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Canon "Digital Rebel" bodies, live-view, flash

 
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Charles Krebs



Joined: 01 Aug 2006
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Location: Issaquah, WA USA

PostPosted: Tue Dec 29, 2015 5:10 pm    Post subject: Canon "Digital Rebel" bodies, live-view, flash Reply with quote

In another thread John ("dolmadis") posed a question:

Quote:
If a radio transceiver is not deployed then what would you recommend as the best "workflow/camera/flash set up" for the Digital Rebel cameras (T3i, T4i...) please with a single or multiple non-Canon flash units?

I didn't want to steer the other thread too far away from it's subject so here's an answer as a new topic.
(Note: My experience with this series of bodies is limited to the T3i, but I believe the situation is the same with other models)

With the "Digital Rebels" and flash there are basically two situations... one with "live-view" on, a second with live-view off.

With live-view on, the camera will not give a flash sync signal unless it senses a Canon (or Canon dedicated flash) attached and powered on, or, the built in flash is up and recycled. The work-around I use if I need to use flash from live view is to have one of my "official" Canon flashes connected to the camera via a remote flash cord with the flash positioned off to the side on a stand or sitting on the table. It is set to manual, either 1/64 or 1/128 power (with these external flash unit on “manual” there is no troublesome metering pre-flash, so basic optical slaves can be used). The flash units actually used to light the subject are then triggered by optical slaves (either ones built into the flash as with most Yougnuo units and some others, or with inexpensive eBay "hot-shoe" units). Unfortunately the built in flash with these cameras can't be set to a useful manual mode. Otherwise it would be a simple matter to set the in-camera flash to a low power manual setting to trip external flashes optically.

(BTW... some optical slaves are less sensitive than others. I know the one built into the first Yongnuo 460 flashes were not very sensitive (560’s are much more sensitive), so if you use this external manual flash technique you may need to adjust flash power setting and positioning until you get reliable triggering.

You can make use of the built-in flash, but no matter what settings you use there is always a metering pre-flash before the main flash. This will can fool many optical slave units (although some slave units and some of the the Yongnuo flashes have two optical slave positions... one that "ignores" the pre-flash). Because of the nature of the high magnification set-ups we typically use here, the internal flash will generally go off at full power. This will really drain the battery quickly and cause about a 3 second delay between shots waiting for recycle. Even though I use an AC power supply for the camera and the battery is not an issue, I don’t work this way since I already had a large Canon flash to set up on "manual" as described above. If you already have slaved flash units that will ignore the “pre-flash” and have an AC power adapter (or lots of batteries) It could be worth exploring further if you do not already have a separate Canon flash that can be set to low manual power settings. I would probably be a little leery of using it for very long stacks until it was ascertained that there was no real heat issue from such constant use. Most of the time you will want to scrim out the light from adding to your actual subject lighting.

When live-view if off, there is no real problem. A flash sync signal is given with each exposure. So you can “tap into” the camera hot-shoe in a variety of ways to trip flash units. I still use mirror lock-up so that two shutter "presses" are required... the first to lift the mirror and the second to take the picture. (Even though it's a flash exposure, I feel that anything I can do to reduce vibration, especially mirror movement is desirable.)
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dolmadis



Joined: 07 Dec 2011
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PostPosted: Wed Dec 30, 2015 3:27 am    Post subject: Reply with quote

Hi Charles

Thanks for your post in a new thread in answer to my question.

As you might have guessed I am new to twin flash off camera options and intend to go for manual units which by way of cost I will go for non Canon flash units as often suggested in posts.

I have a T4i (650D) which has the "Easy Wireless Flash" option. I have been searching on Google for further definitive information on this because it was intimated in a YouTube "tutorial" that the optical trigger flash via "Easy Wireless Flash" was just a single lower powered communication flash. But I cannot confirm that which would help, I assume, with the battery drain issue on the camera.

