE and RELIABLE. Buying "cheap" and then replacing, and then replacing the replacement, etc. etc. is not actually a savings. 

[ScottyP]

TCampbell has very good info and has a good point about the risk in buying less than the very best of everything, but:

1.). The OP seems like a hobby shooter not a paid pro, so the consequence of a flash failing is not exactly dire.
2.). There is no mention of budget for flash. If the OP does not have over $1500 to spend, he will have to cut corners by getting fewer units. Perhaps he would do better to go Strobist and use multiple manual flashes and triggers so he can have 3 or more units for cheap.
3.). Even if he does have a high enough budget to get 3 600's or two plus the Canon trigger, perhaps that is not the best bang for his upgrade buck. What lenses does he have? He might see better overall results going for cheap flashes and triggers to save money to add a good lens and light stands, umbrellas, etc.