If it were not a single flash trigger then a mode to ignore the "pre-flash" would be necessary as you say.

I was hoping to hear that the inexpensive Yongnuo 602 wireless triggers (three for 2 main flash units plus camera) might give me a viable option with the T4i but I am not sure of that when you mention the Yongnuo 622C instead.

Is it that the Yongnuo 602 would not be recognised by the T4i and fail to fire?

Or is it that the Yongnuo 622C will give "Live View" which the Yongnuo 602 will not?

In my learning mode I was interested to see that you also deploy "mirror lock-up" but again I am a little confused because I had discounted that because I thought that this setting had to be re-set at each shutter release. Is there a way on the Rebels to set "mirror lock-up" as on always until re-set?

Lastly I like your work around of using an official Canon flash unit. Presumably the least expensive, non ETTL, good used unit from the compatible T4i list would do?

Many thanks for your help.

Regards


John
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Pau
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PostPosted: Wed Dec 30, 2015 5:12 am    Post subject: Reply with quote

With my 7D I can set the built in flash to manual mode and it doesn't fire preflash. I also can regulate its power (both on the camera or through Canon Utility when tethered to the computer). It is also able to control external EX compatible flashguns, I've done it despite I prefer to use a dedicated flash cord.
Quote:
You can make use of the built-in flash, but no matter what settings you use there is always a metering pre-flash before the main flash.

Charles says that his T3i doesn't allow for it, but being yours a newer body able to control external flashes you can look at the user manual if it is capable to do it.

I have a Yongnuo 565EX and it is powerful, inexpensive (form China) and fully compatible with all Canon dedicated functions, with the only exception of fine tunning the color temperature only present in most modern Canon units. It can be fully controlled by the built in flash or just fired as manual slave by any flash.
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dolmadis



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PostPosted: Wed Dec 30, 2015 5:25 am    Post subject: Reply with quote

Thanks Pau.

I am specifically interested in the capabilities of the Canon "Digital Rebel" series because I was aware that the series including the 7D is different in terms of functionality.

My manual lists the the "Easy Wireless Flash" option but it does not answer the questions that I have posed about single flash and reduced power in what I call the external optical trigger mode using the built in flash.

I was wondering whether other members with the 650D T4i might know from their hands on experience.

Likewise with the Yongnuo 622C as Charles suggested.

Thank you again.

Regards


John
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dolmadis



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PostPosted: Wed Dec 30, 2015 6:03 am    Post subject: Reply with quote

dolmadis wrote:
My manual lists the the "Easy Wireless Flash" option but it does not answer the questions that I have posed about single flash and reduced power in what I call the external optical trigger mode using the built in flash.


Actually on Page 228 of the 650D T4i Manual there is a helpful footnote for me.

"Even though the firing of the built-in flash is disabled when [EasyWireless] is set, it will still fire a small flash to control the slave unit."

So that answers my own first question I think because I presume that this will limit the camera battery drain.

So I am left with the question on the Yongnuo 622C and whether it permits "Live View" and how to set "Mirror Lock-up" for all shutter releases in a stacking sequence.



John
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Pau
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PostPosted: Wed Dec 30, 2015 6:33 am    Post subject: Reply with quote

Charles, do Rebel type bodies allow for mirror lock up?

After a quick look at the Yongnuo 622C manual, it is full compatible with Canon EX functions so it will fire the slave units wirelessly wile the camera is in LV, but of course cycling the mirror and shutter to provide sync signal so effectively disabling EFSC to take the picture, the same than with a EX compatible flash at the hot shoe or the built in one.

Quote:
"Even though the firing of the built-in flash is disabled when
[EasyWireless] is set, it will still fire a small flash to control the slave unit."

This is to transmit info and tigger signal to the slave units, the actual preflash to calculate the expossure if in ETTL mode will be provided by those units.

Although a radiofrequency tigger is more powerful and flexible and it works at longer distances I think you don't need it just to tigger one or two close flasguns for macro, just profit the camera functions.
For one unit I find a ETTL cord that costs about nothing from China the most reliable and simpler solution.
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dolmadis



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PostPosted: Wed Dec 30, 2015 7:03 am    Post subject: Reply with quote

Pau wrote:
Charles, do Rebel type bodies allow for mirror lock up?


Does this mean that it is enabled for all exposures until disabled?

Did I misinterpret this the first time round?

"Mirror lockup is enabled by setting [5: Mirror lockup] to [1: Enable]
in the [54: Custom Functions (C.Fn)] (p.296)."

Many thanks to both Pau and Charles for the help given but will naturally await any further observations on the thread.

Regards

John
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Pau
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PostPosted: Wed Dec 30, 2015 7:13 am    Post subject: Reply with quote

John,

I only use 7D and sometimes 6D and wasn't aware of that feature in Rebel bodies, in fact I was convinced that it was not bundled because they have a single motor to move the mirror and shutter and they need to cycle the mirror between exposures, but of course they can lock up the mirror before opening the shutter like in some film SLRs (XD and XXD series have two motors and they don't need to move the mirror but for ETTL flash)
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ChrisR
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PostPosted: Wed Dec 30, 2015 7:20 am    Post subject: Reply with quote

Yes, T3i mirror lockup available using two "button presses".
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Charles Krebs



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PostPosted: Wed Dec 30, 2015 11:49 am    Post subject: Reply with quote

With the "Digital Rebels" you do have a custom function that sets mirror lock-up on for every exposure until you turn it off (obviously it does noting when shooting from live-view as the mirror is already up).

I am pretty sure that the "Easy Wireless Flash" option (which I have on the T3i as well) is only useful with Canon flash units that has the Canon proprietary wireless capability. I have tried it in the past to no avail with slaved non-Canon flashes. (I'll take another look tonight but I don't think it is the solution we're looking for.

The Yongnuo 602's are very good (and cheap!) but will not work from live-view (I have them and use them for non live-view flash.). The camera/flash transmitter electronics are very basic. As a result the camera does not "know" that there is something attached so it and performs as usual in live-view (no flash sync signal given).

While I have not used a 622C it does mimic electronically a high end dedicated Canon ETTL flash and as such should make the camera go into the mode where is does provide a sync signal. I've never seen anyone address this directly, but have read some anecdotal usage references that make me think this is a real possibility. I too would like to know for sure.
Quote:

Lastly I like your work around of using an official Canon flash unit. Presumably the least expensive, non ETTL, good used unit from the compatible T4i list would do?
You do want one that permits a manual operation with settable power levels (not all do, typically the most basic ones do not have this capability). Otherwise (with ETTL only) you still have a pre-flash and will get a full power flash killing batteries rapidly,

I don't know how you are set up to work. If you really need to shoot flash from live view then this conversation it pertinent. If you only need live-view for the composing and initial focus stages, but can shoot the stack with live-view turned off, then I think using mirror lockup and a simple flash "connection" is the way to go. If you can shoot with live-view off, the basic Yongnuo 602's are an inexpensive effective way to go. If you don't already have any flash unit and are looking to get some, even better would be the YN560TX with a couple of the YN560 III or IV flash units.
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dolmadis



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PostPosted: Wed Dec 30, 2015 12:31 pm    Post subject: Reply with quote

Hi Charles

Many thanks for the specific clarifications and confirmation together with a useful overview.

It was made known by my family to a close relative that I might like flash to add to my photographic macro interests.

As a thoughtful seasonal gift from a non technical relative I now have on the way two NEEWER TT660's hence the desire to quickly, and as certainly as possible, deploy these !!

Far from expensive online, manual but with a few useful modes and power.

I like using Live View so I went to that function first to see "what could be what" but it is not essential and I could, I think, easily use the Yongnuo 602's as a starter with them.

If there is any reason not to do this I would apopreciate an early "holler".

Regards


John
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